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. 2022 May 19;2022(5):CD002118. doi: 10.1002/14651858.CD002118.pub6

Risk of bias for analysis 2.5 Cumulative pregnancy rate from fresh and frozen transfers: grouped by vitrification or slow freezing.

Study Bias
Randomisation process Deviations from intended interventions Missing outcome data Measurement of the outcome Selection of the reported results Overall
Authors' judgement Support for judgement Authors' judgement Support for judgement Authors' judgement Support for judgement Authors' judgement Support for judgement Authors' judgement Support for judgement Authors' judgement Support for judgement
Subgroup 2.5.1 slow freezing
Brugnon 2010 Some concerns Sequence generated but there was no information about concealment. No table of patients' baseline characteristics reported High risk of bias No effort for blindness is described. Considering the nature of the intervention, it is very unlikely that participants and carers and people delivering the intervention were not aware of their assigned intervention. No information about the deviations or the analysis High risk of bias No information. Only proportions were reported Low risk of bias Method of measuring the outcome was probably appropriate, was not different between groups and it is an objective outcome that is unlikely to be influenced by the knowledge of the assigned intervention. Some concerns No protocol registration was found. High risk of bias High risk due to deviation from the intended interventions
Emiliani 2003 Some concerns Concealment was not stated. Only minor differences in age Low risk of bias No effort for blindness is described. Considering the nature of the intervention, it is very unlikely that participants and carers and people delivering the intervention were not aware of their assigned intervention. Low risk of bias All women randomised were analysed Low risk of bias Not reported but inappropriate methotds are unlikely. It is an objective outcome that is unlikely to be influenced by the knowledge of the assigned intervention Some concerns No protocol registration was found. Some concerns There some concerns of risk of bias due to the randomisation process and selection of reported results.
Rienzi 2002 Some concerns No information about the allocation sequence concealed but no baseline differences between groups. High risk of bias Participants, carers and people delivering the intervention were probably aware of their assigned intervention. No information about a deviation from the intended protocols and no information about the total number of randomised women. High risk of bias No information about neither the total number of randomized women nor the missing outcome data. Low risk of bias Method of measuring the outcome was appropriate, it was not different between groups and it is an objective outcome that is unlikely to be influenced by the knowledge of the assigned intervention. Some concerns No protocol registration was found. High risk of bias There is high risk of bias due to deviations from the intended interventions, and there are some concerns of risk of bias due to randomisation process, missing outcomes and selection of reported results.
Van der Auwera 2002 Low risk of bias No information available to know if the allocation sequence was random. However, allocation sequence was concealed and no baseline differences between groups. Some concerns Participants, carers and people delivering the intervention were probably aware of their assigned intervention. There were only few with deviation from the intended protocols, and no imbalance was found. All randomised women were analysed. Low risk of bias Quote: “Three patients were excluded for analysis from group 1 because they wanted an elective blastocyst culture while four patients were excluded from group 2 because they wanted an elective day 2 transfer.” Low risk of bias Method of measuring the outcome was not described. However, it is unlikely that it was not different between groups and it is an objective outcome that is unlikely to be influenced by the knowledge of the assigned intervention. Some concerns No protocol registration was found. Some concerns There are some concerns of risk of bias due to deviations from the intended interventions and selection of reported results.
Subgroup 2.5.2 vitrification
Fernandez‐Shaw 2015 Some concerns No statement about allocation concealment. Low risk of bias No effort for blindness is described. Considering the nature of the intervention, it is very unlikely that participants and carers and people delivering the intervention were not aware of their assigned intervention. Low risk of bias All women randomised were analysed Low risk of bias Method of measuring the outcome was probably appropriate, in both groups and it is an objective outcome that is unlikely to be influenced by the knowledge of the assigned intervention. Some concerns No protocol registration was found. Some concerns There some concerns of risk of bias due to the randomisation process and selection of reported results.