Background: A large number of headache sufferers with features of migraine fail to meet criteria for strict migraine (SM; migraine with or without aura) but do meet criteria for probable migraine (PM).
Objectives: To estimate the prevalence of PM, to compare the epidemiologic profiles of SM and PM, and to assess the disability and impact on the health-related quality of life (HRQoL) of these patients.
Methods: Computer-assisted telephone interviews in a sample recruited from a mixed model health maintenance organization were used. SM, PM, and control subjects were identified. Also assessed were demographic features, disability, HRQoL, and depression.
Results: The 1-year prevalence for SM was 14.7% (19.2% in women and 6.6% in men); for PM, it was 14.6% (15.9% in women, 12.6% in men). Most subjects with PM (82%) did not meet the associated symptom criteria for migraine. HRQoL was reduced in the PM, SM, and all migraine (AM; SM and PM pooled together) groups compared with controls. The proportion of subjects with high disability was elevated in PM (13%), SM (31%), and AM (22%) groups vs controls (3.7%; p < 0.0001).
Conclusions: Within a health plan, probable migraine is a prevalent form of migraine, with symptom and epidemiologic profiles that overlap with strict migraine. Although strict migraine prevalence was consistent with previous studies, a probable migraine prevalence higher than previously reported was found, perhaps reflecting a difference between health plan and population samples.