Context-dependence of race self-classification: Results from a highly mixed and unequal middle-income country.

Ethnic-racial classification criteria are widely recognized to vary according to historical, cultural and political contexts. In Brazil, the strong influence of individual socio-economic factors on race/colour self-classification is well known. With the expansion of genomic technologies, the use of genomic ancestry has been suggested as a substitute for classification procedures such as self-declaring race, as if they represented the same concept. We investigated the association between genomic ancestry, the racial composition of census tracts and individual socioeconomic factors and self-declared race/colour in a cohort of 15,105 Brazilians. Results show that the probability of self-declaring as black or brown increases according to the proportion of African ancestry and varies widely among cities. In Porto Alegre, where most of the population is white, with every 10% increase in the proportion of African ancestry, the odds of self-declaring as black increased 14 times (95%CI 6.08-32.81). In Salvador, where most of the population is black or brown, that increase was of 3.98 times (95%CI 2.96-5.35). The racial composition of the area of residence was also associated with the probability of self-declaring as black or brown. Every 10% increase in the proportion of black and brown inhabitants in the residential census tract increased the odds of self-declaring as black by 1.33 times (95%CI 1.24-1.42). Ancestry alone does not explain self-declared race/colour. An emphasis on multiple situational contexts (both individual and collective) provides a more comprehensive framework for the study of the predictors of self-declared race/colour, a highly relevant construct in many different scenarios, such as public policy, sociology and medicine.

Intragenerational Social Mobility and Changes in Blood Pressure: Longitudinal Analysis From the ELSA-Brasil Study.

BACKGROUND: During the past 4 decades, the highest worldwide blood pressure (BP) levels have shifted from high-income countries to low- and middle-income countries. We investigated the association of intragenerational social mobility with changes in BP and also with the incidence of hypertension over a 4-year follow-up. METHODS: Data for 6,529 baseline participants from ELSA-Brasil born between 1938 and 1975 were used. Based on a social mobility matrix, occupational social mobility was defined as the change in occupational social class between participants' first occupation and current occupation (stable high; upward; downward; stable low). Incident hypertension was defined as systolic blood pressure (SBP) ≥ 140 mm Hg or diastolic blood pressure (DBP) ≥ 90 mm Hg or use of antihypertensive medication. Hypertensive participants at baseline were excluded. Mixed effects regression models were used. RESULTS: Compared to the stable high group, the downwardly mobile group showed a higher increase over time in both SBP (ß = 1.49, 95% CI 0.60; 2.37) and DBP (ß = 0.96, 95% CI 0.32; 1.59) after adjustments for background characteristics and also proximal risk factors such as health-related behaviors and body mass index as time-dependent covariates, and diabetes. In contrast, upward mobility had no influence on BP changes (ß = 0.67, 95% CI -0.07; 1.41 for SBP, and ß = 0.47, 95% CI -0.05; 1.00 for DBP). Social mobility was not associated with the incidence of hypertension. CONCLUSIONS: We showed socioeconomic inequalities in BP progression over the life course. The longitudinal changes in BP varied by social mobility groups in the context of low- and middle-income countries, where high BP has become most prevalent.

Metabolic syndrome determinants in an urban population from Brazil: social class and gender-specific interaction.

INTRODUCTION: The metabolic syndrome (MS) is characterized by multiple cardiovascular risk factors such as central obesity, arterial hypertension, dyslipidemia and hyperinsulinemia and is associated with a higher incidence of cardiovascular events and mortality. The aim of the present work is to describe the prevalence of MS in an urban population from a highly admixed developing country and to characterize the different correlations between this diagnosis, cardiovascular risk factors and demographic variables distributed in this population. MATERIALS AND METHODS: A cross-sectional study of risk factors for cardiovascular diseases was performed in the urban population of Vitoria, Brazil (n=1507). Major cardiovascular risk factors such as smoking habits, alcohol intake, amount of physical activity, diabetes and hypertension were inquired. Blood biochemical assays were performed by standard techniques in 12 h fasting blood sample and Metabolic Syndrome (MS) was characterizes following the ATP III criteria. RESULTS: The analysis of 1507 individuals showed a 25.43% general prevalence of MS without any significant difference between sexes, but a clear relation of the prevalence with progressing age (p=<0.0001). Even though both sexes showed similar prevalence rates, distribution of risk factors that defined MS was different between men and women, with the prevalence of hypertension, fasting hyperglycemia and hypertriglyceridemia being higher in men. Race was not an important risk factor for MS in this population as opposed to social economic class that was highly associated with the risk of MS in women as their social class was lower, but not in men. CONCLUSION: This cross-sectional study from a large urban population in Brazil showed a high general prevalence of MS (25.4%), which is increased as the population becomes older (especially in women) and poorer. Although prevalence was very similar in both genders, the frequency of components defining the syndrome varied greatly amongst them. In particular, a significant interaction between gender and social class was observed and may shed light in our understanding of the complex interplay between demographic and biological risk factors for metabolic syndrome.