Risk of bias assessment of the seven included studies
| Study | QUIPS domain 1 | QUIPS domain 2 | QUIPS domain 3 | QUIPS domain 4 | QUIPS domain 5 | QUIPS domain 6 | QUIPS overall score |
| Atlas et al23 | Low | Moderate | Low | Low | Low | Low | Low |
| Atlas et al24 | Low | High | Moderate | Moderate | Low | Moderate | Moderate |
| den Boer et al26 | Low | Low | Low | Low | Low | Low | Low |
| Grøvle et al25 | Low | Low | Low | Low | Low | Low | Low |
| O’Donnell et al27 | Low | Low | Low | Low | Low | Moderate | Low |
| Schade et al22 | Moderate | High | Moderate | Low | Moderate | Low | Moderate |
| Than et al28 | Low | Moderate | Moderate | Moderate | Moderate | Low | Moderate |
QUIPS domain 1: The study sample adequately represents the population of interest.
QUIPS domain 2: The study data available (ie, participants not lost to follow-up) adequately represent the study sample.
QUIPS domain 3: The prognostic factor is measured in a similar way for all participants.
QUIPS domain 4: The outcome of interest is measured in a similar way for all participants.
QUIPS domain 5: Important confounders are appropriately accounted for.
QUIPS domain 6: The statistical analysis is appropriate, and all primary outcomes are reported.