Pascal Bovet

Body mass index, abdominal adiposity and blood pressure: consistency of their association across developing and developed countries

BACKGROUND: Obesity is increasing worldwide because developing countries are adopting Western high-fat foods and sedentary lifestyles. In parallel, in many of them, hypertension is rising more rapidly, particularly with age, than in Western countries.OBJECTIVE: To assess the relationship between adiposity and blood pressure (BP) in a developing country with high average BP (The Seychelles, Indian Ocean, population mainly of African origin) in comparison to a developed country with low average BP (Switzerland, population mainly of Caucasian origin).DESIGN: Cross-sectional health examination surveys based on population random samples.SETTING: The main Seychelles island (Mahé) and two Swiss regions (Vaud-Fribourg and Ticino).SUBJECTS: Three thousand one hundred and sixteen adults (age range 35–64) untreated for hypertension.MEASUREMENTS: Body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), systolic and diastolic blood pressure (SBP and DBP, mean of two measures).METHODS: Scatterplot smoothing techniques and gender-specific linear regression models.RESULTS: On average, SBP and DBP were found to increase linearly over the whole variation range of BMI, WHR and WC. A modest, but statistically significant linear association was found between each indicator of adiposity and BP levels in separate regression models controlling for age. The regression coefficients were not significantly different between the Seychelles and the two Swiss regions, but were generally higher in women than in men. For the latter, a gain of 1.7 kg/m2 in BMI, of 4.5 cm in WC or of 3.4% in WHR corresponded to an elevation of 1 mmHg in SBP. For women, corresponding figures were 1.25 kg/m2, 2.5 cm and 1.8% respectively. Regression coefficients for age reflected a higher effect of this variable on both SBP and DBP in the Seychelles than in Switzerland.CONCLUSION: These findings suggest a stable linear relation of adiposity with BP, independent of age and body fat distribution, across developed and developing countries. The more rapid increase of BP with age observed in the latter countries are likely to reflect higher genetic susceptibility and/or higher cumulative exposure to another risk factor than adiposity.

Prevalence of hyperuricemia and relation of serum uric acid with cardiovascular risk factors in a developing country

BackgroundThe prevalence of hyperuricemia has rarely been investigated in developing countries. The purpose of the present study was to investigate the prevalence of hyperuricemia and the association between uric acid levels and the various cardiovascular risk factors in a developing country with high average blood pressures (the Seychelles, Indian Ocean, population mainly of African origin).MethodsThis cross-sectional health examination survey was based on a population random sample from the Seychelles. It included 1011 subjects aged 25 to 64 years. Blood pressure (BP), body mass index (BMI), waist circumference, waist-to-hip ratio, total and HDL cholesterol, serum triglycerides and serum uric acid were measured. Data were analyzed using scatterplot smoothing techniques and gender-specific linear regression models.ResultsThe prevalence of a serum uric acid level >420 μmol/L in men was 35.2% and the prevalence of a serum uric acid level >360 μmol/L was 8.7% in women. Serum uric acid was strongly related to serum triglycerides in men as well as in women (r = 0.73 in men and r = 0.59 in women, p < 0.001). Uric acid levels were also significantly associated but to a lesser degree with age, BMI, blood pressure, alcohol and the use of antihypertensive therapy. In a regression model, triglycerides, age, BMI, antihypertensive therapy and alcohol consumption accounted for about 50% (R2) of the serum uric acid variations in men as well as in women.ConclusionsThis study shows that the prevalence of hyperuricemia can be high in a developing country such as the Seychelles. Besides alcohol consumption and the use of antihypertensive therapy, mainly diuretics, serum uric acid is markedly associated with parameters of the metabolic syndrome, in particular serum triglycerides. Considering the growing incidence of obesity and metabolic syndrome worldwide and the potential link between hyperuricemia and cardiovascular complications, more emphasis should be put on the evolving prevalence of hyperuricemia in developing countries.

A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3–19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8–144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries. DOI: http://dx.doi.org/10.7554/eLife.13410.001

Plasma Aldosterone Is Independently Associated With the Metabolic Syndrome

The aim of this study was to analyze the associations of plasma aldosterone and plasma renin activity with the metabolic syndrome and each of its components. We analyzed data from a family based study in the Seychelles made up of 356 participants (160 men and 196 women) from 69 families of African descent. In multivariable models, plasma aldosterone was associated positively (P<0.05) with blood pressure in older individuals (interaction with age, P<0.05) and with waist circumference in men (interaction with sex, P<0.05) and negatively with high-density lipoprotein cholesterol, in particular in individuals with elevated urinary potassium excretion (interaction with urinary potassium, P<0.05); plasma renin activity was significantly associated with triglycerides and fasting blood glucose. Plasma aldosterone, but not plasma renin activity, was associated with the metabolic syndrome per se, independently of the association with its separate components. The observation that plasma renin activity was associated with some components of the metabolic syndrome, whereas plasma aldosterone was associated with other components of the metabolic syndrome, suggests different underlying mechanisms. These findings reinforce previous observations suggesting that aldosterone is associated with several cardiovascular risk factors and also suggest that aldosterone might contribute to the increased cardiovascular disease risk in individuals of African descent with the metabolic syndrome.

Has Blood Pressure Increased in Children in Response to the Obesity Epidemic

The associations between elevated blood pressure and overweight, on one hand, and the increasing prevalence over time of pediatric overweight, on the other hand, suggest that the prevalence of elevated blood pressure could have increased in children over the last few decades. In this article we review the epidemiologic evidence available on the prevalence of elevated blood pressure in children and trends over time. On the basis of the few large population-based surveys available, the prevalence of elevated blood pressure is fairly high in several populations, whereas there is little direct evidence that blood pressure has increased during the past few decades despite the concomitant epidemic of pediatric overweight. However, a definite conclusion cannot be drawn yet because of the paucity of epidemiologic studies that have assessed blood pressure trends in the same populations and the lack of standardized methods used for the measurement of blood pressure and the definition of elevated blood pressure in children. Additional studies should examine if favorable secular trends in other determinants of blood pressure (eg, dietary factors, birth weight, etc) may have attenuated the apparently limited impact of the epidemic of overweight on blood pressure in children.

The PsyCoLaus study: methodology and characteristics of the sample of a population-based survey on psychiatric disorders and their association with genetic and cardiovascular risk factors

BackgroundThe Psychiatric arm of the population-based CoLaus study (PsyCoLaus) is designed to: 1) establish the prevalence of threshold and subthreshold psychiatric syndromes in the 35 to 66 year-old population of the city of Lausanne (Switzerland); 2) test the validity of postulated definitions for subthreshold mood and anxiety syndromes; 3) determine the associations between psychiatric disorders, personality traits and cardiovascular diseases (CVD), 4) identify genetic variants that can modify the risk for psychiatric disorders and determine whether genetic risk factors are shared between psychiatric disorders and CVD. This paper presents the method as well as sociodemographic and somatic characteristics of the sample.MethodsAll 35 to 66 year-old persons previously selected for the population-based CoLaus survey on risk factors for CVD were asked to participate in a substudy assessing psychiatric conditions. This investigation included the Diagnostic Interview for Genetic Studies to elicit diagnostic criteria for threshold disorders according to DSM-IV and algorithmically defined subthreshold syndromes. Complementary information was collected on potential risk and protective factors for psychiatric disorders, migraine and on the morbidity of first-degree relatives, whereas the collection of DNA and plasma samples was already part of the original CoLaus survey.ResultsA total of 3,691 individuals completed the psychiatric evaluation (67% participation). The gender distribution of the sample did not differ significantly from that of the general population in the same age range. Although the youngest 5-year band of the cohort was underrepresented and the oldest 5-year band overrepresented, participants of PsyCoLaus and individuals who refused to participate revealed comparable scores on the General Health Questionnaire, a self-rating instrument completed at the somatic exam.ConclusionDespite limitations resulting from the relatively low participation in the context of a comprehensive and time-consuming investigation, the PsyCoLaus study should significantly contribute to the current understanding of psychiatric disorders and comorbid somatic conditions by: 1) establishing the clinical relevance of specific psychiatric syndromes below the DSM-IV threshold; 2) determining comorbidity between risk factors for CVD and psychiatric disorders; 3) assessing genetic variants associated with common psychiatric disorders and 4) identifying DNA markers shared between CVD and psychiatric disorders.

Country actions to meet UN commitments on non-communicable diseases: a stepwise approach

Strong leadership from heads of state is needed to meet national commitments to the UN political declaration on non-communicable diseases (NCDs) and to achieve the goal of a 25% reduction in premature NCD mortality by 2025 (the 25 by 25 goal). A simple, phased, national response to the political declaration is suggested, with three key steps: planning, implementation, and accountability. Planning entails mobilisation of a multisectoral response to develop and support the national action plan, and to build human, financial, and regulatory capacity for change. Implementation of a few priority and feasible cost-effective interventions for the prevention and treatment of NCDs will achieve the 25 by 25 goal and will need only few additional financial resources. Accountability incorporates three dimensions: monitoring of progress, reviewing of progress, and appropriate responses to accelerate progress. A national NCD commission or equivalent, which is independent of government, is needed to ensure that all relevant stakeholders are held accountable for the UN commitments to NCDs.

Nighttime Blood Pressure and Nocturnal Dipping Are Associated With Daytime Urinary Sodium Excretion in African Subjects

Blood pressure (BP) follows a circadian rhythm, with 10% to 15% lower values during nighttime than during daytime. The absence of a nocturnal BP decrease (dipping) is associated with target organ damage, but the determinants of dipping are poorly understood. We assessed whether the nighttime BP and the dipping are associated with the circadian pattern of sodium excretion. Ambulatory BP and daytime and nighttime urinary electrolyte excretion were measured simultaneously in 325 individuals of African descent from 73 families. When divided into sex-specific tertiles of day:night ratios of urinary sodium excretion rate, subjects in tertile 1 (with the lowest ratio) were 6.5 years older and had a 9.8-mm Hg higher nighttime systolic BP (SBP) and a 23% lower SBP dipping (expressed in percentage of day value) compared with subjects in tertile 3 (P for trend <0.01). After adjustment for age, the SBP difference across tertiles decreased to 5.4 mm Hg (P=0.002), and the SBP dipping difference decreased to 17% (P=0.05). A similar trend across tertiles was found with diastolic BP. In multivariate analyses, daytime urinary sodium and potassium concentrations were independently associated with nighttime SBP and SBP dipping (P<0.05 for each). These data, based on a large number of subjects, suggest that the capacity to excrete sodium during daytime is a significant determinant of nocturnal BP and dipping. This observation may help us to understand the pathophysiology and clinical consequences of nighttime BP and to develop therapeutic strategies to normalize the dipping profile in hypertensive patients.

Prevalence of elevated blood pressure and association with overweight in children of a rapidly developing country

We assessed the prevalence of elevated blood pressure (BP) and the association with excess body weight among a large sample of children in the Seychelles, a middle-income rapidly developing country in the African region. Weight, height and BP were measured in all children of four school grades in the Seychelles (Indian Ocean). Excess weight categories (‘overweight’ and ‘obesity’) were defined according to the criteria of the International Obesity Task Force. Two BP readings were obtained on one occasion. ‘Elevated BP’ was defined based on US reference tables. Data were available in 15 612 (86%) of 18 119 eligible children aged 5–16 years in 2002–2004. In all, 13.0% of Boys and 18.8% of girls were overweight or obese. The prevalence of elevated BP was 9.1% in boys and 10.1% in girls. Both systolic and diastolic BP were strongly associated with body mass index (BMI) in boys and in girls. In children with ‘normal weight’, ‘overweight (and not obesity)’ and ‘obesity’, respectively, proportions with elevated BP were 7.5, 16.9 and 25.2% in boys, and 7.5, 16.1 and 33.2% in girls. Overweight (including obesity) could account for 18% of cases of elevated BP in boys and 26% in girls. Further studies should examine the impact of the relationship between BMI and elevated BP on the burden of hypertension in the context of the epidemic of paediatric obesity.

Prevalence and risk factors for overweight and obesity in children from Seychelles, a country in rapid transition: the importance of early growth

OBJECTIVES: To establish the prevalence of overweight and obesity and related risk factors in children from Seychelles (Indian Ocean), a country in rapid economic and epidemiological transition.DESIGN: Cross-sectional study with retrospective access to early life data.SUBJECTS: All children from all schools of Seychelles, in four selected school grades (kindergarten, fourth, seventh and tenth year of obligatory school) in 1999. A total of 5514 children aged 4.5–17.4 y were measured, corresponding to 83.5% of the eligible population.MEASUREMENTS: Overweight and obesity, using age- and sex-specific body mass index (BMI) cut-off points as defined by the International Obesity Task Force.RESULTS: Some 12.6% (95% confidence interval: 11.8–13.5%) of the children were overweight and 3.8% (3.3–4.4%) were obese. Weight gain (kg) during the first year of life was strongly associated with subsequent overweight (odds ratio 1.46, 95% confidence interval 1.27–1.67) and obesity (1.59, 1.29–1.97) in childhood, independently of birth weight. Increased maternal BMI (kg/m2) was also associated with overweight (1.07, 1.03–1.10) and obesity (1.09, 1.04–1.14) in the offspring.CONCLUSION: Prevalence of overweight and obesity among school children in Seychelles was as high as or higher than in some industrialized countries. If confirmed in other environments, the strong association between weight gain during the first year of life and subsequent obesity in childhood could affect the way optimal infant weight gain is defined in countries where public health priorities are changing.