U-shaped relationship between body mass index and intracerebral hemorrhage-related functional decline

Background: Body mass index (BMI) is associated with the sites of intracerebral hemorrhage (ICH), which affect functional decline. However, the optimal BMI range for minimizing functional decline remains unclear. This study aimed to clarify the relationship between BMI and ICH-related functional decline. Methods: ICH survivors registered in the Japanese Registry Of All Cardiac and Vascular Diseases Diagnosis Procedure Combination (JROAD-DPC) database from April 2016 to March 2020 were included. BMI was categorized according to the World Health Organization Asia-Pacific classification. The primary outcome was ICH-related functional decline, defined as an increase in the modified Rankin Scale (mRS) score at discharge compared to pre-stroke. Results: This study included 155,211 patients with ICH, with a mean BMI of 22.3 kg/m(2). Among these patients, 74.1% experienced ICH-related functional decline. The overweight group (23.0 < BMI <= 25.0 kg/m(2)) exhibited the lowest rate of functional decline (Odds ratio: 0.90, 95% CI: 0.85-0.94). The relationship between BMI and ICH-related functional decline followed a U-shaped curve, indicating that a BMI range of 22.2-30.4 kg/m(2) was associated with reduced odds of functional decline. Conclusion: In patients with ICH, both extremely low and high BMIs were associated with a higher likelihood of functional decline post-ICH onset. Maintaining a BMI within the range of 22.2-30.4 kg/m2 may be beneficial for reducing the risk of functional decline.