Venous thromboembolism in people with

idiopathic pulmonary fibrosis: a population-based study To the Editor: Laboratory studies and animal models have suggested that the activation of the clotting cascade may be important in the pathogenesis of idiopathic pulmonary fibrosis (IPF) [1–3]. Epidemiological studies have also suggested a strong association between IPF and venous thromboembolism (VTE) [4–6]. We estimated the incidence of pulmonary embolus and deep vein thrombosis (DVT) in people with IPF and the general population, and compared these with the prevalence of a warfarin prescription. We used data from THIN (The Health Improvement Network; www.thin-uk.com), a UK longitudinal database of electronic primary care records containing information recorded in routine clinical care, from face-to-face consultations, and following communication from secondary care. Medical and diagnostic data are entered using medical Read codes, a comprehensive list of medical terms for signs, symptoms, diagnoses, procedures and investigations. We used the Read codes H563.00 (idiopathic fibrosing alveolitis), H563.11 (Hamman–Rich syndrome), H563.12 (cryptogenic fibrosing alveolitis), H563100 (diffuse pulmonary fibrosis) and H563z00 (idiopathic fibrosing alveolitis NOS) to identify incident cases of IP