Summary
There have been very few studies that have describe the epidemiology of first-time
venous thromboembolism (VTE) in a large, ethnically diverse population. The California
Discharge Data Set was used to identify a cohort of cases with incidentVTE in 1996.
Cases associated with traditional provoking risk factors were identified and the remaining
cases were labeled as idiopathicVTE. Direct standardization using census information
was performed to compare incidence rates across races, gender, and gender within race.
There were 21,002 cases with incident VTE in 1996, a crude incidence of 90 events
per 100,000 adults. Thirty percent of all VTE events were pulmonary embolism. The
directly standardized incidence per 100,000 California adults was 93 ± 1.7 ( ± 95%
CI) in women, 85 ± 1.7 in men, 103 ± 2.1 in Caucasians, 138 ± 6.5 in African- Americans,
61 ± 2.8 in Hispanics and 29 ± 2.4 in Asian-Pacific Islanders (p<0.001 for all inter-group
comparisons). After adjusting for misclassification of race, the incidence of VTE
per 100,000 was 104 in Caucasians, 141 in African- Americans, 55 in Hispanics, and
21 in Asian/Pacific-Islanders. The incidence of idiopathic VTE was significantly lower
among both Hispanics and Asian/Pacific-Islanders (p<0.001) than Caucasians or African-Americans.
African-Americans were more likely, and Hispanics less likely, to be diagnosed with
idiopathic pulmonary embolism compared to Caucasians. The 28 day case-fatality rate
among cases with idiopathic VTE was 2%, and it was significantly higher among African-Americans
(4.1%) compared to Caucasians (1.8%, p<0.001).There are important differences in the
incidence of total and idiopathicVTE and in the proportion of events diagnosed as
pulmonary embolism among each of the major racial/ethnic groups in California. Further
research is needed to explain these observed differences among the different racial/ethnic
group.
Keywords
Thrombosis - epidemiology - population - statistics