Cushman M, Tsai AW, Heckbert SR, White RH, Rosamond WD, Enright P, Folsom AR. Deep vein thrombosis and pulmonary embolism in two cohorts: the Longitudinal Investigation of Thromboembolism Etiology (LITE). Am J Med 2004;117:19-25.

Abstract: Purpose: We studied the occurrence of deep vein thrombosis and pulmonary embolism in two cohorts representing regions of the United States.

Subjects and Methods: We studied 21,680 participants of the Atherosclerosis Risk in Communities Study and the Cardiovascular Health Study. Subjects were age =45 years, resided in six communities, and were followed for 7.6 years. All hospitalizations were identified and thromboses validated by chart review.

Results: The age-standardized incidence of first-time venous thromboembolism was 1.92 per 1000 person-years. Rates were higher among men than women, and with age. For 175/366 (48%) events there was no antecedent trauma, surgery, immobilization, or diagnosis of cancer. The 28-day case fatality after first venous thromboembolism was 29/265 (11%), and was 17/67 (25%) for cancer-associated thrombosis. With 2.2 years follow-up after a first venous thromboembolism, the recurrence rate was 7.7% per year (95% confidence interval [CI]: 4.5 – 10.9%). Among age, sex, type of thrombosis, and presence of cancer, cancer was the only factor independently associated with 28-day fatality or recurrent thrombosis, with relative risks of 5.2 (95% CI: 1.4 – 19.9) for fatality and 9.2 (95% CI: 2.0 – 41.7) for recurrence.

Conclusions: The incidence of venous thromboembolism in this cohort was similar to that observed in more geographically homogenous samples. Among these middle and older-aged subjects, about half of cases were idiopathic. Short-term mortality and 2-year recurrence rates after thrombosis were appreciable, especially among those with cancer. Based on this study we estimate 187,000 first-time venous thromboembolism are diagnosed yearly among Americans over age 45 years.