| Domain |
Description |
| Random sequence generation |
Low risk: if sequence generation was achieved using computer random number generator or a random numbers table. Drawing lots, tossing a coin, shuffling cards, and throwing dice were also considered adequate if performed by an independent adjudicator. Unclear risk: if the method of randomization was not specified, but the trial was still presented as being randomized. High risk: if the allocation sequence was not randomized or only quasi‐randomized; we excluded these trials. |
| Allocation concealment |
Low risk: if the allocation of participants was performed by a central independent unit, on‐site locked computer, identical‐looking numbered sealed envelopes, syringes prepared by an independent investigator. Unclear risk: if the trial was classified as randomized but the allocation concealment process was not described. High risk: if the allocation sequence was familiar to the investigators who assigned participants. |
| Blinding of participants and personnel |
Low risk: if the participants and the personnel were blinded to intervention allocation and this was described Unclear risk: if the procedure of blinding was insufficiently described or not described at all. High risk: if blinding of participants and personnel was not performed. |
| Blinding of outcome assessment |
Low risk: if it was mentioned that outcome assessors were blinded and this was described. Unclear risk: if it was not mentioned if the outcome assessors in the trial were blinded, or the extent of blinding was insufficiently described. High risk: if no blinding or incomplete blinding of outcome assessors was performed. |
| Incomplete outcome data |
Low risk: if missing data were unlikely to make treatment effects depart from plausible values. This could either be: there were no dropouts or withdrawals for all outcomes, or the numbers and reasons for the withdrawals and dropouts for all outcomes were clearly stated and could be described as being similar in both groups. Generally, the trial was judged at low risk of bias due to incomplete outcome data if dropouts were less than 5%. However, the 5% cut‐off is not definitive. Unclear risk: if there was insufficient information to assess whether missing data were likely to have induced bias on the results. High risk: if the results were likely to be biased due to missing data either because the pattern of dropouts could be described as being different in the 2 intervention groups or the trial used improper methods in dealing with the missing data (e.g. last observation carried forward). |
| Selective outcome reporting |
Low risk: if a protocol was published before or at the time the trial was begun and the outcomes specified in the protocol were reported on. If there was no protocol or the protocol was published after the trial had begun, reporting of all‐cause mortality and periprocedural complications (the 2 primary outcomes) will grant the trial a grade of low risk. Unclear risk: if no protocol was published and the 2 primary outcomes were not reported on. High risk: if the outcomes in the protocol were not reported on. |
| Other risks of bias |
Low risk: if the trial appeared free of other components (e.g. academic bias or for‐profit bias) that could have put it at risk of bias. Unclear risk: if the trial may or may not have been free of other components that could have put it at risk of bias. High risk: if there were other factors in the trial that could have put it at risk of bias (e.g. authors had conducted trials on the same topic, for‐profit bias, etc.). |
