Adherence: Comparison of Methods to Assess Medication Adherence and Classify Nonadherence
- 3 March 2009
- journal article
- research article
- Published by SAGE Publications in Annals of Pharmacotherapy
- Vol. 43 (3), 413-422
- https://doi.org/10.1345/aph.1l496
Abstract
Background: Medication adherence is suboptimal, and clinicians and researchers struggle with identifying nonadherent patients. Various measures of medication adherence exist, but there is controversy regarding which measures provide acceptable data and how nonadherence should be defined. Objective: To assess agreement among patient self-report, pharmacy refill, and electronic adherence measures and compare the sensitivity and specificity of different cut-points for defining nonadherence. Methods: Data were analyzed from 2 similarly designed randomized controlled trials that assessed a pharmacist's intervention to improve medication adherence among patients with hypertension or heart failure. For each participant, adherence was measured by patient self-report, prescription refill records, and electronic lids on medication containers. Agreement among measures was assessed using Spearman's correlation coefficient rho. Correlation coefficients were compared by patient characteristics using Fisher's Z transformation, The sensitivity and specificity of different cut-points for defining nonadherence were calculated. Results: Median adherence was 84% for self-report, 86% for electronic, and 91% for prescription refill adherence measurement. Refill and electronic adherence demonstrated the best agreement among measures (rho = 0.48). Age, depression, and other comorbid conditions influenced agreement among measures. Measures were generally in agreement, regardless of how nonadherence was defined. A cut-point of 80% illustrated a fair balance between sensitivity and specificity for all measures. Conclusions: All measures provided similar estimates of overall adherence, although refill and electronic measures were in highest agreement. In selection of a measure, practitioners should consider population and disease characteristics, since measurement agreement could be influenced by these and other factors. The commonly used, clinically based cut-point of 80% had a reasonable balance between sensitivity and specificity in studies of adherence in patients with heart failure or hypertension.Keywords
This publication has 27 references indexed in Scilit:
- Difficulty Taking Medications, Depression, and Health Status in Heart Failure PatientsJournal of Cardiac Failure, 2006
- Electronic monitoring and counseling to improve medication adherenceBehaviour Research and Therapy, 2004
- Clinically Relevant Levels of Depressive Symptoms in Community‐Dwelling Middle‐Aged African AmericansJournal of the American Geriatrics Society, 2004
- Enhancing patient adherence to medical recommendationsJAMA, 1994
- Social support and stressful life events: age differences in their effects on health-related quality of life among the chronically illQuality of Life Research, 1992
- Concurrent and Predictive Validity of a Self-reported Measure of Medication AdherenceMedical Care, 1986
- Development and validation of a geriatric depression screening scale: A preliminary reportJournal of Psychiatric Research, 1983
- A behavioral medicine perspective on adherence to long-term medical regimens.Journal of Consulting and Clinical Psychology, 1982
- The Analysis of Systems of Qualitative Variables When Some of the Variables Are Unobservable. Part I-A Modified Latent Structure ApproachAmerican Journal of Sociology, 1974
- THE MOMENTS OF THE z AND F DISTRIBUTIONSBiometrika, 1949