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Table 4 A summary of results for tocolytic treatment versus no treatment for extremely preterm birth outcomes in non-RCTs

From: Tocolysis for inhibiting preterm birth in extremely preterm birth, multiple gestations and in growth-restricted fetuses: a systematic review and meta-analysis

Tocolysis compared to no treatment for women with extremely preterm birth (non-RCTs)
Patient or population: Women with extremely preterm birth
Intervention: Tocolysis
Comparison: no treatment
Outcomes Anticipated absolute effects h(95 % CI) Relative effect (95 % CI) № of participants (studies) Quality of the evidence (GRADE)
Risk with no treatment Risk with tocolysis
Prolongation of pregnancy >7 days Study population RR 2.13 (1.12 to 4.06) 148 (1 non-RCT) VERY LOW a,b
16 per 100 33 per 100 (18 to 63)
Prolongation of pregnancy >24 week Study population RR 0.91 (0.76 to 1.09) 101 (1 non-RCT) VERY LOW c
86 per 100 78 per 100 (65 to 94)
Prolongation of pregnancy >28 weeks Study population RR 0.91 (0.69 to 1.20) 222 (1 non-RCT) VERY LOW d
55 per 100 50 per 100 (38 to 66)
Prolongation of pregnancy >32 weeks Study population RR 0.94 (0.76 to 1.17) 323 (2 non-RCTs) VERY LOW e
51 per 100 48 per 100 (39 to 60)
Prolongation of pregnancy >35 weeks Study population RR 0.96 (0.75 to 1.23) 323 (2 non-RCTs) VERY LOW e
43 per 100 41 per 100 (32 to 52)
Neonatal survival Study population RR 1.12 (0.92 to 1.37) 222 (1 non-RCT) VERY LOW d
62 per 100 69 per 100 (57 to 85)
Perinatal death Study population RR 0.73 (0.55 to 0.95) 370 (2 non-RCT) VERY LOW b,f
43 per 100 31 per 100 (24 to 41)
GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect
aThe information was from a study with high risk of confounding variables and unclear risk of outcome data reporting
bA wide confidence interval without confounding variable adjusted
cThe information was from a study with high risk of selective reporting
dThe information was from a study with unclear risk of incomplete outcome data
eThe information was from two studies with unclear risk of incomplete outcome data in one study and high risk of selective reporting in another study
fThis information was from two studies with unclear risk of incomplete outcome data and on study with high risk of cofounding variables and unclear selective reporting
gThis information was from a study with unclear risk of selection of participants, measurement of exposure, incomplete data and selective reporting
  1. CI Confidence interval; RR Risk ratio; OR Odds ratio
  2. hThe risk in the intervention group (and its 95 % confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95 % CI)