Table 2 Quality assessment of included studies using the Newcastle-Ottawa Scale*

Assessment of the quality of cohort studies

Selection (max 4 scores)

Comparability (max 2 scores)

Outcome (max 3 scores)

Total score**

Author/ Year/ Reference

Representativeness of the exposed cohort

Selection of the non-exposed cohort

Ascertainment of exposure

Demonstration that outcome of interest was not present at start of study

Comparability of cohorts on the basis of the design or analysis

Assessment of outcome

Was follow-up long enough for outcomes to occur

Adequacy of follow up of cohorts

Chu et al. (2021) [28]

*

*

*

*

**

*

*

*

9

El-Zein et al. (2021) [24]

*

*

*

*

**

*

*

*

9

Troja et al. (2021) [29]

*

*

*

*

**

*

*

*

9

Assessment of the quality of cross-sectional studies

Selection (max 5 scores)

Comparability (max 1 score)

Outcome (max 3 scores)

Author/ Year/ Reference

Representativeness of the sample

Sample size

Non-response rate

Ascertainment of the measure

Potential confounders were investigated based on the study design or subgroup analysis

Assessment of the outcome

Statistical test

-

Total score

Shim et al. (2016) [20]

-

*

-

**

*

**

*

-

7

Garcia-Carrasco et al. (2015) [23]

-

*

-

**

*

**

*

-

7

Troja et al. (2020) [30]

-

*

*

*

*

*

*

-

6

Mertoğlu et al. (2017) [31]

-

-

-

*

-

*

-

-

2

Çakir et al. (2022) [32]

-

-

-

*

-

*

-

-

2

Assessment of the quality of case-control studies

Selection (max 4 scores)

Comparability (max 2 scores)

Exposure (max 3 scores)

Author/ Year/ Reference

Adequate case definition

Representativeness of the cases

Selection of controls

Definition of controls

Basis of the design or analysis

Ascertainment of exposure

Same method of ascertainment for cases and controls

Non-Response rate

Total score

Ozgu et al. (2016) [21]

*

*

*

*

**

-

*

*

8