Risk of venous thromboembolism in people with lung cancer: a cohort study using linked UK healthcare data

Background: Venous thromboembolism (VTE) is a potentially preventable cause of death in people with lung cancer. Identification of those most at risk and high-risk periods may provide the opportunity for better targeted intervention. Methods: We conducted a cohort study using the Clinical Practice Research Datalink linked to Hospital Episode Statistics and Cancer Registry data. Our cohort comprises 10 598 people with lung cancer diagnosed between 1997 and 2006 with follow-up continuing to the end of 2010. Cox regression analysis was performed to determine which demographic, tumour and treatment-related factors (time-varying effects of chemotherapy and surgery) independently affected VTE risk. We also determined the effect of a VTE diagnosis on the survival of people with lung cancer. Results: People with lung cancer had an overall VTE incidence of 39.2 per 1000 person-years (95% confidence interval (CI), 35.4-43.5), though rates varied depending on the patient group and treatment course. Independent factors associated with increased VTE risk were metastatic disease (hazard ratio (HR) = 1.9, CI 1.2-3.0 vs local disease); adenocarcinoma subtype (HR = 2.0, CI 1.5-2.7, vs squamous cell; chemotherapy administration (HR = 2.1, CI 1.4-3.0 vs outside chemotherapy courses); and diagnosis via emergency hospital admission (HR = 1.7, CI 1.2-2.3 vs other routes to diagnosis). Patients with VTE had an approximately 50% higher risk of mortality than those without VTE. Conclusions: People with lung cancer have especially high risk of VTE if they have advanced disease, adenocarcinoma or are undergoing chemotherapy. The presence of VTE is an independent risk factor for death.