D‐dimer in Adolescent Pulmonary Embolism

AbstractBackgroundD‐dimer is used to aid in diagnosing adult pulmonary embolism (PE). D‐dimer has not been validated in adolescents. Clinicians must balance the risk of overtesting with that of a missed PE. D‐dimer may be useful in this context. This study evaluates D‐dimer in PE‐positive and PE‐negative adolescents.MethodsPE‐positive patients < 22 years were diagnosed with PE by computed tomography (CT) or high‐probability ventilation/perfusion, seen at emergency departments (EDs)/hospitals within a 16‐hospital system across two states, January 1998 through December 2016. Of the 189 PE‐positive patients, 88 (46.5%) had a D‐dimer and were matched 1:1 by age, sex, and race to patients suspected of PE but confirmed negative by CT angiogram.ResultsAges of PE‐positive patients ranged from 13 to 21 years, 64 (73%) were female, and 52 (60%) were Caucasian. Mean D‐dimer was significantly higher (3,256 ng/mL, 95% confidence interval [CI] = 2,505–4,006 ng/mL) in PE‐positive versus PE‐negative patients (1,244 ng/mL, 95% CI = 493–1,995 ng/mL; p < 0.001). Mean D‐dimer was higher in patients with massive or submassive PE (8,742 ng/mL, 95% CI = 5,994–11,491 ng/mL), followed by PE in central (4,795 ng/mL [95% CI = 3,465–6,125 ng/mL), lobar (3,758 ng/mL [95% CI = 1,841–5,676), and distal (2,327 ng/mL [95% CI = 1,273–3,381 ng/mL]) arteries. When comparing thresholds of positive D‐dimer (≥500, ≥750, and ≥1,000 ng/mL), D‐dimer had sensitivities of 90, 82, and 67% and specificities of 16, 53, and 67%, respectively. Negative predictive values were 61, 75, and 71% while positive likelihood ratios were 1.1, 1.8, and 2.2, respectively.ConclusionsThis study represents the largest available cohort of adolescent patients examining the diagnostic value of D‐dimer for PE. Our results indicate that depending on the threshold selected, D‐dimer can be a sensitive test for PE in adolescents and that discriminative value is higher for a cutoff of 750 ng/mL than that for 500 ng/mL. Prospective studies investigating the diagnostic value of D‐dimer and a clinical decision rule for PE in pediatrics are needed.