2.1 Study Population
The design and methods of the KURAMA cohort study have been described
previously10. Briefly, consecutive patients with RA
were recruited from April 1, 2011, and the diagnosis was confirmed using
the revised 1987 American College of Rheumatology (ACR) criteria for RA
or the 2010 ACR/European League Against Rheumatism classification
criteria for RA at the Center for Rheumatic Diseases in Kyoto University
Hospital. Among the 545 RA patients included in the KURAMA study from
June 2016 to December 2016, 340 consecutive patients who had records of
12-lead ECG were included in the present study. All patients provided
informed consent, and procedures were conducted in accordance with the
principles of the Declaration of Helsinki. The study protocol was
approved by the Kyoto University Graduate School and the Faculty of
Medicine Ethics Committee (R0357).