Objective.— To provide evidence for the reliability and validity of the Migraine-Specific Quality of Life Questionnaire Version 2.1 (MSQ) for use in chronic migraine (CM) in adults.
Background.— MSQ is one of the most frequently utilized disease-specific tools assessing impact of migraine on health-related quality of life (HRQL). However, evidence for its reliability and validity are based on studies in episodic migraine (EM) populations. Additional studies assessing the reliability and validity of the MSQ in patients with CM are needed.
Methods.— Cross-sectional data were collected via web-based survey in 9 countries/regions. Participants were classified as having CM (≥15 headache days/month) or EM (<15 headache days/month). Three MSQ domains – Role Function-Preventive (RP), Role Function-Restrictive (RR), and Emotional Function (EF) – were rescaled to 0-100, where higher scores indicate better HRQL, and analyzed for internal consistency reliability (Cronbach's α), construct validity (correlations between MSQ scales and measures of depression/anxiety [Patient Health Questionnaire; PHQ-4], disability [Migraine Disability Assessment Questionnaire; MIDAS], and functional impact [Headache Impact Test; HIT-6], where lower scores indicate better HRQL for each measure), as well as discriminant validity across migraine groups.
Results.— A total of 8726 eligible respondents were classified: 5.7% CM (n = 499) and 94.3% EM (n = 8227). Subjects were mostly female (83.5%) with a mean (±SD) age of 40.3 ± 11.4, and were similar between the 2 groups. MSQ domain scores for CM and EM groups, respectively, were: RP = 61.4 ± 26.1 and 71.7 ± 24.0; RR = 44.4 ± 22.1 and 56.5 ± 24.1; EF = 48.3 ± 28.1 and 67.2 ± 26.7. Internal consistency of the overall sample for RP, RR, and EF was 0.90, 0.96, and 0.87, respectively. Similar values were observed for CM and EM. MSQ scores for the overall sample correlated moderately to highly with scores from the PHQ-4 (r = −0.21 to −0.42), MIDAS (r = −0.38 to −0.39), and HIT-6 (r = −0.60 to −0.71). Similar values were observed for CM and EM. Known-groups validity indicated significant differences (P < .0001) in the hypothesized direction between CM and EM for RP (F = 86.19), RR (F = 119.24), and EF (F = 235.90).
Conclusion.— The MSQ is a reliable and valid questionnaire in the CM population that can differentiate the functional impact between CM and EM. The MSQ can assist researchers in evaluating treatment effectiveness by obtaining input directly from the patients on multidimensional aspects other than frequency of headache days.