Inherited thrombophilia in unprovoked venous thromboembolism: Is non 'O' blood group an additional culprit in Indian patients?

BACKGROUND

Venous thromboembolism (VTE) is a known situation of considerable mortality and morbidity and occurs due to the convergence of multiple acquired and genetic risk factors.

METHODS

In this study, we have comprehensively analyzed the effect of ABO blood groups and inherited thrombophilia factors [Protein C (PC), Protein S (PS), Antithrombin III (AT III), Activated Protein C Resistance (APCR) and Homocysteine (Hcy)] on 150 unprovoked VTE patients, comparing with normal healthy controls. ABO phenotyping was done using gel cards and thrombophilia workup done using standard kits on coagulation autoanalyzer.

RESULTS

Non O blood group was significantly more frequent among cases than controls (77.3% vs. 62.7%) and had higher odds of VTE (OR = 2.03, 95%CI: 1.22-3.37).Positivity for at least one marker of thrombophilia was more in cases (40%) than controls (16%), and led to significantly higher odds (OR = 3.5, 95%CI: 2.03-6.04) of VTE. Deficiency of PS was the commonest thrombophilia abnormality.Combination of non O group with positivity for thrombophilia markers was also more among cases (OR = 5.67, 95%CI: 2.76-11.65). Highest odds of VTE in cases were associated with non O group in combination with increased Homocystein (OR = 10.8, 95%CI: 2.27-51.5).

CONCLUSION

The study results show non O blood group and positivity for factors of inherited thrombophilia in cases impart higher odds of VTE individually. Also combination of both non O blood group and positivity for factors of inherited thrombophilia in cases further increases the odds of VTE. This awareness could assist physicians in identifying those at higher risk of VTE and tailor-made the thromboprophylaxis accordingly.