TABLE 3.
Quality assessment.
| Selection | Comparability | Outcome | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Studies | Representativeness of the exposed cohort a | Selection of the non‐exposed cohort b | Ascertainment of exposure | Outcome of interest was not present at start of study c | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome | Follow‐up duration | Adequacy of follow up of cohorts | Total |
| Kim JM 39 | – | – | ★ | ★ | ★ | – | ★ | ★ | 5 |
| Grogan 35 | – | – | ★ | ★ | – | ★ | ★ | ★ | 5 |
| Kim KJ 31 | – | – | ★ | ★ | ★★ | ★ | ★ | – | 6 |
| Kim HJ 51 | – | – | ★ | ★ | ★ | – | – | ★ | 4 |
| Qu 43 | – | – | ★ | ★ | ★ | ★ | ★ | ★ | 6 |
| Tam 46 | – | – | ★ | ★ | ★ | ★ | – | ★ | 5 |
| Wang W 47 | – | – | ★ | ★ | ★ | – | – | ★ | 4 |
| Kim SK 40 | – | – | ★ | ★ | ★ | ★ | ★ | – | 5 |
| Wang F 22 | – | – | ★ | ★ | ★★ | ★ | ★ | – | 6 |
| Hwangbo 36 | – | – | ★ | ★ | – | ★ | ★ | ★ | 5 |
| Kim Y 41 | – | – | ★ | ★ | – | ★ | ★ | ★ | 5 |
| Khan 38 | – | – | ★ | ★ | ★ | – | ★ | – | 4 |
| Xu 48 | – | – | ★ | ★ | ★ | ★ | – | ★ | 5 |
| Gui 18 | – | – | ★ | ★ | – | ★ | ★ | ★ | 5 |
| Li 34 | – | – | ★ | ★ | ★★ | ★ | – | ★ | 6 |
| Ryu 45 | – | – | ★ | ★ | ★ | ★ | ★ | ★ | 6 |
| Nam 42 | – | – | ★ | ★ | ★ | – | ★ | ★ | 5 |
| Geron 14 | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Feng 33 | – | – | ★ | ★ | ★★ | ★ | – | ★ | 6 |
| Choi 32 | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Shin 32 | – | – | ★ | ★ | ★ | ★ | ★ | ★ | 6 |
| Jiang 37 | – | – | ★ | ★ | ★ | ★ | ★ | ★ | 6 |
| Woo 49 | – | – | ★ | ★ | ★★ | – | ★ | ★ | 6 |
a
Patients were collected from certain medical institutions (subjects from Kim KJ and Gui were only consisted of PTMC).
b
Multifocal and unifocal cases were extracted from a single medical center (except for Wang F, Hwangbo and Geron et al.).
c
Outcome events include recurrence and death.