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Trop Med Int Health. 2009 Aug;14(8):947-56. doi: 10.1111/j.1365-3156.2009.02313.x. Epub 2009 Jun 28.

Evaluation of cluster-randomized trials on maternal and child health research in developing countries.

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Department of Biostatistics, University of North Carolina, Chapel Hill, NC, USA.



To summarize and evaluate all publications including cluster-randomized trials used for maternal and child health research in developing countries during the last 10 years.


All cluster-randomized trials published between 1998 and 2008 were reviewed, and those that met our criteria for inclusion were evaluated further. The criteria for inclusion were that the trial should have been conducted in maternal and child health care in a developing country and that the conclusions should have been made on an individual level. Methods of accounting for clustering in design and analysis were evaluated in the eligible trials.


Thirty-five eligible trials were identified. The majority of them were conducted in Asia, used community as randomization unit, and had less than 10,000 participants. To minimize confounding, 23 of the 35 trials had stratified, blocked, or paired the clusters before they were randomized, while 17 had adjusted for confounding in the analysis. Ten of the 35 trials did not account for clustering in sample size calculations, and seven did not account for the cluster-randomized design in the analysis. The number of cluster-randomized trials increased over time, and the trials generally improved in quality.


Shortcomings exist in the sample-size calculations and in the analysis of cluster-randomized trials conducted during maternal and child health research in developing countries. Even though there has been improvement over time, further progress in the way that researchers utilize and analyse cluster-randomized trials in this field is needed.

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