Impact of Hospital Volume on Outcomes of Lower Extremity Endovascular Interventions (Insights from the Nationwide Inpatient Sample [2006 to 2011])

Abstract

Our primary objective was to study postprocedural outcomes and hospitalization costs after peripheral endovascular interventions and the multivariate predictors affecting the outcomes with emphasis on hospital volume. The study cohort was derived from Healthcare Cost and Utilization Project Nationwide Inpatient Sample database (2006 to 2011). Peripheral endovascular interventions were identified using appropriate International Classification of Diseases, Ninth Revision diagnostic and procedural codes. Annual institutional volumes were calculated using unique identification numbers and then divided into quartiles. Two-level hierarchical multivariate mixed models were created. The primary outcome was inhospital mortality; secondary outcome was a composite of inhospital mortality and postprocedural complications. Amputation rates and hospitalization costs were also assessed. Multivariate analysis (odds ratio, 95% confidence interval, p value) revealed age (1.46, 1.37 to 1.55, p <0.001), female gender (1.28, 1.12 to 1.46, p <0.001), baseline co-morbidity status as depicted by a greater Charlson co-morbidity index score (≥2: 4.32, 3.45 to 5.40, p <0.001), emergent or urgent admissions(2.48, 2.14 to 2.88, p <0.001), and weekend admissions (1.53, 1.26 to 1.86, p <0.001) to be significant predictors of primary outcome. An increasing hospital volume quartile was independently predictive of improved primary (0.65, 0.52 to 0.82, p <0.001 for the fourth quartile) and secondary (0.85, 0.73 to 0.97, 0.02 for the fourth quartile) outcomes and lower amputation rates (0.52, 0.45 to 0.61, p <0.001). A significant reduction hospitalization costs ($-3,889, -5,318 to -2,459, p <0.001) was also seen in high volume centers. In conclusion, a greater hospital procedural volume is associated with superior outcomes after peripheral endovascular interventions in terms of inhospital mortality, complications, and hospitalization costs.