Objective: To determine whether the relationship between hospital volume and mortality has changed over time. Background: It is generally accepted that hospital volume is associated with mortality in high-risk procedures. However, as surgical safety has improved over the last decade, recent evidence has suggested that the inverse relationship has diminished or been eliminated. Methods: Using national Medicare claims data from 2000 through 2009, we examined mortality among 3,282,127 patients who underwent 1 of 8 gastrointestinal, cardiac, or vascular procedures. Hospitals were stratified into quintiles of operative volume. Using multivariable logistic regression models to adjust for patient characteristics, we examined the relationship between hospital volume and mortality, and assessed for changes over time. We performed sensitivity analyses using hierarchical logistic regression modeling with hospital-level random effects to confirm our results. Results: Throughout the 10-year period, a significant inverse relationship was observed in all procedures. In 5 of the 8 procedures studied, the strength of the volume-outcome relationship increased over time. In esophagectomy, for example, the adjusted odds ratio of mortality in very low volume hospitals compared to very high volume hospitals increased from 2.25 [95% confidence interval (CI): 1.57–3.23] in 2000–2001 to 3.68 (95% CI: 2.66–5.11) in 2008–2009. Only pancreatectomy showed a notable decrease in strength of the relationship over time, from 5.83 (95% CI: 3.64–9.36) in 2000–2001, to 3.08 (95% CI: 2.07–4.57) in 2008–2009. Conclusions: For all procedures examined, higher volume hospitals had significantly lower mortality rates than lower volume hospitals. Despite recent improvements in surgical safety, the strong inverse relationship between hospital volume and mortality persists in the modern era.

Bariatric surgery is the most effective therapy available for significant and sustainable weight loss in patients with morbid obesity.^1,2 As a result of the increasing prevalence of obesity, improvements in perioperative safety, and expanded insurance coverage, bariatric surgery use has increased during the last decade.^3,4

Disparities in postoperative mortality based on socioeconomic status (SES) have been consistently demonstrated after major cancer surgery. Patients with low SES undergoing gastrectomy are 55% more likely to die after surgery compared with those with higher SES, and operative mortality after lung resection is 37% higher in low-income patients.^1,2 Although some authors have concluded that patient characteristics account for a portion of these differences,³ other evidence suggests that hospital quality plays an important role in the socioeconomic variations observed in mortality.¹

Although resident involvement has been shown to be safe for most procedures, the impact of residents on outcomes after complex laparoscopic procedures is not well understood. We sought to examine the impact of resident involvement on outcomes after bariatric surgery using a population-based clinical registry. We analyzed 17,057 patients who underwent a primary laparoscopic gastric bypass in the 35-hospital Michigan Bariatric Surgery Collaborative from July 2006 to August 2012. Resident involvement was characterized at the surgeon level. Using hierarchical logistic regression, we examined the influence of resident involvement on 30-day complications, accounting for patient characteristics as well as hospital and surgeon case volume. To evaluate potential mediating factors for specific complications, we also adjusted for operative duration. Risk-adjusted 30-day complication rates with and without residents were 13.0% and 8.5%, respectively (p < 0.01). Resident involvement was independently associated with wound infection (odds ratio [OR] = 2.06; 95% CI, 1.24-3.43) and venous thromboembolism (OR = 2.01; 95% CI, 1.19-3.40), but not with any other medical or surgical complications. Operative duration was longer with resident involvement (median duration with residents 129 minutes vs 88 minutes without; p < 0.01). After adjusting for operative duration, resident involvement was still independently associated with wound infection (OR = 1.67; 95% CI, 1.01-2.76), but not venous thromboembolism (OR = 1.73; 95% CI, 0.99-3.04). Resident involvement in laparoscopic gastric bypass is independently associated with wound infections and venous thromboembolism. The effect appears to be mediated in part by longer operative times. These findings highlight the importance of strategies to assess and improve resident technical proficiency outside the operating room.