Associations between studies of RA (versus SLE and other diseases) and the presence of each study-design feature, by multivariate logistic regression analysis. Odds ratios <1.0 indicate that the study-design feature was less common in studies of RA, whereas odds ratios >1.0 indicate that the study-design feature was more common in studies of RA. Error bars are 95% confidence limits Odds ratios were based on models that also included the type of specimen, journal, the number of patients, data on animals, and category of biomarker as independent variables. Separate models were estimated for each study-design feature. Each model fit the data well (all Hosmer-Lemeshow test, P > 0.09).