The Development of a Bilingual MS-Specific Health Classification System: The Preference-Based Multiple Sclerosis Index (PBMSI)

OBJECTIVE: The global aim of this study was to contribute to the development of the Preference-Based Multiple Sclerosis Index (PBMSI). The specific objective of this foundational work was to qualitatively review the items selected for inclusion in the PBMSI using expert and patient feedback. METHODS: Cognitive interviews were conducted with patients with multiple sclerosis (MS) in English and French. The verbal probing method was used to conduct the interviews. For each PBMSI item, the interviewer probed for specific information on what types of difficulty participants had with the item and the basis for their response for each item. Furthermore, respondents were asked to provide information on the clarity of the item, the meaning of the item, the appropriateness of the response options, and the recall period. All interviews were recorded using a digital voice recorder and were transcribed onto a computer. RESULTS: The mean age of the 22 respondents was 52 years, and 82% were women. Mean time since diagnosis was 12 years, and the highest level of education completed was university or college for 86% of the sample. Modifications were made to each item in terms of recall period, instructions, and phrasing. CONCLUSIONS: Patient and expert feedback allowed us to clarify items, simplify language, and make items more uniform in terms of their instructions and response options. This qualitative review process will increase accuracy of reporting and reduce measurement error for the PBMSI.