Malignancy Is Significant Risk Factor for VTE in Patients With IPF

Venous thromboembolism (VTE) was diagnosed in 2.7% of patients with idiopathic pulmonary fibrosis (IPF) and was associated with ischemic heart disease, ischemic stroke, and malignancy (especially lung cancer) in these patients. These were among study findings published in Therapeutic Advances in Respiratory Disease.

Researchers sought to estimate the incidence of VTE and characteristics associated with VTE in patients with IPF, using of data from the Korean Health Insurance Review and Assessment Service (HIRA) database.

The study included16,691 patients with IPF in the database from January 2011 to December 2019, who were identified using the International Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) code of IPF and the rare intractable disease registration system code of IPF. Patients’ overall mean (SD) age was 70.8 (9.8) years; 29.6% were women. During the median follow-up of 1.96 years (interquartile range [IQR], 0.94-3.32), 446 (2.7%) patients were diagnosed with VTE.

The overall incidence rate of VTE per 1000 person-years was 7.08 (95% CI, 6.44-7.77), with a lower rate in male patients (7.07, 95% CI, 6.30-7.90) vs female patients (7.12; 95% CI, 5.98-8.42).

Peak incident VTE rates generally occurred among male patients aged 50 to 59 years (7.89; 95% CI, 5.43-11.08) and female patients aged 70 to 79 years (9.13; 95% CI, 7.11-11.56). The peak incident rate in the total population occurred in patients aged 50 to 59 years (7.88; 95% CI, 5.87-10.36).

Ischemic heart disease, ischemic stroke, and malignancies were risk factors for VTE in patients with IPF, with an adjusted hazard ratio (aHR) of 1.25 (95% CI, 1.01-1.55), 1.36 (95% CI, 1.04-1.79), and 1.53 (95% CI, 1.17-2.01), respectively.

Diabetes mellitus was associated with a reduced risk of VTE in patients with IPF (aHR, 0.71; 95% CI, 0.59-0.87). The risk for VTE was greater in those who were previously diagnosed with malignancy post-IPF diagnosis (aHR, 3.18; 95% CI, 2.47-4.11). The cumulative incidence of VTE for patients with vs without malignancy after an IPF diagnosis was increased and also was higher in patients with lung cancer (3.78; 95% CI, 2.90-4.96).

The median number of hospitalizations, emergency room visits, and intensive care unit admissions were 5 (IQR, 3-9), 2 (IQR, 1-4), and 1 (IQR, 0-1), respectively, in patients with VTE; notably, these rates were significantly higher in those with vs without VTE. Total medical costs and IPF-related medical costs also were greater in patients with VTE vs those without.

Among several limitations, IPF and VTE were defined according to the ICD-10 code at the time of diagnosis. Also, the association between VTE and mortality was not analyzed, and the association between severity and exacerbation history of IPF and subsequent VTE could not be assessed. Furthermore, causal relationships were not presented owing to the study design.

“Ischemic heart disease, ischemic stroke, and malignancy, especially lung cancer,

were related to higher HR for VTE in IPF,” the study authors concluded. “[M]alignancies could be regarded as significant risk factors, irrespective of the time at which it was diagnosed or the cancer type,” stated the study authors. “Therefore, clinicians might be required to closely monitor for VTE in patients with IPF.”