My Migraine Research
 
 

• All of my papers can be downloaded as PDFs here.

• The migraine questionnaires used in the two original studies:
• Between 1993-1995, a telephone interview in which a diagnostic assessment of psychiatric disorders, including alcohol use and abuse, anxiety, depression and phobias, was administered to an older cohort of twins, born 1902-1964. A total of 5996 individual twins completed the 1993 interview (Heath et al 1997).
• Between 1996-2000, a younger cohort of  twins (born 1961-1975) undertook a more detailed semi-structured telephone interview, designed to assess physical, psychological and social manifestations of alcoholism and related disorders (Heath et al 2001); 6265 individual twins completed the interview.
• Although the wording of questions was identical between cohorts, the younger cohort were asked questions relating to 10 International Headache Society (IHS) diagnostic symptom criteria [see Table 1 and Figure 1 of Nyholt et al. (2004)], while the older cohort were not asked questions relating to “at least five migraine/episodes of headache during lifetime” (“>5 episodes”, “A”), “average typical migraine/headache lasts between 4 and 72 hours” (“4-72hr”, “B”) and “pain associated with headache described as moderate or severe” (“moderate/severe”, “C3a”).
• In my latent class analysis (LCA) approach to obtain empirical clusters of migraine symptoms (Nyholt et al. 2004), the younger and older cohort data are combined, thus allowing the LCA to impute class membership in the older cohort, based on the pattern of all 10 symptoms observed in the younger cohort. To examine the accuracy of imputed class memberships we compared the classification results for the younger dataset utilizing all 10 available IHS symptoms, to the classification results for the younger dataset utilizing only the 7 IHS symptoms which were available for the older cohort. Compared to using all 10 symptoms, when only the 7 symptoms were used, these analyses found 98.5% and 96.0% of individuals were correctly classified as unaffected and affected respectively, indicating that the three missing symptoms in the older cohort would have negligible effect on the accuracy of individual LCA migraine diagnoses (Nyholt et al. 2005).

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