To provide evidence on the responsiveness of social care and well-being preference-based measures (PBMs) compared with health-related quality of life PBMs in the context of multiple sclerosis (MS).
The ICEpop CAPability measure for Adults (ICECAP-A) and Adult Social Care Outcomes Toolkit (ASCOT) were completed online in September 2019, March 2020, September 2020, via the UK MS Register. Responses were linked to EQ-5D-3L and MS Impact Scale-8 Dimensions (MSIS-8D) values, and to MS Walking Scale-12, Hospital Anxiety and Depression Scale (HADS), and Fatigue Severity Scale scores. Responsiveness was assessed in relation to minimal important differences on MS Walking Scale-12, Hospital Anxiety and Depression Scale, and Fatigue Severity Scale between time points, using mean change scores, t tests, standardized effect sizes, standardized response means, and multivariable regression analyses.
Data from 1742 people with MS were available for analysis. When using standardized values, MSIS-8D showed the greatest responsiveness and EQ-5D-3L the least. In contrast, when absolute utility values were used, EQ-5D-3L performed similarly to MSIS-8D and better than ICECAP-A and ASCOT. Standardized regression analyses indicated the MSIS-8Ds to be the most responsive, followed by the ASCOT, ICECAP-A, and EQ-5D-3L.
The ICECAP-A, ASCOT, and MSIS-8D were more responsive than the EQ-5D-3L in the context of MS when compared using standardized scores. The increased responsiveness of EQ-5D-3L when absolute values were used seems an artefact of the wide-ranging scale of this measure. This illustrates how the maximum potential range of values for a given PBM tariff could influence whether an intervention is found to be cost-effective.