Using the ΔPCT/ALB Ratio to Predict Secondary Infections in Sepsis Patients

Introduction

Emerging medical technologies like flow cytometry offer insights into immune cell function to forecast secondary infections. However, these methods come with complexity and high costs. Studies have highlighted Procalcitonin (PCT) as a valuable biomarker for diagnosing sepsis and guiding antibiotic therapy. Yet, relying solely on PCT poses challenges. A recent proposition by Deng et al suggests using the albumin/procalcitonin (ALB/PCT) ratio to predict bloodstream infections in patients with cerebral hemorrhage, underscoring the enhancement in predictive value by combining biomarkers.³

During inflammation and sepsis, PCT production, although understood to be stimulated by bacterial Lipopolysaccharide (LPS) and endotoxins, remains incompletely characterized. Albumin (ALB), primarily synthesized by liver hepatocytes, constitutes 40 to 60 percent of plasma proteins, serving critical roles in maintaining blood pressure and transporting substances. Albumin is also a key nutritional indicator and directly linked to immunocompromised states.⁷

Study Design and Population

A prospective observational study was conducted at Guangdong Provincial People’s Hospital ICU, with ethical approval and informed consent from all participants. The study focused on sepsis patients meeting Sepsis-3 criteria, excluding individuals with chronic diseases, cancer, or immune suppressants. Enrolled patients were evaluated within 24 hours of admission and followed for at least 28 days. The primary outcome was preventing secondary infections, while secondary outcomes included mortality and ICU and hospital stay duration.¹⁰

Methodology

Baseline characteristics such as demographics, vital signs, and laboratory results were recorded. Patients were categorized into groups based on the presence or absence of secondary infections within 28 days. Statistical analysis utilized chi-squared, Fisher’s exact, and Mann-Whitney U tests for comparing categorical and continuous variables. Multivariate logistic regression assessed the association between ΔPCT/ALB change and outcomes, adjusting for various confounding factors.⁹

Results

Figure 1 Schematic of the Study Procedure.

Multivariable analysis identified ΔPCT/ALB adm-72h as a significant independent predictor of secondary infection (OR 2.370; 95% CI 1.138-4.935; p = 0.02), alongside mechanical ventilation. When stratified into quartiles, patients in higher ΔPCT/ALB adm-72h groups exhibited a higher likelihood of secondary infections.5

Table 2 Clinical Features and Prognosis Across Quartiles of ΔPCT/ALB adm-72h

Figure 2 Secondary Infection Rate Across Quartiles of ΔPCT/ALB adm-72h. Notes: Groups were defined according to the ΔPCT/ALB adm-72h quartile. Adjusted for variables including age, sex, SOFA score, APACHE-II score, primary infection source, presence of indwelling catheters, and initial mechanical ventilation.

Discussion

The study revealed ΔPCT/ALB adm-72h as a valuable marker for identifying secondary infections in septic patients, especially among survivors. This marker outperformed the static PCT/ALB ratio, indicating that temporal fluctuations in this ratio may provide more accurate predictions. Elevated initial PCT values suggest bacterial infections, often correlating with higher secondary infection risks and an increased need for antibiotics.13 Lower PCT values, on the other hand, may indicate opportunistic pathogens, potentially underlining ineffective anti-infective treatment that could prolong hospital stays.

Albumin, produced by the liver, serves as a nutritional and immune status indicator. Its changes impact oncotic pressure, organ perfusion, and therapeutic outcomes. Lower albumin levels may predict a more severe disease course and increased morbidity.¹⁵

The robust predictive power of the ΔPCT/ALB ratio underscores its potential clinical utility, yet no threshold has been established. Future research should focus on cultivating larger datasets and identifying appropriate thresholds for improved clinical decision-making.

Limitations

The study’s limited sample size, drawn from multiple ici units, poses a significant limitation. Additionally, it lacked in vitro experiments exploring PCT/ALB interactions with inflammatory and immune functions. The absence of subgroup analyses for different infection sources and pathogens may also limit individualized application of findings.

Conclusion

The ΔPCT/ALB ratio in the initial 72 hours of sepsis onset may serve as a practical and convenient tool for predicting secondary infections, enhancing the course of treatment and patient outcomes.

Abbreviations

ALB, Albumin; APACHE II, Acute Physiology and Chronic Health Evaluation II; CI, Confidence Interval; ICU, Intensive Care Unit; OR, Odds Ratio; PCT, Procalcitonin; SOFA, Sequential Organ Failure Assessment.

Data Sharing Statement

The datasets generated during this study are available from the corresponding author upon reasonable request.

Ethics Approval and Consent to Participate

The study received approval from the Guangdong Provincial People’s Hospital Ethics Committee and obtained informed consent from all participants.

Author Contributions

Detailed contributions of each author are outlined in the supplementary materials.

Funding

Funding information for the study is reported in the supplementary materials.

Disclosure

The authors declare no competing interests.

References

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13. Li Y, Min L, Zhang X. Usefulness of procalcitonin (PCT), C-reactive protein (CRP), and white blood cell (WBC) levels in the differential diagnosis of acute bacterial, viral, and mycoplasmal respiratory tract infections in children. BMC Pulm Med. 2021;21(1):386. doi:10.1186/s12890-021-01756-4

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