Risk factors for deep vein thrombosis and pulmonary embolism - A population-based case-control study

Background: Reported risk factors for venous thromboembolism (VTE) vary wid ely, and the magnitude and independence of each are uncertain. Objectives: To identified independent risk factors for deep vein thrombosis and pulmonary embolism and to estimate the magnitude of risk for each. Patients and Methods: We performed a population based, nested, case-control study of 625 Olmsted County, Minnesota, patients with a first lifetime VTE diagnosed during the 15-year period from January 1, 1976, through December 31, 1990, and 625 Olmsted County patients without VTE. The 2 groups were m atched on age, sex, calendar year, and medical record number. Results: Independent risk factors for VTE included surgery (odds ratio [OR] , 21.7; 95% confidence interval [CI], 9.4-49.9), trauma (OR, 12.7; 95% CI, 4.1-39.7), hospital or nursing home confinement (OR, 8.0; 95% CI, 4.5-14.2) , malignant neoplasm with (OR, 6.5; 95% CI, 2.1-20.2) or without (OR, 4.1;9 5% CI, 1.9-8.5) chemotherapy, central venous catheter or pacemaker (OR, 5.6 , 95% CI, 1.6-19.6), superficial vein thrombosis (OR, 4.3; 95% CI, 1.8-10.6 ), and neurological disease with extremity paresis (OR, 3.0; 95% CI, 1.3-7. 4). The risk associated with varicose veins diminished with age (for age 45 years: OR, 4.2; 95% CI, 1.6-11.3, for age 60 years: OR, 1.9; 95% CI, 1.0-3 .6; for age 75 years: OR, 0.9; 95% CI, 0.6-1.4),while patients with liver d isease had a reduced risk (OR, 0.1; 95% CI, 0.0-0.7). Conclusion: Hospital or nursing home confinement, surgery, trauma, malignan t neoplasm, chemotherapy, neurologic disease with paresis, central venous c atheter or pacemaker, varicose veins, and superficial vein thrombosis are i ndependent and important risk factors for VTE.