Inter- and intra-operator variability in the analysis of packed cell volume

Interobserver Variability in Semen Analysis: Findings From a Quality Control Initiative

Introduction For laboratory tests, precision and accuracy are indispensable to ensure reliable results for both clinical diagnosis and research endeavors. The accuracy and reliability of results are important because they have an impact on both patient management and research. In this study, we evaluated the inter-observer variability between a trained technician and two academic residents, which acted both as a quality control measure as well as an assessment of training outcomes. Material and methods Freshly obtained semen samples from 28 subjects coming to the andrology laboratory were used. Semen analysis was performed by a regular technician permanently posted in the laboratory and two residents on completion of their posting in the andrology laboratory. All three examined the same sample after liquefaction for assessment of sperm motility, sperm concentration, sperm vitality, and sperm morphology. Semen analysis was done as per the recommendations of the WHO. Results The results of the study are presented as a coefficient of variation (CV), S charts, and Bland-Altman plot where we evaluated the interobserver variability in parameters on semen analysis of the same sample by three different assessors. The mean CV for sperm concentration across the samples was 6.24%. For sperm vitality, sperm morphology, and sperm motility the mean CV was 10.14%, 2.66%, and 8.11%, respectively. The S chart and Bland-Altman plot found a few random errors in measurements. Conclusion Regular quality control assessments are essential and should be implemented in andrology laboratories to ensure accurate and reliable results. Proper training of laboratory personnel is also vital for consistent outcomes. Other measures such as equipment calibration, use of high-quality reagents, and standard reporting are also crucial for the best results from a laboratory.

Evaluation of a flash glucose monitoring system in nondiabetic dogs with rapidly changing blood glucose concentrations

Background

A flash glucose monitoring system (FGMS; FreeStyle Libre) is useful for monitoring hypoglycemic dogs with diabetes.

Objective

To assess the utility of this FGMS in dogs with induced hypoglycemia and rapid fluctuations in blood glucose (BG) concentrations.

Animals

Twenty‐four apparently healthy research (n = 10) and teaching (n = 14) dogs.

Methods

Prospective, observational study performed in tandem with a teaching laboratory. Regular insulin was administered to dogs and resulting hypoglycemia was corrected. Before insulin administration and every 10 minutes over a 90‐minute period, serial measurements of interstitial glucose (IG) with FGMS and BG with a portable blood glucose meter (PBGM) and clinical chemistry analyzer concentrations were made. Portable blood glucose meter and FGMS readings were compared to that of the clinical chemistry analyzer. Analytical and clinical accuracy were assessed using ISO 15197:2013 criteria, including Parkes error grid analysis.

Results

The proportions of readings in the low BG range (BG <100 mg/dL) for which the test method measurement was within ±15 mg/dL of the reference BG for the PBGM and FGMS were 81.7% (161/197) and 39.1% (72/184), respectively. The proportions of readings for the PBGM and FGMS, which were not likely to affect clinical outcome according to Parkes error grid analysis, were 97.9% (233/238) and 80.1% (177/221), respectively.

Conclusions and Clinical Importance

In this model, there was limited agreement between the FGMS and reference standard BG measurements. The FGMS (measuring IG concentrations) was compared to peripheral BG concentrations, not brain‐tissue glucose concentrations, and failed to reliably detect hypoglycemia.

Effects of potential confounding variables on accuracy of a commercially available veterinary point-of-care hematocrit meter in the evaluation of blood samples from dogs and cats

OBJECTIVE

To assess the agreement in measurements of Hct values and hemoglobin (Hgb) concentrations in blood samples from dogs and cats between a commercially available veterinary point-of-care (POC) Hct meter and a laboratory-based (LAB) analyzer and to determine the effects of various conditions (ie, lipemia, hyperbilirubinemia, hemolysis, autoagglutination, and reticulocytosis) on the accuracy of the POC meter.

SAMPLES

Blood samples from 86 dogs and 18 cats.

PROCEDURES

Blood samples were run in duplicate on the POC meter, which reported Hgb concentration, measured via optical reflectance, and a calculated Hct value. The POC meter results were compared with results from a LAB analyzer. Blood samples with grossly visible lipemia, icterus, hemolysis, and autoagglutination were noted.

RESULTS

Mean ± SD values for LAB Hct were 33.9 ± 15.73% (range, 3.9% to 75.8%), and for LAB Hgb were 11.2 ± 5.4 g/dL (range, 1 to 24.6 g/dL). Mean bias between POC Hct and LAB Hct values was -1.8% with 95% limits of agreement (LOAs) of -11.1% to 7.5% and between POC Hgb and LAB Hgb concentrations was -0.5 g/dL with 95% LOAs of -3.8 to 2.8 g/dL. There was no influence of lipemia (14 samples), icterus (23), autoagglutination (14), hemolysis (12), or high reticulocyte count (15) on the accuracy of the POC meter. The POC meter was unable to read 13 blood samples; 9 had a LAB Hct ≤ 12%, and 4 had a LAB Hct concentration between 13% and 17%.

CONCLUSIONS AND CLINICAL RELEVANCE

Overall, measurements from the POC meter had good agreement with those from the LAB analyzer. However, LOAs were fairly wide, indicating that there may be clinically important differences between measurements from the POC meter and LAB analyzer.

Interobserver reliability of canine urine specific gravity assessed by analog or digital refractometers

Refractometry is utilized routinely to evaluate canine urine specific gravity (USG) in veterinary clinical settings. We aimed to determine if the magnitude of interobserver reliability when assessing canine USG via refractometry could impact clinical judgment. USG was determined in 38 dogs by 3 registered veterinary technicians (RVTs) using both an optical analog refractometer and a digital refractometer. Summary statistics were reported, interobserver reliability was assessed via intraclass correlation coefficient (ICC) analysis through a 2-way mixed-effects model, and agreement between RVT pairs was compared through Bland-Altman plots. The median analog refractometer USG measurement was 1.018 (range: 1.004-1.040) and for the digital refractometer was 1.0176 (1.0035-1.0357). The analog refractometer average measure ICC was 0.995 (95% CI: 0.992, 0.997; p < 0.001). The digital refractometer average measure ICC was 0.999 (95% CI: 0.999, 1.000; p < 0.001). Strong agreement between all pairs of RVTs was seen via Bland-Altman plots for both analog and digital refractometers, with 95% CIs spanning no more than 0.002 in either the positive or negative direction for all pairings. The interobserver variability in canine USG measurements by RVTs was trivial and did not impact clinical judgment and decision-making.

The effect of myxomatous mitral valve disease severity on packed cell volume in dogs

OBJECTIVES

The aim of this study was to examine whether associations between disease severity and packed cell volume exist in dogs with myxomatous mitral valve disease.

MATERIALS AND METHODS

Data were selected from 289 dogs that had been examined at a research clinic (2004-2017) on multiple occasions (n=1465). American College of Veterinary Internal Medicine stage and echocardiographic measurements were entered in separate multivariable linear mixed effects models with packed cell volume as the dependent variable. Age, breed, sex, weight and blood urea nitrogen concentrations were additionally tested in these analyses to control for patient characteristics.

RESULTS

Packed cell volume (% whole blood) in stages B1 and B2 (B1: 42.62 ±0.27, P=0.001; B2: 41.77± 0.42, P < 0.001) was lower than stage A (44.57 ±0.53). In stage C, packed cell volume was greater than both preclinical stages (C: 43.84 ±0.46). When the administration of loop diuretics was included in statistical models, packed cell volume was inversely related to normalised left ventricular internal diameters (β: -2.37; 95% confidence intervals: -3.49, -1.25; P < 0.001).

CLINICAL SIGNIFICANCE

Dogs with myxomatous mitral valve disease may develop reductions in packed cell volume as their disease progresses. Although this finding was statistically significant at a population level, it should be noted that the differences described are relatively small. This, along with other causes of variation in packed cell volume, means that changes would be challenging to appreciate within individual patients. Plasma volume depletion following diuretic administration may explain why findings differed in stage C.

The use of smartphone-obtained images to extrapolate canine packed cell volume

OBJECTIVE

To determine whether a smartphone-obtained image can be used to extrapolate the PCV of canine blood samples.

DESIGN

Prospective study of surplus blood obtained from clinical cases.

SETTING

University teaching hospital.

INTERVENTIONS

Blood samples were placed on filter paper, and images were obtained with a smartphone in different environments. These results were then compared to the PCV measurements on the same samples following the World Health Organization guidelines.

MEASUREMENTS

Sixty-nine samples were assessed and identified that smartphone images, obtained in a controlled environment, were able to predict the PCV of the samples. This prediction was most accurate when assessing samples of a normal erythroid mass or polycythemic samples.

CONCLUSIONS

The results of this study suggest that smartphone-obtained images do have a utility in predicting canine PCV. If this can be incorporated into a smartphone application, there would be scope to use this in low resource settings.