TY - JOUR T1 - Bias in the Methodology: Sleep Quality Is Related to Worsening Knee Pain in Those With Widespread Pain JF - The Journal of Rheumatology JO - J Rheumatol SP - 303 LP - 303 DO - 10.3899/jrheum.201165 VL - 48 IS - 2 AU - Chieh-Chun Yang AU - Po-Cheng Hung Y1 - 2021/02/01 UR - http://www.jrheum.org/content/48/2/303.1.abstract N2 - To the Editor:We read with great interest the article in The Journal entitled, “Sleep Quality Is Related to Worsening Knee Pain in Those with Widespread Pain: The Multicenter Osteoarthritis Study” by Dai, et al1. The authors reported the association between sleep quality and odds of developing knee pain, and how widespread pain modified this relationship. We highly appreciate the great efforts the authors did by using a prospective cohort while simultaneously considering the potential effect of body pain at other sites. However, there are some methodologies and interpretations in the study that need more clarification.First, the questionnaires conducted at baseline may not be able … Address correspondence to Dr. C.C. Yang, No. 110, Sec. 1, Jianguo N. Rd., South District, Taichung City 40201, Taiwan. Email: jason80035{at}gmail.com. ER -