Validity and reliability of the Migraine-Specific Quality of Life Questionnaire (MSQ version 2.1)

Objective.-To assess the scaling properties, reliability, and validity of the revised Migraine-Specific Quality of Life Questionnaire (MSQ) (Version 2.1) ((C) 1992, 1996, 1998 Glaxo Wellcome Inc.). Background.-The MSQ is a disease-specific, quality-of-life instrument with three hypothesized scales that has been developed, tested, and revised. Methods.-The study used a multicenter, nondrug, prospective, parallel group, quasi-experimental design. Patients with migraine were recruited at outpatient headache specialty practices and were administered the MSQ, the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), and migraine symptom questionnaires at baseline, 4 weeks, and 12 weeks. Internal consistency (Cronbach alpha) and 4-week test-retest reproducibility (intraclass correlation coefficients) were estimated to assess reliability. Construct validity was assessed using an adaptation of the Campbell and Fiske multitrait-multimethod approach and by correlating MSQ scores with symptom measures. Results.-A total of 267 subjects enrolled in the trial. The criteria for summated rating scales were all met. The internal consistency coefficients ranged from 0.86 to 0.96, and the intraclass correlation coefficients ranged from 0.57 to 0.63 across the three dimensions. As anticipated, the MSQ dimensions had low-to-modest correlations with the two component scores of the SF-36 and were modestly to moderately correlated with migraine symptoms. Conclusions.-The MSQ is a reliable instrument in the assessment of quality of life for patients with migraine with items that can be summed without weights. The MSQ has demonstrated evidence of construct validity.