Background Adherence to DMARDs is crucial for the outcome in rheumatoid arthritis (RA) and related diseases. Previous studies report very different rates of adherence to antirheumatic drugs in general (about 25% (1)), to DMARDs (50.5% to 68% (2,3)), to methotrexate (MTX) (81.3% (4)), or to biologics (11% to 43% (5)).
Objectives This study measured adherence to traditional DMARDs (t-DMARDs) as well as biologics in contrast to non-disease modifying drugs in patients with different rheumatic diseases.
Methods 108 consecutive outpatients (male (n=35), female (n=73); RA (n=54), psoriatic arthritis (n=22), spondylarthritis (n=10), others (n=22)) completed a questionnaire concerning their knowledge about medication and drug taking habits. Drugs were classified into 5 groups: analgetics, NSAIDs, corticosteroids, t-DMARDs, biologics. High adherence was defined as patients taking their drugs always or almost always as prescribed.
Results Analgetics and also NSAIDs were prescribed to 45% of the patients, corticosteroids to 40%, t-DMARDs to 61%, (MTX in 53% of those cases) and biologics to 13%. Adherence to all groups of drugs was high (analgetics: 91%, NSAIDs 94%, corticosteroids 98%, t-DMARDs: 99%, biologics: 93%). Regarding the amount of patients taking their drugs always as prescribed, more significant differences appeared (analgetics: 72%, NSAIDs: 76%, corticosteroids: 93%, DMARDs: 91% (MTX: 100%), biologics: 80%).
Satisfaction with (a), subjective effectiveness (b), tolerability (c) and side effects (d) of MTX and biologics were rated on a numerical scale (0-10 (0=minimum; 10=maximum)). Patients’ estimations were a) 7.5 +/- 2.5, b) 7.1 +/- 2.8, c) 7.6 +/- 2.6, d) 2.4 +/- 2.0 for MTX and a) 8.3 +/- 2.0 b) 8.5 +/- 2.0, c) 9.5 +/- 2.3 d) 2.5 +/- 2.8 for biologics.
Conclusions The observed rates of adherence to t-DMARDs and biologics were extremely high, what conflicts to previous studies. A possible explanation is the tight control and intensive patient education within our setting of care.
The high rates of adherence for MTX and biologics corresponded to the high satisfaction, the estimated effectiveness and low side effects, and therefore high tolerability of those drugs in our patients.
The observation that adherence to disease modifying drugs (corticosteroids, MTX, biologics) was higher than to those which just treat symptoms (analgetics, NSAIDs) indicates, that patients have understood or even experienced exactly that difference between the groups of drugs. This supports the theory of the health belief model, by Hochbaum et al (6). It states, that a person will take a medical action (what means being adherent) if special conditions concerning his/her beliefs in this action (e.g. taking medication) are fulfilled. Indicators for that are 1. the perceived susceptibility, 2. the perceived severity of the costs and use, 3. the perceived benefits the action will bring and 4. the perceived barriers/hazards (e.g. side effects).
The study is limited by the relatively small number of patients involved. Nevertheless the data shows that high rates of adherence can be achieved within an adequate setting of care.
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Disclosure of Interest None Declared