Key result
The age-adjusted D-dimer cut-off value increased the proportion of patients with non-high clinical probability in whom deep vein thrombosis could be excluded to 51% compared to 42% with the conventional cut-off.
Why the study?
Does an age-adjusted D-dimer cut-off increase the proportion of older patients in whom deep vein thrombosis can be safely excluded compared to a conventional cut-off?
Cohort (n=2,818)
Yes
Does an age-adjusted D-dimer cut-off increase the proportion of older patients in whom deep vein thrombosis can be safely excluded compared to a conventional cut-off?
Using an age-adjusted D-dimer cut-off safely increases the proportion of older patients in whom deep vein thrombosis can be excluded without increasing the rate of missed diagnoses.
May increase safe DVT exclusion in older patients; leaves open need for prospective validation before practice change.
BACKGROUND: D-dimer testing to rule out deep vein thrombosis is less useful in older patients because of a lower specificity. An age-adjusted D-dimer cut-off value increased the proportion of older patients (>50 years) in whom pulmonary embolism could be excluded. We retrospectively validated the efficacy of this cut-off combined with clinical probability for the exclusion of deep vein thrombosis. DESIGN AND METHODS: Five management study cohorts of 2818 consecutive outpatients with suspected deep vein thrombosis were used. Patients with non-high or unlikely probability of deep vein thrombosis were included in the analysis; four different D-dimer tests were used. The proportion of patients with a normal D-dimer test and the failure rates were calculated using the conventional (500 μg/L) and the age-adjusted D-dimer cut-off (patient's age x 10 μg/L in patients >50 years). RESULTS: In 1672 patients with non-high probability, deep vein thrombosis could be excluded in 850 (51%) patients with the age-adjusted cut-off value versus 707 (42%) patients with the conventional cut-off value. The failure rates were 7 (0.8; 95% confidence interval 0.3-1.7%) for the age-adjusted cut-off value and 5 (0.7%, 0.2-1.6%) for the conventional cut-off value. The absolute increase in patients in whom deep vein thrombosis could be ruled out using the age-adjusted cut-off value was largest in patients >70 years: 19% among patients with non-high probability. CONCLUSIONS: The age-adjusted cut-off of the D-dimer combined with clinical probability greatly increases the proportion of older patients in whom deep vein thrombosis can be safely excluded.
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Douma et al. (2012) conducted a cohort in Suspected deep vein thrombosis (DVT) (n=2,818). Age-adjusted D-dimer cut-off value (age x 10 mg/L for >50 years) vs. Conventional D-dimer cut-off value (500 mg/L) was evaluated on Proportion of patients with non-high clinical probability in whom DVT could be excluded (Absolute increase 8.6%, 95% CI 7.3-10). The age-adjusted D-dimer cut-off value increased the proportion of patients with non-high clinical probability in whom deep vein thrombosis could be excluded to 51% compared to 42% with the conventional cut-off.
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