Validation and reference interval of activated clotting time in dogs using a point-of-care analyzer

BACKGROUND Activated clotting times (ACT) are measured to titrate anticoagulant dose during intravascular procedures. Point-of-care (POC) analyzers could improve test practicality and accuracy compared to manual tests, but a reference interval (RI) for dogs is lacking. OBJECTIVES To establish a RI for ACT in adult dogs using a POC analyzer, to quantify longitudinal intra-subject variability and to investigate device reliability and inter-device agreement. ANIMALS Forty-two healthy dogs, including 28 client-owned and 14 research dogs. METHODS Prospective measurements were performed on fresh venous blood samples using the i-STAT 1 (Abbott) POC analyzer and kaolin cartridges. The RI was determined using the Robust method. Intra-subject within- and between-day variability were quantified between baseline and 2 hour (n=8) or 48 hour (n=10). Device reliability and inter-device agreement were studied by duplicate measurements (n=12) on identical devices. RESULTS Mean, lower and upper reference limits for ACT were 92.9±9.1 seconds, 74.4 seconds (90% confidence interval (CI): 70.1–78.3 seconds) and 111.2 seconds (90% CI: 107.5–115.2 seconds), respectively. Coefficients of variation of intra-subject within-day (8.1%) and between-day (10.4%) variability were low, yet resulted in a small but significant between-day difference (P=0.020). Device reliability assessed by intraclass correlation coefficient was excellent (0.99, 95% CI 0.997–1.000) and measurements between devices were not significantly different (P=0.593). CONCLUSIONS AND CLINICAL IMPORTANCE The POC analyzer has an excellent reliability and test simplicity, which favors its use over manual ACT assays.

Publication year:2022

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