Overall analysis
On pairwise comparison, the combined treatment of pessary and vaginal
progesterone did not reduce the risk of sPTB<34 weeks when
compared to no intervention (OR 0.68; 95%CI 0.16-2.91). Also, pessary
alone (OR 0.78; 95%CI 0.49-1.25), vaginal progesterone alone (OR 0.79;
CI95% 0.45-1.41) and injectable 17-OH progesterone alone (OR 0.85;
CI95% 0.26-2.75) did not showed reduction in PTB. None of the pairwise
comparisons reached statistical significance. (Table 2 & Figure 1)
Compared to the control group, pessary + vaginal progesterone ranked
first according to the SUCRA values, with pessary, vaginal progesterone
and 17-OH progesterone ranked second, third, and fourth respectively
(Table S3).
For overall PTB<34 weeks, the combined treatment pessary +
vaginal progesterone did not show a statistically significant reduction
in PTB (OR 0.56; 95%CI 0.17-1.82) compared to the control group.
Pessary alone (OR 0.76; 95%CI 0.55-1.06) and vaginal progesterone alone
(OR 0.88; CI95% 0.63-1.22) also did not show reduction in PTB.
Injectable 17-OH progesterone showed a non-statistically significant
increase on risk of PTB<34 (OR 1.42; CI95% 0.92-2.20). Again,
none of the pairwise comparisons did reach statistical significance.
(Table 2 & Figure 1) Compared to the control group, the rank according
to the SUCRA values was pessary + vaginal progesterone, pessary, vaginal
progesterone and 17-OH progesterone (Table S3).
Table 2. Comparative treatment effect of intervention to prevent preterm
birth in twin gestations compared to control group for spontaneous
PTB<34 weeks and overall PTB<34 weeks
Figure 1 - Treatment effect of intervention compared to control to
prevent preterm birth in twin gestations compared to control group for
spontaneous PTB<34 weeks and overall PTB<34 weeks
Figure 2 - Evidence network diagram of network meta-analysis comparisons
for spontaneous PTB<34 weeks and overall PTB<34. The
width of each edge is proportional to the number of randomized
controlled trials comparing each pair of treatments, and the size of
each treatment node is proportional to the number of randomized
participants
For overall PTB<34 weeks, the p value for overall network
consistency test was 0.489, indicating overall satisfactory consistency.
When performing node splitting test, the p values for each comparison
ranged between 0.489 and 0.998, suggesting minimal local inconsistency.
The network consistency test was not possible for sPTB<34
weeks because there was no closed loop in the network (Figure 2).