The phenotypic differences between probable migraine and definite migraine in teenage girls

The frequency of probable migraine (PM) remains elusive; some of the published literature estimate PM to be at least as prevalent as definite migraine (DM) while others report PM to affect about 5% of the population or less. We conducted a cross sectional survey of female high school students using a validated questionnaire which covered the diagnostic features of DM, PM and tension type headaches as specified by the international classification of headache disorders. The survey also inquired about subjects' treatment history and analgesic use. Headache related disability was ascertained using headache impact test 6 (HIT-6). The participants included 309 girls with a mean age of 16.0 yr. The prevalence of DM and PM in our cohort were 18% and 25% respectively. Overall, headaches were more frequent in the DM group although this did not reach statistical significance (P < 0.06). There was no statistical significance between DM and PM in respect to seeking medical care (P < 0.30). The individuals with tension type headaches however, were less likely to seek medical care compared to the ones with PM or DM (P < 0.001). The preventative medications were under-utilized in all three groups. Moreover, individuals in the DM group reported higher frequencies of analgesic use (P < 0.001). The girls with DM experienced higher degrees of headache related disability as measured by HIT-6 (P < 0.0001). PM appears to be at least as prevalent of DM in our cohort of teenage girls. We propose that PM may produce a milder phenotype indicated by significantly lower HIT-6 scores.