Table 2.
Characterization table for exclusion of confounders in the inclusion of study participants.
| Studies | Smoke | Drink wine | Occupational exposure | Diabetes | Hyperlipoidemia | Ototoxicity drug use |
|---|---|---|---|---|---|---|
| Zhang (27) | No | No | No | No | No | Yes |
| Umesawa (23) | No | No | Yes | No | No | No |
| Hara (21) | No | No | No | No | No | No |
| Ramatsoma (32) | Yes | No | Yes | No | No | Yes |
| Oh (30) | No | No | No | No | No | No |
| Guo (31) | No | No | No | Yes | Yes | Yes |
| Samelli (28) | No | No | No | No | No | No |
| Wang (29) | No | No | No | No | No | No |
| Kuang (22) | No | No | No | No | No | No |
| Zhou (26) | No | No | No | No | No | Yes |
| Moraes (25) | No | No | Yes | Yes | Yes | Yes |
| Aimoni (24) | No | No | No | No | No | Yes |