Ranking facilitators and barriers of medication adherence by patients with inflammatory arthritis: a maximum difference scaling exercise.

INTRODUCTION: Facilitators and barriers of adherence to disease-modifying anti-rheumatic drugs (DMARDs) have been identified by patients with inflammatory arthritis earlier. However, the relative importance from the patients' perspective of these factors is unknown. Knowledge on this ranking might guide the development of interventions and may facilitate targeted communication on adherence. This study aims to examine 1) the relative importance patients attach to facilitators and barriers for DMARDs adherence, and 2) the relationship between patient characteristics and ranking of these factors. METHODS: One hundred twenty-eight outpatients with inflammatory arthritis; (60% female, mean age 62 years (SD = 12), median disease duration 15 years, IQR (7, 23) participated in a Maximum Difference scaling exercise and ranked 35 items based upon previously identified facilitators and barriers to medication adherence. Hierarchical Bayes estimation was used to compute mean Rescaled Probability Scores (RPS; 0-100) (i.e. relative importance score). Kendall's coefficient of concordance was used to examine a possible association between patients' characteristics (i.e. age, sex and educational level) and ranking of the items. RESULTS: The three most important items ranked by patients were: Reduction of symptoms formulated as "Arthritis medications help to reduce my symptoms" (RPS = 7.30, CI 7.17-7.44), maintaining independence formulated as "I can maintain my independence as much as possible" (RPS = 6.76, CI 6.54-6.97) and Shared decision making formulated as "I can decide -together with my physician- about my arthritis medications" (RPS = 6.48, CI 6.24-6.72). No associations between patient characteristics and ranking of factors were found. CONCLUSIONS: Reducing symptoms, maintaining independency and shared decision making are patients' most important factors for DMARDs adherence. This knowledge might guide the development of interventions and may facilitate communication between health professionals and their patients on medication adherence.