Association of nucleated red blood cells with mortality in critically ill dogs

Validation of the Sysmex XN-V Automated Nucleated Red Blood Cell Enumeration for Canine and Feline EDTA-Anticoagulated Blood

The enumeration of nRBCs (nucleated red blood cells) by manual counting is time-consuming and imprecise. As the first veterinary hematology analyzer, Sysmex XN-V provides automated nRBC counts. This study aimed to evaluate the performance of Sysmex XN-V in the enumeration of nRBCs for cats and dogs by comparing automated nRBC counts to manual counts from a total of 3810 canine and 2844 feline specimens. Repeatability, reproducibility, stability, carry-over, and linearity were assessed. The repeatability and reproducibility of Sysmex XN-V were good, with mean coefficients of variation (CV) of 4.5% and 5.4%, respectively. Bland-Altman difference analysis revealed mean biases shown as nRBCs/100 WBCs of 0.01 in dogs and 0.11 in cats with low nRBCs (<5/100 WBCs), mean biases of -1.27 in dogs and -0.24 in cats with moderate nRBC counts (5-20 nRBCs/100 WBCs), and mean biases of -7.76 in dogs and -1.31 in cats with high nRBC counts (>20 nRBCs/100 WBCs). The total observable error was below 9% in both species and at all ranges. Overall concordance between methods was high (91% in canine and 93% in feline samples). The automated nRBC count by Sysmex XN-V was found to be accurate and precise and can replace manual counts for cat and dog samples. Non-statistical quality assurance by scattergram evaluation, re-gating, and confirmation by blood smear evaluation is, however, recommended, especially in cases with severe normoblastosis. This advancement will save time, reduce errors, and add prognostic value to hematological results for animal patients.

Analytical errors in nucleated red blood cell enumeration

BACKGROUND

Enumeration of nucleated red blood cells (NRBCs) in peripheral blood of dogs and cats is performed by manual counting during blood film evaluation. Automated methods have increased precision and accuracy; however, most analyzers cannot distinguish leukocytes and NRBCs. The Sysmex XN-V Series may distinguish NRBCs and leukocytes; however, analytical errors occur.

OBJECTIVES

We aimed to investigate cases with discrepant automated and manual NRBC counts, and to evaluate reasons for analytical errors.

METHODS

Data from samples with increased NRBCs were collected retrospectively and compared with manual counts performed on blood films using Spearman's correlation, Passing-Bablok agreement analysis, and Bland-Altman comparisons. Precision of the automated method and interobserver agreement of manual counts were evaluated. Cases with discrepant results were investigated.

RESULTS

Agreement between the methods was good at ≤1NRBC ×109 /L in dogs and cats, and inadequate at ≥1NRBC ×109 /L. The automated method demonstrated a negative proportional difference to the manual method. Precision was good for the automated method (overall CV 7.1%) and interobserver agreement for the manual method was poor overall (mean CV 27.3%, range 0%-106.1%). Inaccuracies in NRBC enumeration by the automated method occurred with high hematocrits, the mergence of the cell fragments and leukocyte clouds, and the presence of earlier erythroid precursors.

CONCLUSIONS

NRBC enumeration by the WNR channel on the Sysmex XN-1000 V is precise and has good agreement with manual counts in canine and feline blood samples at ≤1NRBC ×109 /L. Manual film review is indicated for samples with ≥1NRBC ×109 /L, earlier erythroid precursors, samples from greyhounds and dehydrated patients, and if gating errors are noted.

Retrospective evaluation of serum/plasma iron, red blood cell distribution width, and nucleated red blood cells in dogs with acute trauma (2009-2015): 129 cases

OBJECTIVE

To compare the prognostic value of admission hematologic parameters serum/plasma iron, red blood cell distribution width (RDW), and nucleated red blood cells (nRBCs) in dogs presenting with acute traumatic injury.

DESIGN

Retrospective observational study (2009-2015).

SETTING

University teaching hospital.

ANIMALS

One hundred and twenty-nine clinical dogs presenting within 24 hours of acute traumatic injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred and twenty-nine dogs met the inclusion criteria and 109 (84.5%) survived, while 20 (15.5%) died or were euthanized in hospital. Patients with blunt force trauma comprised 79.8% of the patient population; dogs with penetrating trauma comprised 20.2% of cases. Hypoferremia occurred in all nonsurvivors, and the median serum/plasma iron concentration was significantly lower in nonsurvivors than survivors (P = 0.028). Normal or increased serum/plasma iron had 100% specificity and 100% positive predictive value for survival. Red blood cell distribution width was not significantly different between groups (P = 0.417). The presence of nRBCs was significantly associated with nonsurvival (P = 0.030), although the absolute nRBC concentrations were not significantly different (P = 0.070). A multiple logistic regression model found age, type of injury, presence of nRBCs, and serum/plasma iron to be independent predictors of survival with an area under the receiver operator characteristic curve of 0.813.

CONCLUSIONS

The presence of nRBCs and low serum/plasma iron are associated with mortality in patients with acute trauma; however, red blood cell distribution width was not associated with survival. Absence of hypoferremia was highly associated with a favorable prognosis in this patient population. These parameters may warrant inclusion in trauma scoring systems.

Neutrophil-to-lymphocyte ratio, nucleated red blood cells and erythrocyte abnormalities in canine systemic inflammatory response syndrome

Systemic inflammatory response syndrome (SIRS) is the manifestation of the systemic response to an infectious or non-infectious disease. We evaluated the association between erythrocyte parameters, including nucleated red blood cells (NRBCs) and leukocyte ratios (NLR, neutrophil-to-lymphocyte ratio; BLR, band neutrophil-to-lymphocyte ratio; BLNR, band neutrophil-to-neutrophil-to-lymphocyte ratio). A review of the medical records was conducted searching SIRS dogs among those admitted to our intensive care unit and a SIRS grading was obtained based on how many criteria were fulfilled. The Acute Patient Physiology and Laboratory Evaluation (APPLE_fast) score was assessed in each dog. Survival rate was assessed 15 days after admission. Dogs with clinical and/or clinicopathological signs of hemolytic or hemorrhagic disorders were excluded. Dogs with ≥2 criteria of SIRS along with a documented underlying infectious cause were recorded as septic (32/90, 35%). A SIRS grading >2 (p = .001) and an APPLE_fast score > 25 (p = .03) were associated with mortality. Twenty-two of SIRS dogs (24%) showed circulating NRBCs. The occurrence of circulating NRBCs was associated with the mortality in SIRS groups (p = .0025). The median NLR was 11.69 and NLR was lower in septic dogs compared to non-septic ones (p = .0272). APPLE_fast, SIRS grading and circulating NRBCs may be considered as negative prognostic factors in canine SIRS. NLR could be a useful tool in dogs with SIRS, which was significantly lower in the septic group. Further prospective, large-scale studies investigating BLR and BNLR in canine SIRS are warranted.