Table 4.
Classification table for 1000 hypothetical patients based on median prevalence of venous thromboembolism (VTE) in each age subgroup* and on pooled estimates of sensitivity and specificity
| Variables | Age (years) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤50 | 51-60 | 61-70 | 71-80 | >80 | |||||||||||
| Conventional cut-off value | VTE+ | VTE- | Total | VTE+ | VTE- | Total | VTE+ | VTE- | Total | VTE+ | VTE- | Total | VTE+ | VTE- | Total |
| D-dimer high | 120 | 291 | 411 | 134 | 367 | 501 | 154 | 512 | 666 | 212 | 593 | 805 | 151 | 724 | 876 |
| D-dimer low | 3 | 586 | 589 | 0 | 499 | 499 | 2 | 332 | 334 | 3 | 192 | 195 | 1 | 124 | 124 |
| Total | 123 | 877 | 1000 | 134 | 866 | 1000 | 156 | 844 | 1000 | 215 | 785 | 1000 | 152 | 848 | 1000 |
| Sensitivity/specificity | 97.6 | 66.8 | — | 100.0 | 57.6 | — | 99.0 | 39.4 | — | 98.7 | 24.5 | — | 99.6 | 14.6 | — |
| Age adjusted cut-off value | — | — | — | VTE+ | VTE- | Total | VTE+ | VTE- | Total | VTE+ | VTE- | Total | VTE+ | VTE- | Total |
| D-dimer high | — | — | — | 133 | 327 | 460 | 152 | 427 | 578 | 209 | 438 | 647 | 147 | 550 | 697 |
| D-dimer low | — | — | — | 1 | 539 | 540 | 4 | 417 | 422 | 6 | 347 | 353 | 5 | 298 | 303 |
| Total | — | — | — | 134 | 866 | 1000 | 156 | 844 | 1000 | 215 | 785 | 1000 | 152 | 848 | 1000 |
| Sensitivity/specificity | — | — | — | 99.4 | 62.3 | — | 97.3 | 49.5 | — | 97.3 | 44.2 | — | 97.0 | 35.2 | — |
| No of avoided unnecessary imaging examinations | — | — | — | — | 40 | — | — | 85 | — | — | 155 | — | — | 175 | — |
| Additional No of cases missed | — | — | — | 1 | — | — | 2 | — | — | 3 | — | — | 4 | — | — |
*12.3% in patients aged ≤50, 13.4% in patients aged 51-60, 15.6% in patients aged 61-70, 21.5% in patients aged 71-80, and 15.2% in patients aged >80 years.