The aim of this study was to describe the incidence rate (IR) of adverse drug reactions (ADRs) in daily clinical practice, related to disease-modifying antirheumatic drugs (DMARDs) and biologic agents (BA) in rheumatoid arthritis (RA) patients, and to analyze factors causing discontinuation due to ADRs.
This was a prospective observational study (October 2010 to October 2011). RA patients who were attended in our hospital taking DMARDs or BA during the study period were included. ADRs were injuries related to these drugs and registered with a software system in routine visits. ADRs could be mild (lowering dosage), moderate (drug discontinuation), or severe (hospital admission). The IR of ADR per 100 patient-years was estimated using survival techniques. Cox regression models (HR; 95% confidence interval) were used to explore factors associated with discontinuation due to ADRs.
In total, 1202 patients were analyzed, with 158 ADRs (IR = 15.2). Of all ADRs, 80.4% required drug discontinuation (IR = 12.2). Age, less disease and therapy duration, taking corticoids, and combined therapy versus monotherapy (HR = 3; 95% CI: 2.0-4.4) were the factors independently associated to discontinuation due to ADRs. We did not find statistical differences between the different monotherapy regimens. Regarding combinations, Methotrexate + BA had the lowest risk of discontinuation compared to the rest (HR = 0.24; 95% CI: 0.09-0.6).
We have estimated the incidence of ADRs related to DMARDs/BA in real-life conditions. We confirm the role of combined therapy in the development of discontinuations due to ADRs, except for BA + MTX, which did not show an increase of toxicity compared to monotherapy. This combination seems to be safer than others.