The 7 Core Data Set measures to assess rheumatoid arthritis (RA) were analysed for their relative efficiencies to distinguish active from control treatments in 9 comparisons of 5 agents, methotrexate, leflunomide, infliximab, adalimumab, and abatacept, in 8 clinical trials. Among the 7 measures, levels of relative efficiencies were in a similar range, highest for the physician global estimate, ...