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https://repositorio.ufba.br/handle/ri/12789
metadata.dc.type: | Artigo de Periódico |
Title: | Random-Effects Models in Investigating the Effect of Vitamin A in Childhood Diarrhea |
Other Titles: | Annals of Epidemiology |
Authors: | Andreozzi, Valeska Lima Bailey, Trevor Nobre, Flavio Fonseca Struchiner, Claudio Jose Barreto, Mauricio Lima Assis, Ana Marlucia de Oliveira Santos, Leonor Maria Pacheco |
metadata.dc.creator: | Andreozzi, Valeska Lima Bailey, Trevor Nobre, Flavio Fonseca Struchiner, Claudio Jose Barreto, Mauricio Lima Assis, Ana Marlucia de Oliveira Santos, Leonor Maria Pacheco |
Abstract: | Purpose: By adopting more appropriate and powerful statistical methods that fully exploit longitudinal structure, we reanalyze and extend previously published results from a large community trial to investigate the effect of vitamin A supplementation on the prevalence and severity of diarrhea in young children. Methods: Generalized linear mixed models were used to allow for repeated measures in a reanalysis of a double-blind, randomized, placebo-controlled community trial conducted in a cohort of children in northeastern Brazil during 1 year. The response variable was weekly number of days with diarrhea for each child, and Markov Chain Monte Carlo methods were used to estimate model parameters. Results and conclusions: Random effects suitably accounted for the underlying heterogeneity between and within children, and our longitudinal analysis shows a significant beneficial effect of vitamin A supplementation that was inconclusive in previously reported simple summary analyses of these data. Risk for diarrhea infection was estimated to be 1.57 times greater for a child administered a placebo as opposed to vitamin A (95% credible interval, 1.17–2.12). Additionally, we identified previously unreported temporal effects in these data, showing a decreasing daily probability of diarrhea for both groups during the trial and treatment–time interaction. |
Keywords: | Diarrhea Vitamin A Longitudinal Randomized Trial Random Effects Models |
URI: | http://www.repositorio.ufba.br/ri/handle/ri/12789 |
Issue Date: | 2006 |
Appears in Collections: | Artigo Publicado em Periódico (Escola de Nutrição) |
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