Table 2 Methodological assessment of the studies through Newcastle Ottawa scale

Al-Refaie et al. 1992 [17]

*

*

**

*

5

Arboretti et al. 2001 [18]

*

*

*

*

**

*

7

Kidson-Gerber et al. 2006 [19]

*

*

*

*

**

*

7

Lee et al. 2011 [20]

*

*

**

*

**

*

8

Haghpanah et al. 2013 [21]

*

*

*

**

*

6

Haghpanah et al. 2014 [22]

*

*

*

**

*

6

Sobota et al. 2014 [23]

*

*

*

**

**

*

8

Bazi et al. 2017 [24]

*

*

*

*

**

*

7

Sobhani et al. 2019 [25]

*

*

*

**

**

*

8

Yassouf et al. 2019 [26]

*

*

**

*

5

Sukhmani et al. 2019 [27]

*

*

**

*

6

Theppornpitak et al. 2021 [28]

*

**

**

*

6

Badur et al. 2021 [32]

*

**

**

*

6

Mahmoud et al. 2021 [29]

*

*

**

**

*

7

Chai et al. 2021 [30]

*

*

*

**

**

**

*

10

Lam et al. 2021 [31]

*

*

**

**

*

7

Cohort Studies

Study

Representative of exposed cohort

Selection of non-exposed cohort

Ascertainment of exposure

Demonstration of outcome at start

Comparability

Assessment of outcome

Follow up for outcome

Follow up of cohorts

Score

Wolfe et al. 1985 [33]

*

*

*

*

**

*

*

*

9

Richardson et al. 1993 [37]

*

*

*

*

*

*

*

7

Mokhtar et al. 2013 [35]

*

*

*

*

*

*

6

Randomized Controlled Trial

Case definition

Representativeness of the cases

Selection of controls

Control definition

Comparability

Ascertainment of exposure

Same method ?

Non-response rate

Score

Elalfy et al. 2014 [36]

*

*

*

**

*

*

*

8