Figure 1
The flowchart illustrates the four phases of study selection, arranged vertically from top to bottom: “Identification”, “Screening”, “Eligibility”, and “Included”. Each section contains boxes that include document-shaped images representing the records. In the “Identification” phase at the top, two boxes are positioned side-by-side. Box “1” on the left is labeled “Records identified through database search (W o S)”. It contains two document-shaped images: “1st Search String” with “N equals 68” and “2nd Search String” with “N equals 50”. Box “2” on the right is labeled “Records identified through database search (Scopus)”. It contains two document-shaped images: “1st Search String” with “N equals 228” and “2nd Search String” with “N equals 43”. In the “Screening” phase below, Box “3” is centered and labeled “Records after removal of duplicates”. It contains two document-shaped images: “1st Search String” with “N equals 244” and “2nd Search String” with “N equals 53”. This flows downward into two side-by-side boxes. Box “4” on the left is “Records screened based on abstract” and contains two document-shaped images with “N equals 163” and “N equals 26”. Box “5” on the right is “Records excluded” and contains two document-shaped images with “N equals 81” and “N equals 27”. In the “Eligibility” phase further down, Box “6” on the left is labeled “Full-text article assessment for eligibility” and contains a document-shaped image for “1st and 2nd Search String Combined” with “N equals 189”. Box “7” on the right is labeled “Full-text article assessment for exclusion” and contains a document-shaped image for “1st and 2nd Search String Combined” with “N equals 107”. In the final “Included” phase at the bottom, Box “8” is centered and labeled “Studies included in the qualitative assessment”. It contains a single document-shaped image with “N equals 82”.PRISMA flow diagram. Source: adapted from Moher et al. (2009)