Evaluation of sequential serum amyloid A measurements for the prediction of sepsis and survival in critically ill neonatal foals.

Overview

• This study evaluated whether measuring serum amyloid A (SAA), an inflammatory marker, at admission and after 2 days could effectively predict sepsis and survival in critically ill newborn foals.
• Findings indicated that single or repeated SAA measurements alone have limited accuracy and should not be used as the sole test for diagnosing sepsis or predicting death in these foals.

Background and Objective

• Sepsis is a critical, life-threatening condition commonly affecting neonatal foals, making early detection and treatment vital.
• Serum amyloid A (SAA) is a protein that increases during inflammation and infection, proposed as a potential early biomarker for sepsis.
• Prior studies showed that measuring SAA at hospital admission has limited sensitivity in predicting sepsis and mortality.
• The objective was to assess whether changes in SAA levels during the first 48 hours of hospitalization improve prediction accuracy for sepsis and survival in critically ill foals.

Methods

• A prospective cohort study was conducted on 127 neonatal foals younger than 14 days old presenting with critical illness.
• SAA concentrations were measured using a validated point-of-care test at two time points: hospital admission (Day 0) and 48 hours later (Day 2).
• Statistical analyses included logistic regression to evaluate the association between SAA levels and:
  • Sepsis indicators such as neutropenia and positive blood cultures
  • Mortality (death)
• Cox survival analysis was used to analyze the relationship between SAA levels and survival times.

Key Results

• SAA was measured at admission in 127 foals and at Day 2 in 97 foals.
• SAA levels at both admission and Day 2 were not significantly associated with death (p-values: 0.20 and 0.08 respectively), indicating poor predictive value for survival.
• However, higher SAA levels were significantly associated with markers of sepsis such as:
  • Neutropenia (OR 1.001; highly significant)
  • Positive blood culture (OR 1.001; significant)
  • Combination of neutropenia or positive blood culture (OR 1.002; highly significant)
• The optimal cutoff for SAA to indicate sepsis was found to be 419 μg/mL on admission, with moderate sensitivity (80%) and specificity (81%).
• Changes in SAA levels between admission and Day 2 were not predictive for death, neutropenia, blood culture positivity, or combined sepsis indicators.

Conclusions and Clinical Implications

• SAA concentrations at admission provide moderate ability to support identification of sepsis but are insufficient alone to confirm or exclude it.
• Repeating SAA measurements 48 hours after admission does not improve the predictive accuracy for sepsis or mortality.
• Due to these limitations, SAA should not be used as a standalone diagnostic test in critically ill neonatal foals.
• Instead, SAA results should be interpreted alongside a thorough clinical examination and other diagnostic tests such as blood cultures and hematologic evaluation.
• Early recognition and prompt treatment of sepsis remain essential, but reliance on SAA alone may miss or misclassify cases.

Summary

• This research highlights the challenge of using biomarkers like SAA to predict complex diseases like sepsis in newborn foals.
• While useful as part of a broader diagnostic approach, SAA measurements—whether single or sequential—cannot reliably replace comprehensive clinical and laboratory assessments.
• Future work might explore combining SAA with other markers or clinical scoring systems to enhance early detection and improve outcomes in foals with sepsis.