Impact of patient knowledge of hypertension complications on adherence to antihypertensive therapy

Abstract

Background: Poor adherence is thought to be one of the major common causes of uncontrolled high blood pressure over the world leading to useless drug dose or class changes which may lead to increased adverse effects and medical costs. The current study aimed to investigate the relationship between knowledge about complications related to hypertension and adherence to antihypertensive treatment.

Materials and methods: A cross-sectional study was carried out between May and November 2013 on a representative sample of 453 hypertensive patients at public primary care outpatients in the department of Tlemcen in Algeria. The adherence was assessed with the adherence evaluation scale of Girerd which contains six items with closed dichotomous responses (yes/no). The degree of adherence was calculated according to the score resulting from the sum of all "yes" answers. A cut-off value of 80% was used to categorize patients as "adherent" or "non-adherent". To do so, a structured questionnaire has been performed including patients' knowledge about hypertension complications and the other factors which may affect adherence therapy.

Results: Among the 453 patients included in the study, only 35.5% were adherents. Univariate analysis has shown a positive relationship between knowledge about hypertension complications and adherence. However, comorbidities, and number of antihypertensive drugs prescribed, were associated with poor adherence. In a multivariate analysis, a significant difference was shown between adherents and non-adherents according to the factors mentioned above and the insurance status.

Conclusion: This study has shown a positive relationship between patients' knowledge about the hypertensive complications and adherence. In contrast, increased number of antihypertensive drugs taken May affect negatively the adherence to therapy.