Defining the minimal detectable change in scores on the eight-item Morisky Medication Adherence Scale Journal Article

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Authors: Muntner, P; Joyce, C; Holt, E.; He, J; Morisky, D; Webber, L. S.; Krousel-Wood, M
Article Title: Defining the minimal detectable change in scores on the eight-item Morisky Medication Adherence Scale
Abstract: BACKGROUND: Self-report scales are used to assess medication adherence. Data on how to discriminate change in self-reported adherence over time from random variability are limited. OBJECTIVE: To determine the minimal detectable change for scores on the 8-item Morisky Medication Adherence Scale (MMAS-8). METHODS: The MMAS-8 was administered twice, using a standard telephone script, with administration separated by 14-22 days, to 210 participants taking antihypertensive medication in the CoSMO (Cohort Study of Medication Adherence among Older Adults). MMAS-8 scores were calculated and participants were grouped into previously defined categories (lt;6, 6 to lt;8, and 8 for low, medium, and high adherence). RESULTS: The mean (SD) age of participants was 78.1 (5.8) years, 43.8% were black, and 68.1% were women. Overall, 8.1% (17/210), 16.2% (34/210), and 51.0% (107/210) of participants had low, medium, and high MMAS-8 scores, respectively, at both survey administrations (overall agreement 75.2%; 158/210). The weighted kappa statistic was 0.63 (95% CI 0.53 to 0.72). The intraclass correlation coefficient was 0.78. The within-person standard error of the mean for change in MMAS-8 scores was 0.81, which equated to a minimal detectable change of 1.98 points. Only 4.3% (9/210) of the participants had a change in MMAS-8 of 2 or more points between survey administrations. CONCLUSIONS: Within-person changes in MMAS-8 scores of 2 or more points over time may represent a real change in antihypertensive medication adherence.
Journal Title: The Annals of Pharmacotherapy
Volume: 45
Issue: 5
ISSN: 1542-6270; 1060-0280
Publisher: Unknown  
Journal Place: United States
Date Published: 2011
Start Page: 569
End Page: 575
Language: eng
DOI/URL:

10.1345/aph.1P677
Notes: LR: 20151119; GR: R01 AG022536/AG/NIA NIH HHS/United States; JID: 9203131; 0 (Antihypertensive Agents); ppublish