Is Annual Volume Enough? the Role of Experience and Specialization on Inpatient Mortality after Hepatectomy

Objective: To investigate the effect of subspecialty practice and experience on the relationship between annual volume and inpatient mortality after hepatic resection. Background: The impact of annual surgical volume on postoperative outcomes has been extensively examined. However, the impact of cumulative surgeon experience and specialty training on this relationship warrants investigation. Methods: The New York Statewide Planning and Research Cooperative System inpatient database was queried for patients' ≥18 years who underwent wedge hepatectomy or lobectomy from 2000 to 2014. Primary exposures included annual surgeon volume, surgeon experience (early vs late career), and surgical specialization - categorized as general surgery (GS), surgical oncology (SO), and transplant (TS). Primary endpoint was inpatient mortality. Hierarchical logistic regression was performed accounting for correlation at the level of the surgeon and the hospital, and adjusting for patient demographics, comorbidities, presence of cirrhosis, and annual surgical hospital volume. Results: A total of 13,467 cases were analyzed. Overall inpatient mortality was 2.35%. On unadjusted analysis, late career surgeons had a mortality rate of 2.62% versus 1.97% for early career surgeons. GS had a mortality rate of 2.98% compared with 1.68% for SO and 2.67% for TS. Once risk-adjusted, annual volume was associated with reduced mortality only among early-career surgeons (odds ratio 0.82, P = 0.001) and general surgeons (odds ratio 0.65, P = 0.002). No volume effect was seen among late-career or specialty-trained surgeons. Conclusions: Annual volume alone likely contributes only a partial assessment of the volume-outcome relationship. In patients undergoing hepatic resection, increased annual volume did not confer a mortality benefit on subspecialty surgeons or late career surgeons.