Obesity as a risk factor for unanticipated admissions after ambulatory surgery

OBJECTIVE: To test the hypothesis that obesity is an independent risk factor for unplanned hospital admission or readmission among patients scheduled for ambulatory surgery in a tertiary medical center. PATIENTS AND METHODS: Existing databases were used to identify 235 obese patients (body mass index [BMI] >40) scheduled for ambulatory surgery from January 2, 2002, through December 31, 2003, at Mayo Clinic's site in Rochester, MN. Each patient was matched to a normal-weight control (BMI <25) by age, sex, surgical procedure, type of anesthesia, and date of surgery, and the medical records of all patients were reviewed. Conditional logistic regression analysis was performed to assess whether obesity is an independent risk factor for unplanned postoperative hospital admission. In all cases, 2-sided tests were performed. P<.05 was considered statistically significant. RESULTS: Obese patients (mean ± SD BMI, 44±4) were matched with control patients (mean ± SD BMI, 23±2). Comorbidity was more frequent in the obese cohort. The frequency of unplanned hospital admission did not differ between groups: 61 obese patients (26.0%) and 52 control patients (22.1%) were admitted (odds ratio, 1.3; 95% confidence interval, 0.8-2.0; P=.30). CONCLUSION: Obesity is not a significant independent risk factor for unplanned admission after ambulatory surgery, suggesting that obesity per se should not prevent ambulatory surgery from being scheduled.