In general, there is a poor performance of health service delivery systems in the management of hypertension in the country. In this study we estimated that three out of ten Brazilians aged 18 years and over have high blood pressure levels, a little more than half of this population is aware of the diagnosis. However, although almost all participants with a diagnosis are on drug treatment, only half of them have their blood pressure under control. Significant variations were observed by age, sex, education, race/color, marital status, health insurance and region. The best hypertension control performance was observed among younger groups (18–35 years), those with high schooling, those who reported having white skin color and private health insurance.
Middle- and low-income countries achieve prevalence of control of bapproximately 30% [10, 23], values below those shown in the present study. The prevalence of control in Brazil was similar to those estimated in high-income countries [10, 13]. However, some of these countries have already shown better performance of this outcome (70%) [13]. Thus, in more developed countries, national AH screening programs use health check-up, implementation of regular blood pressure measurements, recording and feedback [13]. These actions probably explain the better prevalence of successful control in these countries.
The high prevalence of AH treatment shown in this study can be explained by policy and programmatic factors. Access to treatment depends on availability, price and distance to dispensing services [24, 25]. In one of the richest states in Brazil, a study showed that there are sufficient resources and dispensing of drugs, so there are no barriers to the provision of treatment and access of health service users [26]. This near universalization of access to AH treatment in the SUS reflects government policies prior to 2015, such as improving access to antihypertensive medication, known as the Popular Pharmacy Program of Brazil and Saúde não Tem Preço, which guarantee free antihypertensive drugs in accredited pharmacies and in Primary Health Care facilities [27–30].
Even in the context of broad access to medication, AH control was less than expected. Other strategies for better control should be taken into account, including adherence to treatment [10, 13, 25, 31, 32]. For instance, the linkage and accountability of both the professional and the user [26]are necessary elements to ensure the longitudinality of care. Educational actions could be a linkage strategy, but they are not highly valued and have low frequency [26]. Therefore, the establishment of non-pharmacological measures is crucial for the control of hypertension as coadjuvants interventions to drug treatment. Reducing sodium intake, regular physical activity, smoking cessation and weight control should be considered [33–35].
Another finding of the study was the differences between population subgroups according to sociodemographic variables. These results indicate that it is feasible to improve performance in the prevalence of awareness and control and treatment of AH, at least from a population perspective. In this study, women showed greater awareness, treatment and control of AH, probably due to women's greater access to health services, reported in several studies [31, 36, 37]. In addition to the behavior of greater care for their health and, consequently, greater demand for care [25, 38], primary care assistance programs focus on the maternal and child component [9], including preventive consultations and examinations, and prenatal care. Thus, a more extensive demand for the use of health services creates opportunities for the diagnosis of chronic conditions, such as AH, as well as for their treatment and control.
Another aspect, the higher prevalence of treatment and control in participants who declared themselves white may reflect structural inequalities in Brazilian society [31, 39], being responsible for unequal distribution of social resources, knowledge, employment opportunities and socioeconomic status [34]. Corroborating this hypothesis, a Brazilian study showed a higher prevalence of poor access to health services [40, 41]. Similarly, in the context of social inequalities, the highest prevalence of AH control was observed in participants with high education, reflecting the influence of greater access to information, understanding of the health problem and adherence to treatment [13, 42]. A cohort study conducted with a population of different socioeconomic levels, professors and administrative technicians of Brazilian public universities, showed higher proportions of awareness (80.2%) and control of AH (69.4%) [31].
In this study, contrary to studies in the literature, participants living without partners had higher prevalence of awareness of AH, probably explained by survival bias. A separate comment deserves the increase in age associated with a higher proportion of awareness and treatment of AH already consolidated in other studies [11, 13, 16, 23, 43, 44]. The presence of other comorbidities, mostly NCDs and their risk factors, which increases with age are strong contributors [45, 46]. However, in the elderly there is evidence of falls [13, 14, 23] associated with senescence [47–49], use of multiple medications [50], pharmacological interactions, adverse events and low adherence to treatment [51]. Moreover, there is a lack of consensus regarding the therapeutic goal to be achieved by the elderly, as there is for the adult population [49].
Among the limitations of this study there is the use of casual blood pressure measurement to assess the management of AH, which could cause classification bias, but used in similar studies [13, 31]. The absence of data on antihypertensive medication, time of use and adherence is another limitation. On the other hand, aspects of validity of the study include the use of measured BP in the population, which makes the analysis possible. It is recommended to include these measures in future editions of the PNS, since in the 2019 edition blood pressure measurement was not performed, preventing the reproducibility of this study and the monitoring of these outcomes regarding this condition, beyond the disease prevalence itself.