anemone study: prevalence of risk factors for superficial vein thrombosis in a large italian population of blood donors

Knowledge of the distribution of risk factors for superficial thrombosis (svt) in low-risk population is fundamental to improve the prevention of the disease in each individual and high-risk settings of patients. exact frequency data for the low-risk population are scarce, but could be useful for optimal use of prophylactic strategies against venous thrombosis. blood donors represent a low-risk population, because are healthier than the general population. the objective of this study was to assess the prevalence of vein thrombosis, particularly svt, and associated risk factors in a low-risk population such as blood donors. in this multicentre cross-sectional study, donors from six italian blood banks responded to a self-administered questionnaire. the enrolment lasted from 1st 2017 to 30th 2018. history of vein thrombosis was referred by 89 (0.76%) individuals, (49 men) with an age-dependent effect. the prevalence reached 2.9% in women and 0.8% in men aged ≥ 49 years, with a significant difference only for women. after controlling for potential confounders, a significant and independent association was found between a history of vein thrombosis and age (or: 1.03, 95%ci 1.01–1.05), varicose veins (or: 15.8, 95%ci 7.7–32.6), plaster cast/bed rest (or: 2.3, 95% ci 1.0–5.3) and transfusion (or: 5.1, 95% ci 1.3–19.5). this study shows that low-risk individuals share the same risk factors for svt as patients in secondary care. it also suggests that transfusion confers an increased risk of svt in healthy population.