Trade-Offs in Quality-of-Life Assessment Between the Modified Rankin Scale and Neuro-QoL Measures

Introduction: We aimed to describe the physical and cognitive health of patients with differing levels of post-stroke disability, as defined by modified Rankin Scale (mRS) scores. We also compared cross-sectional correlations between the mRS and the Quality of Life in Neurological Disorders (Neuro-QoL) T-scores to longitudinal correlations of change estimates from each measure.

Methods: Mean Neuro-QoL T-scores representing mobility, dexterity, executive function, and cognitive concerns were compared among mRS subgroups. Fixed-effects regression models with robust standard errors estimated correlations among mRS and Neuro-QoL domain scores and correlations among longitudinal change estimates. These change estimates were then compared to distribution-based estimates of minimal clinically important differences.

Results: Seven hundred forty-five patients with ischemic stroke (79%) or transient ischemic attack (21%) were enrolled in this longitudinal observational study of post-stroke outcomes. Larger differences in cognitive function were observed in the severe mRS groups (ie, 4-5) while larger differences in physical function were observed in the mild-moderate mRS groups (ie, 0-2). Cross-sectional correlations among mRS and Neuro-QoL T-scores were high (r = 0.61-0.83), but correlations among longitudinal change estimates were weak (r = 0.14-0.44).

Conclusions: Findings from this study undermine the validity and utility of the mRS as an outcome measure in longitudinal studies in ischemic stroke patients. Nevertheless, strong correlations indicate that the mRS score, obtained with a single interview, is efficient at capturing important differences in patient-reported quality of life, and is useful for identifying meaningful cross-sectional differences among clinical subgroups.