Body mass index is associated with disability at discharge as indicated by the modified Rankin Scale in patients with ischemic stroke: a JROAD-DPC study.

Background: Body mass index (BMI) of patients with ischemic stroke (IS) has been associated with prognosis and disability in studies in the United States. Although the Asian population is leaner, the optimal BMI for stroke-related disability remains unknown.
Objectives: To clarify the association between BMI and disability in patients with IS from a national database in Japan.
Methods: The present study included 522,421 patients with IS identified in the JROAD-DPC database from April 2016 to March 2020. We used the WHO classification of BMI, which divides Asia-Pacific patients into five groups, to categorize BMI and the modified Rankin Scale (mRS) to assess stroke-related disability at admission and discharge. After multiple imputation for missing values, we conducted a multiple mixed-effect logistic regression analysis for poor mRS score (>2) in September 2023. In addition, we created a restricted cubic spline model between the odds ratio (OR) for poor mRS and BMI.
Results: The mRS score worsened during hospitalization in 60.1% of the patients with IS, and 45.7% had a poor mRS score at discharge. Overweight patients had the lowest OR of having a poor mRS score (OR: 0.898, 95% confidence interval: 0.895-0.902). The spline curve for the OR for poor mRS score was U-shaped with a BMI of 24.7 kg/m ² as the apex value.
Conclusion: The present study revealed a U-shaped relationship between BMI and stroke-related disability, with overweight patients having the lowest OR for disability at discharge.