Clinical features of Japanese patients with acute hepatic porphyria

Acute hepatic porphyria (AHP) is a family of rare genetic diseases of heme biosynthesis characterized by severe neurovisceral attacks. The clinical characteristics of patients with AHP as well as the prevalence of AHP in Japan are not well understood. The objectives of this study were to describe clinical characteristics of AHP at time of diagnosis in Japanese patients and to estimate the prevalence of AHP. Patients with porphyria were selected from Japan's Medical Data Vision health care claims database between April 2008 and June 2020. Patient characteristics before and at time of AHP diagnosis were evaluated. Prevalence per 100 000 was estimated during the study period. A total of 391 cases of AHP were included. At time of AHP diagnosis, mean age was 44 years, and the most common type was acute intermittent porphyria. Median time to diagnosis was 3 months, but some patients remained undiagnosed for several years. The most common complications included metabolic disorders (54%) and diabetes mellitus (39%). In addition, the well‐known complications of AHP, including hypertension (22%) and malignant neoplasms of digestive organs (22%), were observed. About 10% of patients received medications that may have aggravated porphyria attacks. The estimated prevalence of AHP in Japan during the study period was 1.18 cases per 100 000 population. At time of diagnosis, many patients with AHP in Japan are already experiencing a high burden of disease‐related complications. Raising AHP awareness may aid physicians in providing an earlier diagnosis and reducing lifetime disease burden.