# Blood type O increased perioperative blood loss in total knee arthroplasty: a propensity score-based inverse probability of treatment weighting matched analysis

## TL;DR

People with blood type O experience more blood loss during total knee replacement surgery compared to other blood types.

## Contribution

This study identifies a novel association between blood type O and increased perioperative blood loss in knee arthroplasty.

## Key findings

- Blood type O patients had significantly higher blood loss than other blood types.
- After adjusting for baseline factors, blood type O still showed higher blood loss compared to others.

## Abstract

The aim of this study was to compare total perioperative blood loss in patients undergoing total knee arthroplasty (TKA) in different ABO blood types.

This study was approved by the Institutional Review Board of our hospital (IRB No. 1510) on 2 February 2015. A total of 260 knees undergoing unilateral primary cemented cruciate-retaining TKA for knee osteoarthritis were retrospectively registered. Perioperative total blood loss was calculated for each blood types based on the change in hematocrit from pre- to postoperative day 7, preoperative height and weight. Differences in blood loss among the four ABO blood types were assessed. The association between blood type (O versus others) and total blood loss was further evaluated after adjusting for baseline characteristics through inverse probability of treatment weighting (IPTW).

The study population was divided based on the ABO blood type: type O, 87; type A, 82; type B, 54; and type AB, 37. The mean total blood loss was 829 ± 370 ml for type O, 702 ± 384 ml for type A, 574 ± 361 ml for type B, and 528 ± 282 ml for type AB. Patients with blood Type O had significantly higher blood loss than all other blood types. After IPTW adjustment, mean total blood loss remained higher in type O (790 ± 370 ml) compared to other blood types (613 ± 364 ml).

These findings suggest that blood type O may be associated with increased perioperative blood loss in TKA.