Infections and Cost in Obese Patients Undergoing Colectomy

Policymakers utilize rates of surgical site infection (SSI) as a surrogate measure of quality in surgery. Beginning in 2012, hospital SSI rates will be reported to the public. Federal, state, and local pay-for-performance policies are increasingly using SSI rates in their reimbursement algorithms. In addition, healthcare providers are being financially penalized when an SSI occurs. According to researchers, risk factors for SSI are not currently factored into pay-for-performance policies. They note that the most common major SSI risk factor is obesity, a factor that is increasing in prevalence and affects certain minority populations to differing degrees. The researchers hypothesized that, depending on the effect of obesity as an intrinsic risk factor for SSI, pay-for-performance policies may be penalizing surgeons who disproportionately care for high-risk populations. To measure the effect of obesity on SSI rates and to define the cost of SSIs in patients undergoing colorectal surgery, the researchers designed a retrospective study to quantify the rate of SSIs in obese and nonobese patients undergoing colectomy and to determine the cost of SSIs based on payments made by private insurance companies. They reported study results online in Archives of Surgery [doi:10.1001/archsurg.2011.117]. The study utilized data on claims from 7020 members of 8 Blue Cross Blue Shield insurance plans from January 1, 2002, through December 31, 2008. The main outcome measures were 30-day SSI rates among obese and nonobese patients. Inclusion criteria included any of the following: claim with a diagnosis of obesity; a paid or denied claim for bariatric surgery; a paid or denied claim for a medication promoting weight loss; a completed health risk assessment with member height and weight; >12 years of age with a diagnosis of hyperlipidemia, type 2 diabetes mellitus, sleep apnea, gallbladder disease or surgery, or metabolic syndrome. Included patients had a total or segmental colectomy for colon cancer, diverticulitis, or inflammatory bowel disease during the study period. Of the 7020 patients undergoing either segmental or total colectomy, 1243 met the criteria for obesity at the time of the surgery; significantly more women than men were obese (52.6% vs 47.4%). Among obese patients, colectomy for diverticulitis was more common compared with nonobese patients; other diagnoses did not differ between the 2 groups. Overall, the SSI rate was 10.3%. The SSI rate among obese patients was 14.5% compared with 9.5% among nonobese patients (P<.001). Multivariate analysis demonstrated that obesity was the strongest predictor of SSI (odds ratio, 1.59; 95% confidence interval [CI], 1.32-1.91) following adjustment for laparoscopy, diagnosis, sex, and age. Compared with laparoscopic colectomy, open colectomy was also associated with an increased risk of SSI (odds ratio, 1.57; 95% CI, 1.25-1.97). The mean cost of colectomy was $16,399. Regardless of whether a patient developed a postoperative SSI, the cost of colectomy in obese patients was approximately $295 higher than in nonobese patients. Development of a postoperative SSI increased the cost of colectomy by an average of $17,324. Compared with patients who did not develop a postoperative SSI, those who did had longer hospital stays (mean, 8.1 vs 9.5 days, respectively; P<.001) and higher rates of hospital readmission (6.8% vs 27.8%, respectively; P<.001). For those with readmissions, the median length of readmission stay was longer for patients with SSIs compared with those without SSIs (7.0 vs 5.0 days, respectively; P<.001). In summary, the researchers said, “obesity increases the risk of an SSI after colectomy by 60%, and the presence of infection increased the colectomy cost by a mean of $17,324. Pay-for-performance policies that do not account for this increased rate of SSI and cost of caring for obese patients may lead to perverse incentives that could penalize surgeons who care for this population."