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Hepatic resection has become common in the United States for both primary and secondary hepatic tumors.Variation in outcomes after hepatic resection is related to patient characteristics, the indication for operation, and hospital procedural volume.Observational study using a nationally representative database.All patients in the Nationwide Inpatient Sample for 1996 and 1997 with a primary procedure code for hepatic resection (N = 2097).Outcomes included in-hospital mortality and length of stay. Risk-adjusted analyses were performed using hierarchical multivariate models.Overall mortality for the 2097 patients was 5.8%. The most common indications for hepatic resection were secondary metastases (52%), primary hepatic malignancy (16%), biliary tract malignancy (10%), and benign hepatic tumor (5%). High-volume hospitals had a mortality rate of 3.9% vs 7.6% at low-volume hospitals (P.001). In the multivariate analysis adjusting for patient case-mix, high-volume hospitals had a 40% lower risk of in-hospital mortality compared with low-volume hospitals (odds ratio, 0.60; 95% confidence interval, 0.39-0.92; P =.02). Other predictors of mortality in the multivariate analysis included age older than 65 years, hepatic lobectomy (vs wedge resection), primary hepatic malignancy (vs metastases), and the severity of underlying liver disease.Hospital procedural volume is an important predictor of mortality after hepatic resection. Patients who require resection of primary and secondary liver tumors should be offered referral to a high-volume center.

Hypothesis High-volume centers provide superior quality care and therefore have a lower incidence of postoperative complications. Design Observational statewide administrative database. Setting State of Maryland, nonfederal acute-care hospital (n = 52), performing liver resection (n = 35). Patients All patients discharged after undergoing hepatic resection from 1994 to 1998 (N = 569). Main Outcome Measures Two sequential analyses using multiple logistic regression of in-hospital mortality were performed to determine the relative importance of preoperative case-mix and postoperative complications. Results The overall in-hospital mortality rate was 4.8% and was significantly lower in high-volume hospitals (2.8%) than in low-volume hospitals (10.2%) ( P P = .02). Having surgery at a low-volume hospital was associated with increased rates of several postoperative complications: reintubation (relative risk [RR], 2.5; 95% CI, 1.8-3.4), pulmonary failure (RR, 2.3; 95% CI, 1.6-3.5), pneumonia (RR, 0.35; 95% CI, 1.0-5.6), acute renal failure (RR, 2.0; 95% CI, 1.1-3.7), acute myocardial infarction (RR, 2.6; 95% CI, 1.2-5.9), and aspiration (RR, 1.4; 95% CI, 0.9-2.0). When considering all other factors using statistical methods, hospital volume was no longer associated with mortality. Conclusions Patients who undergo hepatic resection at low-volume hospitals are at a higher risk of postoperative complications and death than those who have the same operation at high-volume hospitals. The empirical difference between outcomes at high- and low-volume hospitals seems to be due to a variation in postoperative complications.

Hypothesis We hypothesized that review of randomized controlled clinical trials (RCTs) with nonstatistically significant or "negative" results published in the surgical literature do not have appropriate statistical power to demonstrate equivalency between treatment arms. Data Sources and Study Selection The MEDLINE database was searched to obtain reports of all RCTs with negative results published in 3 surgical journals from 1988 to 1998. Manual review of one year (1997) of publications for each journal was performed to validate our search strategy. Equivalency was evaluated using the Two One-Sided Tests Procedure and post hoc power calculations. Data Synthesis Ninety reports of RCTs with negative results were identified in the surgical literature between 1988 and 1998. The manual review of 1997 showed a 100% retrieval rate for our search strategy. After applying the Two One-Sided Tests Procedure, 35 reports (39%) met the criteria for demonstrating equivalency. The other 55 reports (61%) contained at least a 10% absolute difference in the 90% confidence interval of Δ. Using the power calculation method, only 22 (24%) articles had a power greater than .80 to detect a 50% difference in therapeutic effect. Only 29% of the reports included a formal sample size calculation and these studies were more likely to demonstrate equivalency than those without a sample size estimate ( P Conclusions Many reports from negative RCTs published in the surgical literature lack sufficient statistical power to establish that clinically important differences are not present. Surgeons should perform appropriate sample size calculations when designing RCTs and recognize the utility of confidence intervals when reporting negative results.

ObjectiveThe objective of this study was to determine the coexistence or later development of pararenal and infrarenal abdominal aortic aneurysms (AAAs) in patients with thoracic aortic dissections.MethodsOne hundred forty-five patients (95 men, 50 women) encountered from 1992 to 2001 with thoracic aortic dissections—excluding those associated with trauma, those with Marfan's syndrome, and those with thoracoabdominal aortic aneurysms—were studied. The most common risk factors included hypertension (59%) and a history of tobacco use (52%). Type III dissections affected 86 patients (59%), and type I dissections affected the remaining 59 patients (41%). Aortic computed tomography (CT) scans were obtained annually. Data were assessed by univariate and multivariate analyses.ResultsFive patients (3%) had a history of AAA repair prior to their thoracic aortic dissection diagnosis—3 were type III dissections and 2 were type I dissections. Twelve patient's (8%) AAAs were diagnosed with the initial CT study of their thoracic aortic dissection. Type III dissections accounted for all but one of these (11 of 12, 92%). Ten additional AAAs (7%) developed in the 128 patients with no initial evidence of an AAA being recognized from 1 to 48 months (average 16 months) after the thoracic aortic dissection was diagnosed. Type III dissections affected 8 of these 10 patients. Among the total 27 AAAs noted in this series, 74% (20 AAAs) were not continuous with the thoracic aortic dissection. In the univariate analysis, age (P = .0002), male gender (P = .044), history of smoking (P = .01), chronic obstructive pulmonary disease (P < .001), duration of dissection (P = .05), and presence of type III dissection (P = .009) were associated with the presence of an AAA. In the multivariate analysis, both chronic obstructive pulmonary disease (odds ratio 5.4, 95% CI, 1.3 to 22.3; P = .02) and age (OR 1.06, 95% CI, 1.02 to 1.11; P = .004) were significant predictors of the development of AAAs.ConclusionThis study documented that patients with thoracic aortic dissections are at risk to harbor or develop a later AAA. This finding supports the tenet that abdominal CTs or ultrasound scanning should be mandatory in the follow-up of patients with known thoracic aortic dissections.

Objective: This study was undertaken to determine the effect of gadolinium arteriography on renal function and its diagnostic accuracy in patients with azotemia with suspected renovascular disease. Methods: Catheter-based digital subtraction arteriographic studies with gadolinium as the contrast agent were performed on 25 occasions in 21 consecutive patients with azotemia to evaluate renal arterial circulation. Gadolinium (gadodiamide, 287 mg/mL) was the only contrast used in these studies. Quantities of gadolinium administered ranged from 40 to 264 mL (mean ± standard deviation, 124 ± 74 mL). Serial determinations of renal function were performed in all patients. Arteriography was undertaken 20 times after prior renal revascularizations: seven times as a routine postoperative follow-up study, nine for increasing azotemia, three for worsening hypertension, and once for evaluation of a known renal artery stenosis in patient with an abdominal aortic aneurysm. Three additional arteriograms were performed as part of an evaluation for suspected renovascular hypertension. The two remaining arteriograms were performed in patients with known aortic aneurysms in whom renal artery stenosis was suspected. Results: No adverse changes in renal function followed gadolinium arteriography. Prearteriography serum creatinine values ranged from 1.6 to 9.1 mg/dL (3.0 ± 1.4 mg/dL), compared with postangiography values that ranged from 1.2 to 8.4 mg/dL (2.9 ± 1.3 mg/dL). Comparable blood urea nitrogen values ranged from 23 to 71 mg/dL (40.1 ± 13.5 mg/dL) before arteriography and from 21 to 68 mg/dL (36.5 ± 13.3 mg/dL) after arteriography. All 38 renal arteries evaluated were adequately imaged. First-order and second-order branchings were well visualized on selective renal studies. Twenty-one renal arteries showed no abnormalities, including six of seven reconstructed arteries subjected to early postoperative evaluation. Twelve renal arteries manifested significant disease, including seven with stenoses and five that had become occluded. Among five additional renal arteries studied, two exhibited obstructing thrombus, two had dissections, and one had a kinked aortorenal bypass graft. Conclusion: Catheter-based arteriography in patients with azotemia with gadolinium as a contrast agent is a safe and effective means to evaluate the renal arterial circulation. The preferential use of gadolinium in lieu of nephrotoxic iodinated contrast agents for catheter-based arteriography in patients with azotemia is supported by this experience. (J Vasc Surg 2003;37:346-52.)

Objective To determine whether the introduction of endovascular technology changed the relationship of hospital volume to mortality with abdominal aortic aneurysm repair. Methods Data from all hospitals in the United States that performed abdominal aortic aneurysm surgery on Medicare patients from 2001 to 2003 were obtained from the national Medicare database. The primary outcome variable was death ≤30 days of operation or before hospital discharge. We determined the effect of total hospital volume on operative mortality for all types of repair and for endovascular and open repair separately. All analyses were adjusted for patient risk using logistic regression. Results The proportion of abdominal aortic aneurysms repaired with an endovascular approach increased from 27% to 39% during the 3-year study period. Hospital volume was significantly related to operative mortality in all comparisons. Mortality rates were 80% higher at hospitals in the lowest vs the highest quartile of total volume (odds ratio [OR], 1.81; 95% confidence interval [CI], 1.62-2.04) when considering all types of repair together. A similar relationship between total hospital volume and mortality was found when separately examining open repair (OR, 1.52; 95% CI, 1.33-1.73) and endovascular repair (OR, 1.68; 95% CI, 1.32-2.22). Higher-volume hospitals were more likely to use the endovascular approach. The highest-volume hospitals used the endovascular approach 44% of the time compared with only 18% at the lowest-volume hospitals. This greater use of the endovascular procedure at high-volume hospitals accounted for 37% of the difference in mortality between high- and low-volume hospitals. Conclusion As the endovascular repair becomes more widespread, the relationship between hospital volume and operative mortality still remains. High-volume hospitals are more likely to use the endovascular approach, and this explains a significant portion of the observed impact of hospital volume on mortality.

ObjectiveSurgical treatment of intact thoracoabdominal aortic aneurysm (TAAA) is crucial to prevent rupture but is associated with high perioperative mortality. We tested the hypothesis that provider volume of surgical treatment of TAAA is an important determinant of operative outcome.Patients and methodsClinical information regarding repair of intact TAAA in 1542 patients from 1988 to 1998 was obtained from the Nationwide Inpatient Sample (NIS), a stratified discharge database of a representative 20% of US hospitals. Demographic data included age, sex, race, nature of admission, and comorbid conditions. Annual hospital volume of TAAA treated was grouped into terciles and defined as low (LVH; 1-3 cases [median, 1]), medium (MVH; 2-9 cases [median, 4]), or high (HVH; 5-31 cases [median, 12]). Annual surgeon volume was defined as low (LVS; 1-2 cases [median, 1]) or high (HVS; 3-18 cases [median, 7]). The primary outcome measure was in-hospital postoperative mortality. Secondary outcome measures included length of stay, and cardiac, pulmonary, and renal complications. Adjusted and unadjusted analyses were conducted.ResultsOverall mortality was 22.3%. Mortality improved over time. LVH and HVH differed in mortality rates (27.4% vs 15.0%; P < .001). Mortality between LVS and HVS also differed significantly (25.6% vs 11.0%; P < .001). When controlling for patient demographic data, comorbid conditions, and postoperative complications, both hospital and surgeon volume were significant predictors of mortality for intact TAAA repair (LVS: odds ratio [OR] 2.6, P < .001; LVH: OR 2.2, P < .001; and MVH: OR 1.7, P = .004).ConclusionsGreater hospital and surgeon TAAA treatment volumes contribute to better outcome. Given the relative high perioperative mortality associated with TAAA repair, regionalization of care to high-volume providers with consistently lower postoperative mortality deserves consideration by patients, physicians, and health care planners.

ObjectiveThe Center for Medicare and Medicaid Services recently began assessing financial penalties to hospitals with high readmission rates for a narrow set of medical conditions. Because these penalties will be extended to surgical conditions in the near future, we sought to determine whether readmissions are a reliable predictor of hospital performance with vascular surgery.MethodsWe examined 4 years of national Medicare claims data from 1576 hospitals on beneficiaries undergoing three common vascular procedures: open or endovascular abdominal aortic aneurysm repair (n = 81,520) or lower extremity arterial bypass (n = 57,190). First, we divided our population into two groups on the basis of operative date (2005-2006 and 2007-2008) and generated hospital risk- and reliability-adjusted readmission rates for each time period. We evaluated reliability through the use of the “test-retest” method; highly reliable measures will show little variation in rates over time. Specifically, we evaluated the year-to-year reliability of readmissions by calculating Spearman rank correlation and weighted κ tests for readmission rates between the two time periods.ResultsThe Spearman coefficient between 2005-2006 readmissions rankings and 2007-2008 readmissions rankings was 0.57 (P < .001) and weighted κ was 0.42 (P < .001), indicating a moderate correlation. However, only 32% of the variation in hospital readmission rates in 2007-2008 was explained by readmissions during the 2 prior years. There were major reclassifications of hospital rankings between years, with 63% of hospitals migrating among performance quintiles between 2005-2006 and 2007-2008.ConclusionsRisk-adjusted readmission rates for vascular surgery vary substantially year to year; this implies that much of the observed variation in readmission rates is either random or caused by unmeasured factors and not caused by changes in hospital quality that may be captured by administrative data.

Background Black patients have a higher mortality rate than nonblacks after abdominal aortic aneurysm repair. We sought to understand the factors responsible for this racial disparity in the mortality rate after aneurysm repair. Methods The Medicare database (2001-2006) was used to identify 160,785 patients undergoing open and endovascular abdominal aortic aneurysm repairs. We used risk-adjusted mortality as our primary measure of quality and logistic regression to determine the relationship between race and mortality, sequentially adding contributing factors including patient characteristics, the type of repair (endovascular vs open repair), socioeconomic status, and hospital quality. From these sequential regression models, we estimated the proportion of the disparity that can be explained by each factor. Results Black patients had a 36% higher risk-adjusted mortality after aneurysm repair than nonblack patients (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.20-1.53). Even after accounting for the type of repair, a significant difference in mortality remained (OR, 1.33; 95% CI, 1.18-1.50). Mortality rates were higher in hospitals treating a higher proportion of black patients. Adjusting for these differences in hospital quality, this disparity was no longer significant (OR, 1.07; 95% CI, 0.93-1.25). We estimate that 29% of the observed disparity in mortality is caused by patient comorbidities, 6% from the use of endovascular repairs, 26% due to socioeconomic factors, and 25% because black patients receive care in lower-quality hospitals. Conclusions Although many factors contribute, a large proportion of observed disparities in outcomes are attributable to black patients receiving care in lower-quality hospitals. Efforts aimed at improving disparities must focus on improved access to high-quality hospitals and improved resources at the hospitals that treat higher proportions of black patients.