Table 3.
Whole leg ultrasound test accuracy in a low prevalence population
| Test result | No. of results per 1000 patients tested (95% CI) | No. of participants (studies) | Certainty of the evidence (GRADE) |
|---|---|---|---|
| Prevalence 10%*† in patients with suspected LE DVT | |||
| True positives | 94 (91-96) | 1725 (10) | ⊕⊕⊕⊕High‡§|| |
| False negatives | 6 (4-9) | ||
| True negatives | 876 (853-887) | 1725 (10) | ⊕⊕⊕⊕High‡§|| |
| False positives | 24 (13-47) | ||
| Inconclusive test results | 8 | 1733 (10) | |
| Complications arising from the diagnostic test | NA | ||
An interactive version of this table is available at: https://gdt.gradepro.org/presentations/#/isof/isof_0ad70f88-cd0a-4dac-a120-18537537be4b-1582834618247?_k=p7wkc3.
Patient or population: Patients with suspected lower extremity deep vein thrombosis. Setting: Inpatient and outpatient. Pooled sensitivity: 0.94 (95% CI, 0.91-0.96). Pooled specificity: 0.97 (95% CI, 0.95-0.99).
Clinical PTP and rapid D-dimer testing; mean prevalence of DVT in accuracy studies 11%; mean prevalence of DVT in management studies 25%.60
Disease prevalence applies to the index test in each pathway. Prevalence applied to the accuracy of each subsequent test depends on the result of the previous test in the pathway.
Certainty of evidence not downgraded for risk of bias, although few studies had a combination of reference standards that were judged to be acceptable by the panel.
Although there was inconsistency noted for sensitivity, it was judged as not serious and we did not downgrade the certainty of evidence. There was inconsistency also noted for specificity, but it was judged as not serious and we did not to downgrade the certainty of evidence.
Certainty of evidence was downgraded for indirectness in instances where this test was not the index test in a diagnostic pathway. There was a lack of data on the accuracy of this test following a previous test in a pathway. Thus, sensitivity and specificity used for modeling in these instances were based on the test accuracy of the individual test rather than using the test in a pathway.