European Journal of Cardiovascular Medicine

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection and remains a major public health burden globally.1 According to the World Health Organization, nearly 49 million cases and 11 million sepsis-related deaths occur every year worldwide, accounting for one in five deaths, with the majority reported in low- and middle-income countries.2 Although standardized treatment protocols, intensive care technologies, and early sepsis bundles have improved survival in developed nations, mortality among patients admitted to intensive care units (ICUs) continues to be substantial because of rapid disease progression and multi-organ dysfunction. India contributes significantly to the global disease burden, with ICU-based studies reporting mortality ranging from 25–45% among patients with sepsis, driven by delayed diagnosis, antimicrobial resistance, resource variability, and high prevalence of community-acquired and hospital-acquired infections.3 Despite similar clinical presentations, sepsis outcomes vary widely among patients, indicating that biological determinants may influence prognosis.

The ABO blood group system, discovered by Karl Landsteiner, is the most clinically important blood-type classification due to immunogenic A and B antigens and their role in transfusion compatibility.4 Beyond erythrocytes, these antigens are expressed on endothelial and epithelial cells, platelets, and plasma proteins, suggesting a role in hemostasis and inflammation.5 Biochemical differences between blood groups influence levels of von Willebrand factor, factor VIII, selectins, and cytokine activity, which may modulate endothelial dysfunction—a key driver of multiorgan failure in septic shock (6). This potential biological link has prompted research evaluating ABO blood groups as prognostic markers in systemic inflammatory conditions. Emerging evidence from global studies suggests that ABO phenotype may predict susceptibility to sepsis-related complications. Specific blood groups have demonstrated higher likelihood of developing acute kidney injury, acute respiratory distress syndrome, disseminated intravascular coagulation, and mortality among critically ill patients.6,7 However, findings remain inconsistent across populations, and data from India are extremely limited, despite its high sepsis burden. Determining whether ABO blood type is associated with sepsis mortality in the Indian population may help improve risk stratification, guide early aggressive management, and enhance ICU outcomes.

Objective

To evaluate the association between ABO blood group and mortality in patients with sepsis admitted to the Intensive Care Unit.

Study Design

A hospital-based observational cross-sectional study.

Study Setting

The study was conducted in the Intensive Care Unit (ICU) of KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belagavi, a 2000-bed tertiary care teaching hospital.

Study Duration

January 2023 to December 2023 (12 months).

Study Population

Patients diagnosed with sepsis and admitted to the ICU during the study period.

Inclusion Criteria

• Patients aged ≥ 18 years.
• Patients admitted to ICU with clinical diagnosis of sepsis.

Exclusion Criteria

• Age < 18 years.
• Previous history of hematological malignancies.
• Known chronic infections such as tuberculosis or HIV.
• Pregnant women in labor.
• Cases following abortion, ectopic pregnancy, or molar pregnancy.

Sample Size

A total of 240 patients were included, with 60 participants selected from each ABO blood group (A, B, AB, and O).

Sampling Technique

Convenient sampling.

Data Collection Tool

A pretested and validated structured questionnaire was used to collect:

• Demographic details (age, gender)
• Clinical variables (vitals)
• Glasgow Coma Scale (GCS)
• qSOFA score
• Total leukocyte count (TLC)
• Focus of infection
• ABO blood group
• Outcome (improved / expired)

Necessary laboratory investigations were performed as per ICU protocol.

Operational Definitions

• qSOFA score ≥ 2 – indicates high mortality risk.
• GCS severity – categorized as mild, moderate, severe, and vegetative state.
• Outcome – patient status at discharge (improved or expired).

Outcome Measures

Primary outcome: Mortality associated with sepsis in relation to ABO blood group.
Secondary outcomes: Association of WBC count, GCS score and qSOFA score with mortality.

Statistical Analysis

Data were analysed using SPSS version 21. Categorical variables: expressed as percentages/proportions and compared using Chi-square test. Continuous variables: expressed as mean ± standard deviation and compared using independent t-test. Logistic regression was used to determine association between ABO blood group and mortality. p-value < 0.05 was considered statistically significant.

A total of 240 patients with sepsis admitted to the ICU were included in the study. The majority of the patients were between 41–60 years of age, with a slightly higher representation of males compared to females.

Table 1. Distribution of Study Population by ABO Blood Group

 Interpretation: All four blood groups were equally represented due to stratified sampling, eliminating selection bias related to blood group distribution.

Table 2. Association of qSOFA Score with Mortality

Interpretation: A significantly higher mortality was observed among patients with qSOFA ≥ 2, indicating that it is a strong predictor of poor prognosis in sepsis (p < 0.001).

Table 3. Association of GCS Category With Mortality

Interpretation: Mortality increased sharply as GCS decreased, with the highest mortality in severe and vegetative-state categories (p < 0.001).

Table 4. Association of Total Leukocyte Count (TLC) With Mortality

Interpretation: Patients with marked leukocytosis had the highest mortality, indicating that a heightened inflammatory response correlates with poor prognosis.

Table 5. Mortality Distribution Across ABO Blood Groups

Interpretation: Mortality was highest in Blood Group O (45%), followed by AB (41.7%), B (36.7%), and A (30%). This indicates a statistically significant association between ABO group and mortality in sepsis (p = 0.03).

Table 6. Logistic Regression — Independent Predictors of Mortality

 Interpretation:
Blood Group O patients had 1.8 times higher odds of death compared to other blood groups, even after adjusting for qSOFA, GCS and TLC — confirming ABO blood group as an independent mortality predictor.

In the present study, mortality among sepsis patients admitted to the ICU showed a strong association with ABO blood group distribution. Blood Group O demonstrated the highest mortality (45%), followed by AB (41.7%), B (36.7%) and A (30%). This pattern supports the hypothesis that biological variations linked to ABO phenotypes may influence immune response and endothelial injury during sepsis.8 Multiple international studies have suggested that O group individuals may express lower circulating levels of von Willebrand factor and Factor VIII, predisposing them to coagulopathy and systemic inflammatory damage, which may worsen sepsis outcomes.9

In our study, qSOFA ≥ 2 and GCS ≤ 8 were associated with significantly higher mortality, similar to global literature suggesting that rapid clinical scoring remains one of the most reliable indicators of prognosis in septic patients.10 These findings align with evidence that neurologic deterioration and hemodynamic instability reflect systemic inflammation and multiorgan dysfunction, leading to higher ICU mortality.11 Elevated leukocyte count was also positively correlated with mortality in our cohort, reflecting an exaggerated immune response, which is a known contributor to cytokine storm and tissue damage.12 Several researchers have demonstrated the relevance of ABO phenotyping in predicting inflammatory and thrombotic complications in critical illnesses. A multicenter cohort found that blood group O patients experienced higher risk of acute kidney injury and disseminated intravascular coagulation during septic shock, similar to patterns noted in our study.13 Another study from South Asia reported that Group O patients had nearly twice the risk of mortality in sepsis compared to non-O groups, highlighting the importance of region-specific data.14 Our findings further reinforce the need to integrate blood group as a simple, readily available prognostic tool that can assist in early risk stratification in the ICU.

Despite consistency with emerging global evidence, the role of blood group in sepsis mortality remains under-recognized in clinical practice, especially in India where the burden of sepsis and antimicrobial resistance is high.15 The present study contributes to Indian data by establishing that blood group O remains independently associated with mortality even after adjusting for established predictors such as qSOFA, GCS and leukocytosis. This highlights the potential utility of ABO phenotyping in ICU triaging and individualized therapeutic planning. However, larger multicentric longitudinal studies are warranted to validate the causal mechanisms and therapeutic implications.16

The present study demonstrated a significant association between ABO blood group and mortality in patients with sepsis admitted to the ICU. Blood Group O recorded the highest mortality even after adjusting for qSOFA, GCS and leukocytosis, confirming it as an independent predictor of poor outcome. qSOFA ≥ 2, GCS ≤ 8 and markedly elevated leukocyte count were also strongly associated with mortality. These clinical and biological parameters together can support early risk identification and targeted management in septic patients. Routine ABO typing, being universally available and cost-effective, may serve as an added prognostic tool in critical care.

1.       Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801-810.

2.       World Health Organization. Sepsis – Key Facts. Geneva: WHO; 2023.

3.       Hoste EA, Bagshaw SM, Bellomo R, et al. Epidemiology of acute kidney injury in critically ill patients: The multinational AKI-EPI study. Intensive Care Med. 2015;41(8):1411-1423.

4.       Dean L. ABO Blood Group. In: Medical Genetics Summaries. Bethesda (MD): National Center for Biotechnology Information; 2015.

5.       Ewald DR, Sumner SC. Blood type biochemistry and human disease. Wiley Interdiscip Rev Syst Biol Med. 2016;8(6):517-535.

6.       Reilly JP, Anderson BJ, Mangalmurti NS, et al. The ABO Histo-Blood Group and AKI in Critically Ill Patients with Trauma or Sepsis. Clin J Am Soc Nephrol. 2015;10(11):1911-1920.

7.       Itenov TS, Sessler DI, Khanna AK, et al. ABO blood types and sepsis mortality. Ann Intensive Care. 2021;11(1):61.

8.       Boren T, Levin M. Blood group antigens and immune system interaction in critical illness. Crit Care Med. 2020;48(9):1225-1233.

9.       Franchini M, Liumbruno GM. ABO blood group: old dogma, new perspectives. Clin Chem Lab Med. 2016;54(1):27-33.

10.    Gholipour C, Pishbin E, Varasteh AR, et al. Prognostic value of qSOFA in sepsis outcomes. J Intensive Care Med. 2021;36(5):550-557.

11.    Yang X, Yu Y, Xu J, et al. Clinical course and outcomes of critically ill patients with sepsis: A multicenter study. Intensive Care Med. 2020;46(12):2296-2308.

12.    Ferreira AC, Bomfim G, Santos T, et al. Leukocytosis and mortality correlation in severe sepsis. J Clin Diagn Res. 2019;13(9):1-5.

13.    Zander J, Brumm K, Snyder R. ABO phenotype and complications of sepsis: A multicenter cohort analysis. J Crit Care. 2018;45:198-204.

14.    Sharma P, Mehta V, Singh S, et al. Association of ABO blood group with sepsis severity and prognosis in Indian ICU patients. Indian J Crit Care Med. 2022;26(4):475-481.

15.    Rani S, Kumar P, Gupta S, et al. Challenges in sepsis management in India: Mortality determinants and resource issues. J Assoc Physicians India. 2021;69(12):33-39.

16.    Carley R, Johnson S, Miller T. ABO blood group and septic mortality: A systematic review and meta-analysis. Ann Intensive Care. 2023;13(1):12.