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Background: Chronic obstructive pulmonary disease (COPD) and infections are risk factors for venous thromboembolism (VTE), but the reasons behind the associations are not fully known. Few studies have investigated whether lung function and respiratory symptoms in individuals without COPD are associated with VTE. Objectives: To study the incidence of VTE in individuals without COPD and other major VTE risk factors, in relation to baseline lung function and respiratory symptoms, through a 44-year follow-up prospective cohort study. Methods: As part of a health screening program, a total of 20,253 men and 7361 women underwent a baseline examination from 1974 to 1992, including a spirometry test and a self-administered questionnaire about respiratory symptoms, e.g., chronic bronchitis, cough, phlegm, and dyspnoea. Lung function was assessed through quartiles of forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC). Through linkage with national registers, all individuals were followed for incidence of VTE. Results: Respiratory symptoms (cough and dyspnoea) at baseline were associated with an increased risk of incident VTE in women after adjustments for age, height, BMI, smoking status, varicose veins, and FEV1/FVC. The adjusted hazard ratio in relation to chronic bronchitis was 1.57 (95% confidence interval 1.17–2.11). Poor lung function was not associated with an increased risk of VTE after adjustments for potential confounders. Conclusion: Women with respiratory symptoms of cough and dyspnoea without COPD have an increased risk of VTE, independent of lung function and major VTE risk factors. Further studies are needed to confirm the association and to study the clinical applicability of the results.

Abstract Background Tissue factor is the main initiator of blood coagulation, and tissue factor pathway inhibitor (TFPI) is the primary inhibitor of the initiation of blood coagulation. The genetic variation of TFPI and the relation to venous thromboembolism (VTE), that is, venous thrombosis and pulmonary embolism, remains to be clarified. This exome sequencing study aimed to determine the molecular epidemiology of the TFPI gene and the relation to VTE in a large population‐based cohort of middle‐aged and older adults. Methods The exomes of TFPI were analyzed for variants in 28,794 subjects without previous VTE (born 1923–1950, 60% women), who participated in the Malmö Diet and Cancer Study (1991–1996). Patients were followed until the first event of VTE, death, or 2018. Qualifying variants were defined as loss‐of‐function or nonbenign (PolyPhen‐2) missense variants with minor allele frequency less than 0.1%. Results No common variant was associated with VTE. Nine rare variants (two loss‐of‐function and seven nonbenign missense) were classified as qualifying and included in collapsing analysis. Prevalence of qualifying variants was 0.09%. Five individuals with VTE compared to 17 individuals without VTE carried one qualifying variant. Cox multivariate regression analysis adjusted for age, sex, body mass index, systolic blood pressure, smoking and alcohol consumption, rs6025, rs1799963, and ancestry showed a hazard ratio of 2.9 (95% CI, 1.2–7.1) for rare qualifying variants. Conclusion Rare qualifying TFPI variants were associated with VTE, suggesting that rare variants in TFPI contribute to the development of VTE. The qualifying TFPI gene variants were very rare, suggesting a constrained gene.