Adherence to anti-TNF therapy in outpatients with inflammatory bowel disease
M. van der Have1*, B. Oldenburg1, A.A. Kaptein2, J.M. Jansen3, R.C.H Scheffer4, S.A. van
Tuyl5, A.E. van der Meulen-de Jong6, M. Pierik7, M.G.H. van Oijen8,9, P.D. Siersema1, H.H.
Fidder1
1) Department of Gastroenterology and Hepatology, University Medical Center Utrecht, the
Netherlands
2) Section Medical Psychology, Leiden University Medical Center, the Netherlands
3) Department of Gastroenterology and Hepatology, Onze Lieve Vrouwe Gasthuis, Amsterdam, the
Netherlands
4) Department of Gastroenterology and Hepatology, Jeroen Bosch Hospital, 's Hertogenbosch, The
Netherlands
5) Department of Gastroenterology and Hepatology, Diakonessenhuis, Utrecht, the Netherlands
6) Department of Gastroenterology and Hepatology, Leiden University Medical Center, the
Netherlands
7) Department of Gastroenterology and Hepatology, Maastricht University Medical Center, the
Netherlands
8) Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA
9) UCLA/VA Center for Outcomes Research and Education (CORE), Los Angeles, CA
*Correspondence:
Mike van der Have
Department of Gastroenterology and Hepatology
University Medical Centre Utrecht
PO Box 85500
3500 GA Utrecht, the Netherlands
Email: M.vanderhave@umcutrecht.nl
Tel: 0031 08875 50766
Fax: 0031 08875 55533
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Background:
Non-adherence is associated with poor health outcomes and increased health care costs.
Although anti-TNF agents are increasingly used in the medical management of patients with
inflammatory bowel disease (IBD), data regarding the adherence rates for these agents and
risk factors for non-adherence are limited. Therefore, we assessed adherence to infliximab
(IFX) and adalimumab (ADA) and risk factors for non-adherence in outpatients with IBD.
Methods:
In this multicenter observational study, consecutive IBD patients visiting the outpatient clinic
were included. Patients completed the validated Modified Morisky Adherence Scale-8 with a
score on this scale of <6 indicating low adherence. Clinical disease activity was assessed by
the modified Harvey Bradshaw Index (Crohn’s disease) or the Simple Clinical Colitis Activity
Index (ulcerative colitis). We also assessed demographic and behavioural characteristics,
including medication beliefs (Beliefs about Medicines Questionnaire) and illness beliefs
(Brief-Illness Perception Questionnaire). A hierarchical logistical regression analysis was
performed to determine factors associated with low adherence.
Results:
Seventy-three patients were included (27 IFX, 46 ADA), median age 35 years (IQR 24-51),
27 males (37%). Median disease duration was 11 years (IQR 3-18). Clinical disease activity
was present in 19 patients (26%). Fifteen of 46 patients on ADA (33%) and 6 of 27 patients
on IFX (22%) reported a low adherence (p = 0.32). Attitudinal analysis showed that while
38% of the patients was “accepting” maintenance therapy, including anti-TNF therapy (high
necessity, low concerns), more than half of patients (58%) was “ambivalent” about
maintenance therapy (high necessity, high concerns). Factors independently associated with
low adherence were high perceived personal control over the illness (OR 1.38, 95% CI 1.011.89), symptoms attributed to the illness (OR 0.60, 95% CI 0.39-0.93), and strong beliefs
about how the illness affects one’s emotional well-being (OR 1.61, 95% CI 1.12-2.32). Nonadherence was not significantly affected by young age, male gender, disease activity or
concerns about potential adverse effects of anti-TNF therapy.
Conclusions:
The overall non-adherence rate of anti-TNF therapy is comparable to rates found in oral
medication. A substantial proportion of patients were ambivalent about maintenance therapy,
including anti-TNF therapy and several illness beliefs were significantly associated with non-
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adherence. As illness beliefs are potentially modifiable factors, they may provide a relevant
target for interventions aimed at improving adherence and health outcomes.
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