Evaluation of cluster randomized controlled trials in sub-Saharan Africa

Cluster randomized controlled trials (CRCTs) are attractive in settings in which individual randomization is difficult or impossible. This issue is common when studying several health problems in developing countries. The authors aimed to assess empirically the extent to which the prerequisite design and analysis aspects of cluster randomization were taken into account and reported properly in CRCTs conducted in sub-Saharan Africa. CRCTs published in the last three decades were evaluated by using a checklist based on the Consolidated Standards of Reporting Trials (CONSORT) statement. The authors identified 51 eligible CRCTs; 40 of them (78%) had been published after 1990. Only 10 (20%) studies took clustering into account in sample size or power calculations, and only 19 (37%) took clustering into account in the analysis. Intracluster correlation coefficients and design effects were reported in only one (2%) and three (6%) trials, respectively. An increasing number of CRCTs are conducted in sub-Saharan Africa, but many are not analyzed and reported properly. The special features stemming from cluster randomization need to be addressed in the design, analysis, and reporting of these studies.