Frequency of Migraine Recorded in Primary Care and Hospital Records in Aotearoa New Zealand: a Cross-Sectional Study

Migraine is the second most disabling condition worldwide affecting over one billion people. We aimed to investigate the frequency of recorded migraine utilising general practice and hospital admission data, comparing this with population-based prevalence estimates for Aotearoa New Zealand (NZ). From the electronic health record of de-identified data for 374,071 men and women aged 18 and over enrolled as of 2014 in NZ general practices, any entry of recorded migraine from a patient’s visit to primary care or hospital facility recorded using Read codes, Read terms, or free text entries was extracted. Via an encrypted National Health Identifier (NHI), individual patient linkage identified migraine coded in the national hospitalisation dataset, enabling exploration by gender, age group, ethnicity and NZ deprivation index quintile. Compared to population prevalence (15%), 4.8% of this cohort had recorded migraine (79% in general practice only; 14% in hospital records only; 7.5% in both primary and secondary care). Women (6.7%) had higher recording than men (2.5%), with the highest age-specific recording at 45–54 years (women 7.4%, men 2.7%). By gender and ethnicity, migraine recording was highest for European women (7.9%). Within quintile 5 communities (most deprived), recording was significantly lower for females (p < 0.0001) and males (p = 0.03) than in quintiles 1–4. This study is the first to estimate migraine in NZ using linked primary and secondary care data. As well as highlighting age-, gender-, and ethnicity-specific differences, the underestimate of diagnosis compared to self-reported survey data is likely due to health care access, under-reporting, under-diagnosis, under-recording, and knowledge gaps about migraine symptoms and therapies.