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Background Hyponatremia is a common and under-recognized adverse drug reaction of selective serotonin re-uptake inhibitor (SSRI) antidepressants. Despite its clinical importance, there are few large-scale studies on the factors associated with hyponatremia. Objective The aim of this study was to determine the incidence of hyponatremia and to identify patient factors associated with hyponatremia in a large, population-based cohort initiating new prescriptions for citalopram. Methods We included all patients with a new prescription for citalopram during 2010–2017, inclusive, with baseline and post-initiation serum sodium values available. Data were obtained from an Alberta Health Pharmacy database to identify new citalopram prescriptions. Laboratory values for patients with new prescriptions were obtained from linked Calgary Laboratory Services data. Incident hyponatremia was defined as serum sodium level

BACKGROUND: Prescribing of levothyroxine and rates of thyroid function testing may be sensitive to minor changes in the upper limit of the reference range for thyroid-stimulating hormone (TSH) that increase the proportion of abnormal results. We evaluated the population-level change in levothyroxine prescribing and TSH testing after a minor planned decrease in the upper limit of the reference range for TSH in a large urban centre with a single medical laboratory. METHODS: Using provincial administrative data, we compared predicted volumes of TSH tests with actual TSH test volumes before and after a planned change in the TSH reference range. We also determined the number of new levothyroxine prescriptions for previously untreated patients and the rate of changes to the prescribed dose for those on previously stable, long-term levothyroxine therapy before and after the change in the TSH reference range. RESULTS: Before the change in the TSH reference range, actual and predicted monthly volumes of TSH testing followed an identical course. After the change, actual test volumes exceeded predicted test volumes by 7.3% (95% confidence interval [CI] 5.3%–9.3%) or about 3000 to 5000 extra tests per month. The proportion of patients with newly “abnormal” TSH results almost tripled, from 3.3% (95% CI 3.2%–3.4%) to 9.1% (95% CI 9.0%–9.2%). The rate of new levothyroxine prescriptions increased from 3.24 (95% CI 3.15–3.33) per 1000 population in 2013 to 4.06 (95% CI 3.96–4.15) per 1000 population in 2014. Among patients with preexisting stable levothyroxine therapy, there was a significant increase in the number of dose escalations (p INTERPRETATION: Our findings suggest that clinicians may have responded to mildly elevated TSH results with new or increased levothyroxine prescriptions and more TSH testing. Knowledge translation efforts may be useful to accompany minor changes in reference ranges.

Objectives Helicobacter pylori stool antigen test (HpSAT) appropriateness was investigated by assessing its testing and positivity rates in Calgary, Canada. Methods The laboratory information system was accessed for all patients who received an HpSAT in 2018. Testing volume, test results, age, and sex of patients were collected. Sociodemographic risk factors and geospatial analysis were performed by matching laboratory data to the 2016 census data. Testing appropriateness was defined as a concordance between testing and positivity rates for each sociodemographic variable. Results In 2018, 25,518 H pylori stool antigen tests were performed in Calgary, with an overall positivity rate of 14.7%. Geospatial mapping demonstrated significant distribution variations of testing and positivity rates of HpSAT in the city. Certain sociodemographic groups studied (eg, recent immigrants) appeared to be appropriately tested (testing rate relative risk [RR] = 2.26, positivity rate RR = 4.32; P < .0001), while other groups (eg, male) may have been undertested (testing rate RR = 0.85, positivity rate RR = 1.14; P < .0001). Conclusions Determining concordance of testing and positivity rate of a laboratory test can be used for assessing testing appropriateness for other diseases in other jurisdictions. This study demonstrated some at-risk patients may be missed for H pylori testing.

Introduction The avoidance of repeat chemistry testing such as Complete Blood Count (CBC) and Electrolyte Panel (EP) on clinically stable patients was identified as important utilization goals by Choosing Wisely Canada. The purpose of this study was to assess the volume of overutilization of CBC and EP in an inpatient setting in Alberta, Canada, and provide an estimated cost assessment of unnecessary testing. Methods The total laboratory testing volumes of two common test panels were collected retrospectively for one-year from January to December 2018. Data was collected on test panels performed in an emergency room (ER) and inpatient setting from three separate Laboratory Information Systems covering the provincial population in Alberta, Canada. Total initial test panel instances, total repeated panels, repeated panels that were previously normal or abnormal, and estimated costs were examined. Cost assessment was completed based on Reference Median Cost (RMC) analysis for each of these two common test panels. Results During the study period, 2,020,467 (CBC) and 1,455,983 (EP) initial test panel instances were recorded, of which 67.7% and 73.5% were repeated for the CBC and EP, respectively. There was a higher proportion of EP repeated inappropriately (previously normal; 35.6%) compared to CBCs (5.4%). The cost to the province for inappropriately repeating CBC and EP were estimated to be RMC $0.52 million and RMC $1.90 million CAD, respectively. Conclusion Results from this study can assist policy makers in implementing utilization management initiatives and update clinical practice guidelines to reduce costs to healthcare without compromising patient care.

Introduction We describe the implementation of an Alberta-wide intervention aimed at educating clinicians about redundant vitamin B12 testing. We hypothesized that the introduction of an educational comment outlining recommended vitamin B12 test intervals would reduce the annual number of vitamin B12 tests performed. Materials and methods We performed a cross-sectional observational study that included all vitamin B12 tests ordered in Alberta between May 1, 2017 and April 30, 2018. An educational comment was appended to all vitamin B12 test results in Alberta beginning May 2, 2017. Using a simple seasonal model, we compared predicted versus observed vitamin B12 test volumes for the 12-month period following the introduction of the educational comment. The sole outcome measured was the monthly change in volume of vitamin B12 testing. A cost-analysis of the effects of the intervention on test volumes was also performed. Results Over the sum of the first 12 months of the intervention, 18,000 more vitamin B12 tests were ordered compared to the predicted value in Alberta. With an estimated cost of $7 per test, this resulted in a $126,000 increase in costs for vitamin B12 testing provincially. Conclusions An educational intervention aimed at limiting inappropriate vitamin B12 testing in Alberta did not alter testing as desired. Multiple utilization management strategies and a longer observation period may be needed to reduce redundant vitamin B12 testing.

Background There is widespread variation in testing practice among practitioners, however there has been no objective way to pinpoint target tests for utilization management. We propose to take advantage of inter-physician variance in clinical practice as a quantitative measure to generate lists of potentially misutilized tests. Methods Testing frequencies from a database of clinical testing volumes for outpatients in Calgary, Canada, were obtained for the study period of 2016. For each chemistry, microbiology or hematology test, an arithmetic coefficient of variation (CV) was calculated from family physicians' ordering frequencies. Results The mean CV for all 358 tests considered was 219% (95% CI 206–231%) with a range of 52–729%. The highest variance was observed for human T-lymphotropic virus antibody testing and several tests for heavy metal levels (mercury, copper, zinc and chromium). Among the 100 most commonly run tests, high variance was found for several endocrinology tests including cortisol. Conclusions The utility of ranking clinical tests by ordering variance presents a practical approach to evaluate relative variation in physician practice strategy and to identify potential areas of misutilization.

While there is concern about excessive laboratory test ordering in the ED, it is difficult to quantify the problem. One solution involves the Mean Abnormal Result Rate (MARR), which is the proportion of tests ordered that return abnormal results. The primary objective of this study was to calculate MARR scores, and factors associated with MARR scores, for tests ordered between April 2014 and March 2019 at adult EDs in Calgary.Administrative data were obtained for 40 laboratory tests that met selection criteria. One possible MARR correlate, physician experience, was quantified for 209 ED physicians as number of years since licensure. Analyses were descriptive where appropriate for whole-population data.The condensed dataset comprised 3,395,312 test results on 415,653 unique patients. The aggregate 5-year MARR score was 40.1%. The highest per-test score was for BNP (80.5%), while the lowest was for glucose (7.9%). MARR scores were higher for nurse-initiated orders than for physician-initiated orders (44.7% vs. 38.1%). The MARR score correlated inversely with number of tests per order (r = - 0.90; 95% confidence interval [CI] - 0.65 to - 0.94; p 0.001) and directly with physician experience (r = 0.28, 95% CI 0.20 to 0.27; p 0.001).This is the first study to measure MARR scores in an ED setting. While lower scores (close to 5%) are less optimal in principle, ideal scores will depend on the clinical context in which tests are used. However, once departmental benchmarks are established, MARR score-monitoring allows efficient tracking of ordering practices across millions of tests.RéSUMé: OBJECTIFS: Bien que l'on s'inquiète d'une commande excessive de tests de laboratoire dans le service d'urgence, il est difficile de quantifier le problème. Une solution implique le taux de résultat anormal moyen (MARR), qui est la proportion de tests commandés qui renvoient des résultats anormaux. L'objectif principal de cette étude était de calculer les scores MARR, et les facteurs associés aux scores MARR, pour les tests commandés entre avril 2014 et mars 2019 dans les services d'urgence pour adultes à Calgary. LES MéTHODES: Des données administratives ont été obtenues pour 40 tests de laboratoire répondant aux critères de sélection. Une corrélation possible du MARR, soit l’expérience des médecins, a été quantifié pour 209 médecins urgentistes en nombre d'années depuis l'autorisation d'exercer. Les analyses étaient descriptives, le cas échéant, pour les données sur l’ensemble de la population. RéSULTATS: L'ensemble de données condensé comprenait 3,395,312 résultats de tests sur 415 653 patients uniques. Le score MARR global à 5 ans était de 40,1%. Le score le plus élevé par test était pour le peptide cérébral natriurétique BNP (80,5%), tandis que le plus bas était pour le glucose (7,9%). Les scores de MARR sont plus élevés pour les ordonnances initiées par les infirmières que pour les ordonnances initiées par les médecins (44,7% contre 38,1%). Le score MARR s’est corrélé inversement avec le nombre de tests par ordre (r = − 0,90; intervalle de confiance de 95 % [IC] − 0.65 to − 0,94; p 0.001) et directement avec l’expérience du médecin (r = 0.28, IC à 95 % 0.20–0.27; p 0.001). CONCLUSIONS: Il s’agit de la première étude à mesurer les scores du MARR dans un contexte de service d’urgence. Bien que des scores inférieurs (près de 5%) sont moins optimaux en principe, les scores idéaux dépendront du contexte clinique dans lequel les tests sont utilisés. Cependant, une fois les points de repère ministériels établis, la surveillance des scores du MARR permet de suivre efficacement les pratiques de commande sur des millions de tests.

Objectives The mean abnormal result rate (MARR) has recently been advanced as a metric of laboratory test appropriateness. We used the MARR metric to examine patterns of change in family physician test requisitions over time. Methods We accessed the Laboratory Information System of Calgary Laboratory Services for family physician-ordered testing on outpatients to gather aggregate test and abnormal result counts from 2010 to 2015. Results Over the 6 years, there was an annual average of 3,401,553 tests for 411,295 distinct patients on their first test requisition for the year. The MARR increased from 8.1% to 9.0% through this period. Conclusions The MARR for Calgary and surrounding area gives tentative evidence of a gradual increase in physician test selectivity in recent years. Further data from other catchment areas are needed before making assertions about broader trends in physician awareness of laboratory resource use.

Background The incidence rate of acute myeloid leukemia (AML) was determined in the Calgary Metropolitan Area, a major Canadian city. Methods Data from all patients diagnosed with AML between January 1, 2011 and December 31, 2015 were retrieved from a single, centralized cancer cytogenetics laboratory for bone marrow samples, the sole diagnostic facility of its kind in Southern Alberta. Results The calculated incidence rate was 2.79 cases per 100,000 person-years with a median age of 60, slightly lower than previously published data. The age-standardized incidence rate for Canada was 3.46 cases per 100,000 person-years. The higher value is reflective of Calgary’s younger population compared to the rest of Canada. Higher male incidence and greatest incidence occurring at approximately the age of 85 is similar to data from other developed countries. The lower incidence rates and median age of diagnosis, in comparison with that of other high-income nations, may be due to differences in the proportion of aging citizens in the population. Conclusion This is the first published incidence rate of acute myeloid leukemia (AML) in Canada across all age groups.

Objectives The increasing cost of clinical laboratory testing is a challenge in our health care system. This study aims to calculate the annual clinical laboratory test costs attributed to patients in a major Canadian city and to correlate them to their sociodemographic variables. Methods Retrospective cohort study involving patients who received clinical chemistry, hematology, and microbiology tests in 2011 in Calgary, Canada (n = 610,409). Test volumes were obtained from a laboratory informatics database. Total expenditures per patient were calculated using estimated test costs and then combined with the 2011 Canadian Census Household Survey results to infer sociodemographic correlates. Results While more women received laboratory testing (58.4%), men had slightly higher testing costs per capita. Except for Chinese, visible minority and Aboriginal populations had higher testing costs. There was an inverse correlation between testing cost and household income, and accordingly, higher costs were found in those without postsecondary education and the unemployed. Furthermore, hotspot mapping revealed the geographical distribution of patient test costs within the city. Conclusions There is variation in testing costs for patients among different sociodemographic variables.

All laboratory tests performed within the province of Alberta in Canada are captured by three Laboratory Information Systems (LIS; Millennium, Sunquest and Meditech), which comprise the provincial Consolidated Laboratory Data Repository (CLDR). The following secondary laboratory data for electrolyte panel (EP) and complete blood count (CBC) test panels performed in emergency room (ER) and inpatient settings were collected from January 1 – December 31, 2018: total test panel volume, total number of test panels repeated, number of test panels repeated within the 24 hour period, test result, date of testing, time of test, and patient Provincial Health Number (PHN). Patient PHN were used as a linking variable to match subsequent tests performed on the same patient. The first time a test was recorded per patient was defined as the “index test”. If the same test panel was performed within a 24-h period following the index test for the patient, data for the repeated test panel was also collected. The index test was defined as “normal” or “abnormal” according to established laboratory normal values and laboratory test reference ranges. For CBCs, we considered the panel to be abnormal if any of the hematocrit (Hct), hemoglobin (Hgb), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), platelet (PLT), red blood cell (RBC), red cell distribution width (RDW) or white blood cell (WBC) values were outside the normal laboratory reference range. For electrolyte panels, we considered the panel to be abnormal if any of the chloride (Cl), potassium (K), and sodium (Na) were outside of the normal laboratory reference range. All EP results were from clinical chemistry analyzers only. The reuse potential of this dataset can allow other jurisdictions in Canada to compare their redundant repeat testing in their hospital settings with this dataset as a benchmark. This article was submitted via another Elsevier journal as a co-submission (“Inappropriate repeat testing of complete blood count (CBC) and electrolytes in inpatients from Alberta, Canada” [1]), and readers should refer to the co-submission article for interpretation of the results. Keywords: Laboratory utilization, Repeat testing, Complete blood count, Electrolyte panel, Laboratory medicine, Health informatics

This data incorporates 2016 testing volumes ordered by family physicians and performed at Calgary Laboratory Services (CLS), the sole supplier of clinical laboratory services for the catchment area of the City of Calgary, Alberta, Canada. For each test, the mean number of tests ordered per patient was calculated over ordering Calgary physicians, along with arithmetic coefficients of variation (CV's). The latter parameter is reflective of variance in ordering practice among family physicians practicing in Calgary and is proposed as a benchmark measure for laboratory utilization in our accompanying research article [1]. The data table encompasses 358 tests ordered by at least 3 family physicians at a minimum total frequency of 100 within the 2016 study period and is presented in ascending order of rank in CV. Keywords: Clinical laboratory tests, Utilization, Variance, Laboratory medicine, Family medicine

Background The first Canadian outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was identified in 2004 in Calgary, Alberta. Using a novel model of MRSA population-based surveillance, sociodemographic risk associations, yearly geospatial dissemination and prevalence of CA-MRSA infections over an 11 year period was identified in an urban healthcare jurisdiction of Calgary. Methods Positive MRSA case records, patient demographics and laboratory data were obtained from a centralized Laboratory Information System of Calgary Laboratory Services in Calgary, Alberta, Canada between 2004 and 2014. Public census data was obtained from Statistics Canada, which was used to match with laboratory data and mapped using Geographic Information Systems. Results During the study period, 52.5% of positive MRSA infections in Calgary were CA-MRSA cases. The majority were CMRSA10 (USA300) clones (94.1%; n = 4255), while the remaining case (n = 266) were CMRSA7 (USA400) clones. Period prevalence of CMRSA10 increased from 3.6 cases/100000 population in 2004, to 41.3 cases/100000 population in 2014. Geospatial analysis demonstrated wide dissemination of CMRSA10 annually in the city. Those who are English speaking (RR = 0.05, p

Background The Canadian Diabetes Association recommends testing most individuals with diabetes mellitus using HbA1c once every 3 months. In Alberta, Canada, a provincial intervention to reduce inappropriate HbA1c test orders was implemented to align with this guideline, where only one HbA1c test request every 90 days for most individuals can be processed. Here, we evaluated the provincial intervention to reduce redundant HbA1c testing in Alberta. Methods Total counts of all HbA1c tests ordered within Edmonton and Calgary, Alberta, were collected from the respective Laboratory Information Systems each month between January 2013 and December 2016. Winters' Additive time series model was built to predict the HbA1c test volume after intervention (November 1, 2015 onwards) and compared with the observed test volume to estimate the effect of the intervention. The estimated change in test volume was then multiplied by the estimated cost to determine the economic impact. Results During the first 14 months of the intervention for Alberta, there was a 3.3% reduction in the number of observed HbA1c tests compared to the predicted volume. With an estimated marginal reagent cost of $3.50 per unit, this resulted in a cost savings of $145,422 in the first 14 months of the provincial intervention. Conclusion A modest reduction in HbA1c test orders was observed in the urban areas of Alberta since the implementation of this provincial initiative.

Objective The incidence of the combined myeloproliferative neoplasms (MPNs) was determined for a major Canadian city. Retrospective cases of MPN diagnoses (essential thrombocythemia, polycythemia vera, and primary myelofibrosis) between 2011 to 2015 were retrieved from the Southern Alberta Cancer Cytogenetics Laboratory’s database at Alberta Public Laboratories. Results An incidence rate of 2.05 cases per 100,000 person-years (95% CI 1.73–2.41) was determined, giving an age-standardized Canadian incidence of 2.71 cases per 100,000 person years (95% CI 2.63–2.78). MPN diagnoses occurred at a wide age range of 8–93 (median 66) and an age-dependent increase in incidence. Incidence rates for the MPNs are first reported here for a Canadian population.

Objective The epidemiology of chronic myeloid leukemia is shifting due to the aging global population and the recent discovery and availability of targeted treatment options. This study provides recent data regarding the incidence of CML in Calgary, a major Canadian city. Data from patients diagnosed with CML by bone marrow sample analysis from 2011 to 2015 were collected from the database of the sole centralized cytogenetics facility in service of Calgary and its surrounding area. Results With an average of 10.2 newly diagnosed cases per year in Calgary from 2011 to 2015, the incidence rate was calculated to be 0.75 cases per 100,000 person-years (95% CI 0.57–0.99). With age standardization, the incidence was 0.87 cases per 100,000 person-years (95% CI 0.82–0.91) for the Canadian population, which was low compared to other developed Western nations. The highest incidence rates were observed in the older patient categories, however there was a broad age distribution for incident cases and the median age at diagnosis was 48. There was a general male bias for CML most pronounced at the younger ages. Our description of CML incidence will help to inform healthcare planners amidst the dramatically altered treatment of this hematological neoplasm.

Background Chronic kidney disease (CKD) is often asymptomatic in its early stages but is indicated and is diagnosed with an estimated glomerular filtration rate (eGFR)

Objectives Mitigation of unnecessary and redundant laboratory testing is an important quality assurance priority for laboratories and represents an opportunity for cost savings in the health care system. Family physicians represent the largest utilizers of laboratory testing by a large margin. Engagement of family physicians is therefore key to any laboratory utilization management initiatives. Despite this, family physicians have been largely excluded from the planning and implementation of such initiatives. Our purposes were to (1) assess the importance of lab management issues to family physicians, and (2) attempt to define the types of initiatives most acceptable to family physicians. Design and methods We invited all Alberta family practice residents and practicing physicians to participate in a self-administered online electronic survey. Survey questions addressed the perceived importance of lab misutilization, prevalence of various types of misutilization, acceptability of specific approaches to quality control, and responsibility of various parties to address this issue. Results Of 162 respondents, 95% considered lab misutilization to be either important or very important. Many physicians placed the responsibility for addressing lab misutilization issues on multiple parties, including patients, but most commonly the ordering physician (97%). Acceptability for common strategies for quality improvement in lab misutilization showed a wide range (35%–98%). Conclusions These responses could serve as a framework for laboratories to begin discussions on this important topic with primary care groups.

Aim: Chlamydia trachomatis is the most prevalent bacterial sexually transmitted infection in developed nations and is an important public health concern. We aimed to assess the factors associated with testing and positivity of C. trachomatis in a large population. Methods: A retrospective study of a large Canadian health region was undertaken using 2011 census and laboratory data. Demographic and socioeconomic data from the national household survey were linked to microbiologic data for C. trachomatis. Multivariable generalized estimating equation models were constructed to examine relative risk for C. trachomatis testing and positivity. Results: For testing and positivity, female sex and younger age groups were associated with increased risk. University education and South Asian ethnicity were associated with lower risk of positivity. Conclusion: Incorporating socio-demographic factors will be critical to the success of future sexually transmitted infection public health programs.

Data presented in this article include the top 51 ordered laboratory tests in Calgary and surrounding area, Alberta, from January to December 2017. This data set was collected from Calgary Laboratory Service’s Laboratory Information System, and included top 51 tests ordered from community (n = 11, 224, 330), inpatient (n = 2,340,594) and emergency (n = 1,670,062) settings. Test order mnemonic that were not true laboratory tests (eg: “extra PST tube”, “extra tube”, etc.) were excluded in the analysis. The top test ordered in all 3 test encounters was the complete blood count test (community encounter, n = 921, 873; inpatient setting, n = 357, 375; and emergency setting, n = 276, 954). This data article was submitted as a companion paper to the related research article, “Estimated costs of 51 commonly ordered laboratory tests in Canada” [1]. Keywords: Laboratory medicine, Pathology informatics, Laboratory utilization management

Background Clinical guidelines for H. pylori screening and post-treatment testing endorse the use of urea breath test (UBT), H. pylori stool antigen test (HpSAT), and biopsy-related tests. Due to protracted wait times at our patient service centers and non-compliance in children and elderly with complications for the UBT, we sought to compare UBT and HpSAT in the city of Calgary, Canada with a population close to 1.4 million people. Methods To achieve this, a prospective diagnostic trial was performed comparing UBT to HpSAT in patients presenting with dyspepsia. A total of N = 150 patients agreed to undergo UBT (13C-UBT kit, Helikit, Isodiagnostika Inc.) and consented to provide a stool specimen for simultaneous HpSAT testing (Diasorin LIAISON® XL H. pylori SA Monoclonal chemiluminescent immunoassay) in our centralized laboratory. Results Our data show that concordant results were obtained in 148/150 (98.7%) patients with a positivity rate of 17.4%. One of two discrepants (UBT positive/HpSAT negative) resolved after repeat testing. Using UBT as the gold standard, HpSAT had a sensitivity of 96.30% (95% CI; 81.03% to 99.91%) and specificity of 100% (95% CI; 97.05% to 100.00%). A positive predictive value of 100% and negative predictive value of 99.2% (95% CI; 94.73% to 99.88%) was obtained. For patients where drug information was available, 38/130 (29.2%) had received an antibiotic associated with H. pylori in the preceding 12 months, with UBT and HpSAT providing concordant results in 37/38 (97.4%) of these individuals. Of note, 6/130 (4.6%) patients had received a specific combination anti-H.pylori treatment, and all 6/6 (100%) had concordant negative results suggesting successful eradication. A post-implementation economic evaluation of labor and materials associated with testing demonstrates a cost-savings of approximately USD5.47 per specimen in this locale. Conclusion Our study confirms that HpSAT is a viable alternative to UBT for H. pylori screening in our jurisdiction with equivalent test performance and cost-savings. Pre- and post-implementation analysis of test compliance rates, waiting times, and test turn around times will also be presented. Disclosures D. Pillai, Diasorin: None, Educational grant.

Objectives: Very little is known about the relative contributions of physician specialty groups and individual physicians to overall clinical laboratory expenditures. The objectives of this study were to determine the costs of clinical laboratory test expenditures attributable to 30 medical specialties and the associated per capita physician expenditures for an entire major Canadian city. Only chemistry, hematology, and microbiology tests were included in this study. Methods: Retrospective cohort study involving all physicians in Calgary, Canada, and surrounding areas (n = 3,499) and secondary data on laboratory test orders. Results: Data were obtained on approximately 20 million test requests. The mean clinical laboratory test expenditure, in Canadian dollars, per physician was $27,945 for all physicians combined. Total expenditures by primary care physicians (family physicians and general practitioners) accounted for 58% of total expenditures. Conclusions: There was wide variation in clinical laboratory test expenditures among specialties and on a per capita basis within medical specialties.

In this study we investigate the effects of user skill and task challenge on online shoppers’ experiences. We use a model suggested by flow theory in which shoppers are grouped into four categories (flow, anxiety, boredom, and apathy) based on their perceptions of task challenge and their skill in performing an online shopping task. Results show that anxious shoppers have lower perceptions of the dimensions of flow, believe online shopping Web sites are less useful, and believe they are less likely to use the system in the future compared to the other three groups of online shoppers. In addition to challenge and skill, having a clear goal and fast feedback also contribute to the flow experience.

In this study we investigate the effects of user skill and task challenge on online shoppers' experiences. We use a model suggested by flow theory in which shoppers are grouped into four categories (flow, anxiety, boredom, and apathy) based on their perceptions of task challenge and their skill in performing an online shopping task. Results show that anxious shoppers have lower perceptions of the dimensions of flow, believe online shopping websites are less useful, and believe they are less likely to use the system in the future compared to the other three groups of online shoppers.