Abstract
The aim of this study was to evaluate self-reporting of adherence to cardiovascular medication using electronic pillboxes (medical event monitoring system [MEMS]) as the gold standard comparator. In total, 78 individuals (52% hypertensives, 21% diabetics, 27% with dyslipidemia) were recruited prospectively from an outpatient clinic setting in Switzerland. Participants completed two self-report measures (visual analogue scale [VAS] and a validated self-reporting questionnaire) at baseline and were asked to use MEMS as their pillbox for the subsequent 10 weeks. Patients expressed their medication adherence behaviour on a VAS (0 mm=“I never take any tablets”; 100 mm=“I take all tablets as prescribed”) and entered one of six numbers (from 1: perfect adherence to 6: non-adherence) on the questionnaire. Medication compliance was monitored for 75 d on average. Mean (±SD, range) scores for MEMS with respect to timing adherence, correct dosing, and self-administration adherence were 79±25% (8–100%), 83±20% (24–100%), and 92±17% (54–118%), respectively. A majority of participants (78.8%) over-reported their adherence to the VAS (93±7 mm, 73–100), and VAS scores correlated poorly with MEMS recordings (Spearman's ρ for timing adherence, correct dosing, self-administration adherence 0.29 [p=0.018], 0.24 [p=0.051], 0.26 [p=0.036], respectively). Similarly, we found no correlation between adherence as expressed in the questionnaire and MEMS (regression coefficients < 0.1). We conclude that a majority of patients over-report adherence to cardiovascular medication if asked to complete a visual analogue scale and a validated questionnaire. Therefore, using self-reporting as the sole means of assessing medication compliance is insufficiently accurate to detect poor adherence.
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Zeller, A., Ramseier, E., Teagtmeyer, A. et al. Patients' Self-Reported Adherence to Cardiovascular Medication Using Electronic Monitors as Comparators. Hypertens Res 31, 2037–2043 (2008). https://doi.org/10.1291/hypres.31.2037
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DOI: https://doi.org/10.1291/hypres.31.2037
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