Introduction:

The use of disease modifying antirheumatic drugs (DMARDs) in patients with rheumatoid arthritis (RA) is essential in order to achieve and maintain adequate disease control, and thus preventing irreversible functional damage. However, the rate of adherence to drug therapy has been reported to be between 20% and 107%. This variability may be due to the measurement methods used in the different studies.

Objective:

To test the overall medication adherence to oral treatment with DMARD in patients with RA using the self-report Spanish version Compliance Questionnaire on Rheumatology (CQR) and to identify potential factors associated with non-adherence.

Methods:

A cross-sectional descriptive study was conducted that included patients older than 18 years with RA diagnosed according to the ACR-EULAR 2010 criteria. They also had to have been prescribed oral DMARD for the previous 3 months, and had been seen by a rheumatologist in the last year. Patients completed the CQR to assess adherence, and were asked about disease knowledge, perception about treatment, side effects, Charlson Comorbidity Index, global index of social support, number of medications and DMARD prescribed, access to health resources, and disease activity measured by DAS 28 or CDAI. Good adherence was defined as a cut-off point of CQR > 80 or non-activity (remission or low activity). In the search for factors associated with adherence, the data were analysed using means of median and interquartile range, as well as frequencies and proportions. The comparison between adherent and non-adherent groups was performed using absolute comparisons, with the Mann-Whitney test for continuous, and chi-squared (for expected values > 5), or Fisher (for expected values < 5) tests for categorical variables, taking as a level of significance a value of P < .05. OR and their respective 95% confidence intervals (95% CI) were used.

Results:

Of 170 participants included, 50% (n = 85) had a value greater than 80% (good drug adherence). Most patients had remission (60.6%) or low disease activity (17%). The subsequent analysis showed statistically significant association between adherence measured by CQR and the number of friends (P = .0012). An association was also found between disease activity as an indirect indicator of adherence and the global social support index (P = .004).

Conclusions:

This study found a similar level of adherence to that reported in other populations, which could be due to the behaviour of our population, although the authors perceived difficulties reported by patients in understanding the statements of the questionnaire at all levels of education. Only the social support variables had a statistically significant relationship with adherence, which had also been described in the literature. Further studies are required to evaluate the operational characteristics of the CQR in our population.

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