The effect of social integration on outcomes after major lower extremity amputation.

OBJECTIVE: Major lower extremity (MLE) amputation is a common procedure that results in a profound change in a patient's life. We sought to determine the association between social support and outcomes after amputation. We hypothesized that patients with greater social support will have better post amputation outcomes. METHODS: From November 2011 to May 2013, we conducted a cross-sectional, observational, multicenter study. Social integration was measured by the social integration subset of the Short Form Craig Handicap Assessment and Reporting Technique. Systemic social support was assessed by comparing a United States and Tanzanian population. Walking function was measured using the 6-minute walk test and quality of life (QoL) was measured using the EuroQol-5D. RESULTS: We recruited 102 MLE amputees. Sixty-three patients were enrolled in the United States with a mean age of 58.0. Forty-two (67%) were male. Patients with low social integration were more likely to be unable to ambulate (no walk 39% vs slow walk 23% vs fast walk 10%; P = .01) and those with high social integration were more likely to be fast walkers (no walk 10% vs slow walk 59% vs fast walk 74%; P = .01). This relationship persisted in a multivariable analysis. Increasing social integration scores were also positively associated with increasing QoL scores in a multivariable analysis (ß, .002; standard error, 0.0008; P = .02). In comparing the United States population with the Tanzanian cohort (39 subjects), there were no differences between functional or QoL outcomes in the systemic social support analysis. CONCLUSIONS: In the United States population, increased social integration is associated with both improved function and QoL outcomes among MLE amputees. Systemic social support, as measured by comparing the United States population with a Tanzanian population, was not associated with improved function or QoL outcomes. In the United States, steps should be taken to identify and aid amputees with poor social integration.

Prospective, randomized, multi-institutional clinical trial of a silver alginate dressing to reduce lower extremity vascular surgery wound complications.

OBJECTIVE: Wound complications negatively affect outcomes of lower extremity arterial reconstruction. By way of an investigator initiated clinical trial, we tested the hypothesis that a silver-eluting alginate topical surgical dressing would lower wound complication rates in patients undergoing open arterial procedures in the lower extremity. METHODS: The study block-randomized 500 patients at three institutions to standard gauze or silver alginate dressings placed over incisions after leg arterial surgery. This original operating room dressing remained until gross soiling, clinical need to remove, or postoperative day 3, whichever was first. Subsequent care was at the provider's discretion. The primary end point was 30-day wound complication incidence generally based on National Surgical Quality Improvement Program guidelines. Demographic, clinical, quality of life, and economic end points were also collected. Wound closure was at the surgeon's discretion. RESULTS: Participants (72% male) were 84% white, 45% were diabetic, 41% had critical limb ischemia, and 32% had claudication (with aneurysm, bypass revision, other). The overall 30-day wound complication incidence was 30%, with superficial surgical site infection as the most common. In intent-to-treat analysis, silver alginate had no effect on wound complications. Multivariable analysis showed that Coumadin (Bristol-Myers Squibb, Princeton, NJ; odds ratio [OR], 1.72; 95% confidence interval [CI], 1.03-2.87; P = .03), higher body mass index (OR, 1.05; 95% CI, 1.01-1.09; P = .01), and the use of no conduit/material (OR, 0.12; 95% CI, 0.82-3.59; P < .001) were independently associated with wound complications. CONCLUSIONS: The incidence of wound complications remains high in contemporary open lower extremity arterial surgery. Under the study conditions, a silver-eluting alginate dressing showed no effect on the incidence of wound complications.

Racial Disparities in End-of-Life Care Among Patients With Prostate Cancer: A Population-Based Study.

OBJECTIVE: To examine racial disparities in end-of-life (EOL) care among black and white patients dying of prostate cancer (PCa). METHODS: Relying on the SEER-Medicare database, 3789 patients who died of metastatic PCa between 1999 and 2009 were identified. Information was assessed regarding diagnostic care, therapeutic interventions, hospitalizations, intensive care unit (ICU) admissions, and emergency department visits in the last 12 months, 3 months, and 1 month of life. Logistic regression tested the relationship between race and the receipt of diagnostic care, therapeutic interventions, and high-intensity EOL care. RESULTS: Overall, 729 patients (19.24%) were black. In the 12-months preceding death, laboratory tests (odds ratio [OR], 0.51; 95% CI, 0.36-0.72), prostate-specific antigen test (OR, 0.54; 95% CI, 0.43-0.67), cystourethroscopy (OR, 0.71; 95% CI, 0.56-0.90), imaging procedure (OR, 0.58; 95% CI, 0.41-0.81), hormonal therapy (OR, 0.53; 95% CI, 0.44-0.65), chemotherapy (OR, 0.59; 95% CI, 0.48-0.72), radiotherapy (OR, 0.74; 95% CI, 0.61-0.90), and office visit (OR, 0.38; 95% CI, 0.28-0.50) were less frequent in black versus white patients. Conversely, high-intensity EOL care, such as ICU admission (OR, 1.27; 95% CI, 1.04-1.58), inpatient admission (OR, 1.49; 95% CI, 1.09-2.05), and cardiopulmonary resuscitation (OR, 1.72; 95% CI, 1.40-2.11), was more frequent in black versus white patients. Similar trends for EOL care were observed at 3-month and 1-month end points. CONCLUSIONS: Although diagnostic and therapeutic interventions are less frequent in black patients with end-stage PCa, the rate of high-intensity and aggressive EOL care is higher in these individuals. These disparities may indicate that race plays an important role in the quality of care for men with end-stage PCa.

Testing for independence in J×K contingency tables with complex sample survey data.

The test of independence of row and column variables in a (J×K) contingency table is a widely used statistical test in many areas of application. For complex survey samples, use of the standard Pearson chi-squared test is inappropriate due to correlation among units within the same cluster. Rao and Scott (1981, Journal of the American Statistical Association 76, 221-230) proposed an approach in which the standard Pearson chi-squared statistic is multiplied by a design effect to adjust for the complex survey design. Unfortunately, this test fails to exist when one of the observed cell counts equals zero. Even with the large samples typical of many complex surveys, zero cell counts can occur for rare events, small domains, or contingency tables with a large number of cells. Here, we propose Wald and score test statistics for independence based on weighted least squares estimating equations. In contrast to the Rao-Scott test statistic, the proposed Wald and score test statistics always exist. In simulations, the score test is found to perform best with respect to type I error. The proposed method is motivated by, and applied to, post surgical complications data from the United States' Nationwide Inpatient Sample (NIS) complex survey of hospitals in 2008.

National variation in the utilization of alternative imaging in peripheral arterial disease.

OBJECTIVE: The value and cost-effectiveness of less invasive alternative imaging (AI) modalities (duplex ultrasound scanning, computed tomography angiography, and magnetic resonance angiography) in the care of peripheral arterial disease (PAD) has been reported; however, there is no consensus on their role. We hypothesized that AI utilization is low compared with angiography in the United States and that patient and hospital characteristics are both associated with AI utilization. METHODS: The Nationwide Inpatient Sample (2007-2010) was used to identify patients with an International Classification of Diseases-Ninth Edition diagnosis of claudication or critical limb ischemia (CLI) as well as PAD treatment (surgical, endovascular, or amputation). Patients with AI and those with angiography or expected angiography (endovascular procedures without imaging codes) were selected and compared. Multivariable logistic regression was performed for receiving AI stratified by claudication and CLI and adjusting for patient and hospital factors. RESULTS: We identified 290,184 PAD patients, of whom 5702 (2.0%) received AI. Patients with AI were more likely to have diagnosis of CLI (78.8% vs 48.6%; P < .0001) and receive open revascularizations (30.4% vs 18.8%; P < .0001). Van Walraven comorbidity scores (mean [standard error] 5.85 ± 0.22 vs 4.10 ± 0.05; P < .0001) reflected a higher comorbidity burden in AI patients. In multivariable analysis for claudicant patients, AI was associated with large bed size (odds ratio [OR], 3.26, 95% confidence interval [CI], 1.16-9.18; P = .025), teaching hospitals (OR, 1.97; 95% CI, 1.10-3.52; P = .023), and renal failure (OR, 1.52; 95% CI, 1.13-2.05; P = .006). For CLI patients, AI was associated with black race (OR, 1.53; 95% CI, 1.13-2.08; P = .006) and chronic heart failure (OR, 1.29; 95% CI, 1.04-1.60; P = .021) and was negatively associated with renal failure (OR, 0.80; 95% CI, 0.67-0.95; P = .012). The Northeast and West regions were associated with higher odds of AI in claudicant patients (OR, 2.41; 95% CI, 1.23-4.75; P = .011; and OR, 2.59; 95% CI, 1.34-5.02; P = .005, respectively) and CLI patients (OR, 4.31; 95% CI, 2.20-8.36; P < .0001; and OR, 2.18; 95% CI, 1.12-4.22; P = .021, respectively). Rates of AI utilization across states were not evenly distributed but showed great variability, with ranges from 0.31% to 9.81%. CONCLUSIONS: National utilization of AI for PAD is low and shows great variation among institutions in the United States. Patient and hospital factors are both associated with receiving AI in PAD care, and AI utilization is subject to significant regional variation. These findings suggest differences in systems of care or practice patterns and call for a clearer understanding and a more unified approach to imaging strategies in PAD care.

The effect of surgeon specialization on outcomes after ruptured abdominal aortic aneurysm repair.

OBJECTIVE: Although mortality after elective abdominal aortic aneurysm (AAA) repair has steadily declined, operative mortality for a ruptured AAA (rAAA) remains high. Repair of rAAA at hospitals with a higher elective aneurysm workload has been associated with lower mortality rates irrespective of the mode of treatment. This study sought to determine the association between surgeon specialization and outcomes after rAAA repair. METHODS: The American College of Surgeons National Surgical Quality Improvement Project database from 2005 to 2010 was used to examine the 30-day mortality and morbidity outcomes of patients undergoing rAAA repair by vascular and general surgeons. Multivariable logistic regression analysis was performed for each death and morbidity, adjusting for all independently predictive preoperative risk factors. Survival curves were compared using the log-rank test. RESULTS: We identified 1893 repairs of rAAAs, of which 1767 (96.1%) were performed by vascular surgeons and 72 (3.9%) were performed by general surgeons. There were no significant differences between patients operated on by general vs vascular surgeons in preoperative risk factors or method of repair. Overall 30-day mortality was 34.3% (649 of 1893). After risk adjustment, mortality was significantly lower in the vascular surgery group compared with the general surgery group (odds ratio [OR], 0.51; 95% confidence interval [CI], 0.30-0.86; P = .011). The risk of returning to the operating room (OR, 0.58; 95% CI, 0.35-0.97; P = .038), renal failure (OR, 0.54; 95% CI, 0.31-0.95; P = .034), and a cardiac complication (OR, 0.53; 95% CI, 0.28-0.99; P = .047) were all significantly less in the vascular surgery group. CONCLUSIONS: Despite similar preoperative risk factors profiles, patients who were operated on by vascular surgeons had lower mortality, less frequent returns to the operating room, and decreased incidences of postoperative renal failure and cardiac events. These data add weight to the case for further centralization of vascular services.

Audit-identified avoidable factors in maternal and perinatal deaths in low resource settings: a systematic review.

BACKGROUND: Audits provide a rational framework for quality improvement by systematically assessing clinical practices against accepted standards with the aim to develop recommendations and interventions that target modifiable deficiencies in care. Most childbirth-associated mortality audits in developing countries are focused on a single facility and, up to now, the avoidable factors in maternal and perinatal deaths cataloged in these reports have not been pooled and analyzed. We sought to identity the most frequent avoidable factors in childbirth-related deaths globally through a systematic review of all published mortality audits in low and lower-middle income countries. METHODS: We performed a systematic review of published literature from 1965 to November 2011 in Pubmed, Embase, CINAHL, POPLINE, LILACS and African Index Medicus. Inclusion criteria were audits from low and lower-middle income countries that identified at least one avoidable factor in maternal or perinatal mortality. Each study included in the analysis was assigned a quality score using a previously published instrument. A meta-analysis was performed for each avoidable factor taking into account the sample sizes and quality score from each individual audit. The study was conducted and reported according to PRISMA guidelines for systematic reviews. RESULTS: Thirty-nine studies comprising 44 datasets and a total of 6,205 audited deaths met inclusion criteria. The analysis yielded 42 different avoidable factors, which fell into four categories: health worker-oriented factors, patient-oriented factors, transport/referral factors, and administrative/supply factors. The top three factors by attributable deaths were substandard care by a health worker, patient delay, and deficiencies in blood transfusion capacity (accounting for 688, 665, and 634 deaths attributable, respectively). Health worker-oriented factors accounted for two-thirds of the avoidable factors identified. CONCLUSIONS: Audits provide insight into where systematic deficiencies in clinical care occur and can therefore provide crucial direction for the targeting of interventions to mitigate or eliminate health system failures. Given that the main causes of maternal and perinatal deaths are generally consistent across low resource settings, the specific avoidable factors identified in this review can help to inform the rational design of health systems with the aim of achieving continued progress towards Millennium Development Goals Four and Five.

When to call it a day: incremental risk of amputation and death after multiple revascularization.

BACKGROUND: Patients with critical limb ischemia (CLI) often undergo revascularization before amputation. The exact relationship between multiple procedures and increased risk of amputation is unclear. We sought to determine the increased risk of amputation for each additional revascularization. METHODS: The 2007-2009 California State Inpatient Database (SID) was used to identify a cohort of CLI patients undergoing revascularization and conduct a time-to-event analysis for patients undergoing one or more revascularization procedures. One-year estimates were generated with Kaplan-Meier curves and compared with the log-rank test. The Wei-Lin-Weissfeld (WLW) marginal proportional hazards model was used to assess independent effects of number of revascularization procedures on amputation and death. RESULTS: A total of 11,190 patients with CLI underwent revascularization between July 2007 and December 2009. Their mean age was 71.0 years (interquartile range 62-80 years) and 6255 (55.9%) were male. Over half the subjects (55.2%) were smokers and there was a high burden of comorbidities in the cohort. One-year estimates of amputation by number of revascularizations (1: 23.3%; 2: 27.1%; 3: 30.3%; 4: 26.7%; 5(+): 28.6%; P < 0.001) and death (1: 18.7%; 2: 21.1%; 3: 26.3%; 4: 23.6%; 5+: 32.1%; P = 0.012) increased significantly as procedures increased. In the WLW model for amputation, the hazard increased significantly for patients with 2 revascularization versus 1 (HR = 1.22; 95% CI 1.09-1.37; P = 0.001) and 3 revascularizations versus 2 (HR = 1.33; 95% CI 1.10-1.62; P = 0.004). In the multivariable WLW models for death, the increase in revascularization procedures for 2 compared with 1 (HR = 1.18; 95% CI 1.04-1.34; P = 0.010) was significant. CONCLUSIONS: The risk of amputation increases with each additional revascularization procedure. These findings hold true for both percutaneous transluminal angioplasty only and lower extremity bypass only subsets. In addition, increased revascularization procedures appear to result in an increased risk of death. We advocate for continued communication between clinicians and patients on the true risks and benefits of additional revascularization procedures.

Use of surveillance imaging following treatment of small renal masses.

PURPOSE: With the increasing incidence of small renal masses, there is greater use of ablation, nephron sparing surgery and surveillance compared to radical nephrectomy. However, patterns of care in the use of posttreatment imaging remain uncharacterized. The purpose of this study is to determine the rate of posttreatment imaging after various treatments for small renal mass. MATERIALS AND METHODS: Using SEER (Surveillance, Epidemiology and End Results)-Medicare data during 2005 to 2009, we identified 1,682 subjects diagnosed with small renal mass and treated with open partial nephrectomy (330), minimally invasive partial nephrectomy (160), open radical nephrectomy (404), minimally invasive radical nephrectomy (535), thermal ablation (212) and surveillance (42). Use of imaging was compared within 24 months of treatment and multivariate regression models were constructed to identify factors associated with increased imaging use. RESULTS: On adjusted analyses thermal ablation was associated with almost eightfold greater odds of surveillance imaging compared with open radical nephrectomy (OR 7.7, 95% CI 1.01-59.4). Specifically, thermal ablation was associated with increased computerized tomography (OR 5.28) and magnetic resonance imaging (OR 2.19) use and decreased ultrasound use (OR 0.59). Minimally invasive partial nephrectomy (OR 3.28) and open partial nephrectomy (OR 3.19) were also associated with increased computerized tomography use to a lesser extent. CONCLUSIONS: Subjects undergoing nephron sparing surgery undergo more posttreatment imaging compared to open radical nephrectomy. Although possibly associated with lower morbidity, thermal ablation is associated with significantly greater use of imaging compared to other small renal mass treatments. This may increase costs and radiation exposure, although further study is needed for confirmation.

Comparative methods for handling missing data in large databases.

OBJECTIVE: Analysis of complex survey databases is an important tool for health services researchers. Missing data elements are challenging because the reasons for "missingness" are multifactorial, especially categorical variables such as race. We simulated missing data for race and analyzed the bias from five methods used in predicting major amputation in patients with critical limb ischemia (CLI). METHODS: Patient discharges with fully observed data containing lower extremity revascularization or major amputation and CLI were selected from the 2003 to 2007 Nationwide Inpatient Sample, a complex survey database (weighted n = 684,057). Considering several random missing data schemes, we compared five missing data methods: complete case analysis, replacement with observed frequencies, missing indicator variable, multiple imputation, and reweighted estimating equations. We created 100 simulated data sets, with 5%, 15%, or 30% of subjects' race drawn to be missing from the full data set. Bias was estimated by comparing the estimated regression coefficients averaged over 100 simulated data sets (ß(miss)) from each method vs estimates from the fully observed data set (ß(full)), with relative bias calculated as (ß(full) - ß(miss)/ß(full)) × 100%. RESULTS: Our results demonstrate that reweighted estimating equations produce the least biased and the missing indicator variable produces the most biased coefficients. Complete case analysis, replacement with observed frequencies, and multiple imputation resulted in moderate bias. Sensitivity analysis demonstrated the optimal method choice depends on the quantity and type of missing data encountered. CONCLUSIONS: Missing data are an important analytic topic in research with large databases. The commonly used missing indicator variable method introduces severe bias and should be used with caution. We present empiric evidence to guide method selection for handling missing data.

The effect of postoperative stroke and myocardial infarction on long-term survival after carotid revascularization.

INTRODUCTION: The largest randomized controlled trial that compared the efficacy of carotid endarterectomy (CEA) with carotid artery stenting (CAS) showed equivalent outcomes for the composite end point of postoperative stroke, myocardial infarction (MI), or death. However, CAS had a higher risk of postoperative stroke, and CEA had a higher risk of MI. We hypothesize that there is a differential association of postoperative stroke, compared with that of postoperative MI, with reduced long-term survival after carotid revascularization when compared with neither complication. METHODS: The Vascular Study Group of New England database was used to identify all CEA and CAS procedures performed between 2003 and 2011. Patients were stratified according to whether they experienced an in-hospital postoperative stroke (minor or major), MI (troponin elevation, electrocardiographic changes, or clinical symptoms), or neither. Primary study end point was survival during the first year and the first 5 years postoperatively. Multivariable Cox proportional hazards models compared the magnitude of association of stroke and MI on survival. RESULTS: Of 8315 patients, 81 (0.97%) experienced postoperative MI, and 63 (0.76%) experienced stroke. During the first year after operation, survival significantly differed among the three groups: neither, 96%; MI, 84%; stroke, 77% (log-rank P < .0001). After adjusting for confounders, survival after postoperative stroke (hazard ratio [HR], 6.6; 95% confidence interval [CI], 3.7-12; P < .0001) was nearly twofold less than that after postoperative MI (HR, 3.6; 95% CI, 2-6.8; P < .0001). During the first 5 years postoperatively, multivariable modeling showed postoperative stroke and postoperative MI remained independent predictors of decreased survival, but the magnitude of association was similar (HR, 2.7; 95% CI, 1.7-4.3 [P < .0001] vs HR, 2.8; 95% CI, 1.8-4.3 [P < .0001]). CONCLUSIONS: During the first year after operation, postoperative stroke conferred a twofold lower survival than that after postoperative MI. By 5 years after operation, these survival curves converged, and the survival disadvantage associated with stroke became similar to that of MI. These data suggest that different postoperative complications after carotid revascularization have different implications for patients, with decreased short-term survival in patients experiencing a postoperative stroke. These findings help to inform our interpretation of studies that have used a composite end point in order to evaluate the comparative effectiveness of revascularization strategies.

Factors predicting resource utilization and survival after major amputation.

OBJECTIVE: Major amputation is associated with increased short-term healthcare resource utilization (RU), early mortality, and socioeconomic status (SES) disparities. Our objective is to study patient-specific and SES-related predictors of long-term RU and survival after amputation. METHODS: This retrospective analysis identified 364 adult patients who underwent index major amputation for critical limb ischemia from January 1995 through December 2000 at two tertiary centers with outcomes through December 2010. Age, gender, SES (race, income, insurance, and marital status), comorbidities (congestive heart failure [CHF], diabetes, diabetes with complications, and renal failure [RF]), subsequent procedures, cumulative length of stay (cLOS), and mortality were analyzed. Bivariate and multivariate Poisson regression for subsequent procedures and cLOS and Cox proportional hazard modeling for all-cause mortality were undertaken. RESULTS: During a mean follow-up of 3.25 years, amputation patients had mean cLOS of 71.2 days per person-year (median, 17.6), 19.5 readmissions per person-year (median, 2.1), 0.57 amputation-related procedures (median, 0), and 0.31 cardiovascular procedures (median, 0). Below-knee amputation as the index procedure was performed in 70% of patients, and 25% had additional amputation procedures. Of readmissions at ≤ 30 days, 52% were amputation-related. Overall mortality during follow-up was 86.9%; 37 patients (10.2%) died within 30 days. Among patients surviving >30 days, multivariate Poisson regression demonstrated that younger age (incidence rate ratio [IRR], 0.98), public insurance (IRR, 1.63), CHF (IRR, 1.60), and RF (IRR, 2.12) were associated with increased cLOS. Diabetes with complications (IRR, 1.90) and RF (IRR, 2.47) affected subsequent amputation procedures. CHF (IRR, 1.83) and RF (IRR, 3.67) were associated with a greater number of cardiovascular procedures. Cox proportional hazard modeling indicated older age (hazard ratio [HR], 1.04), CHF (HR, 2.26), and RF (HR, 2.60) were risk factors for decreased survival. Factors associated with SES were not significantly related to the outcomes. CONCLUSIONS: This study found that RU is high for amputees, and increased RU persists beyond the perioperative period. Results were similar across SES indices, suggesting higher SES may not be protective against poor outcomes when limb salvage is no longer attainable. These findings support the hypothesis that SES disparities may be more modifiable during earlier stages of care for critical limb ischemia.

Outcomes of lower extremity bypass performed for acute limb ischemia.

OBJECTIVE: Acute limb ischemia remains one of the most challenging emergencies in vascular surgery. Historically, outcomes following interventions for acute limb ischemia have been associated with high rates of morbidity and mortality. The purpose of this study was to determine contemporary outcomes following lower extremity bypass performed for acute limb ischemia. METHODS: All patients undergoing infrainguinal lower extremity bypass between 2003 and 2011 within hospitals comprising the Vascular Study Group of New England were identified. Patients were stratified according to whether or not the indication for lower extremity bypass was acute limb ischemia. Primary end points included bypass graft occlusion, major amputation, and mortality at 1 year postoperatively as determined by Kaplan-Meier life table analysis. Multivariable Cox proportional hazards models were constructed to evaluate independent predictors of mortality and major amputation at 1 year. RESULTS: Of 5712 lower extremity bypass procedures, 323 (5.7%) were performed for acute limb ischemia. Patients undergoing lower extremity bypass for acute limb ischemia were similar in age (66 vs 67; P = .084) and sex (68% male vs 69% male; P = .617) compared with chronic ischemia patients, but were less likely to be on aspirin (63% vs 75%; P < .0001) or a statin (55% vs 68%; P < .0001). Patients with acute limb ischemia were more likely to be current smokers (49% vs 39%; P < .0001), to have had a prior ipsilateral bypass (33% vs 24%; P = .004) or a prior ipsilateral percutaneous intervention (41% vs 29%; P = .001). Bypasses performed for acute limb ischemia were longer in duration (270 vs 244 minutes; P = .007), had greater blood loss (363 vs 272 mL; P < .0001), and more commonly utilized prosthetic conduits (41% vs 33%; P = .003). Acute limb ischemia patients experienced increased in-hospital major adverse events (20% vs 12%; P < .0001) including myocardial infarction, congestive heart failure exacerbation, deterioration in renal function, and respiratory complications. Patients who underwent lower extremity bypass for acute limb ischemia had no difference in rates of graft occlusion (18.1% vs 18.5%; P = .77), but did have significantly higher rates of limb loss (22.4% vs 9.7%; P < .0001) and mortality (20.9% vs 13.1%; P < .0001) at 1 year. On multivariable analysis, acute limb ischemia was an independent predictor of both major amputation (hazard ratio, 2.16; confidence interval, 1.38-3.40; P = .001) and mortality (hazard ratio, 1.41; confidence interval, 1.09-1.83; P = .009) at 1 year. CONCLUSIONS: Patients who present with acute limb ischemia represent a less medically optimized subgroup within the population of patients undergoing lower extremity bypass. These patients may be expected to have more complex operations followed by increased rates of perioperative adverse events. Additionally, despite equivalent graft patency rates, patients undergoing lower extremity bypass for acute ischemia have significantly higher rates of major amputation and mortality at 1 year.

Impact of hospital market competition on endovascular aneurysm repair adoption and outcomes.

OBJECTIVE: The share of total abdominal aortic aneurysm (AAA) repairs performed by endovascular aneurysm repair (EVAR) increased rapidly from 32% in 2001 to 65% in 2006 with considerable variation between states. We hypothesized that hospitals in competitive markets were early EVAR adopters and had improved AAA repair outcomes. METHODS: Nationwide Inpatient Sample and linked Hospital Market Structure (HMS) data was queried for patients who underwent repair for nonruptured AAA in 2003. In HMS, the Herfindahl Hirschman Index (HHI, range 0-1) is a validated and widely accepted economic measure of competition. Hospital markets were defined using a variable geographic radius that encompassed 90% of discharged patients. We conducted bivariate and multivariable linear and logistic regression analyses for the dependent variable of EVAR use. A propensity score-adjusted multivariable logistic regression model was used to control for treatment bias in the assessment of competition on AAA repair outcomes. RESULTS: A weighted total of 21,600 patients was included in our analyses. Patients at more competitive hospitals (lower HHI) were at increased odds of undergoing EVAR vs open repair (odds ratio, 1.127 per 0.1 decrease in HHI; P < .0127) after adjusting for patient demographics, comorbidities, and hospital level factors (bed size, teaching status, AAA repair volume, and ownership). Competition was not associated with differences in in-hospital mortality or vascular, neurologic, or other minor postoperative complications. CONCLUSIONS: Greater hospital competition is significantly associated with increased EVAR adoption at a time when diffusion of this technology passed its tipping point. Hospital competition does not influence post-AAA repair outcomes. These results suggest that adoption of novel vascular technology is not solely driven by clinical indications but may also be influenced by market forces.

Comparative effectiveness, costs and trends in treatment of small renal masses from 2005 to 2007.

UNLABELLED: What's known on the subject? and what does the study add?: Retrospective data have suggested an increased survival benefit for patients undergoing partial nephrectomy compared to radical nephrectomy, possibly as a result of the avoidance of long-term renalin sufficiency and subsequent sequelae. However, recent level-one evidence has questioned this benefit. Both retrospective studies and randomized controlled trials are not without limitations. There are few population-based data available with respect to the outcomes of partial nephrectomy vs radical nephrectomy. Additionally, there are no population-based studies analyzing the surgical approach (minimally-invasive vs open), as well as other modalities, such as ablation and surveillance. Finally, there is very little information available on the potential differences in cost for each approach. The present study comprises the first comprehensive population-based analysis of the trends, outcomes and costs of all treatment modalities for T1a renal masses from 2005 to 2007. OBJECTIVE: To perform a comprehensive analysis of the outcomes and costs for treatments for small renal masses (SRM) using a population-based approach. Partial nephrectomy may be associated with improved survival, although level-one evidence has questioned this survival advantage. PATIENTS AND METHODS: Using Surveillance, Epidemiology and End Results-Medicare data, we identified 1682 subjects who were diagnosed with SRM from 2005 to 2007. Treatment included open radical nephrectomy (ORN; n = 404), minimally-invasive radical nephrectomy (MIRN; n = 535), open partial nephrectomy (OPN; n = 330), minimally-invasive partial nephrectomy (MIPN; n = 160), ablation (n = 211) and surveillance (n = 42). Postoperative complications, renal insufficiency diagnosis, overall mortality, cancer-specific mortality and postoperative costs were compared. Covariates were balanced before outcomes analysis using propensity score methods. RESULTS: Although the use of nephron-sparing surgery (NSS) increased over the study period, radical nephrectomy remained the predominant approach for SRM in 2007. Minimally-invasive approaches had shorter lengths of stay (P < 0.001), whereas open approaches had more overall complications, respiratory complications and intensive care unit admissions (all P < 0.003). MIRN and ORN were associated with more peri-operative medical complications, acute renal failure, haemodialysis use and long-term chronic renal insufficiency diagnosis vs NSS (all P < 0.001). Ablation, MIRN and ORN were associated with the highest overall mortality rates (P < 0.001), whereas MIRN and ORN were associated with the highest cancer-specific mortality rates (P < 0.001). Treatment costs were lowest for surveillance ($2911) followed by ablation ($10730), MIRN ($15373), MIPN ($15695), OPN ($16986) and ORN ($17803). CONCLUSIONS: Although not the predominant treatment approach for SRM over the study period, the use of NSS increased and was associated with improved survival, fewer complications and less renal insufficiency. Minimally-invasive approaches confer lower costs.

Effect of minimizing tension during robotic-assisted laparoscopic radical prostatectomy on urinary function recovery.

OBJECTIVES: Although most prostatectomy studies emphasize optimal nerve-sparing dissection planes, subtle technical variation also affects functional outcomes. The impact of minimizing assistant/surgeon tension on urinary function has not been quantified. We assess urinary function after attenuating neurovascular bundle (NVB) and rhabdosphincter tension during robotic-assisted radical prostatectomy (RARP). METHODS: Retrospective study of prospectively collected data for 268 (RARP-T) versus 342 (RARP-0T) men with versus without tension on the NVB and rhabdosphincter during RARP. Outcomes compared include Expanded Prostate Cancer Index (EPIC) urinary function, estimated blood loss (EBL), operative time, and positive surgical margins (PSM). RESULTS: In unadjusted analysis, men undergoing RARP-T versus RARP-0T were older, had higher biopsy and pathologic Gleason grade, and higher preoperative prostate specific antigen (all p ≤ 0.023). Baseline urinary function was similar. Postoperatively, RARP-0T versus RARP-T was associated with higher 5-month urinary function scores (69.7 versus 64, p = 0.049). In adjusted analyses, RARP-0T versus RARP-T was associated with improved 5-month urinary function [Parameter Estimate (PE) 7.37, Standard Error (SE) 2.67, p = 0.006], while bilateral versus non-/unilateral nerve-sparing was associated with improved 12-month urinary function and continence (both p ≤ 0.035). RARP-0T versus RARP-T was associated with shorter operative times (PE 6.66, SE 1.90, p = 0.001) and higher EBL (PE 20.88, SE 6.49, p = 0.001). There were no significant differences in PSM. CONCLUSIONS: While the use of tension aids in dissection of anatomic planes, avoidance of NVB counter-traction and minimizing tension on the rhabdosphincter during apical dissection attenuates neuropraxia and leads to earlier urinary function recovery. Bilateral versus non-/unilateral nerve-sparing also improves urinary function recovery.

Predictors of abdominal aortic aneurysm sac enlargement after endovascular repair.

BACKGROUND: The majority of infrarenal abdominal aortic aneurysm (AAA) repairs in the United States are performed with endovascular methods. Baseline aortoiliac arterial anatomic characteristics are fundamental criteria for appropriate patient selection for endovascular aortic repair (EVAR) and key determinants of long-term success. We evaluated compliance with anatomic guidelines for EVAR and the relationship between baseline aortoiliac arterial anatomy and post-EVAR AAA sac enlargement. METHODS AND RESULTS: Patients with pre-EVAR and at least 1 post-EVAR computed tomography scan were identified from the M2S, Inc. imaging database (1999 to 2008). Preoperative baseline aortoiliac anatomic characteristics were reviewed for each patient. Data relating to the specific AAA endovascular device implanted were not available. Therefore, morphological measurements were compared with the most liberal and the most conservative published anatomic guidelines as stated in each manufacturer's instructions for use. The primary study outcome was post-EVAR AAA sac enlargement (>5-mm diameter increase). In 10 228 patients undergoing EVAR, 59% had a maximum AAA diameter below the 55-mm threshold at which intervention is recommended over surveillance. Only 42% of patients had anatomy that met the most conservative definition of device instructions for use; 69% met the most liberal definition of device instructions for use. The 5-year post-EVAR rate of AAA sac enlargement was 41%. Independent predictors of AAA sac enlargement included endoleak, age ≥ 80 years, aortic neck diameter ≥ 28 mm, aortic neck angle >60°, and common iliac artery diameter >20 mm. CONCLUSION: In this multicenter observational study, compliance with EVAR device guidelines was low and post-EVAR aneurysm sac enlargement was high, raising concern for long-term risk of aneurysm rupture.

Use, costs and comparative effectiveness of robotic assisted, laparoscopic and open urological surgery.

PURPOSE: Although robotic assisted laparoscopic surgery has been aggressively marketed and rapidly adopted, there are few comparative effectiveness studies that support its purported advantages compared to open and laparoscopic surgery. We used a population based approach to assess use, costs and outcomes of robotic assisted laparoscopic surgery vs laparoscopic surgery and open surgery for common robotic assisted urological procedures. MATERIALS AND METHODS: From the Nationwide Inpatient Sample we identified the most common urological robotic assisted laparoscopic surgery procedures during the last quarter of 2008 as radical prostatectomy, nephrectomy, partial nephrectomy and pyeloplasty. Robotic assisted laparoscopic surgery, laparoscopic surgery and open surgery use, costs and inpatient outcomes were compared using propensity score methods. RESULTS: Robotic assisted laparoscopic surgery was performed for 52.7% of radical prostatectomies, 27.3% of pyeloplasties, 11.5% of partial nephrectomies and 2.3% of nephrectomies. For radical prostatectomy robotic assisted laparoscopic surgery was more prevalent than open surgery among white patients in high volume, urban hospitals (all p≤0.015). Geographic variations were found in the use of robotic assisted laparoscopic surgery vs open surgery. Robotic assisted laparoscopic surgery and laparoscopic surgery vs open surgery were associated with shorter length of stay for all procedures, with robotic assisted laparoscopic surgery being the shortest for radical prostatectomy and partial nephrectomy (all p<0.001). For most procedures robotic assisted laparoscopic surgery and laparoscopic surgery vs open surgery resulted in fewer deaths, complications, transfusions and more routine discharges. However, robotic assisted laparoscopic surgery was more costly than laparoscopic surgery and open surgery for most procedures. CONCLUSIONS: While robotic assisted and laparoscopic surgery are associated with fewer deaths, complications, transfusions and shorter length of hospital stay compared to open surgery, robotic assisted laparoscopic surgery is more costly than laparoscopic and open surgery. Additional studies are needed to better delineate the comparative and cost-effectiveness of robotic assisted laparoscopic surgery relative to laparoscopic surgery and open surgery.

Stepwise description and outcomes of bladder neck sparing during robot-assisted laparoscopic radical prostatectomy.

PURPOSE: While bladder neck sparing may improve post-prostatectomy urinary continence, there is concern that it may lead to more positive surgical margins and compromise cancer control. We compared the continence and cancer control outcomes of bladder neck sparing vs nonsparing techniques during robot-assisted laparoscopic radical prostatectomy. MATERIALS AND METHODS: Data were prospectively collected on 1,067 robot-assisted laparoscopic radical prostatectomies done from September 2005 through October 2011. We compared the procedures according to bladder neck sparing (791) and nonsparing (276). Continence was defined by zero pad responses on the EPIC (Expanded Prostate Cancer Index) item quantifying daily use. Biochemical recurrence was defined as prostate specific antigen 0.1 ng/ml or greater. Cox regression was performed to assess factors associated with post-prostatectomy continence and biochemical recurrence-free survival. RESULTS: Median followup for bladder neck sparing vs nonsparing was 25.8 vs 51.7 months. Men treated with bladder neck sparing were more likely to have clinical T1c tumors (p <0.001) and less likely to have biopsy Gleason grade 6 or less disease (p = 0.023). They experienced fewer urinary leaks (p = 0.009) and shorter length of stay (p = 0.006). Regarding cancer control outcomes, there was no difference in bladder neck sparing vs nonsparing base (1.2% vs 2.6%, p = 0.146) and overall surgical margin positivity (each 13.8%, p = 0.985). On adjusted analyses bladder neck sparing vs nonsparing was associated with better continence (HR 1.69, 95% CI 1.43-1.99) and similar biochemical recurrence-free survival (HR 1.20, 95% CI 0.62-2.31, p = 0.596). CONCLUSIONS: Bladder neck sparing is associated with fewer urinary leak complications, shorter hospitalization and better post-prostatectomy continence without compromising cancer control compared to bladder neck nonsparing.

Hospital volume, utilization, costs and outcomes of robot-assisted laparoscopic radical prostatectomy.

PURPOSE: Although robot-assisted laparoscopic radical prostatectomy has been aggressively marketed and rapidly adopted, there is a paucity of population based utilization, outcome and cost data. High vs low volume hospitals have better outcomes for open and minimally invasive radical prostatectomy (robotic or laparoscopic) but to our knowledge volume outcomes effects for robot-assisted laparoscopic radical prostatectomy alone have not been studied. MATERIALS AND METHODS: We characterized robot-assisted laparoscopic radical prostatectomy outcome by hospital volume using the Nationwide Inpatient Sample during the last quarter of 2008. Propensity scoring methods were used to assess outcomes and costs. RESULTS: At high volume hospitals robot-assisted laparoscopic radical prostatectomy was more likely to be done on men who were white with an income in the highest quartile and age less than 50 years than at low volume hospitals (each p <0.01). Hospitals at above the 50th volume percentile were less likely to show miscellaneous medical and overall complications (p = 0.01). Low vs high volume hospitals had longer mean length of stay (1.9 vs 1.6 days) and incurred higher median costs ($12,754 vs $8,623, each p <0.01). CONCLUSIONS: Demographic differences exist in robot-assisted laparoscopic radical prostatectomy patient populations between high and low volume hospitals. Higher volume hospitals showed fewer complications and lower costs than low volume hospitals on a national basis. These findings support referral to high volume centers for robot-assisted laparoscopic radical prostatectomy to decrease complications and costs.