Risk of bias
Risk of bias within studies
The risk of bias within the five randomized controlled trials was
evaluated (Supplementary File 7 ) by the bias risk assessment
tool provided in the Cochrane Evaluation Manual, and 30 items were
defined as low risk, 11 items were unclear, and only eight items were
defined as high risk, while the risk of bias within the nine single-arm
studies could not be evaluated. All the studies were open-label trials
because of the inevitable occurrences of treatment-related adverse
events.
Publication bias
Publication bias of OS, ORR, DCR, clinical characteristics subgroups
analyses of OS with HPV positive or HPV negative, any grade and grade ≥3
AE calculated by Egger’s test in Stata 16 software were 0.384, 0.679,
0.248, 0.849, 0.965, 0.704, 0.667, respectively. Publication bias of any
grade AEs of PD-1/PD-L1 inhibitors, any grade AEs of PD-1 inhibitors,
grade ≥3 AEs of PD-1/PD-L1 inhibitors, grade ≥3 AEs of PD-1 inhibitors
were calculated by Egger’s Test, as shown in Supplementary File
8 .
The quality of evidence
The quality of evidence from 27 outcomes across studies was evaluated as
high, 21outcomes’ were moderate by GRADE system (20), which were shown
in Supplementary File 9 .