The Centre for Data and Knowledge Integration for Health (CIDACS): Linking Health and Social Data in Brazil.

The Centre for Data and Knowledge Integration for Health (CIDACS) was created in 2016 in Salvador, Bahia-Brazil with the objective of integrating data and knowledge aiming to answer scientific questions related to the health of the Brazilian population. This article details our experiences in the establishment and operations of CIDACS, as well as efforts made to obtain high-quality linked data while adhering to security, ethical use and privacy issues. Every effort has been made to conduct operations while implementing appropriate structures, procedures, processes and controls over the original and integrated databases in order to provide adequate datasets to answer relevant research questions. Looking forward, CIDACS is expected to be an important resource for researchers and policymakers interested in enhancing the evidence base pertaining to different aspects of health, in particular when investigating, from a nation-wide perspective, the role of social determinants of health and the effects of social and environmental policies on different health outcomes.

Frailty modelling for clustered recurrent incidence of diarrhoea.

Recurrent incidence of infant diarrhoea is studied, using daily data collected in Salvador, Brazil, from 754 children over 455 days. Aalen's additive intensity model is taken as the basis of the modelling strategy and a frailty extension is proposed. The idea is to estimate the frailty dynamically as time proceeds and information accrues. This provides an alternative to the inclusion of dynamic covariates based on individual event patterns. Simulation results indicate good performance of the estimation methods. In our first analysis, there is no account taken in the natural clustering of the children into 21 different districts of the city. The model is therefore extended to incorporate the possibility of spatial or spatio-temporal clustering effects, possibly caused by unobserved environmental factors or infectivity. Significant frailty and significant clustering are both identified in the data.

Early infection with Trichuris trichiura and allergen skin test reactivity in later childhood.

BACKGROUND: Allergic diseases cause a large and increasing burden in developed countries and in urban centres in middle-income countries. The causes of this increase are unknown and, currently, there are no interventions to prevent the development of allergic diseases. The 'hygiene hypothesis' has tried to explain the increase through a reduction in the frequency of childhood infections causing a failure to program the immune system for adequate immune regulation. Intestinal helminth parasites are prevalent in childhood in developing countries and are associated with a lower prevalence of allergen skin test reactivity and asthma. OBJECTIVES: To investigate whether children who had intestinal helminth infections during early childhood have a lower prevalence of allergen skin test reactivity later in childhood. METHODS: We re-visited a population of 1055 children from whom stool samples had been collected for detection of intestinal helminth infections for another study, and collected new stool samples and performed allergen skin prick testing. Information on potential confounding variables was collected. RESULTS: Children with heavy infections with Trichuris trichiura in early childhood had a significantly reduced prevalence of allergen skin test reactivity in later childhood, even in the absence of T. trichiura infection at the time of skin testing in later childhood. CONCLUSION: Early heavy infections with T. trichiura may protect against the development of allergen skin test reactivity in later childhood. Novel treatments to program immune-regulation in early childhood in a way that mimics the effects of early infections with T. trichiura may offer new strategies for the prevention of allergic disease.

Growth faltering in childhood related to diarrhea: a longitudinal community based study.

OBJECTIVE: This study aimed to evaluate the association of diarrhea and acute lower respiratory tract infections (ALRI) with growth of preschool children. DESIGN: A longitudinal community-based study over a 12-month period. Children were followed up with thrice-weekly household visits for collection of morbidity data. Every 4 months (round) clinical and anthropometric examinations were performed. At baseline a questionnaire was used to collect socioeconomic family data and environmental household variables. Generalized estimating equation was used in the statistical analysis. The variations in weight-for-age or height-for-age Z-scores in each round were the dependent variables, while the main independent variables were the number of days with diarrhea and ALRI. SETTING: Serrinha, located in Northeast Brazil. SUBJECTS: In total, 487 children, aged 6-48 months at baseline, with 1-y complete follow-up. RESULTS: The number of sick days with diarrhea or ALRI was not associated with mean changes in weight-for-age Z-scores. However, the mean of height-for-age Z-scores was found to decrease in those children with 7 or more days of diarrhea (beta=-0.0472; P=0.016) but not with 1 or more days of ALRI (beta=0.0022; P=0.406) in all rounds of the follow-up period. CONCLUSION: Results of the study reinforce the concept of diarrhea burden as a major determinant of poor growth in children under 5 y of age. Actions targeted to decrease the risk factors for the occurrence of diarrhea may represent an important component of interventions aimed to ensure satisfactory child growth.

Effect of vitamin A supplementation on diarrhoea and acute lower-respiratory-tract infections in young children in Brazil.

A beneficial effect of periodic vitamin A supplementation on childhood mortality has been demonstrated, but the effect on morbidity is less clear. We investigated the effect of vitamin A supplementation on diarrhoea and acute lower-respiratory-tract infections (ALRI) in children from northeastern Brazil in a randomised, double-blind, placebo-controlled community trial. 1240 children aged 6-48 months were assigned vitamin A or placebo every 4 months for 1 year. They were followed up at home three times a week, and data about the occurrence and severity of diarrhoea and ALRI were collected. Any child with cough and respiratory rate above 40 breaths per min was visited by a paediatrician. The overall incidence of diarrhoea episodes was significantly lower in the vitamin-A-supplemented group than in the placebo group (18.42 vs 19.58 x 10(-3) child-days; rate ratio 0.94 [95% Cl 0.90-0.98]). The benefit of supplementation was greater as regards severe episodes of diarrhoea; the incidence was 20% lower in the vitamin A group than in the placebo group (rate ratio 0.80 [0.65-0.98]). With the standard definition of diarrhoea (> or = 3 liquid or semi-liquid stools in 24 h) the effect of vitamin A on mean daily prevalence did not reach significance, but as the definition of diarrhoea was made more stringent (increasing number of stools per day), a significant benefit became apparent, reaching for diarrhoea with 6 or more liquid or semi-liquid stools in 24 h a 23% lower prevalence. We found no effect of vitamin A supplementation on the incidence of ALRI. The reduction in severity of diarrhoea may be the most important factor in the lowering of mortality by vitamin A supplementation.