Hypertension and cardiovascular risk factors are widespread in developing countries1,2, but little is known about cardiovascular risk profiles in rural communities from Ibero-America and the Caribbean. Ibero-America is a term used since the second half of the 19th century to refer collectively to the countries in the Americas that were formerly colonies of Spain or Portugal and in which Ibero-Romance languages are spoken3. Culturally Ibero-America is one of the largest language areas and culturally cohesive world. Ibero-America is composed of the following countries: Argentina, Brazil, Bolivia, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, México, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Portugal, Spain, Uruguay, and Venezuela4.
With an area of approximately 21 462 000 km2, Ibero-America represents about 15% of the global land area. The Ibero-American population accounts for 9.2% of the world population and is estimated at 712 974 000 inhabitants with a population density of 61.09 inhabitants/km2. Currently the life expectancy in Ibero-America is 75.4 years, an increase of more than 10 years in the past 30 years5.
In Latin America and the Caribbean, non-communicable diseases have an even greater impact on mortality and accounted for 73% of deaths and 76% of disability-adjusted life years in 20006. The hypertension prevalence estimates from the peer-reviewed literature range from 7% to 49%. These studies were primarily done in urban centers and are not evenly distributed throughout the region7,8. According to World Health Organization data, smoking rates average 30%; additionally, obesity and overweight vary from 40% to 72% in the region9.
'Rural population' usually refers to people living in rural areas as defined by national statistical offices. It is calculated as the difference between total population and urban population10. There is no single, universally preferred definition of 'rural area'. Rural definitions are used to identify rural population, places or healthcare providers11. Methods for defining 'rural' are based on geographic units that are sometimes combined with population or provider characteristics. But each country has its own definition of a rural area, which is typically based on identifying what does not fit a particular definition of an urban area. As a rough generalization, most countries form Ibero-America will classify as 'urban' any settlement of more than 1500-2000 people12. In Ibero-America and the Caribbean the rural population represents 27.4% of the total population4.
This study aimed to evaluate the peer-reviewed literature published from 1990 to 2012 on the prevalence of hypertension in rural populations from Ibero-America and the Caribbean.
A bibliographic search was conducted using MEDLINE (for international literature in the medical and biomedical areas), SCIELO and LILACS databases (for Latin American and Caribbean health sciences literature), supplemented by a manual search of bibliographies of retrieved articles using the following search terms in English, Spanish, and Portuguese: hypertension, blood pressure, high blood pressure, prevalence, rural population, cross sectional studies, Latin America, South America, Central America, Caribbean, and the names of all the countries from Ibero-America. The search was restricted to studies published from January 1990 to December 2012. Data were extracted following a standard protocol and using standard data collection forms and a checklist by a single reviewer. Variables extracted included year of survey, country of study, mean age of participants, sampling methods, sample size, devices and methods for preparation and measurement of blood pressure, definition(s) used for hypertension, and type of measuring device used.
Eligibility criteria for inclusion were: (1) rural population-based cross-sectional studies in which prevalence of hypertension (or data to calculate it) was reported; (2) studies with representative samples with more than 100 participants; (3) studies that included subjects aged 15 years and above; (3) hypertension condition defined as an average systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg or use of antihypertensive medications1.
Global prevalence of hypertension, percentage of those with hypertension who had been previously diagnosed, were on treatment, and those controlled were also obtained. Available information was obtained on the prevalence of hypertension by gender, high blood pressure in the elderly population, and the proportion with isolated systolic hypertension. Also evaluated (if available) were the prevalence of diabetes, hypercholesterolemia, smoking, overweight, obesity, and abdominal obesity.
Studies were excluded if the participants were limited to special populations (elderly, pre-hypertensives or pediatric populations under 15 years), or if there were multiple reports of the same results. Also excluded were studies using non-JNC7 standards (140/90 mmHg)13 to avoid inconsistency of outcomes resulting from different blood pressure categories.
Crude prevalence of hypertension was calculated by dividing the number of all patients with hypertension in each study by the total of patients studied in each study. The result is expressed as a percentage. A formal meta-analysis was not conducted because of the heterogeneity in methods used and participants included. All continuous data were expressed as mean ± standard deviation. Comparison between groups was done using a χ2 test for discrete variables and student t-test for continuous variables.
The initial bibliographic search found 41 studies published between 1990 and 2012. Finally, 11 studies were excluded (three based on hospital populations, four that included participants less than 15 years in the analysis, two studies reporting a small sample size, and two using different definition of hypertension). A total of 30 peer-reviewed publications14-43 were identified that reported the prevalence of hypertension in 33 143 patients (60.5% were females). Country of origin, number of participants per study, sex, mean age, global prevalence of hypertension, and general characteristics of the sample are shown in Table 1. The number of participants per study ranged from 116 to 6024.
Fifty-six percent of the studies reported the types of device used to measure blood pressure. The mercury sphygmomanometer was used for measurement of blood pressure in nine studies, aneroid sphygmomanometer was used in four studies and an electronic device was used in four studies. The majority of studies (86%) used two blood pressure measurements on a single visit, with the exception of four studies in which blood pressure was measured in two visits.
Table 1: Population-based studies on hypertension prevalence from rural Ibero-America and the Caribbean
Prevalence: The crude prevalence of hypertension reported from rural Ibero-America was 32.6% (95% confidence interval (CI): 31.4-32.5%; range: 1.8-52%).
Only 14 studies reported the mean age of the study population. Mean age was 45.3 ± 5.5 years (range: 36-60 years). Men had higher prevalence of hypertension than women (35.1% (CI: 32.6-37.5%) vs 32% (CI: 30-33.9%); p=0.0001). The estimated total number of people with hypertension in Ibero-America and the Caribbean was 44 816 036.
Hypertension in older people: The prevalence of hypertension in people aged 60 years and older was 64.8% (range: 38-80%). Only fourteen studies (46.6%) reported specifically the prevalence of hypertension in older patients.
Awareness, treatment, and control: One-third of the studies assessed the level of treatment, awareness, and control of hypertension. Among hypertensives only 54% (range: 39.9-69%) were aware of their condition; of these 57% (range: 22-89%) were undergoing drug therapy, and of those being treated, only 14.8% (range: 0.3-32.6%) were optimally controlled (blood pressure <140/90 mmHg).
Systolic isolated hypertension: The prevalence of isolated systolic hypertension was 24.4% (reported only in two studies).
Aboriginal communities: Five of the 30 studies were conducted in rural aboriginal communities (2714 subjects, mean age 43.6 years). Notably, the prevalence of hypertension was lower in aboriginal populations than in other rural communities (19.5% vs 36%; p=0.001).
Other cardiovascular risk factors
Fourteen studies additionally reported the prevalence of obesity (mean: 17.6%; range: 3-31%) and smoking (mean 19.7%, range: 5.5-32.9%). Twelve studies reported the prevalence of dyslipidaemia (mean: 32.7%; range: 10.5-52%).
The crude prevalence of abdominal obesity was 39% (range: 13-54%). The prevalence of overweight was 39% (range: 17-83.7%) and was reported in nine studies.
Ibero-America is a heterogeneous region with wide economic, ethnic, and sociocultural diversity. The growing epidemic of high blood pressure and other chronic non-communicable diseases in association with economic crises represent a real threat to the economies of this region8. This analysis indicates that more than one-third of the Ibero-American rural population had hypertension. This is the first literature review about prevalence, awareness, treatment, and hypertension control in this special population.
Hypertension prevalence estimates from rural Ibero-American countries are variable. Countries with the highest estimated prevalence of hypertension had had rates nearly four times those of regions with the lowest estimated prevalence (43.2% in Brazil vs 11% in Peru). Moreover, there were differences in hypertension prevalence estimates within countries. In Brazil, for example, depending on where the hypertension studies were done, the estimated prevalence ranged from 32.7% to 57.1%19-23.
In men, the highest estimated prevalences were in Brazil19-23 and Argentina14-18 (50.7% and 48%, respectively). In women the highest estimated prevalences were in Brazil19-23, Spain31-34, and Nicaragua39 (48.3%, 42%, and 43.2%, respectively).
Although there are methodological differences between urban and rural studies the prevalence of hypertension in rural populations is similar or lower than the regional prevalence reported in well-designed population-based studies reported in a recent analysis7. The degree of awareness and control of hypertension is very low in rural Ibero-America and the Caribbean, this being a widespread problem shared with those countries considered developed44.
The countries of Latin America and the Caribbean have the highest level of social inequality of any region of the world. Social inequality is reflected in inequalities in access to health care. The poor and those living in rural areas have less access to health care, which means they have less opportunity to receive treatment to control the risk factors of chronic diseases6,45.
The prevalence and incidence of cardiovascular diseases are increasing among aboriginal peoples. These trends parallel the epidemiological transition that is occurring in other developing populations throughout the world. As more aboriginal people give up their traditional lifestyles and adopt 'unhealthy urban' lifestyles, the prevalence of hypertension and its risk factors will likely increase46. While the overall prevalence of hypertension is low in rural aboriginal people (young adults), the prevalence of hypertension in the elderly aboriginal increases to 68%15,16,28. The prevalence of hypertension in rural aboriginal communities in Ibero-America is higher than previously reported in the Brazilian Yanomami and Xingu tribes included in the INTERSALT study47.
In order to plan cardiovascular prevention strategies in rural areas from Ibero-America there is a need for better documentation of prevalence of hypertension and cardiovascular risk factors. In the past 10 years there has been a trend to increased health research in Latin America; however, it only accounts for 4% of publications compared with North America (26%) and Europe (42%)45. Insufficient funding sources, and underdeveloped research networks and infrastructure, are some limitations to conducting research and publish research in this region7,48.
This work has weaknesses that limit the ability to make direct comparisons between studies:
- large variation in the age structure between studies
- large variation in the methods used for the measurement and classification of blood pressure
- variability in reporting level of awareness, treatment, and control of blood pressure
- due to the absence of data, analyzing the prevalence of hypertension adjusted for age was not possible
- no single standard definition of 'rural population', therefore populations considered rural by the authors of each study were included.
It is necessary to conduct well-designed studies with standardized methodologies to allow comparison between different regions within countries and between countries in order to establish health policies appropriate to each country and region.
Despite the relatively limited evidence base, it is clear that hypertension is a major public health problem in rural populations from Ibero-America and the Caribbean. The high prevalence of cardiovascular risk factors associated with a low degree of control of hypertension represents a short-term threat in these special populations. There is a need to identify barriers to treatment and good control of hypertension and how these could be reduced. There is an urgent need to focus the epidemiological research in these rural areas on the burden of non-communicable diseases and identify potential prevention strategies as strategies of intervention.
Special thanks to Miss Cecilia Alonso for reading and editing the manuscript.
1. Perk J, De Backer G, Gohlke H, Graham I, Reiner Z, Verschuren M, et al. European guidelines on cardiovascular disease prevention in clinical practice (version 2012): The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts). European Heart Journal 2012; 33: 1635-1701.
2. American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics - 2012 update: a report from the American Heart Association. Circulation 2012; 125(1): e2-e220.
3. Wikipedia contributors. Ibero-America. (Online). Available: http://en.wikipedia.org/w/index.php?title=Ibero-America&oldid=529214243 (Accessed 25 January 2013).
4. World Bank. World Bank world development indicators (Online) 2012. Available http://data.worldbank.org/sites/default/files/wdi-2012-ebook.pdf (Accessed 25 January 2013).
5. Organización Panamericana de la Salud. Proyecto de información y análisis de salud. [In Spanish] Washington, DC: Iniciativa Regional de Datos Básicos en Salud, 2010.
6. Perel P, Casas JP, Ortiz Z, Miranda JJ. Noncommunicable diseases and injuries in Latin America and the Caribbean: time for action. PLoS Medicine 2006; 3(9): e344.
7. Burroughs Peña MS, Abdala CVM, Silva LC, Ordúñez P. Usefulness for surveillance of hypertension prevalence studies in Latin America and the Caribbean: the past 10 years. Revista Panamericana de Salud Publica 2012; 32(1): 15-21.
8. Rubinstein A, Alcocer L, Chagas A. High blood pressure in Latin America: a call to action. Therapeutic Advances in Cardiovascular Diseases 2009; 3(4): 259-285.
9. Avezum A, Santos I, Guimaraes HP, Marin-Neto JA, Piegas LD. Cardiovascular disease in South America: current status and opportunities for prevention. Heart 2009; 95: 1475-1482.
11. Coburn AF, MacKinney, AC, McBride TD, Mueller KJ, Slifkin RT, Wakefield MK. Choosing rural definitions: implications for health policy. Issue brief #2. Omaha, NE: Rural Policy Research Institute Health Panel, 2007.
12. Economic Commission for Latin American and the Caribbean. Latin America: urban and rural population projections 1970-2025. Demographic Bulletin 76. (Online) 2005. Available: http://www.eclac.cl/cgi/bin/getProd.asp?xml=/publicaciones/xml/8/22688/P22688.xml&xsl=/celade/tpl/p9f.xsl&base=/celade/tpl-i/top-bottom.xslt (Accessed 25 January 2013).
13. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2003; 42 (6): 1206-1252.
14. De Lena SM, Cingolani HE, Almirón MA, Echeverría RF. Prevalence of arterial hypertension in a rural population of Buenos Aires. Medicina (Buenos Aires) 1995; 55(3): 225-230.
15. Coghlan E, Quero LB, Schwab M, Pellegrini D, Trimarchi H. Prevalence of hypertension in an Indian community in the North of Argentina. Medicina (Buenos Aires) 2005; 65(2): 108-112.
16. Bianchi ME, Farías EF, Bolaño J, Massari PU. Epidemiology of renal and cardiovascular risk factors in Toba Aborigines. Renal Failure 2006; 28(8): 665-670.
17. Pedraza A, Camino Willhuber G, Chaile I. Prevalence and associated risk factors of arterial hypertension in Sobremonte and Ojo de Agua Departments in Cordoba State. Revista de la Facultad de Ciencias Médicas de la Universidad Nacional de Córdoba 2008; 65(3): 87-94.
18. De All J, Lafranconi M, Bledel I, Doval H, Hughes A, Laroti A, et al. Prevalencia de la hipertensión arterial en poblaciones rurales del norte argentino. [In Spanish] Hipertensión y Riesgo Vascular 2012; 29(2): 31-35.
19. Costa Matos A, Ladeia AM. Assessment of cardiovascular risk factors in a rural community in the Brazilian state of Bahia. Arquivos Brasileiros de Cardiología 2003; 81: 297-302.
20. Pimenta AM, Kac G, Gazzinelli A, Corrêa-Oliveira R, Velásquez-Meléndez G. Association between central obesity, triglycerides and hypertension in a rural area in Brazil. Arquivos Brasileiros de Cardiología 2008; 90(6): 386-392.
21. Martins IS, de Oliveira DC, Marinho SP, de Araújo EA. Hypertension in impoverished social segments in the state of São Paulo. Ciência & Saúde Coletiva 2008; 13(2): 477-486.
22. Nascente FM, Jardim PC, Peixoto Mdo R, Monego ET, Moreira HG, Vitorino PV, et al. Arterial hypertension and its correlation with some risk factors in a small Brazilian town. Arquivos Brasileiros de Cardiología 2010; 95(4): 502-508.
23. Matozinhos FP, Mendes LL, Oliveira AG, Velásquez-Meléndez G. Factors associated with arterial hypertension in rural populations. REME: Revista Mineira de Enfermagem 2011; 15(3): 333-340.
24. Merle S Pierre-Louis K, Rosine J, Cardoso T, Inamo J, Deloumeaux J. Prévalence de l'hypertension artérielle en population générale à la Martinique. Revue d'Epidémiologie et de Santé Publique 2009; 57(1): 17-23.
25. Atallah A, Kelly-Irving M, Zouini N, Ruidavets JB, Inamo J, Lang T. Controlling arterial hypertension in the French West Indies: a separate strategy for women? European Journal of Public Health 2010; 20(6): 665-670.
26. Fasce E, Pérez H, Boggiano G, Ibáñez P, Nieto C. Hypertension in rural communities. Study in the VIII Region, Chile. Revista Médica de Chile 1993; 121(9): 1058-1067.
27. Pérez F, Carrasco E, Santos JL, Calvillán M, Albala C. Prevalence of obesity, hypertension and dyslipidemia in rural aboriginal groups in Chile. Revista Médica de Chile 1999; 127(10): 1169-1175.
28. Navarrete Briones C, Cartes-Velásquez R. Prevalencia de hipertensión arterial en comunidades pehuenches, Alto Biobio. Revista Chilena de Cardiología 2012; 31: 102-107.
29. Casteñanos Arias JA, Nerin La Rosa R, Cubero Menendez O. Prevalencia de la hipertensión arterial en una comunidad del municipio Cárdenas. Revista Cubana de Medicina General Integral 2000; 16(2): 138-143.
30. Anselmi M, Avanzini F, Moreira JM, Montalvo G, Armani D, Prandi R, et al. Treatment and control of arterial hypertension in a rural community in Ecuador. Lancet 2003; 361(9364): 1186-1187.
31. Subirats i Bayego E, Vila i Ballester L, Vila i Subirana T, Vallescar i Piñana R. The prevalence of cardiovascular risk factors in a rural population from the north of Catalonia (Spain): La Cerdana. Anales de Medicina Interna 1997; 14(5): 220-225.
32. Banegas JR, Rodriguez F, de la Cruz Troca JJ, Guallar-CastilloŽn P, del Rey Calero J. Blood pressure in Spain distribution, awareness, control, and benefits of a reduction in average pressure. Hypertension 1998; 32: 998-1002.
33. Segura Fragoso A, Rius Mery G. Factores de riesgo cardiovascular en una población rural de Castilla - La Mancha. [In Spanish] Revista Española de Cardiología 1999; 52: 577-588.
34. Vega Alonso AT, Lozano Alonso JE, Álamo Sanz R, Lleras Muñoz S. Prevalence of hypertension in the population of Castile-Leon (Spain). Gaceta Sanitaria 2008; 22(4): 330-336.
35. Guerrero-Romero JF, Rodríguez-Morán M. Prevalence of arterial hypertension and related factors in a marginated rural population. Salud Pública de Mexico 1998; 40(4): 339-346.
36. Guerrero-Romero F, Rodríguez-Morán M, Sandoval-Herrrera F, Alvarado-Ruiz R. Prevalence of hypertension in indigenous inhabitants of traditional communities from the north of Mexico. Journal of Human Hypertension 2000; 14(9): 555-559.
37. Ferreyra MMC, Maldonado VJA, Carranza MJ. Detección de factores de riesgo cardiovascular en una población rural del estado de Michoacán. [In Spanish] Medicina Interna de Mexico 2007; 23(3): 200-204.
38. Arroyo P, Fernández V, Loría A, Pardío J, Laviada H, Vargas-Ancona L, et al. Obesidad, morfología corporal y presión arterial en grupos urbanos y rurales de Yucatán. [In Spanish] Salud Pública de Mexico 2007; 49(4): 274-285.
39. Blondin NA, Lewis J. Prevalence, awareness, treatment and control of hypertension in a rural Nicaraguan sample. Journal of Human Hypertension 2007; 21: 815-817.
40. Miranda JJ, Gilman RH, Smeeth L. Differences in cardiovascular risk factors in rural, urban and rural-to-urban migrants in Peru. Heart 2011; 97(10): 787-796.
41. Simões JA, Gama ME, Contente CB. Prevalence of cardiovascular risk factors in a rural population between 25 and 44 years old. Revista Portuguesa de Cardiología 2000; 19(6): 693-703.
42. Macedo A, Santos A, Rocha E, Perdigão C. AMALIA - estudo piloto. [In Spanish] Revista Factores de Risco 2008; 8: 68-74.
43. Nieto-Martínez RE, González JP, García RJ, Ugel E, Osuna D, Salazar L. Prevalencia de hipertensión arterial y dislipidemias en adultos del páramo del Estado Mérida y su relación con obesidad. Resultados preliminares del estudio VEMSOLS. [In Spanish] Avances Cardiológicos 2011; 31(3): 193-200.
44. Pereira M, Lunet N, Azevedo A, Barros H. Differences in prevalence, awareness, treatment and control of hypertension between developing and developed countries. Journal of Hypertension 2009; 27(5): 963-975.
45. Almeida-Filho N, Kawachi I, Filho AP, Dachs JN. Research on health inequalities in Latin America and the Caribbean: bibliometric analysis (1971-2000) and descriptive content analysis (1971-1995). American Journal of Public Health 2003; 93: 2037-2043.
46. Yusuf S, Reddy S, Ounpuu S, Anand S. Global burden of cardiovascular diseases: Part II: variations in cardiovascular disease by specific ethnic groups and geographic regions and prevention strategies. Circulation 2001; 104(23): 2855-2864.
47. Carvalho JJ, Baruzzi RG, Howard PF, Poulter N, Alpers MP, Franco LJ, et al. Blood pressure in four remote populations in the INTERSALT Study. Hypertension 1989; 14: 238-246.
48. Jahanjir E, Comandé D, Rubinstein A. Cardiovascular disease research in Latin America: a comparative bibliometric analysis. World Journal of Cardiology 2011; 3(12): 383-387.