Received: 19 April 2019
Accepted: 1 July 2019
First Online: 15 July 2019
Ethics approval and consent to participate
: The study was conducted according to the principles of the Declaration of Helsinki and was approved by the Ethics Committee of Kyoto University before the start of the study (E1308).
: Not applicable.
: We received no expense or support specific to this study. However, there exist some competing interests. The Department of Advanced Medicine for Rheumatic Diseases is supported by Nagahama City, Shiga, Japan, and four pharmaceutical companies (Mitsubishi Tanabe Pharma Co., Chugai Pharmaceutical Co. Ltd., UCB Japan Co. Ltd., and AYUMI Pharmaceutical Co.). KURAMA cohort study is supported by grant from Daiichi Sankyo Co. Ltd. HI has received a research grant and/or speaker fee from Bristol-Myers, Astellas, Kyocera, and Asahi-Kasei. MH has received a research grants from Astellas and Bristol-Myers. MT has received research grants from Astellas, Abbvie, Eisai, Pfizer, Takeda, and Taisho-Toyama. TT, KN, KM, MA, AO, KD, MH, TM, and SM declare that they have no competing interests. This study is conducted as an investigator-initiated study. The sponsors were not involved in the study design; in the collection, analysis, interpretation of the data; in the writing of this manuscript; or in the decision to submit the article for publication. The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.