Table 3 Quality assessment of included studies according to the Newcastle-Ottawa Scale
Item/Study | Adequate definition of cases | Representativeness of cases | Selection of control subjects | Definition of control subjects | Control for important factor or additional factor | Exposure assessment | Same method of ascertainment for all subjects | Non-response rate | Total score |
|---|---|---|---|---|---|---|---|---|---|
Bowes [19] 2011 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Das [30] 2015 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Haase [20] 2014 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Han [31] 2016 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Indhumathi [21] 2015 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Li [22] 2014 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 6 |
Munir [26] 2015 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Nair [27] 2009 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Nikamo [28] 2015 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 6 |
Villarreal-MartÃnez [29] 2016 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Yang [23] 2011 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Zhang, Z [24] 2015 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
Zhang, C [25] 2015 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 6 |