Many patients with rheumatoid arthritis (RA) need continuous medication, bringing considerable costs for drugs and a need for monitoring adverse drug reactions. We studied drug exposure, drug costs, and adverse drug reactions in patients with RA in Sweden from 1987 to 1997.
Prescription patterns, drug costs, and adverse drug reactions, and their distributions and trends were analyzed by cross sectional annual data. Drug exposures and costs were assessed from the National Diagnosis and Therapy Survey. All costs were recalculated to the 1997 level using the drug price index. Information on adverse drug reactions was obtained from the national pharmacovigilance system.
The drug prescription level was, on average, 2 defined daily doses (DDD) throughout the study period. Nonsteroidal antiinflammatory drugs (NSAID) accounted for > 40% of the drugs prescribed, methotrexate (MTX) 10%, corticosteroids 10%, and sulfasalazine 5%. Analgesics and opioids made up 14% of prescriptions - a low estimate considering the availability of over-the-counter preparations. Disease modifying antirheumatic drugs (DMARD) increased their proportion from 28.5 to 39.3%. Total costs were stable at $16 million US annually. NSAID costs decreased, while those of sulfasalazine, MTX, and cyclosporine increased. On average, 91 adverse drug reactions were reported annually. Hematological reactions (agranulocytosis, thrombocytopenia, leukopenia, pancytopenia) predominated, constituting 21% of reported reactions. Skin and gastrointestinal reactions, mainly mild, accounted for 15 and 14%, respectively. Deaths from adverse drug reactions were uncommon, about 3 per year, and were mainly attributed to hematological reactions.
The total volume as well as the total cost of drug consumption for RA in Sweden was relatively constant during our 11 year observation period, despite a notable increase in the use of DMARD. This was mainly due to a decrease in costs per DDD of NSAID, and an increased use of cyclosporine. Drug related adverse reactions were dominated by hematological reactions, and fatal events were few. This emphasizes the need for an extended evaluation of which safety procedures are most cost effective for monitoring the drugs used for RA.