Groupe O: Plus de mortalité ?

The impact of blood type O on mortality of severe trauma patients: a retrospective observational study.

Takayama W et Al. Crit Care. 2018 May 2;22(1):100. doi: 10.1186/s13054-018-2022-0

 

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BACKGROUND:

Recent studies have implicated the differences in the ABO blood system as a potential risk for various diseases, including hemostatic disorders and hemorrhage. In this study, we evaluated the impact of the difference in the ABO blood type on mortality in patients with severe trauma.

METHODS:

A retrospective observational study was conducted in two tertiary emergency critical care medical centers in Japan. Patients with trauma with an Injury Severity Score (ISS) > 15 were included. The association between the different blood types (type O versus other blood types) and the outcomes of all-cause mortality, cause-specific mortalities (exsanguination, traumatic brain injury, and others), ventilator-free days (VFD), and total transfusion volume were evaluated using univariate and multivariate competing-risk regression models. Moreover, the impact of blood type O on the outcomes was assessed using regression coefficients in the multivariate analysis adjusted for age, ISS, and the Revised Trauma Score (RTS).

RESULTS:

A total of 901 patients were included in this study. The study population was divided based on the ABO blood type: type O, 284 (32%); type A, 285 (32%); type B, 209 (23%); and type AB, 123 (13%). Blood type O was associated with high mortality (28% in patients with blood type O versus 11% in patients with other blood types; p <  0.001). Moreover, this association was observed in a multivariate model (adjusted odds ratio = 2.86, 95% confidence interval 1.84-4.46; p <  0.001). The impact of blood type O on all-cause in-hospital mortality was comparable to 12 increases in the ISS, 1.5 decreases in the RTS, and 26 increases in age.

 

The comparison of characteristics and outcomes between blood type O and other blood types

	Type O n = 284	Non-O type n = 617	p value
Characteristics
Age, years (SD)	57.3 (20.0)	56.2 (19.4)	0.442
Female, n (%)	64 (22.5)	142 (23)	0.873
Charlson Comorbidity Index, median (IQR)	0 (0–2)	0 (0–1)	0.829
Uncrossmatched type O RBC transfusion, n (%)	28 (9.9)	37 (6)	0.051
RTS, (SD)	6.85 (1.4)	7.13 (1.2)	0.003
ISS, median (IQR)	18 (16–25)	19 (16–25)	0.160
AIS head, median (IQR)	4 (3–4)	4 (3–4)	0.582
AIS face, median (IQR)	0 (0–0)	0 (0–0)	0.783
AIS chest, median (IQR)	0 (0–2)	0 (0–3)	0.342
AIS abdomen, median (IQR)	0 (0–0)	0 (0–0)	0.561
AIS extremities, median (IQR)	0 (0–2)	0 (0–2)	0.443
AIS surface, median (IQR)	0 (0–0)	0 (0–0)	0.652
Outcomes
In-hospital mortality, n (%)	80 (28.2)	71 (11.5)	< 0.001
Death due to exsanguination, n (%)	23 (8.1)	15 (2.4)	< 0.001
Death due to TBI, n (%)	43 (15.1)	44 (7.1)	< 0.001
Death due to other causes, n (%)	15 (1.8)	11 (5.3)	0.005
Ventilator-free days, mean (SD)	18.7 (12.2)	23.1 (9.4)	< 0.001
Units of RBCs administered within 24 h, mean (SD)	3 (9)	2 (7)	0.112

 

Categorical variables are expressed as numbers (%); continuous variables are presented as medians (25–75 percentiles = interquartile range (IQR))

AIS Abbreviated Injury Scale; ISS Injury Severity Score; RBC red blood cell; RTS Revised Trauma Score; SD standard deviation; TBI traumatic brain injury

 

Furthermore, blood type O was significantly associated with higher cause-specific mortalities and shorter VFD compared with the other blood types; however, a significant difference was not observed in the transfusion volume between the two groups.

CONCLUSIONS:

Blood type O was significantly associated with high mortality in severe trauma patients and might have a great impact on outcomes. Further studies elucidating the mechanism underlying this association are warranted to develop the appropriate intervention.