[Secular trends in childhood in the city of São Paulo, Brazil (1984-1996)].

OBJECTIVE: Data from two consecutive households surveys undertaken in mid-80s and mid-90s allow to characterize and analyse secular trends in infant and child anaemia in the city of S. Paulo, Brazil.
METHODS: The two surveys included random population samples aged from zero to 59 months (1,016 in the period of 1984-85 and 1,280 in 1995-96). Capillary blood samples, collected by digital puncture in the two surveys, were analysed regarding their haemoglobin concentration. The anaemic status was determined when haemoglobin concentration was below 11 g/dL. For each survey, the study of the social distribution of child anaemia took into account tertiles of the per capita family income. For the study of the determinants of secular trends, hierarchical causal models, multivariate regression analyses and calculations analogous to the ones used to assess population attributable risks were applied. RESULTS/
CONCLUSIONS: In the time span from the first to the second survey, there was a significant reduction in the average haemoglobin concentration (from 11.6 g/dl to 11.0 g/dl), as well as a considerable increase in anaemia prevalence (from 35.6% to 46.9%). Unfavourable trends were observed in both sexes, all age groups and all income strata. Trends were still less favourable among the poorest families, aggravating the social burden related to child anaemia. Changes in distal (family income and maternal schooling) and proximal determinants (breast or bottle-feeding) of child anaemia were positive in the study period and therefore they cannot explain the increase in the disease. A low iron diet could explain the high prevalence of anaemia in both surveys but could not explain its further increase.