Table 1.
Risk of Bias Within Studies
| Study | Selection Bias | Attrition Bias | Measurement Bias Related to CFS | Measurement Bias Related to Outcomes | Confounding Bias | Analysis/Presentation Bias | The Overall Risk of Bias |
|---|---|---|---|---|---|---|---|
| Anand et al 202028 | Low | Moderate | Moderate | Low | Moderate | Low | Moderate |
| Bagshaw et al 201443 | Low | Low | Low | Low | Low | Low | Low |
| Basic & Shanley 201544 | Low | Low | Low | Low | Low | Low | Low |
| Chan et al 201929 | Low | Low | Low | Low | Moderate | Moderate | Moderate |
| Cheung et al 201730 | Moderate | Low | Low | Low | Moderate | Low | Moderate |
| Chong et al 201731 | Moderate | Low | Low | Moderate | Low | Moderate | Moderate |
| Chong et al 201832 | Moderate | Low | Moderate | Low | Low | Moderate | Moderate |
| Chua et al 202045 | Low | Low | Low | Low | Moderate | Low | Low |
| Curtis et al 201846 | Low | Low | Low | Low | Moderate | Low | Low |
| Darvall et al 201947 | Moderate | Low | Low | Low | Moderate | Low | Low |
| Darvall et al 202048 | Moderate | Low | Low | Low | Low | Low | Low |
| Ekerstad et al 201133 | Low | Low | Low | Low | Moderate | Moderate | Moderate |
| Ekerstad et al 201434 | Low | Moderate | Moderate | Low | Low | Low | Moderate |
| Ekerstad et al 201835 | Low | Moderate | Low | Moderate | Moderate | Low | Moderate |
| Ellis et al 202036 | Low | Low | Low | Low | Moderate | Moderate | Moderate |
| Evans et al 201949 | Low | Low | Low | Low | Moderate | Low | Low |
| Fernando et al 201937 | Low | Low | Moderate | Moderate | Low | Low | Moderate |
| Flaatten et al 201750 | Low | Low | Low | Low | Low | Low | Low |
| Fronczek et al 201851 | Low | Low | Low | Low | Moderate | Low | Low |
| Guidet et al 202052 | Low | Low | Moderate | Low | Low | Low | Low |
| Lewis et al 201938 | Low | Low | Moderate | Moderate | Low | Low | Moderate |
| Li et al 201839 | Low | Low | Moderate | Low | Moderate | Moderate | Moderate |
| MacKenzie et al 201953 | Low | Low | Low | Low | Low | Low | Low |
| Moore et al 201840 | Low | Low | Low | Moderate | Moderate | Moderate | Moderate |
| Ritt et al 201741 | Low | Low | Moderate | Low | Moderate | Low | Moderate |
| Silva-Obregon et al 202054 | Low | Low | Moderate | Low | Low | Low | Low |
| Sze et al 201755 | Low | Low | Moderate | Low | Low | Low | Low |
| Ticinesi et al 201956 | Low | Low | Moderate | Low | Low | Low | Low |
| Wallis et al 201542 | Low | Moderate | Moderate | Low | Moderate | Low | Moderate |
Notes: Risk of bias (RoB) according to the six domains of the Quality in Prognosis Studies (QUIPS) tool. 21 The overall RoB was determined using the following criteria as previously suggested by Grooten et al 22 If all domains were assessed as having low RoB or up to one moderate RoB, the study was classified as low RoB. If one or more domains were assessed as having high RoB, or ≥four moderate RoB, this study was classified as high RoB. All studies in between were classified as having moderate RoB.