Is the MARS questionnaire a reliable measure of medication adherence in childhood asthma?

Abstract

Objective: To assess the reliability of the Medication Adherence Report Scale (MARS-5) for assessing adherence in clinical practice and research. Methods: Prospective cohort study following electronically measured inhaled corticosteroids (ICS) adherence for 1 year in 2–13-year-old children with persistent asthma. The relationship between electronically measured adherence and MARS-5 scores (ranging from 5 to 25) was assessed by Spearman's rank correlation coefficient. A ROC (receiver operating characteristic) curve was performed testing MARS-5 against electronically measured adherence. Sensitivity, specificity, positive and negative likelihood ratios of the closest MARS-5 cut-off values to the top left-hand corner of the ROC curve were calculated. Results: High MARS scores were obtained (median 24, interquartile range 22–24). Despite a statistically significant correlation between MARS-5 and electronically assessed adherence (Spearman's rho = 0.47; p < 0.0001), there was considerable variation of adherence rates at every MARS-5 score. The area under the ROC curve was 0.7188. A MARS-5 score ≥23 had the best predictive ability for electronically assessed adherence, but positive and negative likelihood ratios were too small to be useful (1.65 and 0.27, respectively). Conclusions: Self-report using MARS-5 is too inaccurate to be a useful measure of adherence in children with asthma, both in clinical practice and in research.

Keywords:

• MARS-5
• electronic monitoring
• inhaled corticosteroids
• adherence
• children
• asthma

Declaration of interest

The study sponsors had no role in study design, the collection, analysis and interpretation of data, the writing of the report, and the decision to submit the manuscript. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Funding

This study was supported by a grant from the Netherlands Asthma Foundation (grant no 3.4.06.007) and from the Foundation to Combat Asthma (Stichting Astmabestrijding).