Estimation of minimally important differences in the EQ-5D and SF-6D indices and their utility in stroke

BACKGROUND: The aim of the present study was to estimate minimally important differences (MIDs) in EQ-5D and SF-6D indices and to explore the responsiveness of EQ-5D and SF-6D indices in stroke. METHODS: We used observational longitudinal survey data of EQ-5D and SF-36 that were administered to stroke patients at baseline and at 10 months. A range of MIDs for both indexes was estimated using anchor-based approaches. The modified Rankin scale and the Barthel index were used as an anchor. RESULTS: The MID estimates for EQ-5D ranged from 0.08 to 0.12 and those for SF-6D ranged from 0.04 to 0.14 in stroke patients. The MID values for these two utility measures differed in absolute magnitude, as the SF-6D index has wider range that that of the EQ-5D index. CONCLUSIONS: The MID values for these two utility measures differed in absolute magnitude, as the SF-6D index has wider range that that of the EQ-5D index. These MID estimates may assist the interpretation of health related quality of life assessments related to health care intervention in stroke patients.