Prospective analysis of risk factors and distribution of venous thromboembolism in the population-based Malmö Thrombophilia Study (MATS).

BACKGROUND: Despite venous thromboembolism (VTE) being a major cause of morbidity and mortality, there is still limited information on its prevalence and incidence in the general population. OBJECTIVE: To evaluate risk factors, distribution and epidemiology of VTE in the Malmö area with 280 000 inhabitants. METHODS: Patients diagnosed with VTE at Malmö University Hospital in 1998-2006 were invited to a prospective population-based study. Blood sampling and a questionnaire study could be performed in 70% of patients. Remaining 30% were excluded due to language problems, dementia, other severe disease, or unwillingness to participate. RESULTS: During 1998-2006 1140 VTE patients (559 men [49%, age 62+/-16 years] and 581 women [51%, age 61+/-20 years]) were included. Deep venous thrombosis (DVT) occurred in 882 (77%), pulmonary embolism (PE) in 330 (29%), and both DVT and PE in 72 (6%). The most common acquired risk factors among VTE patients were hormone therapy (24% of female DVT patients and 19% of female PE patients), immobilisation (17% of DVT patients and 18% of PE patients), previous surgery (13% of DVT patients and 19% of PE patients), and concomitant malignant disease (12% of DVT patients and 11% of PE patients). A positive family history for VTE was obtained from 25% of DVT patients and 22% of PE patients. Yearly incidences of VTE, DVT and PE in Malmö were 66, 51, and 19/100.000, respectively. CONCLUSION: Hormone therapy, immobilisation, previous surgery and concomitant malignancy were the most common acquired risk factors among VTE patients in this population-based study. The VTE-incidence was lower than in earlier epidemiological studies.