Prevention and control of lifestyle-related modifiable risk factors, such as smoking, diet, salt intake, and exercise, are well-known strategies to improve blood pressure control and consequently reduce the incidence of vascular and metabolic diseases and other disabling conditions.1 However, in different populations other factors have been associated with hypertension control, such as patient knowledge about hypertension, patient beliefs about medicines, and patient adherence to antihypertensive therapy.2,3 As such, when designing interventions to improve hypertensive patients’ blood pressure control, these other factors should be addressed, and tailored interventions should be designed. Increasing patient knowledge regarding cardiovascular diseases, their treatment and risk factors has become an important goal in public health interventions, with several studies showing that patients who had been educated about the importance of treatment were more involved with their therapy, more likely to adopt healthy lifestyle changes and more likely to see their physician if their blood pressure was outside the ideal range.4,5

In Portugal, some studies have assessed the knowledge of hypertensive patients regarding their disease as well as the relationship between patients’ knowledge and blood pressure control6,7; however, none of these studies used a validated instrument, hindering cross-sectional and longitudinal replicability. In 2017, Cabral et al. developed the Portuguese version of the Hypertension Knowledge Test (HKT),8 a multifaceted instrument that assesses knowledge about hypertension, not only regarding the symptoms and diagnosis of the disease but also regarding the ways of preventing and controlling high blood pressure, antihypertensive medications, and the harmful effects of hypertension over time. With this instrument, a potential standard exists that allows not only the assessment of patients’ knowledge about hypertension but also the evaluation of whether patient knowledge is associated with process variables, such as patients’ beliefs about medicines and treatment adherence.

Identifying the association between these parameters and their extent will enable clinicians, researchers, and health policy decision makers to develop more targeted and effective educational activities.

We aimed to evaluate hypertensive patients’ knowledge about hypertension and its influence on patients’ beliefs about their medication and on patients’ antihypertensive treatment adherence.

This was a cross-sectional study approved by the ethics committee of the Faculty of Medicine at the University of Coimbra (registration number: CE_024.2018). The study aims and procedures were explained to all potentially eligible patients. The acceptance of study participation was indicated by each patient upon signing of the written informed consent form.

Using the HKT as an instrument to evaluate hypertensive patients’ knowledge of their condition and medication, we found that almost all patients identified overweight, sedentary lifestyle, and salt as risk factors for hypertension, and more than 80% of patients knew the blood pressure therapeutic goals. Conversely, the majority of the patients were unaware of the asymptomatic characteristics of hypertension and believed that antihypertensive treatment had to be used for limited time duration.

Increasing public knowledge and awareness of cardiovascular diseases and their risk factors has become a major goal of healthcare professionals. In 2014, Polonia et al. published the PHYSA study12 and concluded that, in the Portuguese population, the salt intake is almost double the WHO recommendations. These findings had important coverage in mass media, which contributed to the development of national strategies to reduce salt consumption. Different societies established May as the “heart month” and organized campaigns to raise awareness. In 2017, the Portuguese Foundation of Cardiology designed the “The Heart in Sport” campaign, which aimed to promote physical exercise and combat sedentarism.13 In 2018, the Portuguese Society of Cardiology launched the “Capable Heart” campaign to alert the population that cardiovascular diseases (CVD) still lead the list of causes of death in our country and to increase awareness of risk factors for CVD, such as hypertension, obesity and a sedentary lifestyle.14 Since 2018, the Portuguese Society of Hypertension has joined the International Society of Hypertension “May Measurement Month” campaign, which aims to increase the population's awareness of measuring their blood pressure and adopting healthy lifestyle habits.15 However, since 2006, on World Hypertension Day (17 May) the Portuguese Society of Hypertension organizes a campaign to raise awareness about hypertension, which includes screening in several public locations and since 2013, it has created a microsite (www.sphta.org.pt) on its website dedicated to the general public where important information about hypertension is made available, including an extensive questions and answers section.

Using two different instruments, we found an uneven association between hypertension knowledge and components of the beliefs about antihypertensive treatment. Increased knowledge was associated with reduced negative beliefs and attitudes about hypertension and treatment but had no effect on positive beliefs and attitudes.

The BMQ has been used for several different medical conditions: for example, to analyze whether HIV-infected patients’ beliefs regarding their combination antiretroviral therapy and their co-treatments have an impact on their medication adherence16 and to investigate whether beliefs about asthma medication are related to poor asthma control.17 In cardiovascular conditions, the BMQ was used to examine the influence of beliefs about medicines on warfarin adherence among atrial fibrillation patients18 or to examine associations between the beliefs of patients with stroke about stroke and drug treatment and their adherence to drug treatment.19 In our study, we identified a negative correlation between the HKT score and the concerns domain of the BMQ but not with the necessities domain of the BMQ. It seems that higher hypertension knowledge reduced negative beliefs about medication (e.g., “these medicines disrupt my life”) but had no effect on positive beliefs related to patient's perceived needs of medication, e.g., “My life would be impossible without these medicines”).

The MUAH-16 is a promising instrument with less clinical use than BMQ. In our study, the MUAH produced similar results to the BMQ, with a negative correlation between the MUAH and both the lack of discipline domain (e.g., “I find it hard to stick to my daily regimen of medication taking”) and the aversion toward medication domain (e.g., “I dislike taking medication every day”). Similar to the BMQ, no correlation was found between positive attitudes toward health care and medication domains (e.g., “The pros of taking medication weigh up against the cons”) or with active coping with the health problems domain (e.g., “I eat less salt in order to avoid cardiovascular diseases”).

The Health Belief Model was one of the first theories explaining patients’ health behavior and remains one of the most widely recognized in the field. It was developed in the 1950s with the purpose of focusing the efforts of those who sought to improve public health by understanding why people failed to adopt a preventive health measure.20,21 The Health Belief Model theorizes that people's beliefs about whether they are at risk for a disease or health problem and their perceptions of the benefits of taking action to avoid it influence their readiness to take action.22

Our results highlight the potential impact of awareness-raising campaigns in decreasing negative attitudes toward treatment. However, further studies should analyze which health promotion activities are most successful in increasing patients’ perceived need for medication.

There was good patient knowledge regarding the risk factors of hypertension, but questions regarding anti-hypertensive treatment and hypertension symptoms resulted in the most incorrect answers. Assessing the gaps in patients’ knowledge about hypertension would enable the development of more targeted educational activities, leading to better outcomes and improving patient adherence to medication and blood pressure control. By increasing patients’ knowledge about hypertension, it was possible to reduce negative attitudes toward medication, but there was no impact on positive attitudes.

No external funding was received.

Ana Cabral: Investigation, Formal analysis, Writing - Original Draft, Writing - Review & Editing,

Marta Lavrador: Investigation, Writing - Original Draft - Preparation, Writing - Review & Editing,

Fernando Fernandez-Llimos: Conceptualization, Formal analysis, Writing - Original Draft, Writing - Review & Editing,

Margarida Castel-Branco: Conceptualization, Writing - Review & Editing,

Isabel Vitória Figueiredo: Conceptualization, Project administration, Writing - Original Draft, Writing - Review & Editing,

The authors have no conflicts of interest to declare.