POPULATION VARIATION IN MIGRAINE PREVALENCE - A METAANALYSIS

A meta-analysis of published studies was conducted to identify factors which explained variation in estimates of migraine prevalence. Twenty -four population based studies contributed a total of 168 gender and a ge specific estimates of migraine prevalence. In linear regression ana lysis, 70.6% of the variation in these prevalence estimates was explai ned by gender, age (AGE + AGE(2)), a binary variable for case definiti on, and an interaction term between age and the case definition. Initi ally, we identified five groups of case definitions among the 24 studi es. Only the definition of Waters (any 2 of warning, nausea, or unilat eral pain) was associated with statistically significant differences i n prevalence estimates among studies; accordingly the other 4 groups w ere combined. Several other factors were examined as predictors of mig raine prevalence including the method of selecting the study populatio n, the source of the population, the response rate and whether diagnos es were confirmed by a clinical assessment. None of these factors subs tantially increased explained variance. We conclude that after taking sociodemographic factors and case definition into account, estimates o f migraine prevalence are remarkably stable among studies.