AB1113 Validity and Reliability of the Morisky Scale for Adherence to Gout Therapy in a Multi-Ethnic Asian Population
Authors: C.S.L. Tan, G.G. Teng, K.J. Chong, P.T. Lee, P.P. Cheung, A.Y.N. Lim, H.L. Wee, A. Santosa
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> Adherence to urate lowering therapy (ULT) is associated with better gout outcomes. Medication Possession Ratio (MPR)<sup>1</sup> is commonly used in administrative database studies to assess adherence. The Morisky medication adherence scale (MMAS-8)<sup>2</sup>, an 8-item patient questionnaire (0-8), has not been studied in gout. <h3>Objectives</h3> To evaluate the validity of the MMAS-8 in determining adherence to ULT in a multi-ethnic Asian gout cohort. <h3>Methods</h3> Adults with gout fulfilling the ACR criteria on ≥9 months of ULT were recruited from rheumatology clinics in a tertiary hospital in Singapore. Baseline and 6-monthly clinical data, MMAS-8, Gout Assessment Questionnaire v2.0, and serum urate levels were collected. Variable MPR over 9-15 months preceding the MMAS-8 survey was calculated from dispensing records. This reflected the proportion of time a patient had access to medications over the analyzed period<sup>1</sup>. Construct validity (Spearman9s correlation), reliability (intra-class correlation coefficient, ICC) and internal consistency (Cronbach9s alpha) of the MMAS-8 was assessed. Validity of MMAS-8 as a measure of adherence was evaluated against MPR. MMAS-8 scores of 8, 6-7.9 and &lt;6 were used as cutoffs for high, medium and low adherence, respectively. MMAS-8 score was analyzed both as an overall score and as 2 factors derived from exploratory factor analysis<sup>3</sup>. <h3>Results</h3> Of the 91 patients included, 92.3% were male, 72.5% Chinese and 26.4% Malay. The mean age at baseline was 52.8 (SD 17) years. The mean BMI was 29.7 (SD 7.7), 73.7% had at least completed secondary school, and 45% had ≥3 comorbidities. The mean duration of ULT at baseline was 2.5 (SD 2.6) years and mean number of medications other than ULT was 3.3 (SD 3.4). Mean MPR and MMAS-8 were 96.3% (SD 19.0) and 6.17 (SD 1.8). High and medium adherence was seen in 24.4% and 37.7%, respectively. Internal consistency of MMAS-8 was good (α=0.725) and test-retest reliability (n=18, 20% sample) was satisfactory (ICC 0.702 (95%CI 0.362-0.877)). There was no relationship between MMAS-8 and MPR (r=0.069, p=0.521). In addition, MMAS-8 scores did not correlate with baseline urate levels (r=-0.023, p=0.83) or the absolute change in urate levels between baseline and final visits (r=-0.042, p=0.69). MMAS-8 scores were not influenced by education level, number of comorbidities, degree of polypharmacy or frequency of gout flares. However, increasing age was associated with higher MMAS-8 scores (β=0.256, p=0.015). Patients who reported "Fear of medication side effects" had lower MMAS-8 scores (p&lt;0.005). Findings were similar when analysing MMAS-8 as 2 factor scores instead of an overall score. <h3>Conclusions</h3> MMAS-8 does not appear to be a valid measure of adherence to ULT in our cohort, despite satisfactory internal consistency and reproducibility. Other feasible methods of reporting ULT adherence should be evaluated in patients with gout. <h3>References</h3> Kozma CM, et al. Patient Prefer Adherence (2013), 7:509–516. Morisky DE, et al. Journal of Clin Hypertens (2008), 10:348–54. Wang J, et al. Journal of Clinical Gerontology &amp; Geriatrics (2013), 4: 119-122. <h3>Disclosure of Interest</h3> None declared