Quality assessment:
The critical appraisal tool developed by Hawker et al. [29] was used
to assess the quality of included papers. The tool includes nine
questions to assess the abstract and title, introduction and aims,
method and data, sampling, data analysis, ethics and bias, results,
transferability or generalisability, and implication and usefulness.
Each question has four options: good, fair, poor or very poor, scored
from 1 (very poor) to 4 (good). This scoring method therefore allows for
a total score to be calculated ranging from 9 to 36 for each paper.
Based on the total score for each paper, four quality categories were
applied to each paper as follows: high quality (score of 30-36), medium
quality (score of 24-29), and low quality (score of 9-24).
Results of the quality assessment were not used as inclusion/exclusion
criteria.