The overall aim of this study was to estimate the total costs for patients with RA, AS and psoriatic arthritis (PsA) treated with DMARDs. Specific aims were to compare the costs across diagnoses and over time.
The main data source was the Norwegian DMARD register (NOR-DMARD) that captures outcomes and resource use among patients starting therapy with synthetic and biologic DMARDs. Costs were estimated for four 6-month periods from the start of a DMARD regimen. We included RA (n=1152), AS (n=186) and PsA (n=374) patients with available 2-year data. Direct costs included pharmaceuticals, imaging examinations, in-hospital and out-hospital care, stays in rehabilitation units and visits to general practitioners, private rheumatologists and physiotherapists. Indirect cost included patients' work absenteeism. Differences in costs across diagnoses were tested by Kruskal-Wallis equality-of-populations rank test and changes in costs between first and fourth 6-month periods were tested by paired t-tests.
Total 2-year costs were similar across diagnoses for patients on synthetic treatment (RA/AS/PsA €64,300/63,200/64,500) and on biologic treatment (€121,900/115,319/111,200). The largest cost component was productivity loss. Total costs decreased significantly from the first to the fourth 6-month periods for all diagnoses, and this decrease was influenced by reductions both in direct and indirect costs.
Total costs were similar across the main inflammatory rheumatic diseases. Biologic DMARD treatment entails considerable drug cost, but the total costs decline during the first 2 years on treatment in both RA, AS and PsA.