The influence of behavioural and psychological factors on medication adherence over time in rheumatoid arthritis patients: a study in the biologics era.

Abstract

To investigate levels of self-reported adherence to biologic treatment and establish the contribution of demographic, physical and psychological factors to biologic medication adherence in an RA cohort. Adalimumab-treated patients were recruited through the British Society for Rheumatology Biologics Register for RA between May 2007 and April 2009. Demographic and baseline psychological measures including illness and medication beliefs were collected. Disease activity (28-item DAS), physical function (HAQ) and quality of life (36-item Short Form Health Survey) were also measured at baseline and at 6, 12 and 18 months. Adherence was assessed at each follow-up using the patient self-completed Compliance Questionnaire for Rheumatology (CQR). Multilevel mixed effects modelling analysis was performed to investigate predictors of adherence. Of the 329 Adalimumab-treated patients included, low adherence (CQR score <65) was reported in 23%, with 41% reporting low adherence at at least one time point. After controlling for age and disease duration, factors independently predictive of increased adherence were increased belief in medication necessity, with baseline effect diminishing over time [β coefficient 1.68 (s.e. 0.19), P = 0.0001], lower medication concerns [0.50 (0.15), P = 0.001], with this effect remaining throughout follow-up, increased professional or family member support [0.81 (0.32), P = 0.01], strong views of illness being chronic [0.32 (0.14), P = 0.025] and increased treatment control [0.41 (0.19), P = 0.032]. Wider recognition of the importance of psychological factors, particularly medication beliefs, in driving medication adherence could have substantial clinical and health economic benefits in RA. The psychological factors we have identified are putative targets for strategies to improve adherence in RA.