Evaluation of the scil vCell 5, a novel laser- and impedance-based point-of-care hematology analyzer, for use in dogs and cats

Abstract

A novel laser- and impedance-based point-of-care hematology analyzer (POCA), the vCell 5 (scil Animal Care), providing a complete blood count with 5-part leukocyte differential count has recently been introduced to veterinary laboratories. We evaluated the analyzer for use in dogs and cats including method comparison and assessment of linearity, carryover, and precision. Fresh blood samples from 192 healthy and diseased dogs and 159 cats were analyzed, and results were compared to reference methods (i.e., microhematocrit [PCV], Advia 2120 hematology analyzer). Total observed error (TEo) was calculated from CV, obtained at 3 concentrations, and bias%, and compared to total allowable error (TEa). For both species, excellent correlation (rs = 0.93–0.99) was seen between methods for WBC and RBC, hematocrit, hemoglobin, and platelet counts (PLT), except for feline PLT (rs = 0.79). Quality requirements (TEo < TEa) were fulfilled for WBC (TEo = 8.6–11.1%; TEa = 20%) and RBC (TEo = 3.5–7%; TEa = 10%), hematocrit (TEo = 5.7–9.4%; TEa = 10%), PCV (cat TEo = 7.8%; TEa = 10%), mean corpuscular volume (cat TEo = 5.1%; TEa = 7%), and PLT (TEo = 13.1–24.1%; TEa = 25%). Excellent linearity was demonstrated for WBC, RBC, and PLT, and hemoglobin. CVs of <2% for WBC, RBC, hematocrit, hemoglobin, and of <5% (dog) and 8% (cat) for PLT were demonstrated for values within the RI. Except for calculated variables and well-known species-specific deviations in feline PLT, scil POCA results were correlated favorably with reference method results and complied with quality requirements for cats and dogs.

Evaluation of canine and feline leukocyte differential counts obtained with the scil vCell 5 compared to the Advia 2120 hematology analyzer and a manual method

“…In addition to the impedance measuring principle for RBC and PLT counts, the scil POCA uses laser light flow cytometry for WBC differentiation providing a 5-part Diff. 62 Results of the Diff are presented both numerically in relative and absolute numbers, as well as graphically as a cytogram (dotplot) with cell size (low-angle scattered-light signals) shown on the y-axis and cell internal complexity (high-angle scattered-light signals) on the x-axis. The WBC populations visualized in the cytogram are NEU, LYM, MON, EOS, and BASO.…”

“… 31 We had determined intra-assay CV by 20 consecutive measurements performed from feline and canine K 3 -EDTA–anticoagulated blood samples with low, normal, and high WBC counts. 62 Briefly, the following CVs were obtained for a canine and feline sample with normal total WBC count and Diff (dog: NEU 2.43%, LYM 6.98%, MON 10.5%, EOS 11.2%; cat: NEU 1.9%, LYM 12.5%, MON 20.8%, EOS 31.0%).…”

“…We determined the total observed error (TEo) for Diffs according to the current ASVCP guidelines for hematology, which allowed an objective assessment of the results of the method validation results and comparability of the methods used. 44 TEo was calculated for absolute numbers of leukocyte populations, utilizing CVs published for the scil POCA, 62 and %bias applying the following formula: TEo = absolute bias% + 2CV. To fulfill quality requirements, TEo should be less than the total allowable error (TEa; i.e., TEo < TEa).…”

“…We have compared standard hematologic parameters of the CBC (i.e., WBC count, RBC count, RBC parameters, and platelet [PLT] count) obtained by the scil POCA with results obtained by manual and automated reference methods. 62 Except for calculated variables, the scil POCA fulfilled quality requirements recommended by the American Society for Veterinary Clinical Pathology (ASVCP). 44 Limited information is available on the accuracy of the scil POCA Diff (POCA-Diff; i.e., neutrophils […”

“…Limited information is available on the accuracy of the scil POCA Diff (POCA-Diff; i.e., neutrophils [NEU], lymphocytes [LYM], monocytes [MON], eosinophils [EOS], and basophils [BASO]). 62 Therefore, we evaluated the scil POCA-Diff in dogs and cats including 1) a method comparison study assessing correlation, agreement, and acceptability by comparing the POCA-Diff with the Advia 2120 hematology analyzer (Siemens) Diff (Advia-Diff) and a manual 200-cell Diff (M-Diff), serving as reference methods, and 2) the assessment of software adaptations, and the analyzer’s WBC cytograms and flagging options regarding their clinical usefulness as quality assurance (QA) tools. The accuracy of the Advia-Diff has been reported for dogs and cats, thus justifying its use as a reference method in our study.…”