New study reveals key blood markers for sepsis diagnosis in burn patients

A recent study published in Scientific Reports, evaluated the efficacy of Complete Blood Count (CBC) parameters in diagnosing sepsis and predicting mortality among burn patients.

Study: Big data insights into the diagnostic values of CBC parameters for sepsis and septic shock in burn patients: a retrospective study. Image Credit: Andrey_Popov/Shutterstock.com

Background 

Sepsis, a life-threatening response to infection, is notably prevalent in burn patients, posing a substantial health challenge globally due to high mortality.

Early detection, crucial for mitigating adverse outcomes, is hindered by the limited efficacy, slow results, and high costs of current biomarkers.

In response, CBC and CBC ratio markers are emerging as viable, cost-effective diagnostic tools. Recent studies validate the Platelet-to-Lymphocyte Ratio (PLR), Neutrophil-to-Lymphocyte Ratio (NLR), and Mean Platelet Volume (MPV) to Platelet count ratio as accessible indicators for early detection and severity assessment of sepsis.

Red Cell Distribution Width (RDW) also shows promise as a predictor of disease severity and mortality. Further research is needed to validate the effectiveness of these biomarkers in diverse clinical settings and to ensure their reliability and applicability across different patient populations. 

About the study

The present study was a retrospective cohort analysis of 2,757 adults aged 18 and over admitted to Hangang Sacred Heart Hospital’s Burn Intensive Care Unit (ICU) between January 2010 and December 2022.

It primarily focused on the incidence of sepsis in all patients, with a secondary analysis on 1806 patients who developed sepsis, specifically examining the occurrence of septic shock.

Data were collected from the Clinical Data Warehouse (CDW), which included key details like sex, diagnosis, age, and ICU stay duration. Sepsis and septic shock diagnosis followed the Sepsis-3 criteria, verified by the institution’s research and the findings from the Surviving Sepsis After Burn (SSABC) guidelines.

Daily CBC parameters during the ICU stay, particularly in the week before sepsis or septic shock onset, were compiled.

Other disease severity indicators, such as Acute Physiology and Chronic Health Evaluation IV (APACHE IV), Sepsis-related Organ Failure Assessment score (SOFA) score, Abbreviated Burn Severity Index (ABSI), Revised Baux score (rBaux), and the Hangang Score, were also recorded.

The Hangang Score, tailored for burn patients, uses logistic regression coefficients for variables like total body surface area burned (% TBSA), age, presence of inhalation injury, and levels of various biochemical markers to estimate mortality risk.

The primary outcomes were the incidence of sepsis and septic shock, while the secondary outcome was the 60-day in-hospital mortality rate.

The study also defined various ratio markers, including NLR, PLR, Monocyte-to-Lymphocyte Ratio (MLR), Systemic Immune-Inflammation Index (SII), and MPV-related ratios, all of which are crucial for understanding the inflammatory response in patients.

Statistical analysis involved presenting continuous variables as means ± standard deviation (SD) or medians with interquartile range (IQR) and categorical variables as percentages. Tests used included independent t-tests, Mann–Whitney U-tests, and the Chi-square test.

Generalized Estimating Equations (GEE) were applied to analyze temporal changes and predict sepsis and septic shock. The predictive value of the GEE model was assessed using Area Under the Curve (AUC) analysis, along with other metrics like accuracy, sensitivity, specificity, and predictive values.

Mortality prediction involved using the log-rank test and calculating hazard ratios (HR) with the Cox proportional hazards model, adjusting for significant predictors like age, TBSA, and inhalation injuries. All analyses were conducted using the R-project program version 4.3.0.

Study results 

In the retrospective study involving 2,757 burn patients, 1,806 (65.5%) developed sepsis, and 669 (24.3%) experienced mortality. Gender did not significantly influence the outcomes of sepsis or mortality.

Most CBC parameters, excluding eosinophils, MCH, MPV-to-Lymphocyte Ratio (MPVLR),  PLR, and MPVMR, displayed significant differences in relation to sepsis and mortality outcomes.

The odds ratios for age, TBSA burned, and inflammation, key prognostic factors in burn patients, were also significant. The study identified certain markers with an AUC over 0.65: RDW, MPV, NLR, MPV-to-Platelet Ratio (MPVPR), and MPVLR as significant for sepsis.

These markers also demonstrated predictive value for mortality, with RDW, MPV, Platelet Distribution Width (PDW), and MPVPR showing Hazard Ratios (HR) and adjusted HRs above 1.

Among patients with sepsis, 484 (26.8%) succumbed to mortality, and 341 (18.9%) developed septic shock. Gender differences were again not significant in septic shock or mortality outcomes.

For diagnosing septic shock, markers such as platelet count, PDW, and MPVPR had AUC values above 0.65. RDW and the SII were significant in all temporal changes for diagnosing septic shock. Most markers, except monocyte count and SII, showed statistical differences in mortality prediction.

The study’s key findings highlight the predictive value of RDW, MPV, MPVPR, NLR, and MPVLR for sepsis. RDW and NLR are particularly notable for their association with increased mortality in septic burn patients.

This is supported by meta-analyses indicating higher baseline RDW in non-surviving sepsis patients. MPV-related ratios, particularly MPVPR and MPVLR, emerged as significant markers in diagnosing sepsis, reflecting the interplay between platelets and lymphocytes.

These findings are insightful for understanding the immune-inflammatory response in burn infections, although factors like TBSA burned, patient age, and overall inflammation status may influence these markers’ effectiveness.