Konomura Keiko, Nagai Hideaki, Akazawa Manabu, Development of a Chronic Obstructive Pulmonary Disease Severity Classification System Using A Japanese Health Insurance Claims Database, Journal of Aging Research And Healthcare, Volume 2, Issue 2, 2017, Pages 1-12, ISSN 2474-7785, https://doi.org/10.14302/issn.2474-7785.jarh-17-1727.
(http://oap-cancer.orgjarh/article/577)
Keywords: Chronic obstructive pulmonary disease; COPD; severity classification system; severity score; principal component analysis; administrative database