Analytical validation and clinical utility of a canine hemoglobin A1c point-of-care assay

Noto, Nicholas Tyler

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https://hdl.handle.net/2142/124236 Copy

Description

Title

Analytical validation and clinical utility of a canine hemoglobin A1c point-of-care assay

Author(s)

Noto, Nicholas Tyler

Issue Date

2024-05-01

Director of Research (if dissertation) or Advisor (if thesis)

Gal, Arnon

Committee Member(s)

• Rosser, Michael
• Connolly, Sara

Department of Study

Vet Clinical Medicine

Discipline

VMS-Veterinary Clinical Medcne

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Canine
• diabetes
• hemoglobin A1c
• glycated hemoglobin
• fructosamine

Abstract

Hemoglobin A1c (HbA1c) is a protein within red blood cells that is found in increased concentrations in people and animals with diabetes mellitus (DM). HbA1c is routinely monitored in people with DM as it is considered the best predictor of certain diabetic complications. However, the routine measurement of HbA1c in diabetic dogs has not yet been adopted, largely due to the wide variability in HbA1c concentrations obtained from previously assessed assays. Due to this variability, HbA1c’s role in the diagnosis and monitoring of dogs with DM remains unclear. Furthermore, a lack of convenient assays for the measurement of canine HbA1c hinders the regular use of this analyte in dogs. The Vet Chroma™ is a point-of-care (POC) benchtop analyzer that utilizes immunofluorescence to quantify HbA1c in whole blood samples and reports HbA1c as a percentage of total hemoglobin. The first objective of this study was to analytically validate the Vet Chroma™ for the measurement of canine HbA1c. Validation was performed in concordance with the American Society for Veterinary Clinical Pathology (ASVCP) Quality Assurance Guidelines and included intra- and inter-assay variability, linearity, effect of interfering substances, storage stability, and a method comparison. Intra- and inter-assay variability assessed on patient samples with three levels of HbA1c concentrations revealed an intra-assay variability of 3.54% – 10.05% and an inter-assay variability of 7.89% – 14.52%. The assay was linear (R2 = 0.986) from 0.89% – 6.67% HbA1c. Linear regression showed no evidence of proportional bias, but a slight positive constant bias was present. Interference testing revealed unpredictable, yet rarely significant, changes in HbA1c concentration at increasing levels of icterus and lipemia. The storage stability study showed that HbA1c remained stable in samples stored at 4C for up to 4 days, at -20C for up to one week, and at -80C for up to three months. Comparison of the Vet Chroma™ HbA1c assay to a previously validated capillary electrophoresis HbA1c assay showed similar results between analyzers, though constant and proportional bias between the analyzers were evident. We conclude that the Vet Chroma™ has acceptable analytical performance for the measurement of canine HbA1c in fresh whole blood samples. Ideally, whole blood samples should be free of interferents. The results of the method comparison study indicate that HbA1c values from the two methods are not commutable, and values obtained by the Vet Chroma™ may not be directly compared with those obtained from other analyzers. The second objective of this study was to assess the clinical utility of the Vet Chroma™ for differentiating diabetic and control dogs. This portion of the study was retrospective and was accomplished by analyzing the medical records of the patient samples used during the validation study. Dogs were included in the diabetic group if they had a history of diabetes or if they were newly diagnosed with diabetes on the date of sample collection. Dogs were included in the control group if they had neither a history of diabetes nor a new diagnosis of diabetes and if their concurrent BG concentration was <160 mg/dL. There was a clear difference (p < 0.0001) in HbA1c concentrations between the diabetic group, which had a mean HbA1c of 3.26%, and the control group, which had a mean HbA1c of 0.66%. ROC curve analysis showed excellent diagnostic performance of the Vet Chroma™ for differentiating diabetic dogs from control dogs with an AUC of 0.912. At a cut off of >0.925% HbA1c, the assay has a sensitivity of 84.4% and a specificity of 97.6% for diagnosing DM in dogs. We concluded that the Vet Chroma™ is excellent at discriminating diabetic from control dogs based on HbA1c alone; however, HbA1c results should be interpreted in conjunction with clinical history and other clinicopathologic findings.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Nicholas Noto

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