Dynamic volume-outcome association for esophagectomies: Do current volume thresholds still apply?

Background: It is unknown if the current minimum case volume recommendation of 20 cases per year per hospital is applicable to contemporary practice.

Methods: Patients undergoing esophageal resection between 2005 and 2015 were identified in the National Cancer Database. High, medium, and low-volume hospital strata were defined by quartiles. Adjusted odds ratios and adjusted 30-day mortality between low-, medium-, and high-volume hospitals were calculated using logistic regression analyses and trended over time.

Results: Only 1.1% of hospitals had ≥20 annual cases. The unadjusted 30-day mortality for esophagectomy was 3.8% overall. Unadjusted and adjusted 30-day mortality trended down for all three strata between 2005 and 2015, with disproportionate decreases for low-volume and medium-volume versus high-volume hospitals. By 2015, adjusted 30-day mortality was similar in medium- and high-volume hospitals (odds ratio 1.35, 95% confidence interval 0.96-1.91). For hospitals with 20 or more annual cases the adjusted 30-day mortality was 2.7% overall. To achieve this same 30-day mortality the minimum volume threshold had lowered to 7 annual cases by 2015.

Conclusion: Only 1.1% of hospitals meet current volume recommendations for esophagectomy. Differential improvements in postoperative mortality at low- and medium- versus high-volume hospitals have led to 7 cases in 2015 achieving the same adjusted 30-day mortality as 20 cases in the overall cohort. Lowering volume thresholds for esophagectomy in contemporary practice would potentially increase the proportion of hospitals able to meet volume standards and increase access to quality care without sacrificing quality.