Sickle Cell Trait: Is There an Increased VTE Risk in Pregnancy and the Postpartum?

Henny H Billett,Peter Whittaker,Hillel W Cohen,Sofya Pintova

doi:10.1371/journal.pone.0064141

Henny H Billett, Peter Whittaker + Show 2 more

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https://doi.org/10.1371/journal.pone.0064141

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Abstract

Blacks are purported to have a higher venous thromboembolism (VTE) risk than whites. We hypothesized that this might be due, in part, to the greater presence of sickle cell trait (SCT) among blacks. We investigated whether the presence of SCT resulted in a higher VTE incidence in a population predisposed to VTE, the pregnant/postpartum women. Methods: Using a mirrored clinical database that prospectively gathered in- and out-patient information for the years 1998–2008, we collected demographic data, including hemoglobin electrophoreses, on all pregnant/postpartum non-Hispanic women who delivered at a large, diverse, urban hospital. We identified those women who developed VTE either while pregnant or postpartum during those 11 years. Charts initially identified as potential VTE cases were subjected to review to ensure accuracy of VTE coding. Results: Of 12,429 women, 679 non-Hispanic SCT black women, 5,465 non-Hispanic Hemoglobin AA (women with HbA as the only hemoglobin present on electrophoresis, with normal amounts of the minor hemoglobins) black women and 1,162 non-Hispanic HbAA white women were included in the analysis. SCT prevalence was high (11.1%) within this black population as compared to 8.3% in the general non-white population. Proportions with VTE were similar for black SCT and black HbAA groups: 0.44% for the SCT group, 0.49% for non-Hispanic black HbAA women. Black HbAA women had a non-significantly higher proportion of VTE than white HbAA women 0.49% vs 0.26% (RR 1.9, 95%CI:0.6,6.3, p = 0.28). Women with VTE were older than those without VTE (32.2 vs. 27.6 years, p = 0.0002) and the majority of VTE occurred postpartum in all groups, and significantly in the HbAA groups. There was no increase in the incidence of pulmonary emboli in the SCT group. Conclusion: In the largest analysis to date, we could not detect a meaningful difference in peripartum VTE incidence between women with and without sickle cell trait.

Highlights

Venous thromboembolism (VTE) is a major cause of mortality in the United States
In order to investigate this aspect, we studied black and white non-Hispanic women with sickle cell trait (SCT) and HbAA to determine whether women with SCT had a higher occurrence of thromboembolic events during pregnancy and the postpartum when compared to non-SCT women
Several studies have described a higher rate of VTE in blacks and some have investigated the association of SCT with thromboembolic disease [6,7,8,9,10,11,16,17,18]

Summary

Introduction

The genetic risk factors for VTE that have been identified, such as non-O blood groups, Factor V Leiden and Prothrombin 20210, are more common in whites than blacks [1,2,3,4,5]. This would favor the hypothesis that the burden of thromboembolic disease would be higher in white than in black individuals. Sickle cell anemia is a genetic disease more prevalent in the black population and results in both an anemia and vaso-occlusion of blood vessels, typically post capillary venules. Sickle cell anemia has been associated with an increased incidence of VTE [13]

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Conclusion