A CASE-CONTROL STUDY OF THE RISK-FACTORS FOR DEEP-VEIN THROMBOSIS

Background: The ain of this study was to demonstrate risk factors for deep-vein thrombosis in adults in a hospital setting. Materials and Me thods: From May 1993 to Februrary 1995, 233 patients hospitalized in t he internal medicine unit at the Montpellier University Hospital for d eep-vein thrombosis were included. Each case was matched to a control case for age, hospitalization unit, and use or not of anti-thrombosis prophylaxy. Venous thrombosis was diagnosed in patients and confirmed to be absent in controls using duplex Doppler when phlebography findin gs were unconvincing. To eliminate possible false negatives (poor sens itivity of duplex Doppler in asymptomatic patients), all controls were contacted by telephone 3 to 6 months after discharge to ascertain whe ther or not they had been rehospitalized and if so for what reason. Th e patients and controls responded to questions designed to identify ri sk factors for deep-vein thrombosis described in the literature (patie nt characteristics, personal and family history, surgical history, ass ociated diseases, abnormal blood tests, medical treatment, life style) . Results: The three main risk factors for deep-vein thrombosis for al l ages and both sexes identified by multivariate analysis were : perso nal history of venous thrombosis (OR = 4.7, 95 % CI = [2.4; 8.9]), fam ily history of venous thrombosis (OR = 3.3, 95 % CI [1.8; 5.9]) and su rgical during the preceding 45 days (OR = 3.7, 95 % CI = [1.2; 10.9]). In non-menopaused women, the main risk factor was minidose oral contr aception (OR = 6.9, 95 % CI = [1.9; 25.4]). Conclusion: In our populat ion of hospitalized patients in an internal medicine unit, the main ri sk factor for thrombosis appeared to be, in general, a past history of venous thrombosis and in non-menopaused women, minidose oral contrace ption.