Figure 1
The flowchart shows a step by step process with a series of rectangular boxes and downward facing arrows. The top rectangle is labeled Original Literature Search with n equals 1872. The next arrow is labeled Double Papers and points to a box with n equals 391. An arrow pointing down from this box is labeled Records Screened By Title and Abstract and points to a box with n equals 272. An arrow from this box is labeled Full text Articles Assessed For Eligibility and points to a box with n equals 212. The final arrow is labeled Documents Included In Review and points to the last box labeled with n equals 53.The search process and inclusion of papers in this review.