Prevalence of risk factors for venous thromboembolism: a case-control study on 150 patients hospitalised in internal medicine

Background. - Risk factors for the thrombo-embolic disease are not yet completely validated in medical setting. Indeed, there is a lack of scientific data concerning their prevalence and their thrombogenic weight. Methods. - We carried out a prospective case-control study in an internal medicine unit where general acute pathologies are recruited. We have included two patients without thrombosis for each patient admitted for a thrombo-embolic event. In all patients, at admission, clinical and biological risk factors for thromboembolism were systematically analysed in a physiopathological and chronological way. Results. - 450 patients were included during the 27 months period of the study. Among these patients, 150 were hospitalised for a deep venous thrombosis of the leg or/and a pulmonary embolism. Height risk factors have demonstrated their high thrombogenic potential: paralysis of the legs (OR = 13; 95% CI: 1.4 to 5.1), post-thrombotic syndromes (OR = 13; CI: 1.7 to 4.3), extrinsic compressions (OR = 8; Cl: 1.3 to 5.4), pregnancy (OR = 6; CL 1.2 to 6), malignancy occurred one year before (OR = 4; CI: 1.1 to 6.7), personal history of deep vein thrombosis (OR = 3; CI: 1.6 to 4.5), varicosity (OR = 2.5; CI: 1.2 to 6.1) and venous insufficiency (OR = 1.7; CI: 1 to 7.4). Four parameters, generally considered as risk factors, didn't prove here their pathogenic power: the age over 60, obesity (BMI > D), bedrest and the presence of an on-going malignancy. Conclusions. - Only risk factors with high thrombogenic power (as paralysis or extrinsic compression for example) could be identified by this kind of study performed in polypathological patients. In this particular population, usually recognised risk factors as age, obesity and bedrest are not determinant parameters for the thomboembolic risk evaluation. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.