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

BACKGROUND AND AIMS: Non-adherence to anti-tumor 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 hospitalization, dose intensification or discontinuation of anti-TNF.

RESULTS: In total, 128 patients were included (67 infliximab, 61 adalimumab), mean age 37 (±SD 14) years, 71 (56%) females. Median disease duration was 8 (IQR 4-14) years. Clinical disease activity was present in 41/128 (32%) patients, 36/127 (28%) patients had a MMAS-8 <6 ("low adherence") and 25/99 (25%) patients had a MPR<80% (non-adherence). Risk factors for non-adherence included adalimumab use (OR 10.1, 95%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.