Key result
Age-adjusted D-dimer nearly triples specificity for PE vs standard cutoff without changing overall discrimination.
Why the study?
Evidence is limited regarding age-adjusted D-dimer test behavior near the individualized cutoff and the safety of excluding pulmonary embolism in age-adjusted D-dimer-negative cases.
Does an age-adjusted D-dimer threshold improve diagnostic specificity without compromising sensitivity for suspected pulmonary embolism in adults ≥ 50 years compared to a standard threshold?
Observational (n=979)
No
Does an age-adjusted D-dimer threshold improve diagnostic specificity without compromising sensitivity for suspected pulmonary embolism in adults ≥ 50 years compared to a standard threshold?
Age-adjusted D-dimer thresholds improve specificity for excluding pulmonary embolism in older adults but should be used cautiously near the threshold and integrated with clinical probability.
Answers are grounded in this paper and cite their sources.
May enhance specificity for excluding PE in older ED patients; leaves open need for prospective validation before practice change.
Background Age‐adjusted D‐dimer (AAD) thresholds are used to reduce false positives in older patients evaluated for pulmonary embolism (PE). However, evidence is limited regarding test behavior near the individualized cutoff (“near‐threshold” zone) and the safety of excluding PE in AAD‐negative cases. Methods We conducted a retrospective diagnostic accuracy study of adults ≥ 50 years presenting to a tertiary emergency department (2015–2019) with suspected PE who underwent D‐dimer testing and definitive imaging (CT pulmonary angiography or V/Q scintigraphy). Diagnostic performance of the standard threshold (0.5 µg/mL, FEU) and AAD (age × 0.01 µg/mL) was assessed using ROC analysis. Accuracy metrics are reported with 95% confidence intervals (CIs) via bootstrap; AUC CIs and between‐curve comparisons used the DeLong method. The near‐threshold zone was defined as ±0.1 µg/mL around the AAD cutoff. Clinical charts of AAD‐negative PE cases were reviewed. Results Among 979 patients, 162 (16.5%) had imaging‐confirmed PE. Standard D‐dimer showed sensitivity 99.4% (95% CI 98.0–100.0) and specificity 4.0% (2.7–5.4); AAD showed sensitivity 97.5% (94.8–99.4) and specificity 11.8% (9.6–13.9). AUCs were 0.734 and 0.727, with no significant difference (DeLong p = 0.41). Within the near‐threshold window, PE prevalence was 7.7%, increasing with age (28.6% in ≥ 80 years). Three patients had PE despite AAD‐negative results; all had segmental or subsegmental emboli, and no in‐hospital complications were documented in the available records. Conclusion In this imaging‐selected retrospective cohort, AAD improved specificity with minimal sensitivity loss. However, AAD should not be used as a stand‐alone rule‐out strategy and should be applied only within clinical probability‐guided diagnostic pathways. Near‐threshold results are not risk‐free, particularly in older adults, and should prompt careful clinical reassessment when overall probability remains concerning.
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Yıldırım et al. (2026) conducted an observational in Suspected pulmonary embolism (n=979). Age-adjusted D-dimer (AAD) threshold vs. Standard D-dimer threshold (0.5 µg/mL) was evaluated on Diagnostic discrimination (Area Under the Curve) for imaging-confirmed pulmonary embolism (AUC 0.727 vs 0.734, p=0.41). Age-adjusted D-dimer improved specificity to 11.8% compared to 4.0% with the standard threshold, while maintaining a high sensitivity of 97.5% for diagnosing pulmonary embolism, with no significant difference in overall AUC (p=0.41).
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