Obesity Paradox for Postoperative Mortality in Young Chinese Patients Undergoing Craniotomy for Brain Tumor Resection

BACKGROUND: There is little evidence regarding the association of body mass index (BMI) with postoperative mortality after craniotomy, especially in the Asian population. Our study aimed to explore the association between BMI and postoperative 30-day mortality in Chinese patients undergoing craniotomy for brain tumor resection. METHODS: This large retrospective cohort study, Supplemental Digital Content 9, http://links.lww.com/JNA/A634 collected data from 7519 patients who underwent craniotomy for brain tumor resection. On the basis of the World Health Organization obesity criteria for Asians, included patients were categorized as underweight (<18.5 kg/m 2 ), normal weight (18.5 to 22.9 kg/m 2 ), overweight (23to 24.9 kg/m 2 ), obese I (25 to 29.9 kg/m 2 ), and obese II (≥30 kg/m 2 ). We used a multivariable logistic regression model to explore the association between different BMI categories and 30-day postoperative mortality. In addition, we also conducted stratified analyses based on age and sex. RESULTS: Overweight (adjusted odds ratio 0.63, 95% CI 0.40-0.99) and obese I (adjusted odds ratio 0.44, 95% CI 0.28-0.72) were associated with decreased 30-day postoperative mortality compared with normal-weight counterparts. Such associations were prominent among younger (age younger than 65 y) patients but not older patients, and there was an interaction between age and overweight versus normal weight on mortality ( P for interaction=0.04). CONCLUSIONS: We found that among Chinese patients undergoing craniotomy for brain tumors, there was a J-shaped association between BMI and postoperative 30-day mortality, with lowest mortality at 27 kg/m². Moreover, in young patients, overweight and obese I were both associated with decreased risk of 30-day mortality.