Prevalence, awareness, treatment, and control of hypertension in a small northern town in Nicaragua: The Elieth‐HIFARI study

Abstract Background and aims Hypertension is considered the most important risk factor for cardiovascular disease and is associated with high levels of morbidity, mortality, and health care expenditure. The negative effects of hypertension and its complications are preventable if those at risk are appropriately treated and controlled. Continually monitoring the epidemiological trends of hypertension is essential to formulate and evaluate public health measures to limit its negative effects. The herein presented Elieth‐HIFARI study sought to estimate the prevalence of hypertension, as well as the prevalence of related awareness, treatment, and control in a small town in Central America. Methods A population survey to assess cardiovascular risk was conducted (n = 577, 55.3% women, mean age 42.4 years) in the municipality of San Rafael del Norte in northern Nicaragua, between November 2016 and March 2017, based on the STEPwise method by the World Health Organization and the recommendations by the World Hypertension League. Results The overall prevalence of hypertension, awareness, treatment, and control was 28.1%, 72.2%, 68.5%, and 36.4%, respectively. Men had a lower prevalence of all indicators (22.5%, 60.3%, 53.4%, and 24.1%, respectively) compared with women (32.6%, 78.8%, 76.9%, and 43.3%, respectively). The median systolic blood pressure was 118.5 mm Hg (20.5 interquartile range [IQR]) (men: 123.0 mm Hg vs women: 115.5 mm Hg, Mann‐Whitney U test P < .001), and the mean diastolic blood pressure was 78.0 mm Hg (13 IQR) (men: 77.0, women: 78.0). Conclusion Hypertension is highly prevalent in San Rafael del Norte, while control rates are low despite the relatively higher levels of awareness and treatment. Furthermore, women have much higher prevalence of hypertension than men, along with higher awareness, treatment, and control. However, the control rate for those treated for hypertension was low, irrespective of sex.


| INTRODUCTION
Cardiovascular disease (CVD) is the most important cause of mortality worldwide, producing nearly one-third of all deaths, half of which are premature (defined by the World Health Organization [WHO] as 70 years or younger). 1,2 Of the 17 million deaths that occur globally each year due to CVDs, 15 million are caused by ischemic heart disease and stroke alone, 1 with hypertension (HTN) as the most important risk factor for these two major diseases. HTN is also associated with nearly half of the deaths related to ischemic heart disease and stroke, 3 close to 9.4 million annually. 4 The high mortality, disability, and social and economic impact of CVDs generate an important burden on health systems and on the productivity of society in general. 4,5 Specifically, HTN alone has been linked to at least half of the economic loss due to noncommunicable diseases, roughly 2% of the gross domestic product (GDP) of middle-and low-income countries. 5 Nicaragua has the highest CVD mortality rate in Central America. 2,6 Managua, the capital of Nicaragua, has the highest prevalence of HTN among various others Central-American capitals. 7 In San Rafael del Norte, a small town in northern Nicaragua, HTN-related visits are among the three most important reasons for seeking medical attention and constitute nearly a third of medical visits for the elderly. 8 CVDs are also the first causes of mortality there, causing more than 25% of all deaths in those 14 years old and older. 9 Prevention of HTN-related complications is a challenge because HTN itself rarely causes symptoms, and therefore, it is usually underdiagnosed, undertreated, and not controlled properly. This is one of the reasons why the WHO considers its early detection and adequate management to be fundamental in order to reduce the risk of complications and death. 3 Because of this, it is necessary to know the prevalence of HTN and other indicators such as prevalence of awareness, treatment, and control, as proposed by the World Hypertension League (WHL). 10 These indicators are also essential to identify populations at higher risk for cardiovascular complications, help characterize these groups, and aid in the formulation of prevention and control strategies. Furthermore, they also help to assess where to focus these efforts and monitor and evaluate the progress made by public health policies. 10,11 Research on HTN prevalence, awareness, treatment, and control has been conducted in many regions of the world, with varying results.
Prevalence of HTN has been reported to be as low as 13.4% in Bogota 12 up to as high as 42.5% in several cities of Chile, Argentina, and Uruguay. 13 In comparison, many other regions of the world have a prevalence that falls within this range, such as Canada (20%), 14 China (29.6%), 15 Korea (33.7%), 16 Lebanon (36.9%), 17 and Estonia (36%). 18 Further variability is seen even within regions and countries, seemingly due to different age compositions of the studied population as the main reason, as well as differences in resources, education, and access to care.
Awareness, treatment, and control rates have also been found to vary widely. Awareness has been measured from as low as 24.6% in a Korean study, 16 up to as high as 74% in Canada 14 and 80% in Estonia. 18 Overall, most studies report that at least more than half of the studied population have awareness. [12][13][14]17,18 Pharmacologic treatment rates among those hypertensive have been observed ranging from 34.1% in China 15 up to 60.5% in Italy 19 and 78.6% in Korea. 16 However, despite awareness and treatment rates, overall control rates have been found to be consistently low (less than 30%) in comparison, as seen in countries like Italy, 19 China, 15 Korea, 16 and Lebanon, 17 and in Latin American cities such as Bogota, Buenos Aires, Lima, and Santiago. 12 Additionally, there are reports of control rates among those treated with medication of between 27.4% (China) 15 and 72.0% (Canada). 14 Within the numerous studies on HTN prevalence and associated indicators referred to previously, generally, men have higher prevalence, and women have higher awareness, treatment, and control rates. In addition, older ages (65 years or older) have been reported to have higher prevalence of HTN 12 ; however, the association, if any, between age and awareness, treatment, and control is unclear.
Considering the recent publication of the aforementioned standards for reporting HTN by the WHL, and the scarce data related to its core indicators in Nicaragua and Central America, the Elieth-HIFARI study sought to provide initial reference data for the epidemiological surveillance of such prevalence indicators in a typical small town of northern Nicaragua, considered as such based on shared social, economic, cultural, topographical, and climatological traits.

| Study population
A population-based cross-sectional survey was conducted in the small town of San Rafael del Norte, in the northern mountainous region of Nicaragua. A sample size of 636 participants was estimated considering an expected HTN prevalence of 25%, based on the most recent prevalence reported for Managua, 7 with a 95% confidence interval (CI), 5% precision margin, and a 10% expected nonresponse rate. This sample size represents an 18.3% of the total adult population, of 3477 individuals. A random stratified sampling method was employed accounting for sex and age groups, based on the official population census of 2010 to 2016 of the municipality. Participants were selected randomly from a community census provided by the local offices of the national health ministry (MINSA). Persons 18 years of age or older were included, except women who were pregnant or had given birth less than 40 days prior to the interview; persons with any mental or physical disability that impeded the interview or measurement taking were also excluded.

| Data collection
The survey was conducted on the basis of door-to-door visits to each of the selected participants' residence where the interview took place, after they were given a detailed explanation of the nature of the visit.
After agreeing to the interview, participants were asked to sign an informed consent form in order to participate in the study. If at the time of the visit the participant did not meet the ideal conditions for the unbiased measurement of blood pressure (BP) as stated in the Recommendations for the Measurement of Blood Pressure in Humans by the American Heart Association, 20 then another time for the interview was agreed upon. The team of interviewers, consisting of medical students, underwent previous training to standardize questioning and procedure methods in order to minimize observer bias.
The instrument used for data collection was based upon the first two steps of the Pan American version of STEPS Instrument 3.1 of the "WHO STEPwise approach to non-communicable disease risk factor surveillance (STEPS)". 21

| Ethical considerations
The present study was done in keeping with the Declaration of Helsinki (2013), and it was remitted to and approved by the Medical Ethics Committee of the National Autonomous University of Nicaragua in Leon. At the end of each interview, participants were informed of their results and received pertinent prevention and health promotion counseling; those who had high BP readings were remitted to appropriate health care services depending on their severity.

| Definitions
We used the definitions recommended by the WHL for core indicators and analysis for HTN surveillance. 10 Prevalence of HTN was defined as the proportion of participants who had a systolic blood pressure (SBP) ≥ 140 mm Hg or a diastolic blood pressure (DBP) ≥ 90 mm Hg, or who reported currently taking medication for high BP for at least the last 2 weeks. Prevalence of awareness was defined as the proportion of participants with HTN who took medication for high BP or were diagnosed with HTN by a health professional; treatment, as the proportion of participants with HTN who took medication for high BP; and controlled HTN, as the proportion of participants with HTN who took medication for high BP and had SBP < 140 mm Hg and DBP < 90 mm Hg. Prevalence of "treatment among those aware" was defined as the proportion of participants who took medication for HTN among those aware and "control among those treated", as the proportion of participants who had a SBP < 140 mm Hg and DBP < 90 mm Hg among those treated.
Prevalence of optimal BP was defined as SBP < 120 mm Hg and DBP < 80 mm Hg in the absence of treatment for HTN; prehypertension (Pre-HTN), as the proportion of participants having SBP > 120 mm Hg and < 140 mm Hg and/or DBP > 80 mm Hg and < 90 mm Hg, without having HTN; and isolated systolic HTN, as the proportion of participants with HTN who had SBP ≥ 140 mm Hg and DBP < 90 mm Hg.

| Statistical analysis
The independent variables studied included age, sex, ethnicity, marital status, education, occupation, income level, SBP, DBP, previous diagnosis of HTN, and medication use for high BP. The sociodemographic variables of the population were summarized and reported with corresponding prevalence rates and 95% CIs. Four age groups were defined as recommended by the WHO, and income level was categorized in quartile groups based on household income per capita. The Median SBP and DBP as well as the interquartile range, are reported for sex and age groups. Likewise, the prevalence of HTN, awareness, treatment and control, treatment among aware, control among treated, optimal BP, Pre-HTN, and isolated systolic HTN were all estimated for sex and age groups, with 95% CIs.
The median values of SBP and DBP were compared by sex groups using the Mann-Whitney U test and age groups using the Kruskal-Wallis H test. The data were stratified by sex, as is recommended by the WHL 10 and the WHO. 22 The prevalence of the indicators mentioned above was compared by sex, age groups, and selected demographic characteristics using the Pearson chi-squared test. A two-sided P value < .05 was considered statistically significant. All data were introduced and processed using the IBM SPSS version 22 statistical software. Normality tests were conducted for age, household income per capita, mean SBP, and mean DBP. None of the tested variables had a normal distribution (per Shapiro-Wilk test, P < .05), observing that while histograms for both SBP and DBP closely resembled a normal distribution, they were slightly skewed to the right. were women. More than 91% of participants self-identified as Mestizo (or mixed ethnicity). Nearly half of the population had only a primary level of education or less, and there was a literacy rate of 95.5%.
Unemployment was at a 4.1%, and the main occupations were housemaker in women and self-employed in men; 8.7% of the population were students. The majority of participants lived with a life partner; 53.9% were either married or cohabitating. The median household income per capita per month was US $56.60 (in January 2017) 24 : less than $3 a day. All four income level groups that are based on quartiles (Q1 = $33.96, Q3 = $101.88) had similar proportions. Besides occupation (P < .001, per Mann-Whitney U test), no significant differences were found between men and women in other demographic variables. Table 1 summarizes the selected sociodemographic characteristics of the participants.  Additionally, HTN prevalence was also statistically higher in those with a college level, primary, or less than primary education than in participants with secondary education only, higher in the retired, and lowest in students (see Tables 3 and 4). Other occupation categories had similar prevalence. Widows had the highest HTN prevalence, singles had the lowest, and those married or cohabitating had similar prevalence to those divorced or separated. No significant differences in HTN prevalence were found by income levels. Table 3 shows prevalence rates for each indicator by sex and age, and Table 4 shows prevalence rates for other sociodemographic variables and comparisons by each variable. The crude prevalence of awareness was 72.2% (95% CI, 65.4-79.0), which was higher in women than in men, and 0% in participants younger than 30 years. In older age groups, no significant differences were found, neither by education level, marital status, or income level. Considering occupation, homemakers, the retired, and the unemployed had higher awareness, whereas students had 0%.  Table 4).
Overall control was higher in women, older age groups, the retired, and homemakers. Additionally, when considering only those treated for HTN, no differences in control rates were found by any sociodemographic characteristic (see Table 4).

| BP categories
Overall  comparable with other Latin American cities with higher HTN prevalence such as Buenos Aires, Santiago, and Barquisimeto, all between 20% and 30%, 12 but higher than that in cities like Lima (12.6%), Bogotá (13.4%), Quito (8.6%), and Mexico City (11.7%). 12 The rates observed are lower than national estimates of Asian countries like China (29.6%) 15 and Korea (33.7%). 16 The majority of participants with HTN were aware and had treat-   In other studies, the prevalence of HTN has been shown to have a linear association with age; however, varying results have been reported regarding sex, where some have found a higher prevalence in men (Argentina), 27 others have found it in women (Costa Rica), 28 and some report no difference at all (Central America and Mexico) 7,29 ; however, most of the revised literature shows men as having, in general, higher prevalence of HTN than women. [12][13][14] The CAMDI survey, which estimated the prevalence of HTN in all Central American capital cities, found that only in Managua did women have a significantly higher prevalence than men, 7 which is consistent with our findings and other research done in Nicaragua. 30,31 Additional unpublished data from our study regarding the prevalence of risk factors for chronic diseases suggest that the higher prevalence of HTN in women in our population may be explained by the higher prevalence of obesity and other metabolic risk factors in this group than in men. It is possible that cultural differences may be an important underlying factor that determines these differences between men and women in different regions of the world. For instance, however, when considering only those with treatment, the control rate was also close to 50%, and there were no differences between groups.

| Strengths and limitations
The Elieth-HIFARI study is the first in Nicaragua to use the recom-

| Implications and future research
In order to achieve a substantial reduction in HTN and the cardiovascular complications that can arise from it, it is essential to adequately surveil the prevalence of HTN to determine its importance as a public health priority and the effectiveness of policy measures designed to reduce it. Consequently, our study provides the starting point for these purposes in a typical small town of northern Nicaragua.
Awareness is a key aspect in avoiding cardiovascular complications as it is associated to higher rates of treatment and control.
The WHL states: "population-level awareness of hypertension indicates the efficiency of community and clinical resources in identifying people who might benefit from clinical management of hypertension." 10 Our results indicate the need for systematic screening and case-finding interventions for the general population, targeted especially at men and younger individuals, groups that have lower awareness rates. As admitted by the WHL, it is not reasonable to assume that all who have HTN require pharmacotherapy, as there are varying criteria and some may be controlled with only lifestyle changes. We found a high rate of treatment among those who were aware of having HTN; therefore, access and availability to health care interventions does not seem to be a major problem in this population. However, despite the high rate of treatment among those aware, the majority of those with HTN were not controlled; therefore, there is much room for improvement in the health system's efforts of identifying and effectively treating hypertensive patients.
Further research must be conducted to explain the significantly higher prevalence of HTN that women have compared with men in Nicaragua. It is important to determine the causes of low BP control in the hypertensive population and especially in those who have treatment. Periodic estimates of HTN prevalence, awareness, treatment, and control must be conducted to evaluate progress.

| CONCLUSIONS
The prevalence of HTN in San Rafael del Norte is high, encompassing more than a quarter of the adult population, and constitutes a major public health problem. The high prevalence of HTN increases the risk for cardiovascular complications, especially in older adults and women. Awareness is a key determinant for treatment and control, and efforts should be made to increase awareness among the population, especially in men and younger adults. However, despite having awareness and treatment, adequate control is still lacking in a significant fraction of both sexes. Future research should be conducted to evaluate the progress in reducing HTN prevalence and increasing awareness and control. Also, further research should aim to clarify the disparity of HTN prevalence between men and women in Nicaragua.
All authors have read and approved the final version of the manuscript.
Marion Jose Valladares and Noel Rodriguez had full access to all of the data in this study and take complete responsibility for the integrity of the data and the accuracy of the data analysis.

TRANSPARENCY STATEMENT
Marion Jose Valladares affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.