Prevalence of established risk factors for venous thromboembolism according to age.

Objective: To date, the factors that contribute to the rise in venous thromboembolism (VTE) risk observed with higher ages remain unknown. Therefore, the aim of the present analysis was to study the distribution of established VTE risk factors in categories of manifestation age in a large cohort of VTE patients.

Methods: Data were taken from the MAISTHRO (MAin-ISar-THROmbosis) registry, a cross-sectional study of patients with acute or documented history of VTE. The registry enrolled 1500 consecutive patients (869 females; median age, 43 years) with a first lower-extremity deep vein thrombosis or pulmonary embolism.

Results: VTE was attributed to established risk factors in 76.6% of cases. By classifying patients into categories of VTE manifestation age, we observed a steep rise in the prevalence of malignancies with advancing age (ie, 1.3% of cases of VTE occurred under the age of 30 and 34.0% of VTE cases manifested over the age of 70; P < .001). In contrast, VTE was more likely to be related to thrombophilia, a family history of VTE, oral contraceptives, and pregnancy in younger patients. Hereditary thrombophilia was detected in 50% of VTE patients younger than 20 and in 21.8% over the age of 70 (P < .001). With regard to other VTE risk factors, the results were insignificant. In addition, we were unable to demonstrate an accumulation of common VTE risk factors among patients at higher ages.

Conclusions: The distribution of established VTE risk factors varies with the age of VTE manifestation. Future studies are needed to clarify the role of age-specific risk factors in the development of VTE and in the incidence gradient with aging.