Comparison of biomarkers adiponectin, leptin, C-reactive protein, S100A12, and the Acute Patient Physiologic and Laboratory Evaluation (APPLE) score as mortality predictors in critically ill dogs.

Objectives: To determine if selected serum biomarkers are superior to the acute patient physiologic and laboratory evaluation (APPLE) complete score in predicting 30-day mortality in a non-homogeneous disease population of critically ill dogs.

Design: Prospective cohort study comparing the serum biomarkers adiponectin, leptin, C-reactive protein, and S100A12 concentrations between surviving and nonsurviving critically ill dogs.

Setting: University small animal teaching hospital.

Animals: Seventy critically ill dogs were prospectively recruited, and an APPLE complete score was calculated within 24 hours of being admitted to the intensive care unit. Logistic regression models were fit to estimate the association between biomarkers and 30-day survival. Results were interpreted at the 5% level of significance.

Measurements and main results: Leptin was the only biomarker that was significantly correlated with the APPLE complete score (P < 0.001). Only the APPLE complete score (P = 0.003) and illness duration of < 1 day (P = 0.043) were significantly associated with outcome.

Conclusion: Based on the results of this study, there appears to be no benefit in using biomarkers over the APPLE score for disease severity stratification. Serum leptin concentration was significantly correlated with disease severity as determined by APPLE scoring. Longer duration of illness prior to admission was associated with a higher risk of death. APPLE scores were highest in dogs with infectious and immune-mediated diseases and bite wounds.