BP monitoring poor measure of adherence to antihypertensive medication
MedWire News: The results of a multicentre study suggest that blood pressure (BP) monitoring is an ineffective method for detecting nonadherence to antihypertensive medication.
"It seems unlikely that this could be easily resolved by using different methods to assess BP," comment the researchers.
They advise that "clinical practice guidelines need to be updated to reflect the limitations of BP measurement as a means of detecting nonadherence and make other recommendations about how this can be achieved."
Andrew Hayen (University of Sydney, Australia) and team assessed the BP of 1709 hypertensive patients who were adherent to antihypertensive medication treatment (perindoril and indapamide), and 1734 who were nonadherent and discontinued their medication during follow-up in the Perindopril Protection Against Recurrent Stroke Study (PROGRESS).
BP was determined by two sets of measurements taken 1 month before and 3 months after commencement of treatment.
Writing in the journal Hypertension, Hayen and team report a mean BP reduction of 15.8 and 4.2 mmHg among the adherent and nonadherent patients, respectively, over the follow-up period.
After adjusting the results to reset the observed mean BP change in the nonadherent group to 0 mmHg, the researchers determined that the absence of a fall in BP by 3 months could detect nonadherence to medication with a sensitivity of 50% and a specificity of 80%.
On extrapolation of their results, they found that the specificity of this method in detecting nonadherence to medication rose to 97% when 10 sets of BP readings were taken before and after the start of antihypertensive therapy instead of two sets of readings.
However, the team notes that the impracticalities of taking so many readings and the finding that sensitivity would still remain at 50% limit the usefulness of such a practice.
Hayen and colleagues say: "Our results align with the findings of several other studies that examined the relationship between change in BP and adherence."
They suggest: "Further research to identify effective ways of detecting nonadherence should probably focus on methods other than BP measurement, or else to objectively test the feasibility and cost-effectiveness of using multiple home measurements."
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By Lauretta Ihonor