Mapping of Multiple Sclerosis Walking Scale (MSWS-12) to five-dimension EuroQol (EQ-5D) health outcomes: an independent validation in a randomized control cohort

Abstract

BackgroundMapping of patient-reported outcomes to the five-dimension EuroQol (EQ-5D) health index is increasingly being used for understanding the relationship of outcomes to health states and for predicting utilities that have application in economic evaluations. The 12-item Multiple Sclerosis Walking Scale (MSWS-12) is a patient-reported outcome that assesses the impact of walking impairment in people with MS. An equation for mapping the MSWS-12 to the EQ-5D was previously developed and validated using a North American Research Committee on MS (NARCOMS) registry cohort.Materials and methodsThis analysis retested the validity of the equation mapping the MSWS-12 to the three-level EQ-5D (EQ-5D-3L) by using an independent cohort of patients with MS enrolled in a randomized controlled trial. Mapping was evaluated at two separate time points (baseline and week 4) during the clinical trial. The mapping equation’s performance was subsequently assessed with mean absolute error (MAE) and root-mean-square error (RMSE) by comparing equation-based estimates to values elicited in the trial using the actual EQ-5D-3L questionnaire.ResultsThe mapping equation predicted EQ-5D-3L values in this external cohort with reasonable precision at both time points (MAE 0.116 and RMSE 0.155 at baseline; MAE 0.105 and RMSE 0.138 at week 4), and was similar to that reported in the original NARCOMS cohort (MAE 0.109 and RMSE 0.145). Also as observed in the original NARCOMS cohort, the mapping equation performed best in patients with EQ-5D-3L values between 0.50 and 0.75, and poorly in patients with values <0.50.ConclusionThe mapping equation performed similarly in this external cohort as in the original derivation cohort, including a poorer performance in MS patients with more severe health-state severity.

Dalfampridine in the treatment of multiple sclerosis: a meta-analysis of randomised controlled trials

“…After WMDs were compared between treatment groups, and although the results were statistically significant, there is no equivalent impact on clinical meaningfulness. Although the MSWS-12 is a validated patient-reported outcome measure for assessing the extent to which MS impacts an individual’s walking ability [ 25 ], few studies have explored the minimal clinically important differences for the tool. As some included studies [ 15 , 16 ] reported significant clinical differences in MSWS-12 for patients receiving dalfampridine versus placebo, future research in this area is required to explore the definite effect of dalfampridine on walking disability and determine the minimal clinically important differences for MSWS-12.…”

“…Dalfampridine is known to be substantially excreted by the kidneys and the risk of adverse reactions, including seizures and anaphylaxis, is greater with increasing exposure. According to the 5-year post-marketing data in the United States [55], among the 107,000 patients treated with dalfampridine, 23.9% (25,526) of patients reported at least one AE. Of these patients, 75% were female, and the mean age was 55.3 years; while the proportion of patients aged ≥ 65 years was 19%.…”