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P094. Adherence with 5-aminosalicylic acid therapy: Results from a large UK pharmacy database

M. Hankins1, M. Jones2, M. Nedham3, S. Jones3, L. Yen4

1King's College London, London, United Kingdom; 2Sciensus Ltd, Falmer, United Kingdom; 3Shire Pharmaceuticals PLC, Chineham, United Kingdom; 4Shire Pharmaceuticals, Wayne, PA, United States

Aim: A significant predictor of relapse in ulcerative colitis is non-adherence with oral mesalazines. The aim of the study was to assess the association between adherence and the use of oral mesalazines such as once-daily high-strength Mezavant XL® compared to more frequent dosing and/or low-strength mesalazines within a UK patient population.

Methods: A retrospective analysis of mesalazine adherence was performed using dispensed drug data for 10 million UK patients. Adherence was defined as the percentage of days in the refill interval for which medication was supplied and was calculated as the number of treatment days divided by the number of days between scripts. Percentage adherence scores were calculated for all patients receiving a dispensed prescription for a study drug between January 2008 to December 2009. Patients who scored ≥90% were considered adherent. Adherence was calculated for each patient on a given drug; then averages were calculated overall and for the relevant drug groups. Study drugs included Asacol® 400 mg and 800 mg, Colazide® 750 mg, Mesren® 400 mg, Mezavant XL 1,200 mg, Pentasa® 500 mg and 1,000 mg. Age- and sex-adjusted proportions and percent means were calculated and compared using chi-square, one-sample t-test and odds-ratio statistics.

Results: Of the 15,356 patient records of dispensed 5-ASAs, 11,608 met inclusion criteria. Overall, 3,587 (30.9%) patients were adherent between January 2008-December 2009. More patients on Mezavant XL were adherent (48.3%), as compared to patients initiated on Asacol 800 mg (40.7%), Mesren 400 mg (36.7%), Pentasa 1,000 mg (31.8%), Pentasa 500 mg (29.7%), Asacol 400 mg (29.6%), and Colazide 750 mg (27.8%); all comparisons were statistically significant (P < 0.001). Adjusted odds ratios with Mezavant XL as the comparator were: 0.69 (Asacol 800 mg), 0.49 (Pentasa 1,000 mg), 0.47 (Mesren 400 mg), 0.42 (Pentasa 500 mg), 0.36 (Asacol 400 mg), and 0.36 (Colazide 750 mg). All comparisons with Mezavant XL were statistically significant (P < 0.05). Continuous measurement of adherence adjusted for age and gender showed highest percent mean adherence for Mezavant XL (87%, 95%CL: 83%-91%). Lower adherence scores were found for Asacol 800 mg (82%, 95%CL: 79%-86%), Pentasa 1,000 mg (75%, 95% CL: 71%-80%), Mesren 400 mg (74%, 95%CL: 71%-77%), Pentasa 500 mg (69%, 95%CL: 68%-70%), Colazide 750 mg (68%, 95%CL: 65%-71%), and Asacol 400 mg (66%, 95%CL: 65%-67%). All comparisons with Mezavant XL were statistically significant (P < 0.001).

Conclusion: This study shows that patients in the UK taking once-daily high-strength Mezavant XL have on average significantly greater adherence than patients on other frequently dosed and/or, lower strength mesalazines including Asacol 800 mg, Pentasa 1,000 mg, and generic Mesren 400 mg. This suggests that Mezavant XL could improve adherence, maintain remission, and reduce overall healthcare resource utilization and costs.