title: Repeated measurements of blood lactate concentration as a prognostic marker in horses with acute colitis evaluated with classification and regression trees (CART) and random forest analysis.
abstract: The objective of this study was to investigate the prognostic value of single and repeated measurements of blood l-lactate (Lac) and ionised calcium (iCa) concentrations, packed cell volume (PCV) and plasma total protein (TP) concentration in horses with acute colitis. A total of 66 adult horses admitted with acute colitis (<24 h) to a referral hospital in the 2002-2011 period were included. The prognostic value of Lac, iCa, PCV and TP recorded at admission and 6 h post admission was analysed with univariate analysis, logistic regression, classification and regression trees, as well as random forest analysis. Ponies and Icelandic horses made up 59% of the population, whilst the remaining 41% were horses. Blood lactate concentration at admission was the only individual parameter significantly associated with probability of survival to discharge (P < 0.001). In a training sample, a Lac cut-off value of 7 mmol/L had a sensitivity of 0.66 and a specificity of 0.92 in predicting survival. In independent test data, the sensitivity was 0.69 and the specificity was 0.76. At the observed survival rate (38%), the optimal decision tree identified horses as non-survivors when the Lac at admission was ≥4.3 mmol/L and the Lac 6 h post admission stayed at >2 mmol/L (sensitivity, 0.72; specificity, 0.8). In conclusion, blood lactate concentration measured at admission and repeated 6 h later aided the prognostic evaluation of horses with acute colitis in this population with a very high mortality rate. This should allow clinicians to give a more reliable prognosis for the horse.
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 8, 1870 Frederiksberg, Denmark. Electronic address: mbp@sund.ku.dk.
authors.forename: M B
authors.initials: MB
authors.lastname: Petersen
authors.affiliation: Department of Mathematical Sciences, Faculty of Science, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Tolver
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegård Alle 5, 2630 Taastrup, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Husted
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegård Alle 5, 2630 Taastrup, Denmark.
authors.forename: T H
authors.initials: TH
authors.lastname: Tølbøll
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegård Alle 5, 2630 Taastrup, Denmark.
authors.forename: T H
authors.initials: TH
authors.lastname: Pihl
mesh_terms: D000208:Acute Disease; D000818:Animals; D015415:Biomarkers / Q000097:blood; D001798:Blood Proteins / Q000032:analysis*; D002118:Calcium / Q000097:blood*; D017610:Calcium Compounds / Q000097:blood; D003092:Colitis / Q000175:diagnosis / Q000209:etiology*; D003663:Decision Trees; D003718:Denmark; D005260:Female; D006400:Hematocrit / Q000662:veterinary*; D006734:Horse Diseases / Q000175:diagnosis / Q000209:etiology*; D006736:Horses; D007477:Ions / Q000097:blood; D019344:Lactic Acid / Q000097:blood*; D000069550:Machine Learning; D008297:Male; D008962:Models, Theoretical; D011379:Prognosis
chemical_list: D015415:Biomarkers; D001798:Blood Proteins; D017610:Calcium Compounds; D007477:Ions; D019344:Lactic Acid; D002118:Calcium
keywords: Classification and regression trees (CART); Colitis; Horses; Lactate; Prognosis