High adherence and concordance within a clinical trial of antihypertensives

Abstract

Objectives: To explore hypertensive patients’ beliefs about their condition and its treatment and their adherence within the context of a clinical trial. To assess the degree of concordance between patients’ beliefs about hypertension and the medical model of the condition. Methods: This was a questionnaire-based study, involving 230 patients participating in the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT), a randomized controlled trial comparing two pharmaceutical approaches to the management of hypertension. A comparison group of 106 hypertensive patients who were screened for ASCOT but did not meet the entry criteria was also recruited. Outcome measures were beliefs about hypertension and antihypertensive medication, and adherence to medication (self-report and tablet count). Results: Adherence to medication was higher than anticipated, with 45% participants reporting complete adherence over the 18-month study and a further 40% only rare non-adherence. Patients’ beliefs about their condition and treatment were generally concordant with the medical model of hypertension. High concordance was associated with high medication adherence (p<0.001). Discussion: Clinical trial volunteers may have beliefs that are unusually concordant with the medical model of hypertension and may demonstrate atypically high adherence. This has implications for the transferability of trial findings to the general hypertensive population.