Characteristics and prognostic factors of patients with community-acquired pneumonia combined with pulmonary embolism: A prospective cohort study

Pulmonary embolism (PE) is a frequently missed complication in elderly patients with community-acquired pneumonia (CAP), partly due to overlapping clinical features. This study aimed to identify early indicators for PE detection in this population. A prospective cohort of 180 elderly CAP patients (≥60 years) admitted between March 2023 and July 2024 was enrolled. Patients with elevated D‑dimer (>0.50 mg/L) underwent computed tomography pulmonary angiography (CTPA). Of 140 CTPA-evaluated patients, 80 had CAP+PE and 60 had CAP alone. Demographics, comorbidities, symptoms, and laboratory parameters (D‑dimer, fibrinogen, CRP, PCT) were compared, and diagnostic performance was assessed using receiver operating characteristic curves. The CAP+PE group was older (71.35 ± 5.04 vs. 69.03 ± 4.57 years; P <.05) and had higher rates of hypertension (65% vs. 40%), coronary artery disease (48% vs. 25%), chronic obstructive pulmonary disease (55% vs. 30%), cancer (35% vs. 15%), diabetes (50% vs. 28%), and long-term bedridden status (38% vs. 18%) (all P <.05). Syncope (28% vs. 8%), chest pain (45% vs. 20%), and dyspnea (75% vs. 55%) were more prevalent in CAP+PE (P <.05). D‑dimer (median [IQR]: 4.2 [2.8-6.1] mg/L vs. 1.9 [1.1-2.7] mg/L) and fibrinogen (4.1 ± 1.2 g/L vs. 3.3 ± 0.9 g/L) were significantly elevated in CAP+PE (P <.05). ROC analysis showed D‑dimer (cutoff 3.13 mg/L) had moderate diagnostic accuracy (AUC 0.73; sensitivity 81%, specificity 63%), while fibrinogen (cutoff 2.79 g/L) had lower accuracy (AUC 0.68). Elevated D‑dimer (>3.13 mg/L) serves as a practical screening tool for PE in elderly CAP patients, particularly in resource-limited settings lacking CTPA; high-risk comorbidities and atypical symptoms (syncope/chest pain) further support early PE evaluation.