Impact of surgical volume on mortality and length of stay after nephrectomy

Abstract

Objectives: To evaluate the volume-outcome relationship in patients undergoing nephrectomy for neoplastic disease by examining the impact of the number of cases performed on in-hospital mortality and length of stay. Surgical volume is associated with postoperative mortality for many complex procedures; however, this relationship has not been characterized for patients undergoing nephrectomy for neoplastic disease.

Methods: Using the Nationwide Inpatient Sample database, 20,765 patients who underwent nephrectomy for neoplasm from 1993 through 1997 were identified by International Classification of Disease, Ninth Revision codes. Cases were stratified into volume groups on the basis of annual nephrectomy rates: low-volume hospitals performed 1 to 14 nephrectomies per year, medium-volume hospitals performed 15 to 33 per year, and high-volume hospitals performed more than 33 per year. Unadjusted and risk-adjusted analyses were performed.

Results: Overall mortality was 1.39%. Mortality declined as surgical volume increased. The mortality rate for low-volume hospitals was 1.60% versus 1.49% for medium-volume hospitals and 1.04% for high-volume hospitals (P = 0.017). After adjusting for case mix, high-volume hospitals had a 32% lower risk of in-hospital mortality than medium-volume hospitals (P = 0.029) and a 25% lower risk than low-volume hospitals (P = 0.094). Length of stay was not affected by hospital volume. Other independent risk factors for in-hospital mortality included age older than 65 years, chronic pulmonary disease, metastatic disease, and the urgent nature of the admission.

Conclusions: A greater surgical volume, age younger than 65 years, elective conditions, and less comorbidity are associated with a significantly decreased risk of in-hospital mortality after nephrectomy. These findings provide compelling evidence that hospital volume and patient characteristics have important effects on surgical outcome specific to renal neoplasms.