Trends in amount of use to upper limb function in patients with subacute stroke: a cross-sectional study using segmental regression analysis

BACKGROUND: Hemiparesis affects approximately 33–80% of patients with stroke, and a quarter of these individuals experience difficulty with the voluntary use of their paretic upper limb for performing activities of daily living within five years of stroke onset. Therefore, assessing upper limb functionality and use after a stroke is crucial. The Fugl-Meyer Assessment (FMA) and the Motor Activity Log (MAL) are the two most widely used methods for assessing post-stroke paretic upper limb. While previous research has shown a strong correlation between the FMA of Upper Extremity (FMA-UE) and the MAL scores, to date, no study has investigated the differences in the characteristics and trends of upper extremity usage frequency in the FMA-UE. This study aimed to statistically categorize the FMA-UE scores using segmental regression analysis and identify disparities in the trends of paretic upper extremity utilization frequency in MAL. METHODS: Patients with first-episode subacute stroke were chosen for the cohort study. The primary assessments used were FMA-UE and MAL Amount of Use (MAL-A); age, gender, and time since onset served as secondary assessments. Segmental regression analysis was used, with FMA-UE as the independent variable and MAL-A as the dependent variable. R(2) values were calculated using linear and polynomial regression on binary values, and the coefficients of determination were compared using segmental regression analysis. RESULTS: The study included 203 participants with a mean age of 70.1 ± 13.1 years; 113 were male and 90 female. The mean time since onset was 29.2 ± 14.8 days, the mean FMA-UE score was 43.6 ± 22.3 points, and the mean MAL-A score was 2.3 ± 2.0 points. The segmental regression analysis revealed that the inflection point for FMA-UE was 45.3 points, and the slope of the regression line underwent a transformation before and after the inflection point. CONCLUSIONS: This study indicates that the trend in the amount of use of paretic upper limb utilization changes around inflection point 45 in the FMA-UE. These findings could be useful for designing rehabilitation strategies to improve paretic upper limb utilization by increasing exercise duration in patients with subacute stroke.