Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are chronic inflammatory diseases of the musculoskeletal system. Although it seems likely that these conditions have a different pathogenesis, the drugs used to treat them are the same. Our study used a cross-sectional clinical database to compare drug use and side-effect profile in these 2 diseases.
The CASPAR study collected data on 588 patients with PsA and 536 controls, 70% of whom had RA. Data on disease modifying drug treatments used over the whole illness were recorded, together with their outcomes, including adverse events, for RA and PsA.
For both diseases methotrexate (MTX) was the most frequently used disease modifying drug (39% of patients with PsA, 30% with RA), with over 70% of patients in both diseases still taking the drug. Other drugs were used with the following frequencies in PsA and RA, respectively: sulfasalazine 22%/13%, gold salts 7%/11%, antimalarial drugs 5%/14%, corticosteroids 10%/17%, and anti-tumor necrosis factor (TNF) drugs 6%/5%. Compared to RA, cyclosporine and anti-TNF agents were less likely to be ineffective in PsA. Compared to RA, subjects with PsA were less likely to be taking MTX and more likely to be taking anti-TNF agents. Hepatotoxicity with MTX was more common in PsA and pulmonary toxicity with MTX was found more often in RA.
These data provide insight into prescribing patterns of disease modifying drugs in RA and PsA in a large international cohort, together with the differential adverse events of these drugs between these diseases.