Prognosis and risk factors in older patients with lung cancer and pulmonary embolism: a propensity score matching analysis

Older patients, especially those with malignancy, may have an increased risk of pulmonary embolism (PE). However, few studies have evaluated the clinical characteristics and prognosis of older patients. We evaluated the clinical characteristics, prognosis, and risk factors in older patients with lung cancer complicated with PE. This was a single-center, prospective cohort study. Older patients (≥65 years) with lung cancer admitted in Beijing Hospital from January 2006 to December 2016 were enrolled. The patients were divided into two groups according to the presence of PE using propensity score matching (PSM). After PSM, one hundred and six patients (53 per group) with an average age of (77.3 ± 10.9) years were enrolled. Adenocarcinoma was the most common histology in patients with PE (52.8%, n = 28), and most lung cancer patients were in stages III and IV (59.4%, n = 63). Patients with PE were stratified to low risk (52.8%, n = 28), intermediate-low risk (24.5%, n = 13), intermediate-high risk (15.1%, n = 8), high-risk (7.5%, n = 4) subgroups. Most PE patients presented with dyspnea (75.5%), and the majority of patients (86.8%, n = 46) developed PE within 3 months after the diagnosis of cancer. The median follow-up time was 23.7 months (12.0–62.0 months), and 7 patients (6.6%) were lost to follow-up. During the follow-up period, 92 patients (86.8%) died, including 8 cases (8.7%) of PE-related death, 73 (79.3%) of tumor death, and 11 (11.9%) of unknown cause. There were significant differences in all-cause mortality (94.3% vs. 83.0%) and PE-related mortality (15.1% vs. 0) between the PE and control groups, but the rate of tumor-related mortality (75.5% vs. 66.0%) was comparable between the groups. Among the 92 patients who died, the mortality rates at 3, 6, 12, and > 12 months after tumor diagnosis were 33.0% (33/106), 57.5% (61/106), 78.3% (83/106), and 89.6% (95/106), respectively. Kaplan–Meier survival analysis showed that the median overall survival time was significantly different between the PE and the control groups (4.3 vs. 9.2 months, P = 0.0015). Multivariate stepwise logistic regression analysis showed that age ≥ 77 years (OR = 2.58, 95%CI: 1.66–4.01), clinical stage III–IV (OR = 2.21, 95%CI: 1.03–4.74), adenocarcinoma (OR = 3.24, 95%CI: 1.75–6.00), high D-dimer (≥600 mg/L) (OR = 2.73, 95%CI: 1.25–5.96), and low partial pressure of oxygen (PaO2; <75 mmHg) (OR = 2.85, 95%CI: 1.74–4.67) were independent risk factors for PE in older patients with lung cancer. Older patients with lung cancer and PE often have poor prognosis. Advanced age, clinical stage III–IV, adenocarcinoma, high D-dimer level, and low PaO2 are independent risk factors for PE.