Validation of scores from a telephone administered multiple sclerosis walking scale-12 in persons with multiple sclerosis

Abstract

BackgroundThe Multiple Sclerosis Walking Scale-12 (MSWS-12) has typically been delivered through paper-and-pencil or computer-based administration. PurposeThis study examined the validity of inferences from scores derived via a telephone administration of the MSWS-12 applied as part of screening of participants with walking dysfunction into a clinical trial of exercise training in MS. MethodThe MSWS-12 was administered on two occasions separated by approximately 2 weeks through the telephone and then in-person (i.e., computer-based administration). Participants further completed the Patient Determined Disease Steps (PDDS) scale, timed 25-foot walk (T25FW), six-minute walk (6MW), Modified Fatigue Impact Scale (MFIS), and Multiple Sclerosis Impact Scale-29 (MSIS-29), and underwent a neurological exam for generating an expanded disability status scale (EDSS) score. The primary set of data (Full Sample) for analyses included all persons who passed the telephone screening for inclusion with MSWS-12 scores between 25 and 75 (N = 374). The secondary set of data (Truncated Sample) included only persons with MSWS-12 scores between 25 and 75 for both the telephone and computer administrations of the MSWS-12 (N = 248). ResultsThe results in the Full Sample indicated a difference in overall and item levels scores between the telephone and computer data collections, and the computer version had higher internal consistency and stronger unidimensionality. Nevertheless, MSWS-12 scores from both modes of administration had comparable correlations with the T25FW, 6MW, EDSS, PDDS, MFIS, and MSIS-29, but the correlation between the two MSWS-12 administrations did not approach unity. There was a systematic difference in scores between telephone and computer administrations across levels of walking dysfunction based on a Bland-Altman plot, and the difference was predicted by MFIS physical, 6MW, and EDSS scores. The comparison of results between the Full and Truncated Samples suggested that the primary analysis might have been influenced by the larger range of scores on the computer than telephone administrations of the MSWS-12. ConclusionThe telephone administration of the MSWS-12 provides an efficient and cost-effective measure of walking dysfunction in persons with MS.