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.

Impact of gestational diabetes mellitus screening strategies on perinatal outcomes: a simulation study.

AIMS: To evaluate the impact on perinatal outcomes of universal gestational diabetes (GDM) screening based on 1999 WHO and IADPSG diagnostic criteria; to assess the quality of the evidence (GRADE) to support GDM screening. METHODS: Simulation of a hypothetical cohort of community-based pregnant women with 10% GDM prevalence (1999 WHO). Most parameters were obtained from recent systematic reviews. RESULTS: Compared to no screening, screening based on 1999 WHO criteria (followed by treatment) reduced the incidence of large for gestational age (LGA) neonates by 0.53% (95% CI 0.37-0.74%; NNS=189) and of preeclampsia by 0.27% (0.10-0.45%; NNS=376). Screening based on IADPSG criteria reduced incidences by 0.85% (0.54-1.29%; NNS=117) and by 0.39% (0.15-0.65%; NNS=257), respectively. Compared to screening based on 1999 WHO criteria, screening with IADPSG criteria reduced the incidence of LGA by 0.32% (0.09-0.63%; NNS=309) and of preeclampsia by 0.12% (0.01-0.25; NNS=808). The quality of evidence for both screening approaches is very low. CONCLUSIONS: Universal screening for GDM has only a modest impact on pregnancy outcomes. The impact of screening based on IADPSG (vs. WHO, 1999) criteria is slightly larger. However, costs and resources should also be considered in local selection of a screening approach.

Effectiveness of gestational diabetes treatment: a systematic review with quality of evidence assessment.

AIMS: To evaluate the effectiveness of gestational diabetes (GDM) treatment compared to usual antenatal care, in the prevention of adverse pregnancy outcomes. Additionally, to assess the quality of the evidence to support GDM treatment according to GRADE guidelines. METHODS: Fourteen electronic databases and reference lists of relevant literature were searched for articles published from inception to February, 2012. Controlled clinical trials comparing GDM treatment to usual antenatal care were included. Independent extraction of articles was done by two authors using predefined data fields. RESULTS: Seven trials involving 3157 women were included. We found high quality evidence that treatment of GDM reduces macrosomia (RR=0.47; 95% CI, 0.34-0.65; NNT=11.4) and large for gestational age birth (RR=0.57; 95% CI, 0.47-0.71; NNT=12.2); moderate quality evidence that treatment reduces preeclampsia (RR=0.61; 95% CI, 0.46-0.81; NNT=21.0) and hypertensive disorders in pregnancy (RR=0.64; 95% CI, 0.51-0.81; NNT=18.1); and low quality evidence that treatment reduces shoulder dystocia (RR=0.41; 95% CI, 0.22-0.76; NNT=48.8). No statistically significant reduction was seen for caesarean section. No increase in small for gestational age or preterm birth was found. CONCLUSIONS: Treatment of GDM is effective in reducing macrosomia (high quality evidence), preeclampsia and shoulder dystocia.