Estimates of intraclass correlation coefficient and design effect for surveys and cluster randomized trials on injection use in Pakistan and developing countries.

BACKGROUND: To assess injection practices and to test interventions aimed at reducing unsafe injections in developing countries, cluster surveys and cluster randomized trials are needed. The design of cluster-based studies requires estimates of intraclass correlation coefficients that have to be obtained from previous studies. This study presents such estimates.
METHODS: Data were derived from a cross-sectional study of injection use and health seeking in Pakistan that used 34 clusters to select 1150 study subjects aged > or =3 months. We analysed variance to separate its components.
RESULTS: Most of intraclass correlation coefficients were in the range of 0.01-0.05. For proportion of injections received during last 3 months, mean number of injections received and health seeking during the past 3 months the intraclass correlation coefficients were 0.02, 0.04 and 0.02, respectively.
CONCLUSION: These estimates can be useful in designing cluster surveys and cluster randomized trials for injection safety in Pakistan and other developing countries.