The original MSRS was designed to minimize respondent burden, using a minimum number of items to cover relevant aspects of patient experience and simple, clear language in both the questions and response options. Patients have indicated in qualitative interviews that the questions are relevant to their experience, easy to understand, and easy to respond to, and provide an accurate profile of their experience of MS over time. Its deployment on PatientsLikeMe led to widespread use by thousands of MS patients, who report that using the site has produced a number of benefits including improved understanding of their condition and improved communication with their healthcare providers . Following cognitive debriefing, a number of small modifications were made to produce the MSRS-R (Revised). After fielding in a survey, statistical analysis shows the MSRS-R exhibits desirable psychometric properties in terms of ceiling and floor effects, internal consistency, factor structure, test-retest, and known-group validity. Importantly, the MSRS-R correlated in expected ways with alternative measures in widespread use (MSIS-29, PDDS, NARCOMS PS, PRIMUS, and MSWS-12), suggesting acceptable concurrent validity and potential use as a research tool.
The MSRS-R has the advantage of being more concise than any of the other instruments fielded in this study; for instance, the PDDS requires a patient to read approximately 360 written words to gauge walking disability; the MSRS-R walking item has 33 words and produces very similar results. Furthermore, our analysis confirmed that the PDDS, like the EDSS it is based upon, is predominantly focused on walking; by contrast, the entire MSRS-R covers eight domains but is only 53 words long and uses a consistent response format, which makes it less burdensome for patients to read and complete.
Currently, MS trial design focuses on the frequency of relapses but is uninformed by the nature of these relapses, and so an attack that leaves one patient unable to walk and another unable to see are counted the same. Analysis of retrospective relapses in the current study demonstrated that the nature of relapses experienced in this population could be characterized by changes from baseline within specific domains of function using the MSRS-R. This may be useful in improving our understanding of MS characterization, progression, and response to therapy. In addition, our known group validity analysis suggested that the MSRS-R might be more sensitive to cumulative burden of disability resulting from recurrent relapses than the PDDS; further study could compare MSRS-R against other measures of cumulative burden such as magnetic resonance imaging.
Following this psychometric validation and upgrade of the existing MSRS to the newer MSRS-R, passively collected profile data in the PatientsLikeMe platform could be studied as a form of observational registry combining demographic, social networking, treatment, and symptom data. Such data would extend to a larger number of patients than described here, and to MS disease types other than RRMS, and could illuminate the real-world impact of newer therapies for MS. For instance, it may be particularly interesting to retrieve the prospective data for patients who did not report any treatment at the time of creating their account and study the amount of MSRS-R change that triggers initiation of treatment, or to gauge the effectiveness of treatment in stabilizing or reducing disability relative to similar patients who did not start treatment.
With regard to administration, although we did not explicitly test for differences between, e.g., paper-and-pencil questionnaires compared with online questionnaires, we expect that there would be no or minimal difference between data collected in these modes. The cognitive interviews did not suggest any significant difference between patients’ responses on paper and how they would have responded (or how they had responded previously) using the report tools on the PatientsLikeMe platform. The online form is two-dimensional, and no wording or format changes are required to adapt the MSRS-R, symptoms, or relapse questions for paper-and-pencil administration.
The limitations of this study are shared by many postal or internet-based questionnaire designs. We have no independent validation that respondents actually do have MS; however, as there was no incentive for participating, there would be little incentive to enter false data. Our analysis of responders found them to be a little older and more affected by MS than non-respondents; this is perhaps unsurprising given that sicker patients may be more inclined to return to PatientsLikeMe to seek support. One advantage of this data collection platform is that we can systematically describe the population of non-responders.
It is likely that the entire PatientsLikeMe population may differ systematically from the broader MS population (see  for a comparison with the Sonya Slifka Longitudinal MS Study), therefore these findings should be generalized cautiously. That said, our findings on the response characteristics of the comparison instruments used proved similar to their own validation studies. The response rate (19%) was relatively low but was not atypical for a survey of this online community . The most significant limitation was that we lacked independent clinical assessment of disease severity from a clinician experienced in the field; we are seeking to address this in future studies.
A further limitation that underscores the difference between passively collected profile data and actively sampled survey data is the mismatch between the 345 completers (43%) who had at least one relapse recorded on their profile and the 424 completers (52%) who reported having at least one relapse when polled on the survey. Passively collected data provides a large body of longitudinal data but suffers from attrition bias; actively collected data provides a more accurate cross-section at one or a few points in time but is more costly to collect and may suffer from responder bias.
Evaluating the quality of the test-retest with a Bland-Altman plot is difficult in the absence of a gold standard and the lack of agreed standards for measurement variability in MS. It is possible that in performing the test-retest, some patients may not have clearly read the instructions to report retrospectively to the first time they completed the survey; if so, the degree of test-retest agreement reported here would be an underestimate and should be investigated further.
A copy of the MSRS-R is included as an appendix to this manuscript, and the instrument is distributed with a Creative Commons “Attribution-ShareAlike3.0 Unported” license, meaning it can be used freely (including commercially), altered, transformed, or built upon, so long as all derivative work is licensed in the same fashion and proper attribution is made (Additional file 1).