Strategy of data synthesisA narrative synthesis of the evidence was applied following the steps proposed by Petticrew and Roberts (2008): 1) organize the description of the studies into logical categories, 2) analyze the findings within each of the categories, and 3) synthesize findings across all included studies.We could not perform a metaanalysis.This was due to the heterogeneity of the studies found. Subgroup analysis Not applicable.Sensitivity analysis Not applicable.
