Clinical characteristics of patients with polyarteritis nodosa based on a nationwide database in Japan

OBJECTIVES: This study aimed to clarify the epidemiological and clinical features and treatment of patients with polyarteritis nodosa (PAN) in Japan. METHODS: We used the database of the Ministry of Health, Labour and Welfare (MHLW) of Japan in 2013 and 2014. We analysed 121 patients who were antineutrophil cytoplasmic antibodies negative among the patients certified as PAN according to the MHLW diagnostic criteria. RESULTS: The analysis included 60 males and 61 females, with a mean age of 52.9 ± 21.0 years. As a general manifestation, fever was observed in 53.7%. Regarding organ involvement, skin manifestations (82.6%), joint and muscle manifestations (75.2%), and neuropsychiatric manifestations (50.4%) were common. Male patients had a higher proportion of mononeuritis multiplex involving motor neuropathy than female patients. Elderly patients had a higher proportion of general and respiratory manifestations. Glucocorticoids were used for treatment in all patients, and 19.0% underwent methylprednisolone pulse. Concomitant immunosuppressants were used in 25.6%, one-third of whom received cyclophosphamide. Methylprednisolone pulse and cyclophosphamide were mostly used in patients with life-threatening organ involvement. CONCLUSIONS: PAN developed in middle-aged people and led to numerous clinical manifestations. The common manifestations varied with age, and treatment was determined based on the type of organ involvement and disease severity.