[Venous thromboembolism--incidence and risk factors in Oslo]

Over a period of three years, 378 patients with objectively verified venous thromboembolism were treated at Aker University Hospital. Below the age of 60, men and women had about the same incidence of venous thromboembolism, but that age the incidence was significantly higher among men than among women. Incidence increased exponentially with age, from about 1:10,000 at age 20 to about 1:1,000 at age 50. The incidence found here is lower than in earlier Nordic studies. The great majority of the patients (93%) had deep venous thrombosis in the lower extremities, 11% had symptomatic and verified pulmonary embolism, and 1% had their thrombus in an inner organ vein. 23% of patients were previously treated for venous thromboembolism, and 22% had cancer. Seven women were on oral contraception, and 22 used postmenopausal hormone substitution. An obvious temporary precipitating factor was present in 42% of the patients, while 36% had a spontaneous venous thromboembolism. Hereditary thrombophilic disorder was found in 32% of patients below the age of 60.