Background: Adherence to medication is an issue of great importance for patients with ulcerative colitis. Once daily mesalazine seems to be no worse than divided doses in preventing relapse in remitting patients. Although this has been attributed to improved adherence, detailed measures of adherence have been lacking from previous studies.
Methods: A 1-year substudy was conducted alongside a trial that compared 2 different dosing regimens (once daily versus three times daily) of mesalazine for patients in remission with ulcerative colitis. Participants in the substudy had their adherence monitored electronically using the medication event monitoring system, self-report, and tablet counts. We compared measures, determined factors associated with adherence and associations between adherence and relapse, modeled adherence over time, and explored behavioral aspects.
Results: We included 58 participants. Adherence was high across all measures (89.3% self-report, 96.7% tablet counts, and 89.2% medication event monitoring system). Agreement between the measures was poor at times. Adherence according to the medication event monitoring system best distinguished between the participants who relapsed (71.4%) and those who remained in remission (93.4%), although this difference was not statistically discernible at the 5% level. Adherence deteriorated over the study period, with three times daily participants generally less adherent than once-daily participants (odds ratio, 0.03; 95% confidence interval, 0.01–0.08). Adherence was higher on weekdays (odds ratio, 1.47; 95% confidence interval, 1.31–1.65) and around clinic visit dates (odds ratio, 1.43; 95% confidence interval, 1.18–1.72).
Conclusions: Simple dosing regimens are preferable to multiple daily dosing regimens. Electronic monitoring of adherence should be used more often in clinical studies. Self-reported adherence and tablet counts may underestimate adherence. Adherence declined over time, and adherence was generally lower and more varied for those allocated to the three times daily regimen.
Article first published online 26 November 2013
*South East Wales Trials Unit, Institute for Translation, Innovation, Methodology and Engagement (TIME),
†Institute of Primary Care and Public Health,
‡Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff, United Kingdom;
§Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; and
¶Department of Medicine, University Hospital of Wales, Cardiff, United Kingdom.
Reprints: David Gillespie, BSc, South East Wales Trials Unit, Institute for Translation, Innovation, Methodology and Engagement (TIME), School of Medicine, Cardiff University, CF14 4YS, Cardiff, United Kingdom (e-mail: firstname.lastname@example.org).
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Supported by an unrestricted educational grant from Warner Chilcott Pharmaceuticals Ltd. The South East Wales Trials Unit is funded by the National Institute for Social Care and Health Research (NISCHR).
A. B. Hawthorne has received payment from Warner Chilcott Pharmaceuticals Ltd for participation in advisory panels. C. Probert has received research support, hospitality, and speakers fees from Warner Chilcott Pharmaceuticals Ltd. All other authors have no conflicts of interest to disclose.
Received August 29, 2013
Accepted October 15, 2013