Association of the body mass index with poor outcome at discharge in patients with aneurysmal subarachnoid hemorrhage: a registry study

Although several studies have reported on the impact of the body mass index (BMI) on functional outcome of aneurysmal subarachnoid hemorrhage (aSAH), the relationship remains unclear. This study aimed to investigate the risk factors of poor outcome of aSAH, with particular attention to BMI. A total of 860 patients with aSAH were enrolled in our registry at Shimane Prefectural Central Hospital between 2000 and 2017, of whom 393 were included in the analysis. Basic patient characteristics, including BMI, and data related to aSAH were recorded. We conducted a univariable analysis, followed by a multivariable analysis to identify the risk factors of poor outcome, defined as a modified Rankin Scale score > 2 at discharge. We also compared our study with previous studies that reported a relationship between BMI and aSAH. Multivariable analysis revealed that age (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.07–1.12), underweight (OR, 2.36; 95% CI, 1.13–4.90), overweight (OR, 2.22; 95% CI, 1.06–4.64), World Federation of Neurosurgical Societies grade (III vs I: OR, 3.10; 95% CI, 1.03–9.35; IV vs I: OR, 8.02; 95% CI, 3.54–18.19; V vs I: OR, 13.37; 95% CI, 5.33–33.54), and symptomatic vasospasm (OR, 3.40; 95% CI, 1.73–6.70) were risk factors for poor outcome at discharge. This study showed the association of underweight (BMI < 18.5 kg/m 2 ) and overweight (≥ 25 kg/m 2 ) with poor outcome; therefore, both high and low BMI are associated with a poor outcome at discharge for patients with aSAH. Clinical trial registry: University Hospital Medical Information Network (UMIN000035160; date of registration: December 6, 2018).