The Association of Body Mass Index and Early Outcomes Following Orthognathic Surgery

Abstract

The existing data on the link between body mass index (BMI), operative characteristics, and surgical outcomes across orthognathic surgery are limited. The purpose was to measure the association between BMI and early postoperative outcomes in orthognathic surgery. This is a retrospective cohort study of patients (n=118) aged > 14years undergoing bimaxillary orthognathic surgery between 2015 and 2018 by a single surgeon within the Kaiser Permanente Northern California-integrated healthcare system. Patients undergoing unilateral or additional procedures, history of prior orthognathic surgery, or pre-existing pain conditions were excluded. The predictor variable was BMI measured as a continuous (kg/m2) and categorical variable (underweight/normal, overweight, obese). The primary outcome variables were additional postoperative antibiotics, increased postoperative visits, wound dehiscence, and wound infection. The secondary outcome variables were total operative and anesthesia time. The demographic covariates included age, sex, and race/ethnicity. The clinical covariates included history of obstructive sleep apnea, Mallampati score, tobacco use, American Society of Anesthesia classification, thyromental distance, history of difficult intubation, and Angle's classification. Bivariate and multivariate analyses were performed to measure the associations between BMI and the primary and secondary outcomes. Multivariable logistic regression analyses were used to measure associations between BMI and the postoperative outcomes. Statistical significance was defined as P<.05. The study sample was composed of 118 subjects with a mean age of 26.91years (standard deviation 9.43). Forty-seven percent (n=55) were male, and the mean BMI was 25.13 (standard deviation 5.19). BMI category was significantly associated with age, with increasing age associated with higher BMI category (P=.02). According to the bivariate and multivariable logistic regression analyses, controlling for age, race/ethnicity, BMI, and total operative time, increased total operative time was associated with additional postoperative antibiotics (odds ratio=1.03, 95% confidence interval: 1.01, 1.05), and increased postoperative appointments (odds ratio=1.02, 95% confidence interval: 1.01, 1.04). No significant association between BMI and other clinical or operative characteristics was seen aside from American Society of Anesthesia classification. Elevated BMI was not associated with worsened operative characteristics or postoperative outcomes. This supports the suitability of orthognathic surgery in a BMI-diverse population.