Table II.
Risk of bias summary of included trials.
| Study, Country (reference) | Allocation sequence generation | Allocation concealment | Blinding of patients | Blinding of physicians | Incomplete outcome data addressed: Clinical pregnancy | Selective reporting | Unequal co-intervention |
|---|---|---|---|---|---|---|---|
| Andersen, Denmark (Andersen et al., 2010) | Low risk | [Low risk] | Low risk | Low risk | Low risk | Low risk | Low risk |
| Arnoldi, Italy (Arnoldi et al., 2010) | Low risk | [High risk]a | High risk | [High risk] | [Low risk]b | Low risk | Low risk |
| Craig, USA (Craig et al., 2007) | [Low risk] | [Low risk] | High risk | Low risk | [Low risk] | Low risk | High risk |
| Dieterle, Germany (Dieterle et al., 2006) | [Low risk] | [Low risk] | Low risk | Low risk | Low risk | Low risk | Low risk |
| Domar, USA (Domar et al., 2009) | Low risk | [Low risk] | High risk | [Low risk] | [Low risk]c | Low risk | Low risk |
| Feliciani, Italy (Feliciani et al., 2011) | [Low risk] | [High risk] | High risk | [High risk] | [Low risk] | Low risk | Low risk |
| Fratterelli, USA (Fratterelli et al., 2008) | Low risk | Low risk | High risk | High risk | Low risk | Low risk | Low risk |
| Madaschi, Brazil (Madaschi et al., 2010) | [Unclear]d | [High risk]e | High risk | [Low risk] | [Low risk]f | Low risk | Low risk |
| Moy, USA (Moy et al., 2011) | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Omodei, Italy (Omodei et al., 2010) | [Low risk] | [Low risk] | High risk | [High risk] | [Low risk] | Low risk | Low risk |
| Paulus, Germany (Paulus et al., 2002) | Low risk | [Low risk] | High risk | Low risk | [Low risk] | Low risk | Low risk |
| Paulus, Germany (Paulus et al., 2003) | [Low risk] | [Low risk] | Low risk | [Low risk] | [Low risk] | Low risk | Low risk |
| Smith, Australia (Smith et al., 2006) | [Low risk] | [Low risk] | Low risk | [High risk] | [Low risk] | Low risk | Low risk |
| So, Hong Kong/China (So et al., 2009) | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| So, Hong Kong/China (So et al., 2010) | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Westergaard, Denmark (Westergaard et al., 2006) | [Low risk] | [Low risk]g | High risk | High risk | [Low risk] | Low risk | Low risk |
Additional data obtained from RCT authors are enclosed in brackets to allow such data to be differentiated from data included only in the publications.
aAlthough sealed envelopes were used, the envelopes were not sequentially numbered and the trial's investigators could not recall whether or not the envelopes were opaque.
bAlthough there was a large imbalance in the number of women who did not proceed to an embryo transfer (i.e. 6/102 in acupuncture group and 20/102 in control group), which the trial authors postulated to be due to the acupuncture increasing the likelihood of a viable embryo being available for transfer, the outcomes for the randomized participants without embryo transfer were known (i.e. not pregnant), so we did not consider this as a bias due to incomplete outcome data.
cThe treatment assignment and the outcomes for 4/150 randomized participants were not recorded by the trial authors. Therefore, the 146 participants analysed were instead used in the authors' analysis (Domar et al., 2009), and for this meta-analysis. However, we scored this criterion as ‘low risk’ for incomplete outcome data because the reasons for missing outcome data were unlikely to be related to the outcomes and the proportion of missing outcomes was not likely to have a clinically relevant impact on the effect estimates (Higgins and Altman, 2011).
dA computer-generated randomization list was used to assign patients to treatment groups. However, this trial was judged as unclear for ‘allocation sequence generation’ because it was not clear how the trial authors assigned to treatment groups 39 new participants who replaced the 39 participants excluded because of no embryo transfer.
eThis trial used an open randomization list, so the investigators enrolling participants could possibly foresee assignments and thus introduce selection bias.
fIn this trial, the randomization occurred prior to the start of the ovarian stimulation, although the participants were not informed of their treatment assignment until the start of the ovarian stimulation. Approximately 15% of participants were randomized, but then decided not to get IVF, primarily because of its costs and withdrew prior to the start of the ovarian stimulation. Because these participants withdrew from the study before they were told whether they had been randomized to acupuncture or control, their decision to withdraw from the trial could not have been affected by knowledge of the randomized intervention (i.e. acupuncture or control), and these withdrawals would not be expected to cause an important bias due to missing outcome data (Higgins and Altman, 2011).
gFor this trial, the randomization treatment assignments were placed in sealed, opaque envelopes, which were shuffled and deposited in a cardboard box, from which each participant selected only one. This procedure has handled by an independent nurse not responsible for obtaining information about patients and enrolling them. Although the envelopes were not sequentially numbered, we considered the safeguards used in the randomization process to have provided adequate assurance of allocation concealment.