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BACKGROUNDNew pay-for-performance metrics are being increasingly used to measure the quality of surgical care, yet these metrics are blind to a patient’s inherent risk for complications and potentially increased costs. Morbid obesity is a known risk factor for surgical complications, yet the impact of obesity on complications and costs has not been well-defined. We hypothesize that morbid obesity has a significant effect on outcomes and costs following commonly performed general surgical procedures.METHODSWe studied 36,483 patients using administrative claims data from seven Blue Cross/Blue Shield Plans who underwent cholecystectomy for cholecystitis or appendectomy for acute appendicitis over a five-year period (2002-2006). For each procedure, we compared 30-day complications as well as total direct medical costs associated with inpatient hospitalization for obese vs. non-obese patients. Multivariate logistic regression was performed to determine the relationship of morbid obesity to cost as well as complications. RESULTSObese patients were more likely to have a surgical complication than non-obese patients (cholecystectomy 24.2% vs. 21.3% p< 0.0001, appendectomy 24.4% vs. 19.6% p=0.003). Obese patients had median total inpatient costs that were $2,978 higher when undergoing cholecystectomy and $1621 higher when undergoing appendectomy. These trends were also significant on multivariate logistic regression incorporating other common comorbidites including diabetes, hypertension, hyperlipidemia, and obstructive sleep apnea. CONCLUSIONMorbid obesity is associated with a higher rate of complication and costs in two commonly performed acute-care general surgical procedures. Pay-for-performance metrics should account for the increased risk of complications and higher cost of this population. Failure to consider these differences could lead to perverse incentives which could unfairly punish surgeons who care for obese patients.

Operation	n	Complication rate, obese	Complication rate, non-obese	Median total cost, obese	Median total cost, non-obese
cholecystectomy	31,028	24.2%	21.3%*	\,175	\,197*
Appendectomy	5,455	24.4%	19.6%*	\,720	\,099*

Complications and costs of obese patients and non-obese patients undergoing cholecystectomy and appendectomy. *p<0.001 for each comparison, obese vs. non-obese.