Understanding the Diagnosis of Primary Headaches in Outpatients Referred to Japanese Headache Specialists.

Background The timely and accurate diagnosis of primary headaches is crucial for enhancing patients' quality of life. However, primary headaches have been reported to be misdiagnosed and underdiagnosed worldwide, especially by nonspecialists. In Japan, despite the high prevalence of primary headaches, research on the extent of headache misdiagnosis and underdiagnosis remains limited. Therefore, we aimed to assess the rates of concordant primary headache diagnoses between previous physicians and headache specialists among outpatients who were referred to the headache center in Japan. Methodology In this retrospective, observational study, we collected data at the renowned Headache Center of Tominaga Hospital in Japan from August 2024 through April 2025. The target population was headache patients aged six years or older who were referred from or previously visited another medical institution. We classified headache diagnoses into the following five categories: migraine; tension-type headache; trigeminal autonomic cephalalgia; other primary headaches; and other headaches, including secondary headaches and painful cranial neuropathies. We calculated the accuracy rate of previous physicians' diagnoses by comparing theirs with those made by board-certified headache specialists at Tominaga Hospital. Results We analyzed 147 patients (mean age = 41.5 years; SD = 18.0 years) who were referred to Tominaga Hospital for headaches. Of these patients, 47 (32.0%) were male, and 100 (68.0%) were female. Overall, 69 (47.3%) patients were undiagnosed by previous physicians. The overall accuracy rate of previous physicians' diagnoses was 43.8% (95% confidence interval (CI) = 36.0-51.9%). The sensitivity and specificity of migraine were 52.6% (95% CI = 43.5-61.6%) and 78.1% (95% CI = 61.2-89.0%), respectively. Conclusions Approximately half of the patients had not received any specific diagnosis, and fewer than half had diagnoses consistent between headache specialists and previous physicians. These findings highlight the challenges of headache diagnosis and underscore the need for further investigation to enhance diagnostic accuracy.