Demographics, Headache Features, and Comorbidity Profiles in Relation to Headache Frequency in People With Migraine: Results of the American Migraine Prevalence and Prevention (AMPP) Study

BACKGROUND: Migraine is typically divided into 2 headache frequency denominated categories, episodic migraine (EM) and chronic migraine (CM). Characterizing more narrow headache day frequency groups may be of value for better understanding the broad range of migraine experience and making treatment decisions. OBJECTIVE: To characterize the impact and burden of migraine in 4 monthly headache day (MHD) categories. METHODS: Respondents to the American Migraine Prevalence and Prevention Study 2005 survey who met criteria for migraine were categorized into low frequency episodic migraine (LFEM) 0-3, moderate frequency episodic migraine (MFEM) 4-7, high frequency episodic migraine (HFEM) 8-14, and CM with ≥15 headache days per month. Data including sociodemographics, headache features and symptomology, comorbidities, cutaneous allodynia, and severe migraine-related disability were compared among groups. We combined the low- and medium-frequency EM groups (L/MFEM) and compared them with the HFEM group in 1 set of models and compared the HFEM and CM groups in a second set of models. Binary logistic regression, linear regression, and ordered logistic regression were used depending upon the variable type and adjusted for sociodemographics. RESULTS: Among 11,603 eligible respondents with migraine, 67.7% (7860/11,603) were categorized with LFEM, 17.7% (2051/11,603) with MFEM, 7.8% (898/11,603) with HFEM, and 6.8% (794/11,603) with CM. The mean age was 46 (SD 13.7), 80.2% (9301/11,603) were female, and 90.0% (10,187/11,323) were White, 6.9% were Black (784/11,323), and 3.1% (352/11,323) were identified as Other race(s). Individuals with HFEM differed from L/MFEM on a wide range of sociodemographic variables in the categories of headache features, disability, and comorbidities while few differences were found when modeling HFEM vs CM. In comparison with L/MFEM and HFEM, the HFEM group was more likely to have severe disability (P < .001 OR = 1.74 [1.42, 2.15]), chronic pain (P ≤ .007 OR = 1.35 [1.09, 1.69]), arthritis (P = .001 OR = 1.44 [1.15, 1.80]), high cholesterol (P = .005, OR = 1.37 [1.10, 1.70]), ulcers (P = .016, OR = 1.44 [1.07, 1.93]), and depression (Patient Health Questionnaire [PHQ-9]) (P < .001 OR = 1.50 [1.22, 1.84]). CONCLUSION: While rates of migraine symptoms, headache impact and disability, and comorbidities generally increased with increases in MHD frequency, respondents with HFEM and CM were remarkably similar on a broad range of variables including sociodemographics, disability/impact, and comorbidities. There were many more significant differences between the HFEM and L/MFEM groups on the same variables. Future work should use empirical strategies to identify naturally occurring groups and possibly reconsider the boundary between CM and HFEM.