Relation of surgical volume to outcome in eight common operations: results from the VA National Surgical Quality Improvement Program

Abstract

Objective: To examine, in the Veterans Health Administration (VHA), the relation between surgical volume and outcome in eight commonly performed operations of intermediate complexity.

Summary background data: In multihospital health care systems such as VHA, consideration is often given to closing low-volume surgical services, with the assumption that better surgical outcomes are achieved in hospitals with larger surgical volumes. Literature data to support this assumption in intermediate-complexity operations are either limited or controversial.

Methods: The VHA National Surgical Quality Improvement Program data on nonruptured abdominal aortic aneurysmectomy, vascular infrainguinal reconstruction, carotid endarterectomy (CEA), lung lobectomy/pneumonectomy, open and laparoscopic cholecystectomy, partial colectomy, and total hip arthroplasty were used. Pearson correlation, analysis of variance, mixed effects hierarchical logistic regression, and automatic interaction detection analysis were used to assess the association of annual procedure/specialty volume with risk-adjusted 30-day death (and stroke in CEA).

Results: Eight major surgical procedures (68,631 operations) were analyzed. No statistically significant associations between procedure or specialty volume and 30-day mortality rate (or 30-day stroke rate in CEA) were found.

Conclusions: In VHA hospitals, the procedure and surgical specialty volume in eight prevalent operations of intermediate complexity are not associated with risk-adjusted 30-day mortality rate from these operations, or with the risk-adjusted 30-day stroke rate from CEA. Volume of surgery in these operations should not be used as a surrogate for quality of surgical care.

Figure 1. Relation of procedure volume to risk-adjusted 30-day mortality rate after eight operations and to risk-adjusted 30-day stroke rate after CEA. Each small circle represents a single VAMC. In each panel, the ordinate is the risk-adjusted outcome expressed as the O/E ratio, and the abscissa is the procedure volume expressed as the number of operations performed per year. The Pearson correlation coefficient (r) and the probability value for each relation are shown in the right upper corner of each panel. There were no significant correlations in any of the nine scattergrams shown on this figure.