Questionnaire-based survey on the prevalence of medication-overuse headache in Japanese one city—Itoigawa study

OBJECTIVE: The medication-overuse headache (MOH) prevalence has not been investigated in a general Japanese population. We performed questionnaire-based survey and revealed MOH prevalence and its characteristics. We also performed clustering to obtain insight for MOH subgrouping. METHODS: In this cross-sectional study, the 15–64-year-old population was investigated in Itoigawa during their COVID-19 vaccination under the national policy. MOH was defined as ≥ 15 days/month plus self-report of use of pain medications ≥ 10 or 15 days/month in the last 3 months. Ward method and k-means + + were used to perform clustering MOH patients. RESULTS: Among 5865 valid responses, MOH prevalence was 2.32%. MOH was common among females and the middle-aged. Combination-analgesic is the most overused as 50%. MOH had aggravation by routine physical activity, moderate or severe pain, and migraine-like, compared to non-MOH. The 136 MOH patients could be grouped into 3 clusters. Age and frequency of acute medication use were essential factors for clustering. CONCLUSIONS: This is the first study of MOH prevalence in Japan. Most MOH characteristics were similar to previous reports worldwide. Public awareness of proper headache treatment knowledge is still needed. Clustering results may be important for subtype grouping from a social perspective apart from existing clinical subtypes.