Flow diagram outlining the selection process for the inclusion of studies in the systematic review and meta-analysis.
The electronic database searches identified 14,069 citations. After evaluating these citations and their bibliographies, 11 cross-sectional and 3 cohort studies met the inclusion criteria for quantitative analysis for this systemic review. From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISAM Group (2009). Preferred Reporting ltems for Systematic Reviews and Meta-Analyses: The PRISAM Statement. PloS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097. For more information, visit www.prisma-statement.org.