Defining the optimal annual institutional case volume for minimally invasive repair of pectus excavatum through a systematic review of literature and meta-analysis of outcomes

Background: The Nuss procedure is the accepted standard approach to correct pectus excavatum. Still, is associated with potential major complications that are in part believed to be preventable as they might be the consequence of institutional case-volume differences. The objective is to evaluate the presence of a volume-outcome relation for the Nuss procedure and determine the optimal annual institutional case-volume threshold, defining high-volume centers. Methods: A systematic literature search was performed, considering studies from unique centers reporting on pectus excavatum patients who underwent the Nuss procedure. Primary and secondary outcomes were, respectively: the incidence of significant perioperative complications (Clavien-Dindo = grade-III and significant intraoperative complications) and bar displacement. The presence of a non-linear volume-outcome relation was evaluated through restricted-cubic-spline-analyses. If present, the optimal annual institutional case-volume was determined by the elbow method. Results: Forty-nine studies from 49 unique centers were included, enrolling 13,352 patients in total. The significant perioperative complication rate was low [7.7%, 95% confidence interval (CI): 6.4–9.0%] and demonstrated a significant non-linear volume-outcome relation (P<0.001), even after covariate adjustment. The optimal annual institutional case-volume was determined at 73 cases/year (95% CI: 67–89). In this scenario, the number needed to treat to prevent a single perioperative complication compared to a low volume center was 11 (95% CI: 8–19). A similar volume-outcome relation (P<0.001) and optimal case volume of 73 cases/year was observed for bar displacement. Conclusions: A significant volume-outcome relation for repair of pectus excavatum by the Nuss procedure exists with an optimal annual institutional case-volume of 73 cases/year. These findings provide rationale for centralization.