Monitoring adherence to medication by measuring change in blood pressure

Andrew Hayen*, Katy Bell, Paul Glasziou, Bruce Neal, Les Irwig

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)


After starting antihypertensives, blood pressure is monitored for several reasons, including assessment of adherence. We aimed to estimate the accuracy of blood pressure monitoring for detecting early nonadherence. We conducted a secondary analysis of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), a large randomized trial of blood pressure lowering to reduce the risk of recurrent stroke. We compared change in blood pressure 3 months after randomization in people who had discontinued treatment (nonadherent) with those who stayed on treatment (adherent). We also used an indirect method, assessing whether change in blood pressure discriminated between active (adherent) and placebo (nonadherent) groups. Both methods gave similar results. For the 3433 subjects, the mean (SD) of the change in systolic blood pressure was -15.8 mm Hg (SD 18.7 mm Hg) in the adherent group and -4.2 mm Hg (SD 18.1 mm Hg) in the nonadherent group. After recalibration of the mean change in the nonadherent group to 0 mm Hg and in the adherent group to -11.6 mm Hg, the absence of a fall in systolic blood pressure at 3 months had a sensitivity of 50% and a specificity of 80% for detecting nonadherence (50% of nonadherent patients and 20% of adherent patients had a rise in blood pressure). Discriminatory power was modest over the range of cutoffs (area under the receiver-operator curve 0.67). Monitoring blood pressure is poor at detecting nonadherence to blood pressure-lowering treatment. Further research should look at other methods of assessing adherence.

Original languageEnglish
Pages (from-to)612-616
Number of pages5
Issue number4
Publication statusPublished - Oct 2010
Externally publishedYes


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