Incidence of Idiopathic Deep Venous Thrombosis and Secondary Thromboembolism Among Ethnic Groups in California

Background: Few studies have compared the incidence of deep venous thrombosis among ethnic groups.

Objective: To determine the incidence of deep venous thrombosis among ethnic groups.

Design: Analysis of the linked California Patient Discharge Data Set from 1991 to 1994.

Setting: California.

Patients: 17991 patients with idiopathic deep venous thrombosis (thrombosis without cancer or hospitalization within preceding 6 months) and 5573 patients with secondary thromboembolism (thromboembolism occurring within 3 months of seven different events).

Measurements: Ethnicity was determined by using race as documented in the data set. For idiopathic deep venous thrombosis, standardized age- and sex-adjusted incidences were calculated. For secondary thromboembolism, proportional hazards modeling was done.

Results: The annual incidence of idiopathic deep venous thrombosis per 1000000 persons older than 18 years of age was 230 for white persons, 293 for African Americans (rate ratio, 1.27 [95% CI, 1.07 to 1.51]), 139 for Hispanic persons (rate ratio, 0.60 [CI, 0.54 to 0.67]), and 60 for Asians and Pacific Islanders (rate ratio, 0.26 [CI, 0.22 to 0.30]). Compared with white persons, Asians and Pacific Islanders who developed secondary thromboembolism had a significantly lower relative risk (range, 0.22 to 0.61) for all seven conditions analyzed.

Conclusions: Compared with white persons, Asians and Pacific Islanders have a very low incidence of idiopathic deep venous thrombosis and a very low relative risk for secondary venous thromboembolism.