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P281 One simple question is sufficient for measuring medication adherence in inflammatory bowel disease patients using self-report

M. Severs*1, M.-J. Mangen2, H. H. Fidder1, M. E. van der Valk1, M. van der Have1, A. A. van Bodegraven3, 4, C. H. M. Clemens5, G. Dijkstra6, J. M. Jansen7, D. J. de Jong8, N. Mahmmod9, P. C. van de Meeberg10, A. E. van der Meulen- de Jong11, M. Pierik12, C. Y. Ponsioen13, M. J. L. Romberg- Camps3, P. D. Siersema1, J. R. Vermeijden14, J. van der Woude15, P. N. Zuithoff16, B. Oldenburg1

1University Medical Centre Utrecht, Gastroenterology and Hepatology, Utrecht, Netherlands, 2University Medical Centre Utrecht, Julius Centre for health sciences and primary care, Utrecht, Netherlands, 3ORBIS medical Centre, Gastroenterology and Hepatology, Sittard, Netherlands, 4VU medical Centre, Gastroenterology and Hepatology, Amsterdam, Netherlands, 5Diaconessenhuis, Gastroenterology and Hepatology, Leiden, Netherlands, 6University Medical Centre Groningen, Gastroenterology and Hepatology, Groningen, Netherlands, 7Onze Lieve Vrouwe Gasthuis, Gastroenterology and Hepatology, Amsterdam, Netherlands, 8University Medical Centre st. Radboud, Gastroenterology and Hepatology, Nijmegen, Netherlands, 9Antonius Hospital, Gastroenterology and Hepatology, Nieuwegein, Netherlands, 10Slingeland Hospital, Gastroenterology and Hepatology, Doetinchem, Netherlands, 11Leiden University Medical Centre, Gastroenterology and Hepatology, Leiden, Netherlands, 12University Medical Centre Maastricht, Gastroenterology and Hepatology, Maastricht, Netherlands, 13Academic Medical Centre Amsterdam, Gastroenterology and Hepatology, Amsterdam, Netherlands, 14Meander Medical Centre, Gastroenterology and Hepatology, Amersfoort, Netherlands, 15Erasmus Medical Centre, Gastroenterology and Hepatology, Rotterdam, Netherlands, 16University Medical Centre Utrecht, Julius Centre for Health Sciences and Primary Care, Utrecht, Netherlands

Background

Non-adherence is a frequently encountered problem in the treatment of inflammatory bowel disease (IBD) patients; however, capturing adherence remains a challenge. We aimed to compare 3 different tools to measure self-assessed medication adherence of IBD patients.

Methods

A large Dutch cohort of adult patients with Crohn’s disease (CD) and ulcerative colitis (UC) was prospectively followed for more than 2 years. Data on disease course and IBD-specific consumption of healthcare including medication use were collected by 3-monthly questionnaires. At 1 time-point during follow-up, adherence to IBD-specific medical prescriptions was assessed, employing 3 different tools: (1) the 8-item Morisky Medication Adherence Scale (“MMAS-8”) (including 8 questions covering various aspects of adherence behaviour, with the possible answers ‘yes’ and ‘no’, and higher total scores indicating a better adherence), (2) the single question of how well patients take their daily medication, using a Visual Analogue Scale (‘VAS’, ranging from 0 to 100, with 100 indicating a perfect adherence), and (3) the Forget Medicine scale (‘FM’), which aimed to assess how often patients forget to take their medicine (on a 6-point scale, with inclining rates of times patients forget their medicine). Cross-sectional agreement amongst measures was visualised with scatterplots and quantified with Spearman rank correlations.

Results

In total, 913 patients (462 CD, 335 UC, and 116 IBD-unknown) were analysed, 697 (77.1%) of whom received medication for their IBD. High adherence scores on the MMAS-8 scale were consistent with high scores on the VAS and low scores on the FM-scale. Disagreement between tools increased when patients had worse adherence scores. The correlation was 0.44 between the MMAS-8 and VAS, -0.59 between the MMAS-8 and FM, and -0.55 between the VAS and FM (all p < 0.001). Moderate discordances in adherence outcomes could be attributed to differences in scaling of used tools. The VAS most optimally represented the quantitative variability of adherence, whereas both the FM- and MMAS-8 scale might result in over- or underestimation of true adherence of patients, because of unequal differences in outcome possibilities. Nonetheless, the different aspects enclosed in the MMAS-8 might provide insight in barriers for non-adherence.

Conclusion

In the absence of a gold standard, a simple and easy-to-use VAS seems the most appropriate tool for quantifying medication adherence in clinical practice. The MMAS-8 could be used additionally to provide insight in specific reasons for non-adherent behaviour in IBD patients.