Evaluating the Effect of Ethnicity on the Risk of Venous Thromboembolism (VTE): A Systematic Review

Background

Studies of hospital discharge data and large observational cohorts show that the incidence of venous thromboembolism (VTE) varies by race. We sought to determine the incidence of VTE in each of the following ethnic groups Caucasians, Africans, Asians, and Hispanics.

Methods

A systematic literature search strategy was used to identify potential studies in MEDLINE, EMBASE, and CENTRAL using an OVID interface. The methodological quality of eligible studies was assessed according to Newcastle-Ottawa Quality Assessment Scale. The primary outcome measure was to identify the incidence/prevalence of VTE of each ethnic group available for the study in the context of a population based study.

Results

Out of 3418 potential studies, 19 met our inclusion criteria (Table). Of these, 9 studies were population based studies: 5 reported VTE incidence per 100,000 person-years (PY), 2 measured the standardized incidence ratio, and 2 European studies assessed VTE rate according to country of origin but not ethnicity (data not shown). In addition, 7 studies measured the hospital incidence rate of VTE, and 3 assessed VTE prevalence. Data could not be pooled due to marked heterogeneity including varied periods of study. VTE incidence per 100,000 PY was found to be between 162 and 439 in Caucasians, 143 and 746 in Africans, 3.2 and 16.6 in Asians. Hospital incidence of VTE per 100,000 PY was found to be between 21 and 131 in Caucasians, 22 and 155 in Africans, 2 and 26 in Asians, 33.1 and 71 in American Indians/Alaskan Indians, and 9 in Hispanics.

Conclusions

Our findings suggest a wide variation in reported incidence rates for VTE among different ethnic groups, even within the same group. In general, studies in Asian populations suggest a lower incidence of VTE. A marked heterogeneity of study designs, population settings prevent drawing firm conclusions. A significant risk of bias cannot be excluded for several studies. Further studies assessing concurrently the risk of VTE among different ethnicities in the same geographical area are needed.