Adherence to biologic disease-modifying antirheumatic drugs in adult patients with rheumatic diseases

The emergence of biologics has revolutionized the management of refractory rheumatic diseases (RD) by improving clinical outcomes. Unfortunately, the impact of non-adherence to the emerging therapy can limit their potential benefit. The objective of our study was to evaluate biologics' adherence in Tunisian patients with RD and to assess the determinants of non-adherence.

We conducted a cross-sectional study involving patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) treated with bDMARDs (biologic disease-modifying antirheumatic drugs) for at least three months. Socio-demographic, clinical and biological data were collected. Biologic adherence was assessed using the compliance questionnaire for rheumatology (CQR).

One hundred patients with RD (45 RA and 55 SpA) were collected. Non-adherence to bDMARDs was found in 70% of cases. In univariate analysis, non-adherence to bDMARDs was statistically related to the absence of coxitis (P=0.003), to a low ASDAS-CRP (ankylosing spondylitis disease activity score) prior to the initiation of the bDMARDs (P=0.01), to a rate of administration of bDMARDs less than one injection per month (P=0.01), to the subcutaneous delivery route (P=0.02) as well as to non-adherence to csDMARDs (conventional disease-modifying antirheumatic drugs) (P=0.001). In multivariate analysis, the predictors of non-adherence were the absence of coxitis (OR=6.01; IC 95% [1.88-19.12]; P=0.002], and a rate of administration of bDMARDs less than one injection per month (OR=8.79; IC 95% [2.13-36.22]; P=0.003).

This work has revealed the low rate of adherence to biological treatments in Tunisian patient with RD. Predictors of poor adherence were the absence of coxitis and a rate of administration of bDMARDs less than one injection per month. Detection of these factors could help us to adapt our strategies to improve adherence that are essentially based on therapeutic education program.