The following is a summary of “Age-adjusted D-dimer, clinical pre-test probability-adjusted D-dimer, and whole leg ultrasound in ruling out suspected proximal and calf deep venous thrombosis,” published in the August 2023 issue of Hematology by Sartori et al.
D-dimer (DD) and ultrasound (US) are diagnostic tools for lower-extremity deep vein thrombosis (DVT). Researchers conducted a retrospective study to evaluate the impact of adjusting DD level cut-offs by age or clinical pre-test probability (PTP) on the use of US in patients with suspected DVT.
They evaluated diagnostic precision by comparing PTP-adjusted DD and age-adjusted DD in 3,883 patients (61.1% F; age: 65.3 ± 16.8 y) referred to their unit due to suspected DVT, with all patients undergoing clinical assessment, DD, and US.
The results showed that 12.4% of patients had proximal DVT, 8.9% had distal DVT, and 3,064 patients, 0.75% (95% CI: 0.50–1.12) experienced venous thromboembolic events over a 3-month follow-up. In patients without high PTP levels, the specificities were 47% (95% CI: 45–49) for DD, 61% (95% CI: 59–62) for age-adjusted DD, and 67% (95% CI: 65–68) for PTP-adjusted DD. The negative predictive value (NPV) across all strategies was 96% (95% CI: 95–97), rising to 99% (95% CI: 98–99) for proximal DVTs alone. The utilization of US decreased 37% (95% CI: 36–38) with fixed DD, 48% (95% CI: 47–50) with age-adjusted DD, and 52% (95% CI: 51–54) with PTP-adjusted DD. The failure rates for all DVTs were 2.0% (95% CI: 1.6–2.5), 2.7% (95% CI: 2.2–3.2), and 2.5% (95% CI: 2.1–3.0) for DD, age-adjusted DD, and PTP-adjusted DD, respectively.
They concluded that age-adjusted and PTP-adjusted DD reduced US use in DVT with a slight increase in failure rate.
