Utility of the Morisky Medication Adherence Scale in gout: a prospective study

CSL Tan,1 GG Teng,1,2 KJ Chong,2 PP Cheung,1,2 AYN Lim,1,2 HL Wee,3,4 A Santosa1,2 1University Medicine Cluster, Division of Rheumatology, National University Health System, 2Department of Medicine, Yong Loo Lin School of Medicine, 3Department of Pharmacy, Faculty of Science, 4Saw Swee Hock School of Public Health, National University of Singapore, Singapore Background: The outcomes of any chronic illness often depend on patients’ adherence with their treatment. A tool is lacking to assess adherence in gout that is standardized, allows real-time feedback, and is easy to understand.Objective: We set out to evaluate the utility of the 8-item Morisky Medication Adherence Scale (MMAS-8) in monitoring medication adherence in a multiethnic Asian gout cohort on urate-lowering therapy (ULT).Methods: This cohort study recruited patients with gout where baseline and 6-monthly clinical data, self-report of adherence, and health status by Gout Impact Scale (GIS) and EuroQoL-5 dimension 3 levels were collected. Those who received at least 9 months of ULT were analyzed. Convergent and construct validities of MMAS-8 were evaluated against medication possession ratio (MPR) and known groups, clinical outcomes, and patient-reported outcomes. Internal consistency and test–retest reliability were assessed using Cronbach’s alpha and intraclass correlation coefficient (ICC), respectively.Results: Of 91 patients, 92.3% were male, 72.5% Chinese with mean age 53.5 years. MMAS-8 (mean 6.17) and MPR (mean 96.3%) were poorly correlated (r=0.069, P=0.521). MMAS-8 did not differ between those who did or did not achieve target serum urate (SU)