Table 2 Quality assessment of the included studies according to Cochrane collaboration’s tool for assessing risk of bias
| Included studies |
Randomized methods | Blind methods | Allocation concealment | Incomplete outcome data |
Selective reporting |
Other biases |
|---|---|---|---|---|---|---|
| POLLUX | Low risk | Unclear | Unclear | Low risk | Unclear | Unclear |
| CASTOR | Low risk | Unclear | Unclear | Low risk | Unclear | Unclear |
| NCT02252172 | Low risk | Unclear | Unclear | Low risk | Unclear | Unclear |
| ALCYONE | Low risk | High risk | Unclear | Low risk | Unclear | Unclear |
| ICARIA - MM | Low risk | High risk | Unclear | Low risk | Unclear | Unclear |
| CASSIOPEIA | Low risk | High risk | Unclear | Low risk | Unclear | Unclear |
| KEYNOTE-183 | Low risk | High risk | Unclear | High risk | Unclear | Unclear |
| KEYNOTE-185 | Low risk | High risk | Unclear | High risk | Unclear | Unclear |
| NCT01478048 | Low risk | High risk | Unclear | Low risk | Unclear | Unclear |
| ELOQUENT-3 | Low risk | Unclear | Unclear | Low risk | Unclear | Unclear |
| ELOQUENT-2 | Low risk | Unclear | Unclear | Low risk | Unclear | Unclear |