Ventilation/perfusion scan sensitivity and specificity for a low-prevalence population
| . | No. of results per 1000 patients tested (95% CI) . | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| . | Prevalence 5%*† in patients with suspected PE . | No. of participants (studies) . | Certainty of the evidence (GRADE) . | ||||||
| Test result . | A . | B . | C . | A . | B . | C . | A . | B . | C . |
| True positives | 29 (25-33) | 49 (48-50) | 48 (46-49) | 3994 (13) | 3994 (13) | 1799 (13) | ⨁⨁⨁◯ MODERATE‡§ | ⨁⨁⨁◯ MODERATE‡|| | ⨁⨁⨁⨁ HIGH‡||¶ |
| False negatives | 21 (17-25) | 1 (0-2) | 2 (1-4) | ||||||
| True negatives | 931 (912-941) | 342 (257-428) | 903 (845-931) | 3994 (13) | 3994 (13) | 1799 (13) | ⨁⨁⨁◯ MODERATE‡§ | ⨁⨁⨁◯ MODERATE‡|| | ⨁⨁⨁⨁ HIGH‡||¶ |
| False positives | 19 (9-38) | 608 (522-693) | 47 (19-105) | ||||||
| Inconclusive test results | 1849 | 1849 | 0 | 3994 (13) | 3994 (13) | 1799 (13) | |||
| Complications arising from the diagnostic test | Not reported | ||||||||
| . | No. of results per 1000 patients tested (95% CI) . | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| . | Prevalence 5%*† in patients with suspected PE . | No. of participants (studies) . | Certainty of the evidence (GRADE) . | ||||||
| Test result . | A . | B . | C . | A . | B . | C . | A . | B . | C . |
| True positives | 29 (25-33) | 49 (48-50) | 48 (46-49) | 3994 (13) | 3994 (13) | 1799 (13) | ⨁⨁⨁◯ MODERATE‡§ | ⨁⨁⨁◯ MODERATE‡|| | ⨁⨁⨁⨁ HIGH‡||¶ |
| False negatives | 21 (17-25) | 1 (0-2) | 2 (1-4) | ||||||
| True negatives | 931 (912-941) | 342 (257-428) | 903 (845-931) | 3994 (13) | 3994 (13) | 1799 (13) | ⨁⨁⨁◯ MODERATE‡§ | ⨁⨁⨁◯ MODERATE‡|| | ⨁⨁⨁⨁ HIGH‡||¶ |
| False positives | 19 (9-38) | 608 (522-693) | 47 (19-105) | ||||||
| Inconclusive test results | 1849 | 1849 | 0 | 3994 (13) | 3994 (13) | 1799 (13) | |||
| Complications arising from the diagnostic test | Not reported | ||||||||
Patient or population: patients with suspected PE. Setting: inpatient and outpatient. A: V/Q scan with high probability scan interpreted as positive, normal/low/nondiagnostic scan as negative. An interactive summary of findings is available at: https://gdt.gradepro.org/presentations/#/isof/isof_88bb7995-dec1-4116-9b07-a2f15691c2c4-1570046058781?_k=fmsw16. Pooled sensitivity of A: 0.58 (95% CI, 0.50-0.66); pooled specificity: 0.98 (95% CI, 0.96-0.99). B: V/Q scan with high/nondiagnostic/low probability scan interpreted as positive, normal scan as negative. An interactive summary of findings is available at: https://gdt.gradepro.org/presentations/#/isof/isof_2564a7dd-52d5-442b-bfee-0d6495de7cfc-1570045676857?_k=pihtmp. Pooled sensitivity of B: 0.98 (95% CI, 0.95-0.99); pooled specificity: 0.36 (95% CI, 0.27-0.45). C: V/Q scan with high probability scan as positive, normal scan as negative. An interactive summary of findings is available at: https://gdt.gradepro.org/presentations/#/isof/isof_3f842c9a-15d3-4b16-8ed5-0011f3157c53-1570045878061?_k=vgsgvi.
Pooled prevalence of PE with low PTP in North American studies 6.5% (5% used in table).18
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 a panel of clinical experts.
Certainty of evidence was downgraded for serious unexplained inconsistency in sensitivity, with a range from 13.9% to 84.6%. Minor inconsistency for specificity noted but judged to be insufficient to downgrade the certainty of evidence.
Although there was inconsistency noted for sensitivity, it was judged as not serious and we did not downgrade the certainty of evidence. Certainty of evidence was downgraded for serious unexplained inconsistency in specificity, with a range from 10.9% to 81.8%.
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.