Determination of the reference interval of the C-reactive protein/albumin ratio and its efficiency, CRP and albumin as prognostic markers in dogs

Abstract

The objective of this research was to creates a reference interval for C-reactive protein (CRP)/albumin ratio (CAR) in the canine species and to analyze the potential of CRP, albumin and the relationship between both, to serve as indicators of disease severity, length of hospital stay (LoS) and mortality in this species. For this, an outcome study was conducted in a Veterinary Teaching Hospital in southern Brazil. One hundred ninety dogs were included randomly, without distinction of gender, age, or breed, from June 2013 to November 2016. Plasma was collected from them and analyzed for assessment of CRP and albumin. The reference range stipulated for CAR in dogs was 0.36-0.60, as determined by the confidence interval of mean resamplings (in percentiles). The frequencies mean, and standard deviations of the variables, correlation analysis, and comparative analysis (Kruskal-Wallis in α = 5%) were calculated. Elevation (above reference) of CAR was determined to be proportional to the severity of the underlying disease, and CRP means were reasonable. Besides, hypoalbuminemia was indicative of systemic disease, but not of severity. Thus, CAR was a better marker of disease severity than were CRP and albumin, analyzed separately. Concerning LoS, there was a positive correlation with CAR (p<0.01) in patients, and the same was not observed with CRP and albumin. Concerning mortality, hypoalbuminemia was the only marker valid in animals with a critical illness (p=0.04). In conclusion, CAR is a better marker of disease severity and LoS in dogs than are CRP and albumin analyzed separately.