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P413. Persistence with 5-ASA therapy in the UK: a matched sample study

A. Robinson1, M. Hankins2, G. Wiseman3, M. Jones4, 1Salford Royal NHS Foundation Trust, Salford, United Kingdom, 2University of Southampton, Southampton, United Kingdom, 3Medical Affairs, Warner Chilcott UK Ltd, Weybridge, United Kingdom, 4Health Informatics Research, Sciensus Ltd, Brighton, United Kingdom


Persistence refers to the duration of time a patient continues to take a particular medication and may be influenced by both patient behaviour and clinical strategies. The aim of this study was to assess persistence with oral 5-ASAs using a UK pharmacy database. Analyses of persistence are often challenged by confounding factors such as population size and patient characteristics. This study controlled for such confounding factors to obtain a standardised view by conducting a matched sample analysis.


A retrospective matched sample study was conducted using dispensed drug data. Patients who were treatment naïve for all 5-ASA formulations in the 6 months prior to the index date were followed for more than 3 years. Persistence was defined as the length of time each patient received continuous therapy with a single 5-ASA formulation. Non-persistence was defined as a change in 5-ASA or failure to refill a prescription within a time frame of up to twice the duration of the prescription. Persistence was analysed in six matched samples of patients receiving different 5-ASA formulations; each sample comprised 200 patients selected randomly from eligible records, matched by age and gender. Oral 5-ASA formulations included Asacol® 400 mg and 800 mg, Mesren® 400 mg, Mezavant XL® 1200 mg, Pentasa® 500 mg tablet and 1g sachet. Persistence was assessed using Kaplan–Meier survival statistics; comparisons between 5-ASAs were conducted using chi-squared tests.


49,990 patients' records for 5-ASA dispensing data were extracted from the database, of which 10,717 provided demographic and prescribing data for inclusion in the analysis (n = 1200). Each matched sample was 50% male, with a mean age of 50 years. 9% of patients had a change in their 5-ASA and 63% of patients failed to refill a prescription. Overall, the median persistence with 5-ASA was 404 days (95% CI 362.4–445.5). No significant differences in persistence were observed across the 5-ASA formulations (log rank test p = 0.101). Dosage and administration regimen were not taken into account.


This study shows that a substantial majority of patients were not continuing to take their original 5-ASA formulation by the end of the study period. Persistence with oral 5-ASA is similar across all 5-ASA formulations. Further analyses will evaluate how a change in 5-ASA or failure to refill a prescription influence these results.