Cost-utility analysis of contaminated appendectomy wounds

Abstract

Background: The influence of patient preference and treatment costs has not been considered in previous analyses of wound management decisions for contaminated right lower quadrant incisions.

Study design: We performed a decision and cost-utility analysis, conducting a MEDLINE search of the postappendectomy wound infection literature to establish assumptions and assign baseline probability estimates. Institution-specific cost data were obtained, and utility assignments were made by the authors. Studies used to assign baseline probabilities fulfilled the following criteria: perforated appendix or gangrenous appendicitis, use of perioperative antibiotics active against aerobic and anaerobic bacteria, and data stratified by wound management, operative findings, and infection rate.

Results: We constructed a decision tree comparing three methods of wound management for contaminated right lower quadrant incisions: primary closure, delayed primary closure, and secondary closure. Utility (a quality of life measure) was assigned to ultimate health states to incorporate patient preference. We calculated the cost-utility for each method of wound management and found that primary closure was of optimum cost-utility compared with delayed primary closure and secondary closure. To gain one quality-adjusted life year treating a population of patients with contaminated incisions, primary closure saves $22,635 over delayed primary closure and another $22,340 over secondary closure. This decision, tested by two-way sensitivity analyses, was sensitive only to high primary closure infection rates.

Conclusions: Challenging traditional surgical dogma, cost-utility analysis shows that primary closure is the favored method of management for contaminated right lower quadrant incisions. This analysis is specific to right lower quadrant incisions and the conclusion is valid for all estimated primary infection rates less than 0.27.