Validation of a migraine screening questionnaire in a Colombian university population.

In studies of migraine prevalence, it is important to be aware of the discriminative capacity of the test used. We set out to validate a Spanish translation of Michel's Standardized Migraine Diagnosis Questionnaire. The questionnaire was applied on all active students of the School of Psychology of the Universidad Autónoma de Bucaramanga, Colombia. A neurologist interviewed a random sample to substantiate the diagnosis of migraine. Cronbach's alpha was calculated and factors analysis was made in order to estimate internal consistency, test-retest to find reproducibility, and ROC curve and diagnostic indicators were calculated to estimate the criteria validity. Of 357 students that answered the questionnaire, 188 (52.7%) were selected at random to attend an appointment with a neurologist, but only 170 had this interview. Cronbach's alpha on these 357 questionnaires is 0.7497. All the questions on the questionnaire represented two main factors. This test had sensitivity in 37.9% [95% confidence interval (CI) 25.8, 51.7], specificity in 99.1% (95% CI 94.4, 100), positive predictive value in 95.7% (95% CI 76.0, 99.8), and negative predictive value in 75.5% (95% CI 67.6, 82.1) for 17 or more points. The area below ROC curve is 0.8529 (95% CI 0.8035, 0.9217). Among 84 students who took the questionnaire a second time, the average score on the first survey was 12.33 +/- 7.46 points, while the average score on the second take was 11.26 +/- 7.85 (P = 0.069). Agreement for migraine is 83.3% (95% CI 73.6, 90.6; Cohen's kappa = 0.6650 +/- 0.1061). The Spanish translation of Michel's Questionnaire is easy to answer and has good internal consistency, but its reproducibility and sensibility are modest; however, the ROC curve is acceptable to discriminate migraine patients from normal subjects.