Rasch analysis of the upper-limb subscale of the stroke rehabilitation assessment of movement (STREAM) tool in an acute stroke cohort Rasch analysis of the upper-limb subscale of the STREAM tool in an acute stroke population

Background \ud \ud Stroke is a leading cause of disability worldwide. The most common impairment resulting from stroke is upper-limb weakness.\ud \ud Objectives\ud \ud To determine the usefulness and psychometric validity of the upper-limb subscale of the STREAM in an acute stroke population.\ud \ud Methods\ud \ud Rasch Analysis, including unidimensionality assumption testing, determining model fit, and analysis of: reliability, residual correlations, and differential item functioning.\ud \ud Results\ud \ud 125 individuals were assessed using the upper-limb subscale of the Stroke Rehabilitation Assessment of Movement (STREAM) tool. Rasch analysis suggests the STREAM is a unidimensional measure. However, when scored using the originally proposed method (0–2), or using the response pattern (0–5) neither variant fit the Rasch model (p < 0.05). Although, the reliability was good (Person-Separation Index – 0.847 and 0.903, respectively). Correcting for the disordered thresholds, and thereby producing the new scoring pattern, led to substantial improvement in the overall fit (chi-square probability of fit – 22%), however, the reliability was slightly reduced (PSI – 0.806).\ud \ud Conclusions \ud \ud The study proposes a new scoring method for the upper-limb subscale of the STREAM outcome measure in the acute stroke population.