Establishment of the consecutive registration system for pulmonary alveolar proteinosis in Japan: Updated incidence, prevalence and surveillance for intractable cases

In 2007, we reported a large cohort of autoimmune pulmonary alveolar proteinosis (n=248, PAP) in Japan, and showed the incidence and prevalence were 0.24 - 0.49/million/year and 2.04 - 6.2/million (AJRCCM 2007), and 1.4%, 1.4%, and 5.7% of patients had interstitial lung diseases (ILD), autoimmune diseases, and infections. The aims of this study are; (1) To establish a nationwide consecutive registration system for PAP, updating the incidence and prevalence, and (2) To show the usefulness of the system via a surveillance of intractable cases. Methods: (1) All patients, who received the serum anti-GM-CSF autoantibodies tests and were definitely diagnosed, were annually consecutively registered to our database (2011-2014). Three institutes (Niigata, Kinki-Chuo, Aichi) measured the antibodies. (2) Surveillance for the intractable cases (dead, complications such as ILD, infection, etc.) was conducted via the system. Results: (1) Total 903 cases were registered. 88 cases/year have been newly diagnosed in average. The incidence and the prevalence were 0.69/million/year and 6.11/million. 92.9, 6.1, 0.4, and 0.6% were autoimmune, secondary, congenital, and unclassifiable PAP. (2)50% of the institutes responded, providing the data of 579 cases (64% of total patients). 14, 11.2, 10.2, 3.8, 6.7, and 7.9% had dead, respiratory failure, ILD, autoimmune diseases, infections, extra-pulmonary complications. Conclusions: We established a simple consecutive nation-wide registration system for PAP in Japan, providing updated annual epidemiological data and effective surveillance data. This study was granted from AMED (#15652554 , YI).