Roles for specialty societies and vascular surgeons in accountable care organizations

With the passage of the Affordable Care Act, accountable care organizations (ACOs) represent a new paradigm in healthcare payment reform. Designed to limit growth in spending while preserving quality, these organizations aim to incant physicians to lower costs by returning a portion of the savings realized by cost-effective, evidence-based care back to the ACO. In this review, first, we will explore the development of ACOs within the context of prior attempts to control Medicare spending, such as the sustainable growth rate and managed care organizations. Second, we describe the evolution of ACOs, the demonstration projects that established their feasibility, and their current organizational structure. Third, because quality metrics are central to the use and implementation of ACOs, we describe current efforts to design, collect, and interpret quality metrics in vascular surgery. And fourth, because a “seat at the table” will be an important key to success for vascular surgeons in these efforts, we discuss how vascular surgeons can participate and lead efforts within ACOs

Adjusting for bias introduced by instrumental variable estimation in the Cox Proportional Hazards Model

Instrumental variable (IV) methods are widely used for estimating average treatment effects in the presence of unmeasured confounders. However, the capability of existing IV procedures, and most notably the two-stage residual inclusion (2SRI) procedure recommended for use in nonlinear contexts, to account for unmeasured confounders in the Cox proportional hazard model is unclear. We show that instrumenting an endogenous treatment induces an unmeasured covariate, referred to as an individual frailty in survival analysis parlance, which if not accounted for leads to bias. We propose a new procedure that augments 2SRI with an individual frailty and prove that it is consistent under certain conditions. The finite sample-size behavior is studied across a broad set of conditions via Monte Carlo simulations. Finally, the proposed methodology is used to estimate the average effect of carotid endarterectomy versus carotid artery stenting on the mortality of patients suffering from carotid artery disease. Results suggest that the 2SRI-frailty estimator generally reduces the bias of both point and interval estimators compared to traditional 2SRI.Comment: 27 pages, 8 figures, 4 table

Factors associated with stroke or death after carotid endarterectomy in Northern New England

ObjectiveThis study investigated risk factors for stroke or death after carotid endarterectomy (CEA) among hospitals of varying type and size participating in a regional quality improvement effort.MethodsWe reviewed 2714 patients undergoing 3092 primary CEAs (excluding combined procedures or redo CEA) at 11 hospitals in Northern New England from January 2003 through December 2007. Hospitals varied in size (25 to 615 beds) and comprised community and teaching hospitals. Fifty surgeons reported results to the database. Trained research personnel prospectively collected >70 demographic and clinical variables for each patient. Multivariate logistic regression models were used to generate odds ratios (ORs) and prediction models for the 30-day postoperative stroke or death rate.ResultsAcross 3092 CEAs, there were 38 minor strokes, 14 major strokes, and eight deaths (5 stroke-related) ≤30 days of the index procedure (30-day stroke or death rate, 1.8%). In multivariate analyses, emergency CEA (OR, 7.0; 95% confidence interval [CI], 1.8-26.9; P = .004), contralateral internal carotid artery occlusion (OR, 2.8; 95% CI, 1.3-6.2; P = .009), preoperative ipsilateral cortical stroke (OR, 2.4; 95% CI, 1.1-5.1; P = .02), congestive heart failure (OR, 1.6; 95% CI, 1.1-2.4, P = .03), and age >70 (OR, 1.3; 95% CI, 0.8-2.3; P = .315) were associated with postoperative stroke or death. Preoperative antiplatelet therapy was protective (OR, 0.4; 95% CI, 0.2-0.9; P = .02). Risk of stroke or death varied from <1% in patients with no risk factors to nearly 5% with patients with ≥3 risk factors. Our risk prediction model had excellent correlation with observed results (r = 0.96) and reasonable discriminative ability (area under receiver operating characteristic curve, 0.71). Risks varied from <1% in asymptomatic patients with no risk factors to nearly 4% in patients with contralateral internal carotid artery occlusion (OR, 3.2; 95% CI, 1.3-8.1; P = .01) and age >70 (OR, 2.9; 95% CI, 1.0-4.9, P = .05). Two hospitals performed significantly better than expected. These differences were not attributable to surgeon or hospital volume.ConclusionSurgeons can “risk-stratify” preoperative patients by considering the variables (emergency procedure, contralateral internal carotid artery occlusion, preoperative ipsilateral cortical stroke, congestive heart failure, and age), reducing risk with antiplatelet agents, and informing patients more precisely about their risk of stroke or death after CEA. Risk prediction models can also be used to compare risk-adjusted outcomes between centers, identify best practices, and hopefully, improve overall results

“Medical high risk” designation is not associated with survival after carotid artery stenting

BackgroundWhile medical high risk (MHR) has been proposed as an indication for carotid artery stenting (CAS), the impact of MHR on long-term survival and stroke after CAS has not been described.MethodsA retrospective chart review of CAS procedures at our institution was performed. One hundred seventy-nine consecutive patients who underwent 196 CAS procedures were classified by MHR status based on cardiac, pulmonary, and renal criteria routinely used in high-risk clinical trials. Survival and stroke rates were compared after 90 CAS procedures in MHR patients vs 106 CAS procedures in normal risk patients. Survival results were also compared with 365 contemporaneous carotid endarterectomy (CEA) procedures in 346 patients.ResultsThe mean age of CAS patients was 72 years, with 87% having a smoking history, 85% hypertension, 38% diabetes, 39% symptomatic, and 74% documented coronary artery disease. Mean follow-up was 23 months. Recurrent stenosis after CEA comprised 21% of all CAS procedures. During the 30-day post-procedure period, there were five minor strokes, one major stroke, and one death, for a combined stroke/death rate of 3.6%. Kaplan-Meier analysis demonstrated mortality of 5% at 1 year and 21% at 3 years for the entire cohort. Cox regression analysis found that MHR designation was not associated with increased mortality or an increase in a composite end point of death or stroke. MHR patients had mortality of 4% at 1 year and 22% at 3 years. Normal risk patients had mortality of 6% at 1 year and 20% at 3 years. Preoperative age over 80 years old, low density lipoprotein (LDL) ≥160 mg/dL, and serum creatinine ≥1.5 mg/dL conferred statistically significant risk for death (Hazard ratios: 2.9, 4.3, and 2.4, respectively). As a point of comparison, a contemporaneous group of CEA patients were analyzed similarly. After adjusting for age over 80 years old and serum creatinine ≥1.5 mg/dL, there was no survival difference between MHR patients undergoing CAS or CEA.ConclusionsThe presence of MHR did not impact long-term survival or stroke rate after CAS, and overall survival of MHR patients in our series was comparable with risk-adjusted controls undergoing CEA. These results suggest the need for more refined predictors of medical risk to optimally guide patients in selecting carotid revascularization strategies

Assembling and Validating Data from Multiple Sources to Study Care for Veterans with Bladder Cancer

Despite the high prevalence of bladder cancer, research on optimal bladder cancer care is limited. One way to advance observational research on care is to use linked data from multiple sources. Such big data research can provide real-world details of care and outcomes across a large number of patients. We assembled and validated such data including (1) administrative data from the Department of Veterans Affairs (VA), (2) Medicare claims, (3) data abstracted by tumor registrars, (4) data abstracted via chart review from the national electronic health record, and (5) full text pathology reports

Outcomes of acute intraoperative surgical conversion during endovascular aortic aneurysm repair

PurposeOutcomes and predictors of acute surgical conversion during endovascular aortic aneurysm repair (EVAR) were examined using the American College of Surgeons-National Safety and Quality Improvement Project (ACS-NSQIP) Database (2005 to 2008).MethodsAcute intraoperative surgical conversions occurring during elective EVAR were identified using Current Procedural Terminology codes. Nonemergent EVAR and primary open surgical repairs of infrarenal aneurysms were examined for comparison. Perioperative morbidity was categorized as wound, pulmonary, venous thromboembolic, genitourinary, cardiovascular, operative, and septic. Mortality, overall morbidity, and length of stay (LOS) were examined.ResultsWe identified 72 acute conversions, 2414 open repairs, and 6332 EVAR without acute conversion. Demographics and comorbidities were generally similar among operative groups. Mean operative time was 274 minutes for acute conversion vs 226 minutes for primary open repair and 162 minutes for EVAR (conversion vs EVAR and open repair vs EVAR P < .0001 for each; conversion vs open repair P = .0014; analysis on rank operative time). Blood transfusion was required in 69% of acute conversions (mean volume, 6.0 units) vs 73% of open repairs (mean volume, 3.3 units) and 12% of EVARs (mean volume, 2.6 units; P < .0001 for each pair-wise comparison; analysis on rank number of units among those transfused). Major morbidity was 28% for acute conversions, 28% for open repairs, and 12% for EVARs. Mortality was 4.2% for acute conversions, 3.2% for open repairs, and 1.3% for EVARs. Median (quartile 1, quartile 3) LOS was 7 (5, 9) days for acute conversion and open repair, and 2 (1, 3) days for EVAR. Morbidity and mortality were significantly higher for acute conversion and open repair vs EVAR. The OR (95% confidence interval) for morbidity was 2.9 (1.7-4.8) after conversion and 2.8 (2.5-3.2) after open repair (P < .0001 for both) and for mortality was 3.4 (1.0-10.9; P = .0437) for conversion and 2.5 (1.9-3.5; P < .0001) for open repair. Morbidity and mortality were similar between acute conversion and open repair. A similar pattern among repair groups was demonstrated for LOS, with similar LOS for acute conversions and open repair, which were significantly longer than those observed for EVAR. No significant demographic or medical risk factor predictors of acute conversion during EVAR were identified.ConclusionAcute surgical conversion was a rare complication affecting 1.1% of EVAR cases, with no broadly identifiable at-risk population. When conversion did occur, morbidity and mortality rates paralleled those observed for elective open repair