Utility-weighted modified Rankin Scale: Still too crude to be a truly patient-centric primary outcome measure?

BackgroundThe utility-weighted modified Rankin Scale (UW-mRS) is an outcome measure recently proposed to improve statistical efficiency and interpretability of the mRS. Statistical properties of the UW-mRS have been well investigated, but construct validity has yet to be established.AimsTo investigate the construct validity of the UW-mRS as a primary outcome measure by assessing variability in utility values within and between mRS categories, over time post-stroke, and by different derivation methods.MethodsUW-mRS was derived using assessment of quality of life (AQoL-4D) and mRS scores at 3 and 12 months (n = 2030) from a large randomized controlled trial, A Very Early Rehabilitation Trial (AVERT). Receiver operator characteristic (ROC) analysis of AQoL-4D was conducted to differentiate between sequential mRS categories. Intraclass correlation was used to explore variability in utility values over time post-stroke, UW-mRS values, and derivation methods from multiple studies.ResultsUW-mRS values for mRS ca...