Ancestry-independent risk of venous thromboembolism in individuals with sickle cell trait vs factor V Leiden

Sickle cell trait (SCT) is a risk factor for venous thromboembolism (VTE). Prior studies investigating the association between SCT and VTE have been performed nearly exclusively in Black populations. However, race-based research can contribute to systemic racism in medicine. We leveraged data from the 23andMe research cohort (4 184 082 participants) to calculate the ancestry-independent risk of VTE associated with SCT as well as comparative risk estimates for heterozygous factor V Leiden (FVL). Odds ratios (ORs) were calculated using a meta-analysis of 3 genetic ancestry groups (European [n = 3 183 142], Latine [n = 597 539], and African [n = 202 281]) and a secondary full-cohort analysis including 2 additional groups (East Asian [n = 159 863] and South Asian [n = 41 257]). Among the full cohort, 94 323 participants (2.25%) reported a history of VTE. On meta-analysis, individuals with SCT had a 1.45-fold (confidence interval [CI], 1.32-1.60) increased risk of VTE compared with SCT noncarriers, which was similar to the full-cohort estimate. The risk of pulmonary embolism (PE) in SCT (OR, 1.95; CI, 1.72-2.20) was higher than that of isolated deep venous thrombosis (DVT; OR, 1.04; CI, 0.90-1.21). FVL carriers had 3.30-fold (CI, 3.24-3.37) increased risk of VTE compared with FVL noncarriers, with a higher risk of isolated DVT (OR, 3.59; CI, 3.51-3.68) than PE (OR, 2.72; CI, 2.64-2.81). In this large, diverse cohort, the risk of VTE was increased among individuals with SCT compared with those without, independent of race or genetic ancestry. The risk of VTE with SCT was lower than that observed in FVL; however, the pattern of VTE in SCT was PE predominant, which is the opposite to that observed in FVL.