| Study | Design | ROB Rating(s) | Rationale for Rating(s) |
|---|---|---|---|
| Bili et al., 201411 | Retrospective cohort study | High | Not possible to draw valid conclusions from study findings because of how medication use classified. Medication use evaluated as “exposure periods”, and individual patients could contribute data to multiple exposure periods for different drugs. Furthermore, MTX group included MTX monotherapy and combination therapies. |
| ERAN, 2013137 | Prospective cohort study | High | High risk of bias from classification of interventions. Comparisons of treatment use vs. no use provides insufficient information to draw clear usable conclusions because no-use patients would have taken at least one of seven alternative treatments (Table 1). No information on which alternative treatments patients switched to after discontinuing initial DMARD treatment. |
| Nijmegen RA Inception Cohort, 200926 | Prospective cohort study | High | High risk of selection bias for treatment discontinuation. High risk of attrition bias at 6 months (overall: 24.3%) and 12 months (overall: 41.3%; differential: 16.1%). High risk of confounding from indication. |
| NOR-DMARD analysis, 201228 | Retrospective cohort study | High | High ROB from confounding by indication, from time-varying reduction in patients being prescribed SSZ in favor of MTX, and from unbalanced use of concomitant PNL (use in MTX arm exceeded use in MTX arm). |
DMARD = disease-modifying antirheumatic drug; MTX = methotrexate; PNL = prednisolone; RA = rheumatoid arthritis; ROB = risk of bias; SSZ = sulphasalazine; TNF = tumor necrosis factor; TNFi = TNF inhibitor(s)
From: Appendix D, Risk of Bias Ratings and Rationales for Included Studies
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