A nationwide epidemiological survey of alpha1-antitrypsin deficiency in Japan

Background: Alpha1-antitrypsin (ΑAT) deficiency (AATD), a condition of little or no AAT in the serum, is believed to be extremely rare in Japan. However, no such nationwide epidemiological survey has been conducted. The Respiratory Research Failure Group and Japanese Respiratory Society (JRS) cooperated to conduct this survey.

Methods: The survey questionnaire was sent by post to 1598 hospitals that have 200 or more beds (excluding mental hospitals), and by e-mail to members of the JRS. Hospitals failing to respond were followed-up by phone.

Results: 1467 hospitals replied [response rate=91.8% (1467/1598)], and 114 members responded. Of the 14 probands registered from 10 hospitals and one local practitioner, 9 had severe and 5 had mild AATD. Eleven of these patients were diagnosed with COPD, 1 with COPD and bronchiectasis, 1 with pulmonary emphysema without airflow obstruction, and the remaining 1 with bronchiectasis without airflow obstruction. Mutation analysis of the SERPINA1 gene was performed in 7 patients, 6 of whom (85.7%) had homozygous PI*Siiyama. The prevalence of AATD in Japan was thus estimated to be 24 patients, with a 95% confidence interval (22, 27). When asked if they would prescribe AAT augmentation therapy, 6 of the 10 (60.0%) of respondent attending physicians answered affirmatively if health insurance would cover the treatment.

Conclusions: This nationwide survey confirmed that AATD is extremely rare in Japan. Six of 10 care-giving physicians would offer AAT augmentation therapy if the therapy were covered by health insurance in Japan.