GRADE test accuracy evidence summary for using a platelet-dependent VWF activity assay/VWF:Ag ratio < 0.6 to diagnose type 1 VWD
| Outcome . | Studies/ patients . | Study design . | Factors that may decrease CoE . | Effect per 1000 patients tested; pretest probability of 30% . | Test accuracy CoE . | ||||
|---|---|---|---|---|---|---|---|---|---|
| Risk of bias . | Indirectness . | Inconsistency . | Imprecision . | Publication bias . | |||||
| True positives* | 3/97 | Cohort and case-control type | Serious† | Not serious | Serious‡ | Serious§ | None | 203-291 | ⨁◯◯◯ Very low |
| False negatives¶ | 9-97 | ||||||||
| True negativesǁ | 1/87 | Cohort and case-control type | Serious† | Not serious | Not serious | Serious | None | 612 | ⨁⨁◯◯ Low |
| False positives# | 88 | ||||||||
| Outcome . | Studies/ patients . | Study design . | Factors that may decrease CoE . | Effect per 1000 patients tested; pretest probability of 30% . | Test accuracy CoE . | ||||
|---|---|---|---|---|---|---|---|---|---|
| Risk of bias . | Indirectness . | Inconsistency . | Imprecision . | Publication bias . | |||||
| True positives* | 3/97 | Cohort and case-control type | Serious† | Not serious | Serious‡ | Serious§ | None | 203-291 | ⨁◯◯◯ Very low |
| False negatives¶ | 9-97 | ||||||||
| True negativesǁ | 1/87 | Cohort and case-control type | Serious† | Not serious | Not serious | Serious | None | 612 | ⨁⨁◯◯ Low |
| False positives# | 88 | ||||||||
Sensitivity, 0.68-0.97, specificity, 0.87-0.88.
Prevalences are 30%; typically seen in patients investigated for type 2 VWD because of a low VWF:RCo/Ag ratio.
CoE, certainty of the evidence.
Patients with type 2 VWD.
Serious patient selection risk of bias due to the case-control design. Also, issues around labeling as type 2M were noted.
Confidence intervals do not cross the effect estimates of different studies.
Small number of subjects.
Patients incorrectly classified as not having type 2 VWD.
Patients without type 2 VWD.
Patients incorrectly classified as having type 2 VWD.