The use of complementary therapies is highly prevalent among patients with rheumatoid arthritis (RA). Nevertheless, the use of complementary medicine could involve problems in the following of scientifically accepted treatments. To date, there is limited information regarding the association of nonconventional therapies with problems regarding compliance with the treatment. Therefore, the objective of this study was to identify whether the utilization of complementary therapies is associated with a high risk of problems regarding therapeutic adherence to conventional synthetic disease-modifying anti-rheumatic drugs (cs-DMARDs) in RA patients. A survey was performed with RA patients in an outpatient rheumatology clinic in a university hospital; the use of complementary therapies, as well as their type, was identified. To assess problems with therapeutic adherence, we used the four-item Morisky-Green scale. A comprehensive assessment of clinical and therapeutic characteristics was performed. Univariable and multivariable models were performed to identify the risk of problems with therapeutic adherence in users of complementary therapies. In total, 250 RA patients were included; 92% used complementary therapies. Of them, the most frequently used were herbal medicine (65%), homeopathy (64%), and cannabis and its derivatives (51%). In the univariable logistic regression analysis, the factors associated with problems in the therapeutic adherence to cs-DMARDs were age (p = 0.019), the presence of other comorbidities (p = 0.047), and the use of complementary therapies (p = 0.042). After controlling for potential confounders, the use of complementary therapies increased the risk of problems with therapeutic adherence to cs-DMARDs (adjusted OR = 2.84, 95% CI = 1.06-7.63, p = 0.037). We concluded that the use of complementary therapies increases the risk of problems with therapeutic adherence. Therefore, for physicians and healthcare professionals, the early identification of the use of nonconventional therapies in their RA patients is required, followed by a directed discussion with their patients about the risks and benefits to which they could be exposed to complementary therapies.
Keywords: Morisky–Green scale; complementary therapies; conventional synthetic disease modifying anti-rheumatic drugs; cross-sectional study; rheumatoid arthritis; therapeutic adherences.