Non-communicable diseases (NCD) are emerging as a major concern for health in developing countries [1]. In 2000, two thirds of all deaths in Latin America and the Caribbean were due to NCDs, with cardiovascular disease (CVD) alone accounting for 31% of deaths [2]. In Peru, CVD was the second most common cause of death in those aged 65 years or more (mortality rate 4 per 1000 population) in 2000. Ischaemic heart disease, heart failure and hypertension are also among the ten most common causes of death reported in this age group [3]. The increasing importance of cardiovascular disease in Latin American has been commented on [2, 4, 5] and the need for preventative action to be taken to limit, or prevent, a predicted epidemic of cardiovascular disease has been highlighted [6].

Hypertension is a major modifiable risk factor for CVD, and if treated can significantly reduce the risk of CVD. Despite this, many countries, including Europe, America and South Africa, have reported a high proportion of adults with hypertension remain unaware of their condition and fail to be treated [7–11]. Studies investigating hypertension in Peru are scant, with estimates of the prevalence of hypertension range from 16% to 31% in men, and 15% to 23% in women depending on the population studied [12–15]. In some regions of Peru it has been found that approximately 50% of adults with hypertension are unaware of their condition and in many their condition is poorly controlled [12, 14]. In this study, we report the prevalence of hypertension in adults in a deprived urban area of Lima, Peru, and provide information on the diagnosis and treatment of hypertension among this population.

In 2001, newborn children were enrolled in a cohort study established for diarrhoeal disease surveillance in San Juan de Miraflores, a deprived urban area of Lima, Peru. This cohort followed similar methodologies to previous diarrhoeal studies carried out by our research group in the same area before [16, 17]. Enrolled children acted as the index children from which adult family members were invited to participate in a cross-sectional study on hypertension, the results of which are presented in this paper. In 2006, 497 index children were revisited and adult (aged >17 years) family members living in the same house as each child were invited to participate in the hypertension study. Informed consent was obtained. No information was recorded on adults who declined to participate. Participating adults were asked if they had ever had a medical diagnosis of hypertension, and if they were prescribed anti-hypertensive medications. Age, height and weight were recorded at interview and the body mass index (BMI) calculated (kilogram per metre²). BMI was classified as not overweight (BMI<25), overweight (25 ≤ BMI <30) or obese (BMI ≥ 30). Household bedroom ratio (number of household residents per bedroom) and number of years of education were obtained from the diarrhoeal cohort dataset. Blood pressure (BP) was measured using appropriate cuffs for arm circumference and measurements recorded in triplicate. The BP mean of the last two systolic and diastolic measurements were used in the analysis. Hypertension was defined as systolic blood pressure (SBP) ≥ 140 mmHg or diastolic blood pressure (DBP) ≥ 90 mmHg [18, 19], or self report of receiving antihypertensive medication at the time of interview. Prevalence is the proportion of adults with hypertension and presented as a percentage. Direct standardisation was used to calculate age-standardized prevalence of hypertension by applying age group-specific prevalence (five yearly age groups: 20–24, 25–29 up to 70+ years) to the World Health Organization standard population [20]. Differences between those with hypertension and without were compared using logistic regression and odds ratios (OR) and their 95% confidence intervals (CI) are presented. Multiple adults were recruited within a single family unit, and so all analyses were adjusted for the clustering at family unit level. Awareness was defined as the proportion of hypertensive adults reporting a prior medical diagnosis of hypertension or high BP. Controlled hypertension was defined as SBP < 140 mm Hg and DBP < 90 mmHg. Ethical approval was granted by the Universidad Peruana Cayetano Heredia ethics committee.

A total of 584 adults agreed to participate, representing 67.8% of the families visited (337/497). Only one adult was recruited from 166 family units, and multiple adults were recruited from the remaining 331 families (average number of adults per family unit 1.3 (range 2 to 10)). The majority of the participants (61.0%) were parents of the children recruited in the cohort.

The mean SBP was 119.3 mmHg (SE 1.0) in men and 109.5 mmHg (SE 0.7) in women. The mean DBP was 74.9 mmHg (SE 0.8) in men and 68.2 mmHg (SE 0.6) in women (Table 1). A positive correlation between BP and age was found, with a single year increase in age equating to a 0.5 mmHg (95% CI 0.4, 0.6, p < 0.001) increase in SBP and a 0.2 mmHg (95% CI 0.1, 0.3, p < 0.001) increase in DBP. Forty-seven adults had evidence of hypertension, equating to a crude prevalence of 8.0% (95% CI 5.8%, 10.3%) in the study population. Hypertension was more prevalent in men compared with women, and increased with increasing age group (Table 1). Age standardized prevalence of hypertension was 13.2% (95% CI 5.0%, 21.5%), and greater in men (19.5% (95% CI 9.9%, 29.1%)) than women (11.4% (95% CI 3.7%, 19.1%)). Among those with untreated hypertension the predominant type of hypertension was isolated diastolic hypertension (42.5%, 17/40) compared to isolated systolic hypertension (27.5%, 11/40) and systodiastolic hypertension (30.0%, 12/40).

Only one third (38.3% (95% CI 22.7%, 53.9%)) of all hypertensive adults were aware of their condition (Figure 1). There was evidence to suggest a greater proportion of women (55.6% (95% CI 34.9%, 76.2%), n = 15/27) were aware of their hypertension, compared to men (15.0% (95% CI -2.1%, 32.1%), n = 3/20) (F statistic = 8.5, p value = 0.006). A trend of increasing awareness with decreasing household bedroom ratio, an indicator of socio-economic status, was found (F statistic = 2.8, p = 0.042). There was no evidence to suggest a difference in awareness with age (F statistic = 0.9, p = 0.419), and no evidence of greater awareness in the obese compared to the non-obese (F statistic = 3.1, p = 0.084). Among adults aware of their hypertension 61.1% (95% CI 36.3%, 85.9%, n = 11/18) reported receiving anti-hypertensive medication, equating to 23.4% (95% CI 10.1%, 36.7%, n = 11/47) of all adults with hypertension (Figure 1). Although the numbers are small there was some evidence of a sex difference in the treatment of hypertension, with only 53.3% (95% CI 26.4%, 80.2%, n = 8/15) of the women aware of their hypertension receiving treatment, compared to all of the men (100%, n = 3/3). Among treated, 63.6% (95% CI 27.3%, 100.0%, n = 7/11) had controlled hypertension, equating to only 14.9% (95% CI 3.0%, 26.8%, n = 7/47) of all adults with hypertension.

In our study, we report the age standardised prevalence of hypertension among young adults in a deprived urban area of Lima was 13.2% (95% CI 5.0%, 21.5%). Overall, 38% (95% CI 22.7%, 53.9%) of all adults with hypertension were aware of their diagnosis, 23% (95% CI 10.1%, 36.7%) were receiving treatment, and control was achieved in only 15% (95% CI 3.0%, 26.8%) of hypertensive adults.

Hypertension is a major modifiable risk factor and if left uncontrolled it can result in major cardiovascular problems in later life.Although this study is small and has a number of limitations it does raise some important questions about the provision of care and treatment for patients with hypertension in a deprived urban area of Peru. The results, along with that from other published studies indicate a large burden of undiagnosed hypertension in the population of Peru, and poor levels of control. This set within the context a country with underlying difficulties in the provision of health care represents a great challenge for public health in Peru.