Antirheumatic treatment

Information on antirheumatic drug use was collected from SRQ, from 1 month prior until 12 months after the RA diagnosis. The antirheumatic treatment was categorised into five groups: (1) MTX monotherapy, (2) conventional synthetic (cs)DMARDs excluding MTX, (3) MTX combination therapy with other csDMARDs, (4) biological/targeted synthetic (b/ts)DMARDs with or without other csDMARDs, (5) no DMARD treatment. Information about DMARD use at 30 days before to 30 days after RA diagnosis in SRQ was counted as DMARD use at RA diagnosis. MTX monotherapy is the standard first-line DMARD therapy in early RA, and retention of this treatment indicates good effect and tolerance. We therefore extended the evaluation of MTX monotherapy to 36 months after RA diagnosis. We chose to use SRQ as our source of drug information because bDMARDs administered through infusion are only found in SRQ, and SRQ enables a better control of drug discontinuation than the PDR.