| Study |
Bias due to confounding |
Bias in selection of participants into the study |
Bias in classification of interventions |
Bias due to deviations from the intended intervention |
Bias due to missing data |
Bias in measurement of outcomes |
Bias in selection of the reported result |
Overall risk of bias |
| Judgement |
One or more prognostic variables are likely to be unbalanced between the compared groups. There is a baseline characteristics table comparing the two groups with limited items. However, the study did not compare essential characteristics, such as participants already using anticoagulants, participants who underwent surgery during the hospitalisation, concomitant antiplatelet use, and history of venous thromboembolism. |
The participants of the two groups (intervention and comparator) were selected from the same hospital, but as the study was retrospective, it is not possible to know if the selection was free from bias. The selection for the study was strongly related to both the intervention and the outcome of interest. We could not adjust the analyses for this selection bias. |
There is a risk that the interventions received by participants in the same group have not been standardised. There is a high risk of differential classification errors because the information on the status of the interventions was obtained retrospectively. |
No deviations from the intended intervention were reported in the study, and if any deviation occurred from usual practice, it was unlikely to impact on the outcome. |
No missing data were reported for this outcome. |
It is unlikely that the outcome assessment (length of hospital stay) was influenced by the knowledge of the intervention received by the study participants. |
The study protocol was not identified but all reported results corresponded to the intended outcome. |
The study is too problematic to provide useful evidence. |
