Electronic supplementary material
The online version of this article (doi:10.1186/1477-7525-10-70) contains supplementary material, which is available to authorized users.
An erratum to this article is available at http://dx.doi.org/10.1186/1477-7525-11-60.
PW, TV, & MM are all current or former employees of PatientsLikeMe and hold stock / stock options in the company. The PatientsLikeMe R&D team has received research support from Abbott, Accorda, Avanir, Biogen, Genzyme, Merck, Novartis, Sanofi and UCB.
PW: Designed MSRS, project design, revised manuscript, statistical analysis. TV: Data analysis, reviewed manuscript. MM: Drafted manuscript, project design, cognitive debriefing, statistical analysis. All authors read and approved the final manuscript.
In developing the PatientsLikeMe online platform for patients with Multiple Sclerosis (MS), we required a patient-reported assessment of functional status that was easy to complete and identified disability in domains other than walking. Existing measures of functional status were inadequate, clinician-reported, focused on walking, and burdensome to complete. In response, we developed the Multiple Sclerosis Rating Scale (MSRS).
We adapted a clinician-rated measure, the Guy’s Neurological Disability Scale, to a self-report scale and deployed it to an online community. As part of our validation process we reviewed discussions between patients, conducted patient cognitive debriefing, and made minor improvements to form a revised scale (MSRS-R) before deploying a cross-sectional survey to patients with relapsing-remitting MS (RRMS) on the PatientsLikeMe platform. The survey included MSRS-R and comparator measures: MSIS-29, PDDS, NARCOMS Performance Scales, PRIMUS, and MSWS-12.
In total, 816 RRMS patients responded (19% response rate). The MSRS-R exhibited high internal consistency (Cronbach’s alpha = .86). The MSRS-R walking item was highly correlated with alternative walking measures (PDDS, ρ = .84; MSWS-12, ρ = .83; NARCOMS mobility question, ρ = .86). MSRS-R correlated well with comparison instruments and differentiated between known groups by PDDS disease stage and relapse burden in the past two years. Factor analysis suggested a single factor accounting for 51.5% of variance.
The MSRS-R is a concise measure of MS-related functional disability, and may have advantages for disease measurement over longer and more burdensome instruments that are restricted to a smaller number of domains or measure quality of life. Studies are underway describing the use of the instrument in contexts outside our online platform such as clinical practice or trials. The MSRS-R is released for use under creative commons license.