SUMMARY Little is known about the biological epidemiological and clinical risk factors for thrombosis and venous thromboembolism (VTE) among Black Africans. with VTE occurrence. Additionally 16 cases and 2 controls had protein S (PS) values of less than 48.4% (M-2SD) exhibiting a highly significant difference (< 1 × 10?4). The number of cases with a low protein C (PC) level was significantly higher than the respective number of controls. Using logistic regression methods we established a correlation between significantly associated variables and deep venous thrombosis (DVT) occurrence. Age obesity sickle cell disease and PC deficiency were not significantly associated with thrombosis. In contrast gender PS deficiency varicose veins surgery non-O blood type and the presence of antiphospholipid antibodies were significantly and independently associated with DVT. These findings are extremely useful for clinical management of patients suffering from DVT and can help to reduce the high recurrence rate observed in our study. < 0.05. Multivariate analysis was conducted using Stata software enabling the actual effect of various risk factors to be measured by logistic regression. Ethical approval This study was approved by ethical committee of each of the five hospitals where we recruited patients and controls. All samples were performed after patient consent. Results Patients and controls A total of 150 cases were found but statistical analysis was performed on 105 patients as 45 cases have missing information or MLN 0905 technical issues with their samples. Epidemiological and clinical risk factors Age and sex factors The mean age for cases was 42 years ranging from 17 to 78 years. The mean age of the control population was 38 years ranging from 18 to 65 years. Women were more prone to thrombosis accounting for 81 of the 105 cases (77%). Women made up 62% (125 of 200) of the control population. This difference was statistically significant (= 0.009). Clinical locations of thrombosis Most DVT cases occurred in the lower limbs (71%) predominantly on the left side (58%). We also observed 17 cases of PE four of which were associated with DVT of the left lower limb (LLL) at the time of diagnosis; ten cases of cerebral venous thrombosis (CVT); three cases of retina central vein IL13RA1 antibody thrombosis and two of upper limb thrombosis (ULDVT). A total MLN 0905 of 42 cases were included because of recurrent thrombotic events. Recurrence mainly involved the initial thrombosis site (66%). In two patients the recurrence affected the opposite limb. Two patients experienced multiple recurrence of thrombosis that might be described as true thromboembolic disease. Fourteen patients had a family history of DVT. Additional findings Other signs MLN 0905 of thrombotic disease were iterative fetal losses (IFL). Apart from cases of LL thrombophlebitis or PE 21 women suffered obstetrical accidents such as IFL. This accounted for a quarter of the female case population ie a significantly higher proportion than in the female control population (= 0.006). Four patients suffered a kidney disease-related failure associated with DVT as a result of thrombosis of renal vessels. No control suffered any kidney disease. Sickle cell disease was diagnosed (both homozygote and heterozygote) in 14 patients and 13 individuals in the control group with a significant difference between the two populations (= 0.043). Other risk factors for thrombosis Some risk factors related to patient background were significantly associated with DVT risk: oral contraceptives immobilization by casts surgery and ABO blood group. There was no association with other factors such as smoking or obesity (Table 1). Table 1 Demographics of case and control. Biological risk factors PS 16 cases and 2 controls had PS values below 48.4% (M-2SD); the difference was significant (< 0.01). The free antigen assay performed on 11 patients confirmed decreased SP anti-clotting activity. PC The number of cases with a low PC rate was significantly greater than the number of controls exhibiting a comparable decrease (nine compared to five subjects) with = 0.015 (cut off value = 54%). Antithrombin A decreased antithrombotic rate (<76%) was found in only two cases and one control. The difference between the two populations was not significant (= 1.39). No factor II or V mutation was observed either among patients or controls (Table 2). Table 2 Biological abnormalities.