AB1113 Validity and Reliability of the Morisky Scale for Adherence to Gout Therapy in a Multi-Ethnic Asian Population. (9th June 2015)

• Record Type: Journal Article
• Authors: Tan, C.S.L.; Teng, G.G.; Chong, K.J.; Lee, P.T.; Cheung, P.P.; Lim, A.Y.N.; Wee, H.L.; Santosa, A.
• Is Part Of: Annals of the rheumatic diseases. Volume 74(2015)Supplement 2
• Page Start: 1273
• Page End: 1273
• Publication Date: 2015-06-09
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2015-eular.1422
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Adherence to urate lowering therapy (ULT) is associated with better gout outcomes. Medication Possession Ratio (MPR) 1 is commonly used in administrative database studies to assess adherence. The Morisky medication adherence scale (MMAS-8) 2, an 8-item patient questionnaire (0-8), has not been studied in gout. Objectives: To evaluate the validity of the MMAS-8 in determining adherence to ULT in a multi-ethnic Asian gout cohort. Methods: 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 1 . Construct validity (Spearman's correlation), reliability (intra-class correlation coefficient, ICC) and internal consistency (Cronbach's 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 <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 3 . Results: 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<0.005). Findings were similar when analysing MMAS-8 as 2 factor scores instead of an overall score. Conclusions: 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. References: 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 & Geriatrics (2013), 4: 119-122. Disclosure of Interest: None declared