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P464 Assessing medication adherence in patients with inflammatory bowel disease: what do we choose, self-adherence scales or pharmacy rates?

M. L. De Castro*1, L. Sanromán1, A. Martín2, N. Martínez2, M. Figueira1, V. Hernández1, J. R. Pineda1, J. Martínez-Cadilla1, S. Pereira1, V. Del Campo3, J.-I. Rodríguez-Prada1

1Hospital Alvaro Cunqueiro. Complexo Hospitalario Universitario de Vigo. CHUVI, Gastroenterology, Vigo, Spain, 2Hospital Alvaro Cunqueiro. Complexo Hospitalario Universitario de Vigo. CHUVI, Hospital Pharmacy, Vigo, Spain, 3Hospital Alvaro Cunqueiro. Complexo Hospitalario Universitario de Vigo. CHUVI, Epidemiology, Vigo, Spain

Background

The assessment of medication adherence in inflammatory bowel disease (IBD) is important to efficiently identify patients for intervention, because of the worst clinical and economic outcomes related to low adherence. Pharmacy rates such as medication possession ratio (MPR) measures medication availability, and recently the Morisky Medication Adherence Scale: MMA8 has been validated in IBD patients. We aimed to compare self-reported adherence scales with pharmacy refill data as a reliable measure of medication adherence.

Methods

All consecutive patients with non-active Crohn’s disease (CD) or ulcerative colitis (UC) visited in the IBD outpatient clinic of the Hospital Alvaro Cunqueiro of Vigo (Spain) from October 2014 to April of 2015, were invited to participate in this prospective study. Patients who consented answered anonymously the scale MMA8 and their pharmacy refills were reviewed from the previous 3 months to calculate MPR as the proportion (or percentage) of days supply obtained during a specified time period or over a period of refill intervals. MMA8 scale contains 8 items measuring a specific medication-taking behaviour and not a determinant of adherent behaviour. Response categories are yes/no for each item (ie, a dichotomous response) and a 5-point Likert response for the last item. Low adherence was defined as a MPR score < 0.8 and/ or MMA8 score < 6.

Results

In total, 203 patients were enrolled: 121 UC and 82 CD; 50.7% were male; 149 (73.8%) were on monotherapy; and 53 (26.2%) on polytherapy for IBD. At baseline, 64.9% were on 5-aminosalicylic (5-ASA); 46.5% on an immunomodulator; and 15.8% on a biologic drug. MMA8 identified 22.4% as low adherents; however, MPR identified 36%. Receiver operator curve analysis of MMA8 score compared with MPR (good/low adherence) gave an area under the curve of 0.6 (p = 0.001), using a cut-off of <6, the MMAS-8 score has a sensitivity of 69.7% and a specificity of 51.7% to predict medication adherence with a positive predictive value 85.5% and negative predictive value 34.3%. Patients on a 5-ASA or an immunomodulator had a survey score that positively correlated with adherence (p = 0.01 and p = 0.004, respectively).

Conclusion

Because of a low sensibility, MMA8 scale is an imperfect tool to look for non-adherent IBD patients. Nevertheless patients on 5-ASA or immunomodulator were likely to have a MMA8 score predicting adherence behaviour.