Responsiveness and validity of two outcome measures of instrumental activities of daily living in stroke survivors receiving rehabilitative therapies

Objective: To comprehensively investigate and compare the responsiveness and validity of two instrumental activities of daily living (ADL) measures: a modified version of the Nottingham Extended ADL Scale and the Frenchay Activities Index, after stroke rehabilitation. Setting: Rehabilitation clinics. Subjects: Seventy stroke patients received a three-week intervention (mean (SD) age, 55.5 (12.1) years; 46 (65.7%) men; mean (SD) time post stroke, 19.9 (12.5) months). Measures: Four outcome measures (modified Nottingham Extended ADL Scale, Frenchay Activities Index, Stroke Impact Scale and Motor Activity Log) were administered before and after treatment. We used the standardized response mean (SRM) to examine responsiveness and the Spearman correlation coefficient (rho) to examine concurrent validity. Results: Responsiveness was significantly larger for the modified Nottingham Extended ADL Scale (SRM = 0.9) compared with the Frenchay Activities Index (SRM = 0.5). The correlations between the modified Nottingham Extended ADL Scale and Frenchay Activities Index were good to excellent before (rho = 0.8) and after treatment (rho = 0.8). The modified Nottingham Extended ADL Scale and Frenchay Activities Index showed fair correlations with the Stroke Impact Scale ADL/Instrumental ADL domain, Stroke Impact Scale total score and Motor Activity Log before treatment (rho = 0.3-0.4). After treatment, the modified Nottingham Extended ADL Scale and Frenchay Activities Index demonstrated moderate to good correlations with the Stroke Impact Scale ADL/Instrumental ADL domain (rho = 0.6) and fair correlations with the Stroke Impact Scale total score and Motor Activity Log (rho = 0.2-0.5). Conclusions: The modified Nottingham Extended ADL Scale and Frenchay Activities Index are both valid outcome measures but the modified Nottingham Extended ADL Scale is more responsive than the Frenchay Activities Index. While simultaneously considering the properties of responsiveness and validity, the modified Nottingham Extended ADL Scale may be a relatively sound measure of instrumental ADL function in stroke patients receiving rehabilitation.