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Table 4 Secondary outcomes

From: Double- versus single-balloon catheters for labour induction and cervical ripening: a meta-analysis

Outcomes

Number of studies analysed

Interventions

Effect measure

Pooled effect

(95% CI)

Q p-value

I2- statistic

p-value

Sensitivity analysis

Double

Single

placement difficulty/failure

4 [15–16,18,20]

382

384

RR

1.34 [0.66, 2.71]

0.55

0

0.42

stable

spontaneous expulsion

4 [15,17,19–20]

337

332

RR

0.86 [0.60, 1.23]

0.0002

85%

0.40

stable

insertion to delivery intervalA

6 [15–20]

532

532

MD

0.98 [− 0.03, 2.00]

0.16

36%

0.06

Unstable I

1.36 [−0.63, 3.34]

0.02

61%

0.18

Unstable II

insertion to expulsion/removal intervalB

4 [15,17,19–20]

278

267

MD

1.72 [−0.35, 3.79]

< 0.00001

93%

0.10

Unstable III

expulsion to delivery interval

2 [19,21]

145

150

MD

−2.81 [−10.82, 5.19]

0.06

72%

0.49

–

Bishop score incrementC

5 [15,17,19–21]

382

382

MD

0.57 [0.28, 0.86]

0.30

18%

0.0001

stable

vaginal delivery within 24 h

3 [17–18,20]

305

303

RR

0.95 [0.72, 1.26]

0.11

54%

0.74

Unstable IV

normal vaginal deliveryD

6 [15–20]

532

532

RR

1.02 [0.86, 1.20]

0.03

59%

0.84

Unstable V

assisted vaginal deliveryD

4 [16,18–20]

443

445

RR

1.08 [0.84, 1.41]

0.48

0

0.54

stable

analgesia usage

4 [17–20]

405

403

RR

1.07 [0.99, 1.16]

0.72

0

0.10

stable

maternal adverse events

 maternal infection

5 [17–21]

450

453

RR

1.04 [0.66, 1.66]

0.38

5%

0.85

stable

 postpartum haemorrhage

3 [15,18–19]

246

249

RR

1.03 [0.74, 1.42]

0.73

0

0.88

stable

neonatal adverse events

 low Apgar score (< 7 at 5 min)E

3 [17–18,20]

305

303

RR

0.53 [0.15, 1.88]

0.46

0

0.32

–

 NICU admission

3 [17–18,20]

305

303

RR

0.70 [0.45, 1.07

0.90

0

0.10

stable

length of hospitalisation

2 [19–20]

248

245

MD

0.16 [−0.10, 0.41]

0.28

15%

0.22

–

satisfactionF

 pain during the process

2 [15,19]

139

139

MD

0.07 [−0.53, 0.67]

0.42

0

0.82

–

 maternal total satisfaction

2 [15,19]

139

139

MD

−0.10 [−1.25, 1.04]

0.08

68%

0.86

–

  1. A: No studies, except for those of Hoppe 2015 [17] and Salim 2011 [20], specifically defined delivery as being either total delivery or vaginal delivery. Hoppe 2015 [17] offered data on the time from insertion to vaginal delivery, while Salim 2011 [20] reported both measurements. We synthesised these data by involving Hoppe 2015 [17]. The upper and lower data shows the effects when we added the total and vaginal delivery data from Salim 2011 [20]
  2. B: Salim 2011 [20] excluded 124 women (70 in the double-balloon catheter group and 54 in the single-balloon catheter group) with spontaneous expulsion during this process
  3. C: We depended primarily on the Bishop score increment. For those studies that included only a second Bishop score, we included these data and conducted sensitivity analyses
  4. D: Hoppe 2015 [17] reported only vaginal deliveries but did not define whether assisted vaginal deliveries were included; we treated these data as though it did not include assisted vaginal deliveries
  5. E: Salim 2011 [20] reported no events on this outcome for either arm, which was inestimable
  6. F: All measured by VAS
  7. I: When we eliminated Salim 2011 [20], the MD pooled effect changed to 2.16 [0.76, 3.57] (p-value, 0.003), in favour of the single-balloon catheter. The results remained comparable after all other sensitivity analyses were performed
  8. II: Excluding Rab 2014 [19], though heterogeneity disappeared, the effect remained comparable (Q p-value, 0.17; I2, 38%; p-value, 0.58). Excluding Salim 2011 [20], the result was shown in superscript note I
  9. III: Significant heterogeneity existed regardless of which study we excluded; however, when we repeated the analysis after excluding Salim 2011 [20], the result changed (MD, 2.40 [0.32, 4.48]; supporting the single-balloon catheter)
  10. IV: Stable effect but became homogeneous only when we excluded Hoppe 2015 [17]
  11. V: Stable effect but became homogeneous only when we excluded Rab 2014 [19] or Salim, 2011 [20]