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BACKGROUND: Despite enormous public sector expenditures, the effectiveness of universal coverage for health care in reducing socioeconomic disparities in health has received little attention. STUDY OBJECTIVE:s: To evaluate whether universal coverage for health care reduces socioeconomic disparities in health. DESIGN: Information on participants of the 1990 Nova Scotia Nutrition Survey was linked with eight years of administrative health services data and mortality. The authors first examined whether lower socioeconomic groups use more health services, as would be expected given their poorer health status. They then investigated to what extent differential use of health services modifies socioeconomic disparities in mortality. Finally, the authors evaluated health services use in the last years of life when health is poor regardless of a person's socioeconomic background. SETTING: The Canadian province of Nova Scotia, which provides universal health care coverage to all residents. PARTICIPANTS: 1816 non-institutionalised adults, aged 18-75 years, from a two stage cluster sample stratified by age, gender, and region. Main results: People with lower socioeconomic background used comparatively more family physician and hospital services, in such a way as to ameliorate the socioeconomic differences in mortality. In contrast, specialist services were comparatively underused by people in lower socioeconomic groups. In the last three years of life, use of specialist services was significantly higher in the highest income group. CONCLUSIONS: Universal coverage of family physician and hospital services ameliorate the socioeconomic differences in mortality. However, specialist services are underused in lower socioeconomic groups, bearing the potential to widen the socioeconomic gap in health. [ABSTRACT FROM AUTHOR]

Objective: To measure family practice patients' adherence to statin medications and to identify factors associated with adherence to these medications.Design: Cross-sectional study using a mailed self-report survey sent to 400 patients.Setting: Two academic family practice clinics in Halifax, NS.Participants: A total of 284 patients aged 40 or older who were prescribed statin medications by their family physicians, either for the first time or as a renewal during a 20-month period.Main Outcome Measures: Level of adherence to statin medications as measured by patients' self-report on the Morisky scale; association between high adherence on the Morisky scale and 38 patient-reported factors.Results: Response rate was 82.5%. Average age of patients was 65 years, 57% were men, 62% had been on statin medications for more than 2 years, and 97% reported that their family physicians managed their cholesterol levels. More than 63% of patients reported high adherence as measured by the Morisky scale. On multiple logistic regression, being older than 65, taking 4 to 6 other prescribed medications, and having a lifestyle that included regular exercise or a healthy diet were significant independent predictors of high adherence scores on the Morisky scale.Conclusion: Almost two-thirds (63%) of patients who were prescribed statins by their family physicians reported high adherence to the medications. Strategies to improve adherence would best be directed at patients who are younger or taking fewer than 4 or more than 6 other prescribed medications. Patients should be encouraged to maintain a lifestyle of regular exercise and a healthy diet, as this was associated with better adherence to statin medications. [ABSTRACT FROM AUTHOR]

Cross-linking strategies have found wide applications in chemical biology, enabling the labeling of biomolecules and monitoring of protein-protein interactions. Nitrone exhibits remarkable versatility and applicability in bioorthogonal labeling due to its high reactivity with strained alkynes via the strain-promoted alkyne-nitrone cycloaddition (SPANC) reaction. In this work, four cyclometalated iridium(III) polypyridine complexes functionalized with two nitrone units were designed as novel phosphorogenic bioorthogonal reagents for bioimaging and phototherapeutics. The complexes showed efficient emission quenching, which is attributed to an efficient nonradiative decay pathway via the low-lying T 1 /S 0 minimum energy crossing point (MECP), as revealed by computational studies. However, the complexes displayed significant emission enhancement and lifetime extension upon reaction with (1 R ,8 S ,9 s )-bicyclo[6.1.0]non-4-yne (BCN) derivatives. In particular, they showed a remarkably higher reaction rate toward a bis -cyclooctyne derivative ( bis -BCN) compared with its monomeric counterpart ( mono -BCN). Live-cell imaging and (photo)cytotoxicity studies revealed higher photocytotoxicity in bis -BCN-pretreated cells, which is ascribed to the enhanced singlet oxygen ( 1 O 2 ) photosensitization resulting from the elimination of the nitrone-associated quenching pathway. Importantly, the cross-linking properties and enhanced reactivity of the complexes make them highly promising candidates for the development of hydrogels and stapled/cyclized peptides, offering intriguing photophysical, photochemical, and biological properties. Notably, a nanosized hydrogel ( 2-gel ) demonstrated potential as a drug delivery system, while a stapled peptide ( 2- bis -pDIKK ) exhibited p53-Mdm2 inhibitory activity related to apoptosis and a cyclized peptide ( 2- bis -RGD ) showed cancer selectivity.

The dual functionality of 1,2,4,5-tetrazine as a bioorthogonal reactive unit and a luminescence quencher has shaped tetrazine-based probes as attractive candidates for luminogenic labeling of biomolecules in living systems. In this work, three cyclometalated iridium(III) complexes featuring two tetrazine units were synthesized and characterized. Upon photoexcitation, the complexes were non-emissive but displayed up to 3900-fold emission enhancement upon the inverse electron-demand Diels-Alder (IEDDA) [4+2] cycloaddition with (1R,8S,9s)-bicyclo[6.1.0]non-4-yne (BCN) substrates. The rapid reaction kinetics (k 2 up to 1.47×10 4  M -1  s -1 ) of the complexes toward BCN substrates allowed effective peptide labeling. The complexes were also applied as live cell bioimaging reagents and photocytotoxic agents. One of the complexes was utilized in the preparation of luminescent nanosized hydrogels that exhibited interesting cargo delivery properties., (© 2022 Wiley-VCH GmbH.)

Background: Predicting relapses of post-operative complications in obese patients who undergo cardiac surgery is significantly complicated by persistent metabolic maladaptation associated with obesity. Despite studies supporting the linkages of increased systemic branched-chain amino acids (BCAAs) driving the pathogenesis of obesity, metabolome wide studies have either supported or challenged association of circulating BCAAs with cardiovascular diseases (CVDs). Objective: We interrogated whether BCAA catabolic changes precipitated by obesity in the heart and adipose tissue can be reliable prognosticators of adverse outcomes following cardiac surgery. Our study specifically clarified the correlation between BCAA catabolizing enzymes, cellular BCAAs and branched-chain keto acids (BCKAs) with the severity of cardiometabolic outcomes in obese patients pre and post cardiac surgery. Methods: Male and female patients of ages between 44 and 75 were stratified across different body mass index (BMI) (non-obese = 17, pre-obese = 19, obese class I = 14, class II = 17, class III = 12) and blood, atrial appendage (AA), and subcutaneous adipose tissue (SAT) collected during cardiac surgery. Plasma and intracellular BCAAs and BC ketoacids (BCKAs), tissue mRNA and protein expression and activity of BCAA catabolizing enzymes were assessed and correlated with clinical parameters. Results: Intramyocellular, but not systemic, BCAAs increased with BMI in cardiac surgery patients. In SAT, from class III obese patients, mRNA and protein expression of BCAA catabolic enzymes and BCKA dehydrogenase (BCKDH) enzyme activity was decreased. Within AA, a concomitant increase in mRNA levels of BCAA metabolizing enzymes was observed, independent of changes in BCKDH protein expression or activity. BMI, indices of tissue dysfunction and duration of hospital stay following surgery correlated with BCAA metabolizing enzyme expression and metabolite levels in AA and SAT. Conclusion: This study proposes that in a setting of obesity, dysregulated BCAA catabolism could be an effective surrogate to determine cardiac surgery outcomes and plausibly predict premature re-hospitalization., (Copyright © 2020 Biswas, Tozer, Dao, Perez, Mercer, Brown, Hossain, Yip, Aguiar, Motawea, Brunt, Shea, Legare, Hassan, Kienesberger and Pulinilkunnil.)

This communication reports novel luminescent rhenium(I)-polypyridine complexes appended with a perylene diimide (PDI) or benzoperylene monoimide (BPMI) moiety through a non-conjugated linker. The photophysical and photochemical properties originating from the interactions of the metal polypyridine and perylene units were exploited to afford new cellular reagents with thiol-sensing capability and excellent photocytotoxic activity., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Transcatheter aortic valve implantation (TAVI) is evolving rapidly and is increasingly being adopted in the treatment of aortic valve disease. The goal of this study was to examine regional differences in surgical aortic valve replacement (SAVR) and TAVI across Atlantic Canada., Methods: We identified all patients who underwent SAVR or TAVI between Jan. 1, 2010, and Dec. 31, 2014, in New Brunswick, Nova Scotia and Newfoundland and Labrador. Data obtained included patient demographic characteristics and surgical procedure details. We performed univariate descriptive analyses and calculated crude and age- and sex-adjusted incidence rates., Results: A total of 3042 patients underwent SAVR or TAVI during the study period, 1491 in Nova Scotia, 1042 in New Brunswick and 509 in Newfoundland and Labrador. Patient demographic characteristics were similar across regions. A much higher proportion of patients in Newfoundland and Labrador (43.6%) than in Nova Scotia (4.2%) or New Brunswick (13.6%) received a mechanical versus a bioprosthetic valve. Rates of TAVI increased over the study period, with New Brunswick adopting their program before Nova Scotia (144 v. 74 procedures). Adjusted rates of all AVR procedures remained stable in Nova Scotia (40-50 per 100 000 people). Adjusted rates were lower in New Brunswick and Newfoundland and Labrador than in Nova Scotia; they increased slowly in New Brunswick over the study period., Conclusion: Despite geographical proximity and similar patient demographic characteristics, there existed regional differences in the management of aortic valve disease within Atlantic Canada. Further study is required to determine whether the observed differences in age- and sex-adjusted rates of AVR may be explained by geographical disease-related differences, varying practice patterns or barriers in access to care.

Background: Invasive cardiac care is the preferred method of treatment for patients with acute coronary syndromes (ACS) complicated by cardiogenic shock (CS). In Nova Scotia, invasive cardiac care is only available in Halifax at the Queen Elizabeth II Health Sciences Centre (QEII-HSC)., Methods: All consecutive patients diagnosed with ACS and CS in 2009-2013 in Nova Scotia were included. Data were obtained from the clinical database of Cardiovascular Health Nova Scotia. The primary outcome was in-hospital mortality., Results: A total of 418 patients with ACS and CS were admitted to the hospital. Access to invasive care was limited to 309 (73.9%) of these patients. For those who presented elsewhere in the province, 64.2% were transferred to the QEII-HSC. The mortality rate among the 309 patients with access to invasive care was significantly lower than that among the 109 patients who did not have access (41.7% vs 83.5%; P < 0.0001). Unadjusted mortality was lowest among patients undergoing primary percutaneous coronary intervention (33.1%). After adjustment for clinical differences, access to cardiac catheterization remained an independent predictor of survival (odds ratio, 0.2; 95% confidence interval, 0.11-0.36). Heat map analysis revealed that access was lowest in regions furthest from Halifax., Conclusions: ACS complicated by CS has a high mortality rate. We demonstrate that access to health care centres offering cardiac catheterization is independently associated with survival, and public health initiatives that improve access should be considered. Patients presenting furthest from Halifax were the least likely to be transferred, suggesting that geography remains an important barrier to livesaving care., (Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Background: Lysophosphatidic acid (LPA) receptor signaling has been implicated in cardiovascular and obesity-related metabolic disease. However, the distribution and regulation of LPA receptors in the myocardium and adipose tissue remain unclear., Objectives: This study aimed to characterize the mRNA expression of LPA receptors (LPA1-6) in the murine and human myocardium and adipose tissue, and its regulation in response to obesity., Methods: LPA receptor mRNA levels were determined by qPCR in i) heart ventricles, isolated cardiomyocytes, and perigonadal adipose tissue from chow or high fat-high sucrose (HFHS)-fed male C57BL/6 mice, ii) 3T3-L1 adipocytes and HL-1 cardiomyocytes under conditions mimicking gluco/lipotoxicity, and iii) human atrial and subcutaneous adipose tissue from non-obese, pre-obese, and obese cardiac surgery patients., Results: LPA1-6 were expressed in myocardium and white adipose tissue from mice and humans, except for LPA3, which was undetectable in murine adipocytes and human adipose tissue. Obesity was associated with increased LPA4, LPA5 and/or LPA6 levels in mice ventricles and cardiomyocytes, HL-1 cells exposed to high palmitate, and human atrial tissue. LPA4 and LPA5 mRNA levels in human atrial tissue correlated with measures of obesity. LPA5 mRNA levels were increased in HFHS-fed mice and insulin resistant adipocytes, yet were reduced in adipose tissue from obese patients. LPA4, LPA5, and LPA6 mRNA levels in human adipose tissue were negatively associated with measures of obesity and cardiac surgery outcomes. This study suggests that obesity leads to marked changes in LPA receptor expression in the murine and human heart and white adipose tissue that may alter LPA receptor signaling during obesity.

Background: Much has been published about the effect of obesity on adverse outcomes after cardiac operations, yet little is known regarding the effect of obesity on intensive care unit (ICU) resource utilization. This study examined the effect of obesity on ICU resource utilization after cardiac operations., Methods: All patients with a body mass index (BMI) of 18.5 kg/m 2 or higher who underwent a cardiac surgical procedure between 2006 and 2013 were stratified into the following weight categories: normal (BMI 18.5 to 24.99 kg/m 2 ), preobese (BMI 25 to 29.99 kg/m 2 ), obese class I (BMI 30 to 34.99 kg/m 2 ), obese class II (BMI 35 to 39.99 kg/m 2 ), and obese class III (BMI ≥40 kg/m 2 ). Comparisons between weight categories were done, and the risk-adjusted effect of weight category on prolonged ICU stay, prolonged ventilation, and ICU readmission was determined., Results: Of the 5,365 included patients, 1,948 were obese. Patients with greater obesity experienced longer ICU time, longer ventilation time, and increased ICU readmission. After adjustment, increasing obesity remained independently associated with greater likelihood of prolonged ICU stay (obese class II: odds ratio [OR], 2.4; 95% confidence interval [CI], 1.55 to 3.61; obese class III: OR, 4.1; 95% CI, 2.38 to 7.05), prolonged ventilation (obese class III: OR, 3.4; 95% CI, 1.57 to 7.22), and ICU readmission (obese class II: OR, 3.0; 95% CI, 1.70 to 5.31; obese class III: OR, 2.9; 95% CI, 1.32 to 6.36)., Conclusions: Increasing obesity was associated with a significant increase in ICU resource utilization after cardiac operations. Further study is needed to determine the mechanisms underlying this association and how the adverse effects of obesity may be mitigated., (Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

We report the synthesis, characterization, photophysical and electrochemical behaviour and biological labelling applications of new phosphorogenic bioorthogonal probes derived from iridium(III) polypyridine complexes containing a 1,2,4,5-tetrazine moiety. In contrast to common luminescent cyclometallated iridium(III) polypyridine complexes, these tetrazine complexes are almost non-emissive due to effective Förster resonance energy transfer (FRET) and/or photoinduced electron transfer (PET) from the excited iridium(III) polypyridine unit to the appended tetrazine moiety. However, they exhibited significant emission enhancement upon reacting with (1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH) (ca. 19.5-121.9 fold) and BCN-modified bovine serum albumin (BCN-BSA) (ca. 140.8-1133.7 fold) as a result of the conversion of the tetrazine unit to a non-quenching pyridazine derivative. The complexes were applied to image azide-modified glycans in live cells using a homobifunctional crosslinker, 1,13-bis((1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethyloxycarbonylamino)-4,7,10-trioxatridecane (bis-BCN)., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Evidence regarding the safety and efficacy of intraoperative cell salvage (ICS) in transfusion reduction during cardiac surgery remains conflicting. We sought to evaluate the impact of routine ICS on outcomes following cardiac surgery., Methods: We conducted a retrospective analysis of patients who underwent nonemergent, first-time cardiac surgery 18 months before and 18 months after the implementation of routine ICS. Perioperative transfusion rates, postoperative bleeding, clinical and hematological outcomes, and overall cost were examined. We used multivariable logistic regression modelling to determine the risk-adjusted effect of ICS on likelihood of perioperative transfusion., Results: A total of 389 patients formed the final study population (186 undergoing ICS and 203 controls). Patients undergoing ICS had significantly lower perioperative transfusion rates of packed red blood cells (pRBCs; 33.9% v. 45.3% p = 0.021), coagulation products (16.7% v. 32.5% p < 0.001) and any blood product (38.2% v. 52.7%, p = 0.004). Patients receiving ICS had decreased mediastinal drainage at 12 h (mean 320 [range 230-550] mL v. mean 400 [range 260-690] mL, p = 0.011) and increased postoperative hemoglobin (mean 104.7 ± 13.2 g/L v. 95.0 ± 11.9 g/L, p < 0.001). Following adjustment for other baseline and intraoperative covariates, ICS emerged as an independent predictor of lower perioperative transfusion rates of pRBCs (odds ratio [OR] 0.52, 95% confidence interval [CI] 0.31-0.87), coagulation products (OR 0.41, 95% CI 0.24-0.71) and any blood product (OR 0.47, 95% CI 0.29-0.77). Additionally, ICS was associated with a cost benefit of $116 per patient., Conclusion: Intraoperative cell salvage could represent a clinically cost-effective way of reducing transfusion rates in patients undergoing cardiac surgery. Further research on systematic ICS is required before recommending it for routine use.

Purpose of Review: Resting heart rate has long been thought to be a risk factor in cardiovascular disease and a prognostic factor in heart failure. β-Blockers were originally used in heart failure for their heart rate control abilities. However, they also have negative inotropic effects contributing to their overall benefit. The role of isolated heart rate modification is unclear in left ventricular systolic dysfunction., Recent Findings: Two recent studies looked at the heart rate-lowering effects of the If, or funny current inhibitor ivabradine and its potential role in heart failure therapy. At the doses chosen for the studies, ivabradine is presumed to have only effects on heart rate with no other cardiotropic effects. Thus, the cardiovascular outcome benefits are presumed to be secondary to heart rate modification., Summary: The two recent trials showed both heart rate and cardiovascular events to be significantly lower in the ivabradine-treated group of patients with left ventricular systolic dysfunction and initial heart rate at least 70 beats/min. However, neither of these trials proved causality. Hence, the link between heart rate and improved cardiovascular outcomes still remains muddled.

Background: Numerous studies have examined the effect of geographic place of residence on access to cardiovascular care, but few have examined their effect on outcomes after cardiac operations. This study examined the effect of geographic place of residence on in-hospital and 30-day outcomes after cardiac operations., Methods: We performed a retrospective analysis of all patients undergoing nonemergency cardiac operations at a single institution between April 2004 and March 2011. Geographic place of residence was defined as the driving distance from the patient's home to the tertiary cardiac care center divided into the following categories: 0 to 50 km, 50 to 100 km, 100 to 150 km, 150 to 200 km, 200 to 250 km, and more than 250 km. Multivariable logistic regression was used to determine the independent effect of driving distance on in-hospital and 30-day outcomes., Results: The final study population included 4,493 patients, of whom 3,897 (86.7%) had 30-day follow-up. After adjusting for differences among patient groups, no consistent relationship existed between distance and in-hospital outcomes. However, increased distance beyond 100 km was significantly associated with a greater risk of adverse outcomes at 30 days (0 to 50 km: referent; 50 to 100 km: odds ratio, 1.16 [95% confidence interval, 0.83 to 1.62]; 100 to 150 km: 1.32 [1.05 to 1.65], 150 to 200 km: 1.68 [1.33 to 2.11], 200 to 250 km: 1.41 [1.06 to 1.88], and >250 km: 1.30 [1.04 to 1.63])., Conclusions: Patients who live at an increased distance from the tertiary cardiac care center are more likely to have worse 30-day outcomes after cardiac operations. Further study is required to determine the mechanisms underlying this relationship and how such inequalities may be minimized., (Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

The synthesis, characterization, photophysics, lipophilicity, and cellular properties of new phosphorescent ruthenium(II) polypyridine complexes functionalized with a dibenzocyclooctyne (DIBO) or amine moiety [Ru(N^N)2 (L)](PF6 )2 are reported (L=4-(13-N-(3,4:7,8-dibenzocyclooctyne-5-oxycarbonyl) amino-4,7,10-trioxa-tridecanyl-aminocarbonyl-oxy-methyl)-4'-methyl-2,2'-bipyridine bpy-DIBO, N^N=2,2'-bipyridine bpy (1 a), 1,10-phenanthroline phen (2 a); L=4-(13-amino-4,7,10-trioxa-tridecanylaminocarbonyl-oxy-methyl)-4'-methyl-2,2'-bipyridine bpy-NH2 , N^N=bpy (1 b), phen (2 b)). The strain-promoted alkyne-azide cycloaddition (SPAAC) reaction of the DIBO complexes 1 a and 2 a with benzyl azide were studied. Also, the DIBO complexes 1 a and 2 a can selectively label N-azidoglycans located on the surface of CHO-K1 and A549 cells that were pretreated with 1,3,4,6-tetra-O-acetyl-N-azidoacetyl-D-mannosamine (Ac4 ManNAz). Additionally, the intracellular trafficking and localization of these biomolecules were monitored using laser-scanning confocal microscopy. Interestingly, the biolabeling and cellular uptake efficiency of the DIBO complexes 1 a and 2 a were cell-line dependent, as revealed by flow cytometry and ICP-MS. Furthermore, the complexes showed good biocompatibility toward the Ac4 ManNAz-pretreated cells in the dark, but exhibited photoinduced cytotoxicity due to the generation of singlet oxygen., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Objectives: Rates of perioperative transfusion vary widely among patients undergoing cardiac surgery. Few studies have examined factors beyond the clinical characteristics of the patients that may be responsible for such variation. The purpose of this study was to determine whether differing practice patterns had an impact on variation in perioperative transfusion at a single center., Methods: Patients who underwent cardiac surgery at a single center between 2004 and 2011 were considered. Comparisons were made between patients who had received a perioperative transfusion and those who had not from the clinical factors at baseline, intraoperative variables, and differing practice patterns, as defined by the surgeon, anesthesiologist, perfusionist, and the year in which the procedure was performed. The risk-adjusted effect of these factors on perioperative transfusion rates was determined using multivariable regression modeling techniques., Results: The study population comprised 4823 patients, of whom 1929 (40.0%) received a perioperative transfusion. Significant variation in perioperative transfusion rates was noted between surgeons (from 32.4% to 51.5%, P < .0001), anesthesiologists (from 34.4% to 51.9%, P < .0001) and across year (from 28.2% in 2004 to 48.8% in 2008, P < .0001). After adjustment for baseline and intraoperative variables, surgeon, anesthesiologist, and year of procedure were each found to be independent predictors of perioperative transfusion., Conclusions: Differing practice patterns contribute to significant variation in rates of perioperative transfusion within a single center. Strategies aimed at reducing overall transfusion rates must take into account such variability in practice patterns and account for nonclinical factors as well as known clinical predictors of blood transfusions., (Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Women undergoing coronary artery bypass grafting (CABG) are at increased risk for morbidity and mortality. Factors responsible for this observation include smaller coronary size and delayed presentation. To date, no studies have examined the effect of the degree of myocardium at risk (MAR) on the relationship between female sex and adverse postoperative events., Methods: Consecutive patients undergoing first-time isolated CABG at a single institution from 2002-2007 were identified. MAR was calculated using the weighted Duke Index and was categorized as low, moderate, or high. Multivariable logistic regression models were created to compare the impact of MAR on adverse clinical events., Results: We identified 3741 patients, 3325 (89%) of whom had complete angiographic data. Women (n = 755) were older (P = 0.0001) and presented more often with hypertension (P = 0.0001), diabetes (P = 0.0001), heart failure (P = 0.0001), and an urgent/emergent situation (P = 0.002). After surgery, women experienced greater rates of adverse events (15.2% vs 9.3%; P = 0.0001). In a fully adjusted logistic regression model, the nested interaction of sex in MAR showed that women had a significantly greater risk of major adverse cardiovascular events (MACE) when MAR was high (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.3-2.6; P = 0.0004). Greater severity of MAR emerged as an independent predictor of adverse events among women (high: OR, 2.9; 95% CI, 1.2-7.3; moderate: OR, 2.2; 95% CI, 0.8-5.7; low: OR, 1.0), but not among men., Conclusions: MAR was independently associated with higher rates of adverse events among women but not in men undergoing CABG. This finding may help explain differences in outcomes seen between women and men after revascularization., (Copyright © 2014 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Background: Marked variation exists concerning the utilization of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The objective of this study was to examine differences in predictors of mode of revascularization across 3 provincial jurisdictions., Methods: All patients who underwent PCI and isolated CABG in British Columbia, Alberta, and Nova Scotia between 1996 and 2007 were considered. Age- and sex-standardized rates of PCI and CABG per 100,000 population and PCI to CABG ratios were calculated by year and province. Logistic regression models were constructed to identify independent predictors of mode of revascularization in each province., Results: A total of 32,190 and 69,409 patients underwent CABG and PCI, respectively, during the study period. Significant increases in the age- and sex-adjusted PCI to CABG ratios were observed in all 3 provinces, but these ratios differed between provinces. Across all 3 jurisdictions, female sex and diagnosis of acute coronary syndrome favoured increased PCI vs CABG, and increased age, left main, or 3-vessel disease occurring before myocardial infarction, and diabetes favoured lower PCI vs CABG. After adjusting for clinical and angiographic factors, there remained a significant variation in choice of PCI vs CABG between the 3 provinces over time., Conclusions: Significant interprovincial variability in PCI to CABG ratios was observed. Though certain patient-related factors predictive of either PCI or CABG were identified, factors beyond clinical presentation played a role in the choice of revascularization approach., (Copyright © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

In this paper, we consider the problem of segmentation of large collections of images. We propose a semisupervised optimization model that determines an efficient segmentation of many input images. The advantages of the model are twofold. First, the segmentation is highly controllable by the user so that the user can easily specify what he/she wants. This is done by allowing the user to provide, either offline or interactively, some (fully or partially) labeled pixels in images as strong priors for the model. Second, the model requires only minimal tuning of model parameters during the initial stage. Once initial tuning is done, the setup can be used to automatically segment a large collection of images that are distinct but share similar features. We will show the mathematical properties of the model such as existence and uniqueness of solution and establish a maximum/minimum principle for the solution of the model. Extensive experiments on various collections of biological images suggest that the proposed model is effective for segmentation and is computationally efficient.

Loss of information in a wavelet domain can occur during storage or transmission when the images are formatted and stored in terms of wavelet coefficients. This calls for image inpainting in wavelet domains. In this paper, a variational approach is used to formulate the reconstruction problem. We propose a simple but very efficient iterative scheme to calculate an optimal solution and prove its convergence. Numerical results are presented to show the performance of the proposed algorithm.

In this paper, we develop a robust and effective algorithm for texture segmentation and feature selection. The approach is to incorporate a patch-based subspace learning technique into the subspace Mumford-Shah (SMS) model to make the minimization of the SMS model robust and accurate. The proposed method is fully unsupervised in that it removes the need to specify training data, which is required by existing methods for the same model. We further propose a novel (to our knowledge) pairwise dissimilarity measure for pixels. Its novelty lies in the use of the relevance scores of the features of each pixel to improve its discriminating power. Some superior results are obtained compared to existing unsupervised algorithms, which do not use a subspace approach. This confirms the usefulness of the subspace approach and the proposed unsupervised algorithm., (© 2011 Optical Society of America)

We propose a variant of the Mumford-Shah model for the segmentation of a pair of overlapping objects with additive intensity value. Unlike standard segmentation models, it does not only determine distinct objects in the image, but also recover the possibly multiple membership of the pixels. To accomplish this, some a priori knowledge about the smoothness of the object boundary is integrated into the model. Additivity is imposed through a soft constraint which allows the user to control the degree of additivity and is more robust than the hard constraint. We also show analytically that the additivity parameter can be chosen to achieve some stability conditions. To solve the optimization problem involving geometric quantities efficiently, we apply a multiphase level set method. Segmentation results on synthetic and real images validate the good performance of our model, and demonstrate the model's applicability to images with multiple channels and multiple objects.

The popularity of digital microscopy and tissue microarrays allow the use of high-throughput imaging for pathology research. To coordinate with this new technique, it is essential to automate the process of extracting information from such high amount of images. In this paper, we present a new model called the Subspace Mumford-Shah model for texture segmentation of microscopic endometrial images. The model incorporates subspace clustering techniques into a Mumford-Shah model to solve texture segmentation problems. The method first uses a supervised procedure to determine several optimal subspaces. These subspaces are then embedded into a Mumford-Shah objective function so that each segment of the optimal partition is homogeneous in its own subspace. The method outperforms a widely used method in bioimaging community called k-means segmentation since it can separate textures which are less separated in the full feature space, which confirm the usefulness of subspace clustering in texture segmentation. Experimental results also show that the proposed method is well performed on diagnosing premalignant endometrial disease and is very practical for segmenting image set sharing similar properties., (© 2010 Bioinformatics Institute.)

Objectives: Sequential anastomoses in coronary artery bypass grafting (CABG) offer theoretical advantages including increased graft flow and more complete revascularisation. However, published studies concerning the safety and efficacy of this technique are not definitive. The objective of this study was to assess the effect of sequential anastomoses on outcomes following CABG., Methods: Perioperative data were prospectively collected on all patients with triple-vessel disease who underwent first-time, isolated, on-pump CABG between 1995 and 2005 at a single centre. Patients with a left internal mammary artery graft to the anterior wall and saphenous vein grafts to the lateral and posterior walls were included., Results: Compared to patients without sequential anastomoses (n=1108), patients with sequential anastomoses (n=1246) were more likely to have an ejection fraction (EF)<40% (14.9% vs 10.8%, p=0.004), a recent myocardial infarction (19.3% vs 14.3%, p=0.001) and an urgent/emergent operative status (19.6% vs 14.4%, p=0.0008). Median follow-up was 78 months. After adjusting for clinical covariates, sequential grafting was not an independent predictor of in-hospital adverse events (odds ratio (OR) 1.15, 95% confidence interval (CI) 0.88-1.50, p=0.31) or long-term mortality and/or readmission to hospital (hazard ratio (HR) 0.98, 95% CI 0.86-1.12, p=0.74). Sequential grafting was an independent predictor of receiving greater than three distal anastomoses (OR 9.26, 95% CI; 6.27-13.67, p<0.0001)., Conclusions: Patients undergoing sequential grafting presented with greater acuity and worse systolic function. After adjusting for baseline differences, sequential grafting was not found to be an independent predictor of adverse events. These results support the safety of sequential anastomoses in patients undergoing CABG., (Copyright © 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.)

We consider the recovery of degraded videos without complete knowledge about the degradation. A spatially shift-invariant but temporally shift-varying video formation model is used. This leads to a simple multiframe degradation model that relates each original video frame with multiple observed frames and point spread functions (PSFs). We propose a variational method that simultaneously reconstructs each video frame and the associated PSFs from the corresponding observed frames. Total variation (TV) regularization is used on both the video frames and the PSFs to further reduce the ill-posedness and to better preserve edges. In order to make TV minimization practical for video sequences, we propose an efficient splitting method that generalizes some recent fast single-image TV minimization methods to the multiframe case. Both synthetic and real videos are used to show the performance of the proposed method.

We propose a novel image segmentation model which incorporates subspace clustering techniques into a Mumford-Shah model to solve texture segmentation problems. While the natural unsupervised approach to learn a feature subspace can easily be trapped in a local solution, we propose a novel semi-supervised optimization algorithm that makes use of information derived from both the intermediate segmentation results and the regions-of-interest (ROI) selected by the user to determine the optimal subspaces of the target regions. Meanwhile, these subspaces are embedded into a Mumford-Shah objective function so that each segment of the optimal partition is homogeneous in its own subspace. The method outperforms standard Mumford-Shah models since it can separate textures which are less separated in the full feature space. Experimental results are presented to confirm the usefulness of subspace clustering in texture segmentation.

We sought to develop a predictive model based exclusively on preoperative factors to identify patients at risk for PrlICULOS following coronary artery bypass grafting (CABG). Retrospective analysis was performed on patients undergoing isolated CABG at a single center between June 1998 and December 2002. PrlICULOS was defined as initial admission to ICU exceeding 72 h. A parsimonious risk-predictive model was constructed on the basis of preoperative factors, with subsequent internal validation. Of 3483 patients undergoing isolated CABG between June 1998 and December 2002, 411 (11.8%) experienced PrlICULOS. Overall in-hospital mortality was higher among these patients (14.4% vs. 1.2%, P

A wavelet inpainting problem refers to the problem of filling in missing wavelet coefficients in an image. A variational approach was used by Chan et al. The resulting functional was minimized by the gradient descent method. In this paper, we use an optimization transfer technique which involves replacing their univariate functional by a bivariate functional by adding an auxiliary variable. Our bivariate functional can be minimized easily by alternating minimization: for the auxiliary variable, the minimum has a closed form solution, and for the original variable, the minimization problem can be formulated as a classical total variation (TV) denoising problem and, hence, can be solved efficiently using a dual formulation. We show that our bivariate functional is equivalent to the original univariate functional. We also show that our alternating minimization is convergent. Numerical results show that the proposed algorithm is very efficient and outperforms that of Chan et al.

Objective: To explore Chinese women's perceptions of human papillomavirus (HPV) vaccination and their intention to be vaccinated., Design: A cross-sectional community-based survey study., Setting: Thirteen community women's health centres of The Family Planning Association of Hong Kong., Sample: A total of 1450 ethnic Chinese women aged 18 or above who attended the health centres., Methods: Participants completed a written consent and an anonymous questionnaire onsite., Main Outcome Measures: Knowledge and beliefs about HPV and HPV vaccination against cervical cancer and participants' own intention to be vaccinated., Results: About 38% of the participants (n = 527) had heard of HPV and 50% (n = 697) had heard of vaccination against cervical cancer. HPV infection was perceived to be stigmatising and detrimental to intimate, family and social relationships. Despite misconceptions and a grossly inadequate knowledge about HPV and HPV vaccination, 88% of the participants (n = 1219) indicated that they would likely be vaccinated. Majority of the participants believed that sexually experienced women should be vaccinated, while 27% opposed vaccinating sexually naive women. Younger age women who perceived a disruptive impact of HPV infection on intimate relationship and their partners' approval were significantly associated with a positive intention to be HPV vaccinated., Conclusions: The easy acceptability of HPV vaccination among the mostly sexually experienced Chinese participants and their knowledge deficit on the subject may implicate potential misuse of the vaccines and a false sense of security against cervical cancer. There is a dire need for culturally sensitive and tailored education for the public, women of different ages and their partners about HPV and HPV vaccination. Emphasis must be placed on the prophylactic nature of the current vaccines, the uncertain effects when given to sexually experienced women, the importance of adolescent vaccination and the need for continued cervical screening whether vaccinated or not.

Background: Hemisternotomy has been suggested as a way to reduce morbidity by limiting the invasiveness of surgical interventions but it is often limited to aortic valve disease. This study reviews the experience of one center employing hemisternotomy and compares patient outcomes, both in-hospital and post-discharge, with a matched group of full sternotomy patients., Methods: Propensity scores were used to match all hemisternotomy valve cases (Hemi) to full sternotomy valve cases (Full) (1:2). An in-hospital composite outcome (COMP) was defined as mortality, stroke, deep sternal wound infection, sepsis, or return to operating room (OR) for bleeding or valve dysfunction. Provincial administrative health databases were used to determine freedom from mortality and hospital readmission for cardiac cause., Results: During the study period, 70 patients received hemisternotomy for various cardiac surgical interventions with only 38 patients undergoing isolated aortic valve replacement. Examining valve surgery exclusively, 65 Hemi were matched to 130 Full. In-hospital complications were low in both groups, with 1.0% mortality and a non-significant trend toward COMP in the Full group (Hemi=4.6%; Full=8.5%; p=0.39). Ventilation time was significantly decreased in Hemi (median four vs. six hours; p=0.002). At two years follow-up, survival was excellent for both (Hemi=95.0%; Full=93.6%) and freedom from cardiac morbidity (Hemi=76.8%, Full=73.2%) was comparable., Conclusion: Hemisternotomy appears to be a safe, effective, and versatile alternative for many cardiac surgical interventions. With a median follow-up of four years, this study represents the longest cardiac morbidity follow-up for hemisternotomy patients. However, we were unable to conclusively show a morbidity benefit with this incision.

The Mumford-Shah model is one of the most successful image segmentation models. However, existing algorithms for the model are often very sensitive to the choice of the initial guess. To make use of the model effectively, it is essential to develop an algorithm which can compute a global or near global optimal solution efficiently. While gradient descent based methods are well-known to find a local minimum only, even many stochastic methods do not provide a practical solution to this problem either. In this paper, we consider the computation of a global minimum of the multiphase piecewise constant Mumford-Shah model. We propose a hybrid approach which combines gradient based and stochastic optimization methods to resolve the problem of sensitivity to the initial guess. At the heart of our algorithm is a well-designed basin hopping scheme which uses global updates to escape from local traps in a way that is much more effective than standard stochastic methods. In our experiments, a very high-quality solution is obtained within a few stochastic hops whereas the solutions obtained with simulated annealing are incomparable even after thousands of steps. We also propose a multiresolution approach to reduce the computational cost and enhance the search for a global minimum. Furthermore, we derived a simple but useful theoretical result relating solutions at different spatial resolutions.

Objectives: To explore perceptions towards cervical cancer, human papillomavirus (HPV) infection and HPV vaccination and to identify factors affecting the acceptability of HPV vaccination among Chinese adolescent girls in Hong Kong., Methods: Six focus groups were conducted with Chinese adolescent girls (median age 16 years, age range 13-20, n = 64) in Hong Kong in April 2007. Thematic analysis was employed to identify major themes related to cervical cancer and HPV vaccination. A supplementary questionnaire was administered to all participants before and after group discussion to assess their knowledge, attitudes and intention to be vaccinated and to collect demographic information., Results: Participants' knowledge on cervical cancer was limited and HPV was largely unheard of. They had difficulty understanding the mechanism linking cervical cancer with HPV infection. Participants held a favourable attitude towards HPV vaccination but the perceived timing of vaccination varied. Barriers to vaccination include high monetary cost, uncertain length of vaccine effectiveness, low perceived risk of HPV infection, no immediate perceived need of vaccination, anticipated family disapproval and fear of the pain of injection. Factors conducive to vaccination include perceived family and peer support and medical reassurance on safety and efficacy of vaccine. The differences on knowledge, attitudes, intention to be vaccinated now and willingness to conform to significant others before and after the discussion were statistically significant, with an increased tendency towards favouring vaccination after the focus group., Conclusions: Participants favoured HPV vaccination despite not feeling an immediate need to be vaccinated. Interventions could focus on providing professional information on HPV vaccination and raising adolescents' perceived need to take preventive measures against HPV infection.

This paper studies image deblurring problems using a total variation-based model, with a non-negativity constraint. The addition of the non-negativity constraint improves the quality of the solutions, but makes the solution process a difficult one. The contribution of our work is a fast and robust numerical algorithm to solve the non-negatively constrained problem. To overcome the nondifferentiability of the total variation norm, we formulate the constrained deblurring problem as a primal-dual program which is a variant of the formulation proposed by Chan, Golub, and Mulet for unconstrained problems. Here, dual refers to a combination of the Lagrangian and Fenchel duals. To solve the constrained primal-dual program, we use a semi-smooth Newton's method. We exploit the relationship between the semi-smooth Newton's method and the primal-dual active set method to achieve considerable simplification of the computations. The main advantages of our proposed scheme are: no parameters need significant adjustment, a standard inverse preconditioner works very well, quadratic rate of local convergence (theoretical and numerical), numerical evidence of global convergence, and high accuracy of solving the optimality system. The scheme shows robustness of performance over a wide range of parameters. A comprehensive set of numerical comparisons are provided against other methods to solve the same problem which show the speed and accuracy advantages of our scheme.

We propose and study the notion of dense regions for the analysis of categorized gene expression data and present some searching algorithms for discovering them. The algorithms can be applied to any categorical data matrices derived from gene expression level matrices. We demonstrate that dense regions are simple but useful and statistically significant patterns that can be used to 1) identify genes and/or samples of interest and 2) eliminate genes and/or samples corresponding to outliers, noise, or abnormalities. Some theoretical studies on the properties of the dense regions are presented which allow us to characterize dense regions into several classes and to derive tailor-made algorithms for different classes of regions. Moreover, an empirical simulation study on the distribution of the size of dense regions is carried out which is then used to assess the significance of dense regions and to derive effective pruning methods to speed up the searching algorithms. Real microarray data sets are employed to test our methods. Comparisons with six other well-known clustering algorithms using synthetic and real data are also conducted which confirm the superiority of our methods in discovering dense regions. The DRIFT code and a tutorial are available as supplemental material, which can be found on the Computer Society Digital Library at http://computer.org/tcbb/archives.htm.

Purpose: Promoter hypermethylation is a common phenomenon in neoplasm. The aims of this study were (a) to compare the methylation profiles in different types of ovarian tumors and (b) to determine the possible relationship between the methylation status and different clinicopathologic characteristics., Methods: We examined the promoter methylation status of 9 tumor suppressor genes (RARbeta2, TMS1, RIZ1, P15, P16, PTEN, MINT31, APC and HIC1) in 89 ovarian cancers, 16 borderline ovarian tumors, 19 benign ovarian tumors, 16 normal ovarian tissue and 5 ovarian cancer cell lines. The methylation status was examined with respect to clinicopathologic characteristics of the ovarian cancer patients., Results: Methylation indices for ovarian cancer, borderline ovarian tumor, benign ovarian tumor, normal ovarian tissue and ovarian cancer cell lines were 28.8, 20.1, 10.5, 11.8 and 42.2%, respectively. It was significantly higher in ovarian cancer, borderline ovarian tumor and ovarian cancer cell lines (X (2) test, P < 0.001, P = 0.01 and P < 0.001, respectively) than benign or normal ovarian tissues. In ovarian cancer, concurrent methylation of at least two genes (CM2) was associated with early stage disease (X (2) test, P = 0.035) and less recurrence (X (2) test, P = 0.020). When the methylation statuses of the nine genes as well as CM2 were included in multivariate Cox Regression analysis, CM2 was the only independent predictor for survival (P = 0.013)., Conclusion: CM2 was an independent predictor for survival in ovarian cancer.

Background: Network methods are increasingly used to represent the interactions of genes and/or proteins. Genes or proteins that are directly linked may have a similar biological function or may be part of the same biological pathway. Since the information on the connection (adjacency) between 2 nodes may be noisy or incomplete, it can be desirable to consider alternative measures of pairwise interconnectedness. Here we study a class of measures that are proportional to the number of neighbors that a pair of nodes share in common. For example, the topological overlap measure by Ravasz et al. 1 can be interpreted as a measure of agreement between the m = 1 step neighborhoods of 2 nodes. Several studies have shown that two proteins having a higher topological overlap are more likely to belong to the same functional class than proteins having a lower topological overlap. Here we address the question whether a measure of topological overlap based on higher-order neighborhoods could give rise to a more robust and sensitive measure of interconnectedness., Results: We generalize the topological overlap measure from m = 1 step neighborhoods to m > or = 2 step neighborhoods. This allows us to define the m-th order generalized topological overlap measure (GTOM) by (i) counting the number of m-step neighbors that a pair of nodes share and (ii) normalizing it to take a value between 0 and 1. Using theoretical arguments, a yeast co-expression network application, and a fly protein network application, we illustrate the usefulness of the proposed measure for module detection and gene neighborhood analysis., Conclusion: Topological overlap can serve as an important filter to counter the effects of spurious or missing connections between network nodes. The m-th order topological overlap measure allows one to trade-off sensitivity versus specificity when it comes to defining pairwise interconnectedness and network modules.

Density-based clustering has the advantages for 1) allowing arbitrary shape of cluster and 2) not requiring the number of clusters as input. However, when clusters touch each other, both the cluster centers and cluster boundaries (as the peaks and valleys of the density distribution) become fuzzy and difficult to determine. We introduce the notion of cluster intensity function (CIF) which captures the important characteristics of clusters. When clusters are well-separated, CIFs are similar to density functions. But, when clusters become closed to each other, CIFs still clearly reveal cluster centers, cluster boundaries, and degree of membership of each data point to the cluster that it belongs. Clustering through bump hunting and valley seeking based on these functions are more robust than that based on density functions obtained by kernel density estimation, which are often oscillatory or oversmoothed. These problems of kernel density estimation are resolved using Level Set Methods and related techniques. Comparisons with two existing density-based methods, valley seeking and DBSCAN, are presented which illustrate the advantages of our approach.

Plasma human papillomavirus (HPV)-DNA level was measured to evaluate the clinical usefulness of circulating DNA for cervical cancer management. DNA extracted from pretreatment plasma of 50 cervical cancer patients and from serial longitudinal plasma of 21 patients was quantified for HPV16/HPV18 by means of quantitative polymerase chain reaction. Another 15 patients with low-grade lesion (LG), 18 patients with high-grade lesion (HG), and 96 normal individuals were studied as controls. Plasma HPV16-DNA was detectable in 50% of cancer patients. The incidence and median level were statistically higher than those in LG patients and normal, but similar to HG patients. Plasma HPV18-DNA was only detected in 6% of cancer patients and 1% of normal. Same type of HPV present in plasma was also detected in its primary tumor; and the level of plasma HPV16-DNA was dependent on the viral load in primary tumor. Plasma HPV-DNA was not detected in 16 of 21 patients after treatment, and those patients had complete response to therapy. HPV-DNA persisted or reappeared in five patients after treatment (one had persistent disease and another had recurrence). Plasma HPV-DNA might be a valuable marker for monitoring therapeutic response and disease progression in cervical cancer.

Delivery of health services is an important determinant of health. Restricted availability and access may result in health inequalities. To determine the extent of geographic variation in the delivery of health services and its effect on the health of community residents in terms of under-diagnosis and under-treatment of hypertension, we carried out a multilevel study of participants in the 1995 Nova Scotia Heart Health Survey (n = 3,094). We used individual level survey data and health status measurements linked to geographical level information to examine the importance of adequate delivery of health services to the diagnosis and treatment of hypertension in the universal health care setting of the province of Nova Scotia. The delivery of primary care services across Nova Scotia varied moderately with physician visit rates ranging from 3.3 to 5.5 visits per resident per year. There were neither substantial nor statistically significant differences in the diagnosis and treatment of hypertension among residents of communities varying in the delivery of health services. We concluded that a geographic variation in the delivery of primary care services is a public health concern that is not consistent with the objectives of universal coverage of health services; however, it was not confirmed to result in health inequalities.

We have previously demonstrated the presence of human papillomavirus (HPV) DNA in several gynecological cancers using conventional PCR. In the present study, to further understand the role of HPV in malignant transformation of these cancers, the infection rates and viral loads of HPV 16 and 18 in gynecological cancers were analyzed using real-time quantitative PCR (qPCR). HPV 16 DNA was detected in 61.0% (58/95), 15.2% (7/46) and 32.1% (18/56) of cases of cervical, endometrial and ovarian cancers, respectively. On the other hand, HPV 18 DNA was detected in 23.2% (22/95) of cervical cancers, 1.8% (1/56) of ovarian cancers, and in no cases of endometrial cancer. Thus, HPV 16 is much more prevalent than HPV 18 in malignancies of the female genital tract. We also found that both HPV 16 and 18 were significantly (p < 0.05) less frequently present in endometrial and ovarian cancers than in cervical cancer. The median copy numbers of HPV 16 DNA in endometrial and ovarian cancers were 3,500 and 7,590 copies/microg DNA, respectively. These amounts were also significantly (p < 0.05) lower than HPV 16 DNA in cervical cancer (492,800 copies/microg DNA). Thus, HPV 16 could be detected in all three types of gynecological cancer, whilst HPV 18 is extremely rare in endometrial and ovarian cancers. The lower HPV 16 infection rates and lower copy numbers when compared with cervical cancer tend to suggest that HPV plays a less essential role in the development of endometrial cancer and ovarian cancer., (Copyright 2003 S. Karger AG, Basel)

To further our understanding of factors underlying geographic variation in health and the potential role of availability of and access to health services, we sought to quantify the geographic variation in health services use in the province of Nova Scotia. For the period 1996 to 1999 we examined the variation in the use of health services across 64 geographic areas in conjunction with health and socio-economic factors, using multilevel methods and empirical Bayesian estimates based on provincial physician billings and hospital separation records. We revealed moderate geographic variation in the use of family physician services and large variation in specialist and hospital services. In the two urban centres, Metropolitan Halifax and the Cape Breton Regional Municipality, use of specialist services was respectively 26.24% and 15.59% higher than the provincial average, and use of hospital services was respectively 21.55% and 37.67% higher. Geographic areas in which residents had better health were characterized by more use of family physician services and reduced use of specialist and hospital services. These associations seem to support policy strategies that aim to improve health and to reduce health care costs by investing in prevention and primary health care, and they highlight the potential implications of the shortage of family physicians across Canada.

Objectives: To investigate the importance of both individual and neighbourhood socioeconomic characteristics for health care utilization., Methods: Various linkage procedures generated a longitudinal dataset with information on 2,116 Nova Scotians, their residential neighbourhoods, 8 years of health care utilization and vital status. Unilevel and multilevel regression analyses were employed to examine the effects of both individual and neighbourhood characteristics on health care use., Results: Individual income and education determined physician and hospital use. Also, neighbourhood characteristics, specifically average income and percentage of single mother families, were found to determine health care use. When considering individual and neighbourhood characteristics simultaneously, individual income and education determined physician and hospital use independently, while neighbourhood income determined physician use independently., Conclusions: Both individual and neighbourhood socioeconomic characteristics determine health care use. Acknowledging this allows better targeting of health policy and planning, and enables more accurate needs-based resource allocation.