Background The initial treatment of rheumatoid arthritis (RA) consists of pharmacological therapy with one or more conventional DMARDs. The treatment target is to obtain early low disease activity, resulting in better radiological and functional outcomes. Non-adherence to DMARDs interferes with reaching this target. The consequences of non-adherence will not only affect the individual patient, but also increase health care costs.
Objectives This study investigates if, and to what extent non-adherence to DMARD therapy in RA patients would lead to higher DAS28 scores in the first year of treatment.
Methods DMARD naïve patients with rheumatoid arthritis (RA) were consecutively recruited for a cohort study on DMARD adherence in 11 participating hospitals. Patients were selected if they fulfilled the ACR2010 criteria for RA, were above 18 years old and were prescribed DMARDs. Clinical variables were assessed at baseline and every 3 months. Non-adherence was continuously measured using electronically monitored medication containers. Non-adherence was defined as the number of days when the observed amount of openings of the container was lower than the amount of days with expected openings. We calculated the non-adherence proportion in the previous 3 months before DAS28 measurement. The influence of non-adherence on DAS28 after 3, 6, 9 and 12 months after diagnosis was univariately and multivariately tested with 4 generalized linear mixed models using backward elimination. Covariates that were taken into account in the model were age, sex, baseline DAS28, RF positivity, ACPA positivity, anxiety, depression, weeks on DMARD therapy, number of DMARDs at the particular time point, use of subcutaneous methotrexate and use of biologicals.
Results 275 patients with inflammatory arthritis were invited to participate, of whom 203 were willing to participate. Of these patients 120 fulfilled the ACR2010 score for RA, which were used for this analysis. During the study, 17 patients became lost to follow up. Non-adherence percentages differed per DMARD. For sulfasalazine, non-adherence was highest (20.9%). For methotrexate, the mean percentage was 13.4%, as for hydroxychloroquine, the percentage was 14%. Overall, there was a decline in adherence over time, except for prednisone (mean 8.5%). The mean baseline DAS28 was 4.7 (SD 1.3), which decreased to 3 (SD 1.3)at 3 months, 2.7 (SD 1.4) at 6 months, 2.5 (SD 1.2) at 9 months and 2.5 (SD1.3) at 12 months. In all models, except for the 12-month model, non-adherence has a significant influence on DAS28, next to weeks on DMARDs, and baseline DAS28 (see figure 1).
Conclusions In the first year after diagnosis, it is important to quickly achieve low disease activity or remission, in order to avoid irreversible damage. Non-adherence relates to disease outcome, and thus to irreversible damage. Therefore, interventions towards enhancing adherence can improve disease outcome.
Disclosure of Interest None declared
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