Fetal programming and metabolic abnormalities: design of a case-control study. / Programação fetal e alterações metabólicas em escolares: metodologia de um estudo caso-controle.

ABSTRACT

OBJECTIVE: To describe the methodological features of a study on the association between restricted intrauterine growth and prevalence of overweight, obesity and hypertension in school aged children. METHODS: The study was conducted in two stages in two public schools in Niterói (RJ), from June through December 2010. All students aged 6 to 14 years were eligible to participate. The first stage consisted of an interview to collect information on demographic variables, diet and other variables. A sample was selected for the second stage, in order to conduct an equivalent of a case-cohort study. There was an interval of about 15 days between the two stages. Cases were overweight students, defined as a Z-score for BMI/age/sex > +1.00 in the first stage. Controls were selected by using a random schedule in which the sample frame was the whole cohort. Bioelectrical impedance analysis, carotid ultrasound to measure intimal-medial thickness, blood measurements and interviews were obtained. Gestational age and weight at birth were used to define proxy variables of restricted intrauterine growth. Early health information was obtained from medical registers. RESULTS: The study participation was 76.4% (n = 795) out of 1,040 eligible to participate). 85.1% of parent's questionnaires were returned. 62.5% of the eligible children participated in the case-control study (case control ratio = 11.8). Early life health information was obtained from 292 children. CONCLUSION: The present study has the potential to provide important information about multiple outcomes and exposures related to restricted intrauterine growth and metabolic abnormalities.