Body Mass Index and Overall Outcome Following Subarachnoid Hemorrhage: An Obesity Paradox?

Abstract

Background: Conventional understanding of obesity demonstrates negative consequences for overall health, whereas more modern studies have found that it can provide certain advantages. The current literature on the effect of body mass index (BMI) in subarachnoid hemorrhage (SAH) is similarly inconsistent.

Methods: cohort of 406 patients with SAH were retrospectively reviewed and stratified into 3 BMI categories: normal weight, 18.5-24.9 kg/m²; overweight, 25-29.9 kg/m²; and obese, >30 kg/m². Neurologic status, the presence of clinical cerebral vasospasm, and outcome as assessed by the modified Rankin scale (mRS) were obtained.

Results: Statistical differences were evident for all outcome categories. A categorical analysis of the different groups revealed that compared with the normal weight group, the overweight group had an odds ratio (OR) for mortality of 0.415 (P = 0.023), an OR for poor mRS score at 90 days of 0.432 (P = 0.014), and an OR for poor mRS score at 180 days of 0.311 (P = 0.001), and the obese group had statistically significant ORs for poor mRS score at 90 days of 2.067 (P = 0.041) and at 180 days of 1.947 (P = 0.049). These significant ORs persisted in a multivariable model controlling for age and Hunt and Hess grade.

Conclusions: The overweight group exhibited strikingly lower odds of death and poor outcome compared with the normal weight group, whereas the obese group demonstrated the opposite. These associations persisted in a multivariable model; thus, BMI can be considered an important predictor of outcome after SAH.

Keywords: Body mass index; Functional outcomes; Mortality; Obesity; Subarachnoid hemorrhage.