BODY MASS INDEX AND OVERALL OUTCOME FOLLOWING SUBARACHNOID HEMORRHAGE: AN OBESITY PARADOX?

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

Methods: 406 patients with SAH were retrospectively reviewed and stratified into three BMI categories: normal weight between 18.5 and 24.9 kg/m²; overweight between 25 and 29.9 kg/m²; and obese greater than 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 to the normal weight BMI, the overweight group had an odds ratio for mortality of 0.415 (p = 0.023), poor mRS at 90 days of 0.432 (p = 0.014), and poor mRS at 180 days of 0.311 (p = 0.001). The obese group had a statistically significant odds ratio for poor mRS at 90 days of 2.067 (p = 0.041) and at 180 days of 1.947 (p = 0.049). These significant odds ratios persisted in a multivariable model controlling for age and Hunt & Hess grade.

Conclusions: The overweight BMI group exhibited a striking decrease for the odds of death and poor outcome compared to the normal weight BMI, whereas the obese group demonstrated the contrary. 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.