Blood pressure and body mass index in an ethnically diverse sample of adolescents in Paramaribo, Suriname

The increasing prevalence of cardiovascular diseases (CVD) is putting a tremendous pressure on already overburdened resources in non-industrialised countries. [1] High blood pressure (BP) is a leading cause of CVD. [2] The rising prevalence of hypertension in non-industrialised countries reflects well on the high prevalence of CVD. [2]

In children, BP tracking patterns confirm that persistent BP increase may be related to hypertension in adulthood. [3–5] Increased BP in childhood has also been linked with left ventricular hypertrophy. [6] Consequently, in most industrialised countries assessment and management of BP in childhood is strongly recommended to promote improved cardiovascular health in adulthood. [7] However, in some non-industrialised countries, BP data on children and adolescents are very scarce. In Suriname, for example, there is no published data on BP in children and adolescents. Information on BP in adults in Suriname is also very limited. A report from II PAHO-DOTA Workshop on Quality of Diabetes Care in 2003 indicates that hypertension is a major public health burden with prevalence rates ranging from 24% in Javanese to as high as 33% in African-Surinamese in Suriname. [8] The annual report of the Regional Health Service in 2000 also showed that hypertension care alone accounted for 15% of the total number of consultations. [8] This reflected the mortality data with CVD being the leading cause of death in Suriname.

Suriname's population is made up of several ethnic groups. As in industrialised countries, [9–12] the limited data in Suriname suggest ethnic inequalities in BP and hypertension in adults. [8] However, it is unclear whether these BP patterns in adults reflect on adolescents. In some industrialised countries such as the UK, ethnic differences in BP in adults [9–12] do not correspond with children's and adolescents' BP patterns. [13, 14] In addition, the prevalence of overweight and obesity in children and adolescent have increased dramatically over the past few decades. This may have an impact on BP. In the United States of America, for example, overweight children have been shown to be 2–4 times more likely than non-overweight children to have high BP. [15–17] However, information on the relationship between body sizes and BP among different ethnic groups in non industrialised countries is limited. There is an urgent need for research in children and adolescents so that appropriate cost-effective interventions can be introduced early in life to prevent the burden of CVD in adulthood. [18, 19] The main objective of this study was to assess BP patterns, and to determine the association of BP with BMI among adolescents from different ethnic backgrounds in Paramaribo, Suriname. We hypothesised that the BP patterns in adults would reflect adolescents' BP patterns in various ethnic groups in Suriname.

As far as we know, this is the first study on BP patterns amongst adolescents in Suriname, and one of the few studies in adolescents comparing different ethnic groups in a non-industrialised country. Maroon boys had a lower BP than all ethnic groups including Creoles with similar West African descent. The lower BP in Maroon boys as compared to other ethnic groups was accounted for by their lower BMI. This might reflect differences in environmental factors such as lifestyle between Maroons and other ethnic groups. Maroon adolescents moved from the Suriname interior to Paramaribo to continue their education. Most Maroon people in Suriname interior still live traditional African lifestyles with female subsistence horticulture and male hunting and fishing. [22] Most Maroon villages are located along the rivers of the interior of Suriname and access is heavily dependent on canoes and other watercraft. [22] This population is therefore isolated and is less exposed to unhealthy urban lifestyles such as excessive consumption of energy-dense foods and frequent use of automobiles [23, 24] in urban Paramaribo. It is possible they were still benefiting from their earlier exposure to the traditional lifestyles, which have been suggested to be protective against high BP. [25] Maroon girls, however, had relatively high prevalence of overweight and obesity compared with other ethnic groups. The lower BP in Maroon girls became apparent only after further adjustment for BMI. It is possible that they have adopted different lifestyles such as excessive energy intake and decreasing physical activity once in unban Paramaribo, which may contribute to their rapid increase in BMI and subsequently higher BP. In this study, only 4% of Maroon girls reported ≥ 5–7 days/week physical activity outside of school. These findings clearly indicate the need to promote physical activity among this group in Suriname.

Studies in adults have consistently shown higher BP levels in African descent people than in other ethnic groups. [5, 9–11] Studies in Suriname and the Netherlands, for example, showed higher BP levels in African-Surinamese than in other ethnic groups. [8, 9] In this present study, however, African descent adolescents in Suriname (both Creoles and Maroons) had lower mean diastolic BP levels than other ethnic groups. The lack of higher BP levels in African descent adolescents in Suriname is consistent with the findings in the UK. Studies in the UK show higher BP levels in African descent adults than in other ethnic groups. [10, 26] By contrast, in adolescents, BP levels were either lower or similar in African descent youth than in other ethnic groups. [13, 14] A recent study, for example, found that BP in ethnic minority adolescents was generally lower than in White adolescents except for diastolic BP among Indian girls in the UK. [13]

The explanations for the different patterns of BP in adolescents and adulthood among African descent populations are unclear and require a cohort study to unravel the possible mechanisms underlying these differences. These observations suggest that environmental factors may be very important. The higher BP among Javanese adolescents was unexpected given the lower BP reported among the Javanese adult population in Suriname. The reason for the higher mean BP among Javanese adolescents is unclear. One possible explanation may relate to generational differences or changes in lifestyles. This requires further study. Left unchecked, the comparatively high BP among Javanese adolescents may abolish or reverse the current lower BP advantage enjoyed by the Javanese adult population in Suriname. These observations clearly indicate the need for early intervention in adolescents for preventing high BP in later life. [13]

The relationship between BMI and BP is well established in children and adolescents. [15–17] The strong and independent relationship between BMI and BP in our present study is consistent with previous findings. Although the mechanisms by which BMI may lead to high BP are not well understood, it is now generally recognised that high BMI significantly increases the risk of high BP. [27] Sinaiko and colleagues' prospective study showed that increases in BMI in early life were significantly related to an increased risk of high BP and other CVD in adulthood. [27] Our findings clearly indicate the need to prevent the increasing prevalence of overweight and obesity especially in Maroon girls early in life to prevent future sequelae of overweight/obesity related diseases.

Our study has limitations. As in many epidemiological studies, our BP level was based on an average of two measurements at a single visit. A more precise estimate of BP level would be obtained by multiple measurements obtained during several visits. Also, evidence suggests that during puberty BP increases more rapidly, with a significant gender difference in the age of onset. [28] In the present study, pubertal status was not assessed and this may affect the study conclusions. Nevertheless, in the recent UK study, late puberty was not associated with high BP in ethnic minority groups. [13] Another possible limitation is the combined mixed-ethnicities due to the small study samples. It is possible that BP patterns differ among these different ethnic groups. [29] Future studies should assess this possibility. In addition, social circumstances between the groups were not assessed, which might also affect our study conclusions. Despite these limitations, our present findings provide very important insights into ethnic differences in BP in adolescents in non-industrialised setting.

The study findings indicate a higher mean BP among Hindustani boys and Javanese boys and girls whereas in the adult population these groups have lower mean BP levels in Suriname. BMI was positively related to BP in all the ethnic groups. These observations underscore the urgent need for public health measures early in life to prevent high BP and its sequelae in later life. BP reductions in adolescents can be achieved by weight loss through reducing excessive energy intake [30] and increasing physical activity strategies. [31] These cost-effective measures may lead to an important reduction in BP in adolescents thereby sparing the next generation from hypertension related complications [32].