Outcome Prediction in Dogs with Overt DIC

DIC is a severe complication of life-threatening disorders.^[1] In the absence of any single gold-standard diagnostic test, a number of scoring systems have been developed in an attempt to improve the reliability of currently available tests.

We’re reviewing a publication by Goggs, et al published in Journal of Veterinary Emergency and Critical Care in 2018, which evaluated 4 DIC scoring systems and their ability to predict mortality in critically ill dogs.^[2]

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It was hypothesized that dogs with laboratory abnormalities consistent with overt DIC have increased mortality and hence survival could be used to evaluate the performance of DIC scoring systems.

Four DIC scoring systems were compared in clinically-ill dogs:

1. The International Society of Thrombosis and Haemostasis (ISTH) score ^[3]
2. A system using in‐house reference intervals (RIs) for coagulation assays ^[2]
3. A previously published veterinary DIC score ^[4]
4. The published veterinary DIC score modified by use of in‐house RI values.^[2]

1. The International Society of Thrombosis and Hemostasis (ISTH) overt DIC scoring system – looks at the following:

• Platelet count – scoring a progressively higher score with decreasing platelet count. So, the lower your platelet count is, the higher your DIC for platelet counts is.
• Prothrombin time – again, scoring a higher score with increasing prothrombin time above reference ranges
• Fibrinogen concentration
• D-dimer – with an increasing score, the higher the d-dimer count was.

1. The reference interval method – used animals with values that fell outside the study institution’s reference ranges for standard tests of coagulation. These were collated and those that met the criteria for DIC were included. Criteria measured included:

• aPTT
• PT
• Anti-thrombin activity
• Fibrinogen concentration
• D-dimer assays
• Platelet count

1. A veterinary DIC scoring system published by Wiinberg and colleagues in 2010 utilised the following to arrive at a coagulation score with sensitivity of 91% and specificity of 90%:

• aPTT
• PT
• Fibrinogen
• D-dimer

They also utilised the ISTH scoring system, but lowered the threshold value required for a diagnosis of DIC from a score of 5 to a score of 4, for the diagnosis of DIC, which resulted in increased sensitivity (from 46% to 76%) and decreased specificity from 100% to 79%. So, it was not as good as the score that they had developed themselves using a reasonably complex formula.

1. The modified Wiinberg score utilised the formula developed by Wiinberg and colleagues in 2010, and adjusted the values of diagnostic tests using scaling factors to allow incorporation of the testing facility reference intervals into the Wiinberg formula.

The study used laboratory data from 804 client-owned dogs with naturally-occurring DIC. The four scoring methods of DIC detection were then applied to laboratory data obtained from the patients, to see which was the most reliable scoring system in predicting mortality outcome.

In this study population, the reference interval method – using criteria measured within the hospital institution – provided the most accurate assessment of mortality. A score based on abnormalities in 3 of the 6 criteria tested was 72.7% sensitive, and 80.9% specific for mortality – with the mortality rate for dogs diagnosed with overt DIC being 62.5%, versus a mortality rate of 12.9% in dogs without overt DIC.

Summary

This study demonstrated that in dogs with diseases recognised as triggers for DIC, comparison of a coagulation panel (including platelet count, using a cut-off of 3 or more abnormal values), increased PT, aPTT, d-dimer, decreased antithrombin and platelet count – was both sensitive and specific for prediction of non-survival to hospital discharge, and performed better than previously-reported human and veterinary scoring systems – and will likely be useful for identification of overt DIC.

References:

1. de Laforcade AM, Freeman LM, Shaw SP, Brooks MB, Rozanski EA, Rush JE. Hemostatic changes in dogs with naturally occurring sepsis. Journal of Veterinary Internal Medicine. 2003 Sep;17(5):674-9.
2. Goggs, R. Mastrocco, A. and Brooks, M. B. (2018), Retrospective evaluation of 4 methods for outcome prediction in overt disseminated intravascular coagulation in dogs (2009–2014): 804 cases. Journal of Veterinary Emergency and Critical Care, 28: 541-550.
3. Toh CH, Hoots WK, SSC on Disseminated Intravascular Coagulation of the ISTH. The scoring system of the Scientific and Standardisation Committee on Disseminated Intravascular Coagulation of the International Society on Thrombosis and Haemostasis: a 5‐year overview 1. Journal of Thrombosis and Haemostasis. 2007 Mar;5(3):604-6.
4. Wiinberg B, Jensen AL, Johansson PI, Kjelgaard-Hansen M, Rozanski E, Tranholm M, Kristensen AT. Development of a model based scoring system for diagnosis of canine disseminated intravascular coagulation with independent assessment of sensitivity and specificity. The Veterinary Journal. 2010 Sep 1;185(3):292-8.

Disclaimer: Every effort has been made to ensure that the information contained in this article is current and correct. No responsibility is assumed by the publisher for loss or injury resulting from any use or operation of methods described herein. Because of rapid advances in medical sciences, independent verification of drug doses and recommendations should be made.

About the Author

Dr. Philip Judge

BVSc MVS PG Cert Vet Stud MACVSc (VECC; Medicine of Dogs)

Director: Vet Education Pty Ltd
Consultant in Veterinary Emergency and Critical Care
Internationally renowned lecturer and published author
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