Epidemiology and diagnosis of pulmonary embolism in lung cancer patients: is there a role for age adjusted D-dimers cutoff?

Our knowledge about the incidence of pulmonary embolism (PE) and the performance of age adjusted D-dimers (Dd) cutoff amongst patients with lung cancer (LC) and suspected PE, remains limited. We retrospectively analyzed all clinically suspected patients who underwent computed tomography pulmonary angiography (CTPA) in a tertiary hospital during a 19 month period. Cancer diagnosis was established using ICD10 code. Eligible for Dd analysis were those tested up to 24 h prior to the scan. We analyzed 2549 patients (54.6% males, median age 68.8 years, IQR 57-78), 15.8% had active LC and 5.4% other cancers (oC), while 70% were scanned in the Emergency Department (ED) and the rest during hospitalization. Overall incidence of PE was 16%. LC, but not oC, increased significantly the risk for PE (OR 1.58, 95% CI 1.21-2.06). LC patients were less likely to have bilateral (aOR 0.16, 95% CI 0.07-0.4) or central PE (aOR 0.2, 95% CI 0.09-0.48). Amongst those diagnosed with PE in the ED, LC increased all-cause inhospital mortality (aOR 6.7, 95% CI 2.64-16.95). When age adjusted instead of conventional Dd cutoff was used for ruling out PE in the ED, specificity for LC patients increased (10.16% vs 3.91%) without false negative tests (negative likelihood ratio-NLR = 0). A higher cutoff of 1.13 mg/l raised specificity to 28.9%, with only one case missed (sensitivity: 97.4%, NLR: 0.09, 95% CI 0.01-0.64). LC increases the risk for PE and adversely affects prognosis. Age adjusted and probably an even higher, "LC adjusted" Dd cutoff, could increase the specificity of the test without compromising its sensitivity.