Baseline medication adherence and blood pressure in a 24-month longitudinal hypertension study

Abstract

Aim and objectives: We sought to identify the feasibility and predictive validity of an easy and quick self-reported measure of medication adherence and to identify characteristics of people with hypertension that may warrant increase attentiveness by nurses to address hypertensive self-management needs.

Background: Current control rates of hypertension are approximately 50%. Effective blood pressure control can be achieved in most people with hypertension through antihypertensive medication. However, hypertension control can only be achieved if the patient is adherent with their medication regimen. Patients who are non-adherent may be in need of additional intervention.

Design: This secondary analysis evaluated the systolic blood pressure of patients who received usual hypertension management across 24 months at six-month intervals.

Methods: A longitudinal study of 159 hypertensive patients in two primary care clinics.

Results: In a sample of 159 patients receiving care in a primary care facility, baseline medication non-adherence was associated with a 6·3 mmHg increase in systolic blood pressure (p < 0·05) at baseline, a 8·4 mmHg increase in systolic blood pressure (p < 0·05) at 12 months and a 7·5 increase in systolic blood pressure at 24 months (p < 0·05) compared with adherent patients, respectively. Results also indicate a significant increase in systolic blood pressure across 24 months among people who identified as minority and of low financial status.

Conclusions: Non-adherence with antihypertensive medication at baseline was predictive of increased systolic blood pressure up to 24 months postbaseline.

Relevance to clinical practice: This study demonstrates the use of an easy-to-use questionnaire to identify patients who are non-adherent. We recommend assessing medication adherence to identify patients who are non-adherent with their anti-hypertensive medication and to be especially vigilant with patients who are minority or are considered low income.

Figure 1

Change in SBP (mmHg) across 24 months by adherence at baseline

Figure 2

Change in SBP (mmHg) by race and baseline medication adherence