Influence of body mass index and age on functional outcomes in patients with subarachnoid hemorrhage.

Background: Recent studies have highlighted the obesity paradox where patients with obesity have a greater chance of survival than patients with normal weight.

Objective: To investigate the association between body mass index (BMI) and age with severity of subarachnoid hemorrhage (SAH) and functional outcome.

Methods: We retrospectively reviewed the charts of 274 consecutive patients admitted with SAH between June 2008 and June 2012. Data collected included patient demographic features (age, sex, BMI), severity of SAH at admission (Fisher grade, Hunt and Hess grade, Glasgow Coma Scale score, and the World Federation of Neurosurgeons Scale score), as well as functional outcome measured by the modified Rankin Scale (mRS) by death or discharge.

Results: The median age was 57 years (range, 18-99), and 62% were female; the median BMI was 27 (range, 14.3-55.1). On multivariate analysis adjusting for age and sex, there was no evidence of an association between BMI and Hunt and Hess grade, Fisher grade, World Federation of Neurosurgeons Scale score, Glasgow Coma Scale score, or mRS score (all P≥.17). On multivariate analysis adjusting for BMI and sex, there was evidence of a higher mRS score (P<.001) and lower WFNS grade (P=.016) in older patients, with no significant association observed between age and the remaining 3 measures of SAH severity (all P≥.10).

Conclusion: The results of our study indicate that BMI is not noticeably associated with severity of bleeding or functional outcome in patients with SAH. This finding was discovered after performing a multivariate analysis adjusting for age where older age was associated with worsened severity and outcome.