Non-adherence to Anti-TNF Therapy is Associated with Illness Perceptions and Clinical Outcomes in Outpatients with Inflammatory Bowel Disease: Results from a Prospective Multicentre Study

Abstract

Background and aims: Non-adherence to anti-tumour necrosis factor [TNF] agents in patients with inflammatory bowel disease [IBD] is a serious problem. In this study, we assessed risk factors for non-adherence and examined the association between adherence to anti-TNF agents and loss of response [LOR].

Methods: In this multicentre, 12-month observational study, outpatients with IBD were included. Demographic and clinical characteristics were recorded. Adherence was measured with the Modified Morisky Adherence Scale-8 [MMAS-8] and 12-month pharmacy refills [medication possession ratio, MPR]. Risk factors included demographic and clinical characteristics, medication beliefs, and illness perceptions. Cox regression analysis was performed to determine the association between MPR and LOR to anti-TNF, IBD-related surgery or hospitalisation, dose intensification, or discontinuation of anti-TNF.

Results: In total, 128 patients were included [67 infliximab, 61 adalimumab], mean age 37 ( ± standard deviation [SD] 14) years, 71 [56%] female. Median disease duration was 8 (interquartile range [IQR] 4-14) years. Clinical disease activity was present in 41/128 [32%] patients, 36/127 [28%] patients had an MMAS-8 < 6 ['low adherence'], and 25/99 [25%] patients had an MPR < 80% [non-adherence]. Risk factors for non-adherence included adalimumab use (odds ratio [OR] 10.1, 95% confidence interval [CI] 2.62-40.00), stronger emotional response [OR 1.16, 95% CI 1.02-1.31], and shorter timeline perception, i.e. short perceived illness duration [OR 0.60, 95% CI 0.38-0.96]. Adherence is linearly and negatively [OR 0.14, 95% CI 0.03-0.63] associated with LOR.

Conclusion: Non-adherence to anti-TNF agents is strongly associated with LOR to anti-TNF agents, adalimumab use, and illness perceptions. The latter may provide an important target for interventions aimed at improving adherence and health outcomes.

Keywords: Inflammatory bowel disease; adherence; illness perceptions; medication beliefs; predictors.