Stefan Elbers

36 Chapter 2 Records identified through database searching (n = 31933) Additional records identified through other sources (n=129) Records after duplicates removed (n = 17988) Records screened (n = 17988) Full-text articles assessed for eligibility (n = 380) Studies included in qualitative synthesis (n = 65) Studies included in quantitative synthesis (meta-analysis) (n = 57) Records excluded (n = 17608) Full-text articles excluded, with reasons (n = 315) Figure 1. Flow Chart of Study Records.