@article{Keiko20171 title = "Development of a Chronic Obstructive Pulmonary Disease Severity Classification System Using A Japanese Health Insurance Claims Database", journal = "Journal of Aging Research And Healthcare", volume = "2", number = "2", pages = "1 - 12", year = "2017", note = "", issn = "2474-7785", doi = "https://doi.org/10.14302/issn.2474-7785.jarh-17-1727", url = "https://openaccesspub.orgjarh/article/577", author = "Konomura Keiko and Nagai Hideaki and Akazawa Manabu", keywords = "Chronic obstructive pulmonary disease", keywords = "COPD", keywords = "severity classification system", keywords = "severity score", keywords = "principal component analysis", keywords = "administrative database" }