Quality assessment
The Newcastle-Ottawa Scale (NOS) was used to assess the quality of
studies25; studies were scored according to three
variables regarding the study population representativeness,
comparability, and ascertainment of exposure/outcome. As NOS was for
cohort and case-control studies, an adapted version of NOS was created
for cross-sectional studies. All studies were graded according to the
original (maximum score, 9) and adapted versiona (maximum score, 10) of
NOS. A detailed NOS assessment of all included studies is presented in
Supplementary Table 3. We defined the NOS score of ≥7 points as good
quality and <7 points as fair or poor quality.