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

BACKGROUND: Single measurements of serum amyloid A (SAA) concentration at hospital admission has limited sensitivity for predicting sepsis and death. HYPOTHESIS/OBJECTIVES: To determine whether differences in SAA during the first 2 days of hospitalization could predict sepsis and death in critically ill foals. ANIMALS: One hundred twenty-seven critically ill neonatal foals, <14 days of age. METHODS: Prospective cohort study. SAA was measured at hospital admission and on day 2 of hospitalization using a validated point-of-care test. Logistic regression was conducted to evaluate the predictive value of individual SAA measurements for diagnosing sepsis and assess whether change in SAA during 48 h could predict sepsis or death. Cox survival analysis assessed the association between SAA concentration and death. RESULTS: Serum amyloid A (SAA) concentrations were measured on day 0 (n = 127) and day 2 (n = 97) of hospitalization. On admission and day 2, SAA was not significantly associated with death (P = .20 and P = .08), but was significantly associated with neutropenia (OR 1.001; 95% CI, 1.001-1.1002; P ≤ .001), blood culture positivity (OR 1.001; 95% CI, 1.0-1.1001; P = .002), or both (OR 1.002; 95% CI, 1.001-1.1003; P ≤ .001), with optimal cut-offs of 419 μg/mL on day 0, with moderate sensitivity and specificity (80% and 81%, respectively). Changes between day 0 and day 2 were not predictive for death (P = .49), neutropenia (P = .36), blood culture positivity (P = .41) or both (P = .17). CONCLUSIONS AND CLINICAL IMPORTANCE: In this cohort, SAA only had moderate ability to rule in or rule out sepsis or predict death. Repeated measurements after 48 h did not improve accuracy, suggesting that SAA should not be used as a standalone test.