According to the National Survey on Access, Use and Promotion of Rational Use of Medicines (PNAUM, Pesquisa Nacional sobre Acesso, Utilização e Promoção do Uso Racional de Medicamentos ),¹ conducted in urban areas of the five geographical regions of Brazil, the prevalence of self-reported hypertension in the country is 23.7% (95% confidence interval, CI, 22.8-24.6), with a greater predominance in the elderly (>60 years old) (59.0%). The access to hypertension drug therapy is greater in the South and lower in the Midwest and Northeast regions; 56% of these therapies were provided by the Brazilian Unified Health System (SUS), 16% by the Popular Pharmacy Program ( Programa Farmácia Popular ), and 2.3% by other sources.

Although the management of systemic arterial hypertension (SAH) is easily achieved in primary health care, hypertension control rates are still low (18.0-19.6%).² Poor treatment adherence has been considered the main cause of increased morbidity and mortality from cardiovascular diseases, reduced quality of life, increased medical costs, and increased demand for medical services.^{3 - 5} These facts not only highlight the importance of the early detection of SAH, but also create an opportunity for the implementation of a pharmacotherapeutic follow-up program. The pharmacist contributes to the improvement of therapy adherence, and consequently, of the quality of life of hypertensive patients. This is of particular importance in regions like the North of Brazil, as the pharmacist provides an individual assessment of patients, based on their culture, experience with the therapy, and autonomy, to develop a “care plan” for the rational use of medications that can be shared by patients and professionals.⁶

In the northern region of Brazil, the adherence rate to drug therapy for chronic diseases is of 22.7%, lower than the rates in the southern (26.8%) and northern (29.2%) regions.⁷ Thus, the present study was based on the assumption that adherence to drug treatment by hypertensive patients is low in the Brazilian north, leading to a high number of individuals with uncontrolled hypertension. In addition, pharmacotherapy follow-up in the primary care seems to improve the outcomes of this condition, unless issues like the correct use of medications and cultural diversity are addressed. Thus, we aimed to assess blood pressure control in hypertensive patients attending primary care clinics after the implementation of the pharmacotherapeutic follow-up program in a city in the north of Brazil.

Of the 163 hypertensive patients included in the study, 154 (94.5%) were non-adherent to treatment and 126 (77.2%) had uncontrolled hypertension. Most patients were women (73.0%), aged from 40 to 79 years (82.9%), and of black race (74.8%). Regarding educational attainment, 20.2% had no schooling, and 57.1% had elementary school; 35.6% earned less than one minimum wage, and 58.9% used medicinal plants. No statistically significant differences were found in sociodemographic characteristics and treatment adherence between patients with controlled and uncontrolled blood pressure ( Table 1 ).

Of the 63 patients who accepted to participate in the “pharmacotherapy follow-up group” patients attending urban health care centers (n=52) were those who most benefited from the program, with significant increase in the number of patients with controlled hypertension (p<0.001), and significant reduction in systolic and diastolic blood pressure (p<0.001). This was not observed among participants from the riverbank community (n=11) (p>0.05) ( Tables 2 and 3 ). In addition, a significant improvement in blood pressure levels, especially systolic blood pressure (p<0.001), was seen in participants from both urban and riverside health center centers ( Table 4 ).

Before the pharmacotherapeutic follow-up program, the number of patients with uncontrolled hypertension was 77.2%, with no significant differences between patients attending urban and riverside medical centers. A cross-sectional study conducted in Porto Velho, a city located in the Amazon area, showed a prevalence of 53.1% of hypertensive patients aged between 35 and 80 years.¹⁷ In riverbank communities of Madeira river (western Amazon), 26% (95% CI; 23-29%) of adults had hypertension, 29% of men (95% CI: 24-33%) and 23% of women (95%CI: 19-27%).¹⁸

In addition, 94.5% of participants were non-adherent to treatment. Based on the literature, adherence to treatment in the north region of Brazil is only 22.7%, compared with 38.1% and 31.6% in the northeast and middle west regions, respectively, and 26.8% and 29.2% in the in the South and Southeast, respectively.⁷ In a study conducted with data from the PNAUM,¹ the prevalence of non-adherence to drug therapy in the North was 24.2%, which was higher than in the south (17.0%) and southeast (17.5%) regions.¹⁹

According to Barreto et al.,²⁰ intervention measures aimed at improving blood pressure control are needed. Also, the authors support that hypertensive patients should be counseled regarding anti-hypertensive treatment, according to the Brazilian Ministry of Health protocol, requiring a multiprofessional teamwork in this regard. The presence of a pharmacist in multiprofessional teams is warranted to redefine healthcare models for chronic diseases, especially in primary care, to obtain better therapeutic results.²¹

Uncontrolled blood pressure has been frequently associated with low treatment adherence.^{3 , 22} Araújo & Aras Junior²³ reported that most of their studied patients had uncontrolled hypertension, regardless of treatment adherence. However, the authors observed an expected trend: patients with controlled hypertension had good treatment adherence, and most of patients with uncontrolled hypertension had poor adherence. Also according to the authors, adherence to anti-hypertensive therapy may be improved by patient education regarding the correct use of medication, making sure the patient understands it, and establishing strategies with family members to help the patient remember to take medication help.

In the present study, patients with uncontrolled hypertension but adherent to the therapy were referred to their physicians for assessment of their drug therapy and need for adjustments. One case food-drug interaction was detected in a patient adherent to drug therapy. The patient was instructed about the correct use of medication, and blood pressure levels were normalized after that. However, according to Araújo & Aras Junior,²³ although the Morisky-Green test is the most used method to quantify adherence to anti-hypertensive treatment in Brazil, enabling comparison between studies, the instrument may not be the most appropriate considering its low sensitivity (43.6%).

Our results also showed that men were more adherent to treatment than women (p=0.006). This contrasts with the literature that indicates a greater concern about health among women, who tend to seek more medical care and have a better blood pressure control than men,^{24 , 25} probably due to some cultural association that still needs to be elucidated. Besides, no statistically significant association was found between non-adherence to drug therapy and age (p=0.683). In the elderly, greater adherence to drug therapy is associated with more advanced age, as aging is associated with a higher prevalence of chronic degenerative diseases, which may make the patient more aware of his/her health condition and increase treatment adherence.²⁶

Although the relationship between socioeconomical factors, like income and educational attainment, and adherence to treatment has been well established,^{7 , 21 , 27} we did not observe a statistically significant correlation between adherence and educational level (p=0.589). Low levels of educational attainment and income had a negative impact on drug treatment adherence. Indeed, users of the public health system in Brazil, with low socioeconomic status, may not be able to purchase medications covered by the public system, in case of lack of them.²⁸

In contrast with the literature, we did not find statistically significant differences in adherence or race between adherent and non-adherent patients (p=0.075). Most participants self-identified as Black, which may be explained by the high concentration of African descendants and indigenous in the west of Pará State, where the study was conducted. According to the literature, Black individuals have higher blood pressure levels and lower blood pressure control, which may be due to low socioeconomic status, complexity of drug therapy and presence of comorbidities.²⁹

One aspect that may interfere with the therapy is the lack of medications in the public health care sector, especially when cities and states do not receive the minimum financial resources, in contrast to what is predicted by the law number 8080/90³⁰ and ordinances 204/2007³¹ and 1.555/13.³² Vaz et al.,³³ who evaluated the participation of the central, state and municipal governments in the funding of the basic components of pharmaceutical assistance in the city of Santarem, Pará, between 2010 and 2015, found that the minimum per capita expenditure value, legally established, was not achieved. The study by Mendes et al.,³⁴ revealed a low availability of medications to all population strata.³⁴ Tavares et al.,⁷ reported that a low adherence to the drugs prescribed for the treatment of chronic diseases was more frequent among patients who had to pay for part of their medications than among those who obtained the medications for free.

In addition, our results showed that the pharmaceutical follow-up program improved blood pressure control, with reduction of systolic and diastolic blood pressure levels, particularly in participants living in urban areas than in riverbank areas. This may be due to the greater access to health care by urban populations, which requires further studies to be confirmed. Also, a study performed in Porto Velho showed higher rates of hypertension in urban than riverbank areas (55.48% vs. 48.87% [p = 0.02] and 61.25% vs. 52.30% [p < 0.01], respectively).¹⁸

Regarding the stage of the pharmacotherapeutic follow-up program, we identified some drug-related problems, including patients with health problems and uncontrolled blood pressure due to a non-quantitative ineffectiveness of the medication.

Limitations of the study include the assessment of treatment adherence by self-reporting and the observational nature of the study, which prevents causal inferences.

The present study showed a low adherence to drug therapy and uncontrolled hypertension among users of the Hiperpedia. It also pointed out the need for referral of adherent and non-adherent patients with uncontrolled hypertension to their general practitioner. This finding justifies the importance of an individualized treatment through a pharmacotherapeutic follow-up in the primary care setting, which may improve the outcomes of chronic diseases, such as systemic arterial hypertension, mainly when regional and cultural specificities are respected.

The pharmacist plays an important role in the healthcare team. This role becomes even more vital in the north of the country, considering its territorial and cultural diversity, as well as poor access to health services and even to drug treatment. The pharmacist needs to develop and provide individualized care, considering all particularities of this geographic region.

Finally, further studies may elucidate the causes of differences in treatment adherence in the city of Santarem, and in hypertension control rates between urban and riverside communities in the north region of Brazil.