Covariates at the time of enrollment included sex, ethnicity, race, age, body mass index, weight, height, tobacco use, methotrexate dose, duration of RA, duration of methotrexate use, duration of etanercept use, SDAI score, CDAI score, DAS-28-ESR, DAS-28-CRP, all definitions of Boolean remission, TJC and SJC (28 joints, 66/68 joints), physician global assessment, PGA, CRP, ESR, and Health Assessment Questionnaire Disability Index. The gene discussed is CRP; the disease is rheumatoid arthritis.