Finding the body mass index cutoff for hospital readmission after ambulatory hernia surgery.

BACKGROUND: The suitability of ambulatory surgery in obese patients remains controversial. This study aimed to investigate the "cutoff" value of body mass index (BMI) associated with increased likelihood of hospital readmissions within the first 24 hours of surgery in patients undergoing ambulatory hernia repair. MATERIALS AND METHODS: The study used data from the 2012-2016 American College of Surgeons National Surgical Quality Improvement (ACS-NSQIP). Cochran Armitage trend tests were conducted to assess progression in rates hospital readmissions across categories of patient BMI. The minimum p-value method, Kolmogorov-Smirnov goodness of fit tests, logistic regression, and receiver-operating characteristic (ROC) curve analyses were used to investigate the cutoff of patient BMI indicative of increased likelihood of readmissions. RESULTS: A total of 214,125 ambulatory hernia repair cases were identified. Of those, 908 patients (0.42%) had an unexpected hospital admission within the first 24 hours after surgery. The readmission rates did not significantly increase across the categories of BMI. However, some of the reasons for readmission significantly differed by BMI category. Logistic regression analysis revealed no statistically significant association between BMI and hospital readmissions (odds ratio [95% Cl], 0.96 [0.91-1.02] P = .179). An optimal BMI threshold predictive of an increased likelihood of hospital readmissions was not identifiable by any of the statistical methods used. CONCLUSIONS: Although reasons for readmission differed by BMI category, there is no clear cutoff value of BMI associated with increased hospital readmission within the first 24 hours after surgery.