# Classic Coagulation Traits Vary According to Rh(D) (But Not ABO) Blood Groups

## TL;DR

This study found that coagulation traits differ based on Rh(D) blood group but not ABO blood group, suggesting a possible inhibitory effect of Rh(D) on blood clotting.

## Contribution

The study reveals novel evidence that Rh(D) blood group influences coagulation parameters, unlike the ABO system.

## Key findings

- Rh-positive individuals had higher prothrombin time (PT), activated partial thromboplastin time (APTT), and INR values compared to Rh-negative individuals.
- No significant coagulation differences were found between ABO blood groups.
- The Rh(D) antigen may inhibit the coagulation pathway, leading to slower clotting in Rh-positive individuals.

## Abstract

Background: This study evaluated possible variations in classic blood coagulation parameters according to groups formed from the main erythrocyte antigen systems. Methods: Consecutive patients admitted to a transfusion hemotherapy service at a private hospital in the Brazilian Federal District were evaluated for coagulation profile and blood type according to routine laboratory practices. The international normalized ratio (INR), the activated partial thromboplastin time (APTT) and the prothrombin time (PT) were compared according to the ABO blood group and the Rh factor in analyses controlled for classic influencers such as age, sex and comorbidities. Results: No significant differences in coagulation were found between groups defined by the ABO antigen system, despite a body of evidence in favor of this correlation. Rh-positive individuals showed increased mean values in PT (13.7 vs. 12.6 s), in APTT (32.0 vs. 30.1 s) and in INR (1.23 vs. 1.15 s) when compared to the Rh-negative counterparts. Conclusions: Our results suggest a lowered rate of coagulation among Rh-positive individuals, possibly owing to inhibitory effects of the Rh(D) erythrocyte antigen on the coagulation pathway.