RT Journal Article SR Electronic T1 Confounding by indication and ethnicity difference? Comment on ‘Hypersensitivity reactions with allopurinol and febuxostat: a study using the Medicare claims data’ JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP e122 OP e122 DO 10.1136/annrheumdis-2020-218056 VO 81 IS 7 A1 Hsu, Po-Ke A1 Lee, Yung-Heng A1 Wei, James Cheng Chung YR 2022 UL http://ard.bmj.com/content/81/7/e122.abstract AB