Rapid testing of red blood cells, white blood cells and platelets in intensive care patients using the HemoScreen™ point-of-care analyzer

Analytical Performance Evaluation of Three Point-of-Care CBC Analyzers for Management of Clozapine Therapy in Ambulatory Psychiatry Clinics

BACKGROUND

Clozapine is a first-line therapy and the only FDA-approved drug for patients with treatment-resistant schizophrenia (TRS). However, frequent measurement of absolute neutrophil count (ANC) is required to monitor for potential adverse severe neutropenia from clozapine therapy. We evaluated 3 point-of-care (POC) instruments that perform the complete blood count (CBC) with differential to assess their analytical performance and potential to meet the clinical need for clozapine therapy management.

METHODS

A CBC with differential was performed on 104 residual whole blood specimens using 3 CBC analyzers (Sight OLO, PixCell HemoScreen, and Sysmex pocH-100i) to assess analytical precision, linearity, and accuracy vs the ADVIA 2120i and manual differential reference methods. Clinical concordance of ANC between POC devices and manual differential at medical decision points for mild, moderate, or severe neutropenia, and the threshold for clozapine therapy discontinuation (1.0 × 109/L) were determined.

RESULTS

For CBC parameters, a CV ≤ 6.4% was observed on the OLO, CV ≤ 6.2% for the HemoScreen, and CV ≤ 5.1% with the pocH-100i. Each device accurately identified ANC with the greatest mean bias ±0.42 × 109/L using the pocH-100i vs manual differential. For results near the medical decision points (ANC <1.5 × 109/L), clinical concordance of ANC results was 55.6% for the OLO, 89.5% for the HemoScreen, and 82.4% for the pocH-100i.

CONCLUSIONS

The HemoScreen device demonstrated the best clinical concordance in ANC values at medical decision thresholds for clozapine therapy management.

Novel Assays to Solve the Clinical and Scientific Challenges of Chronic Hepatitis B

Chronic infection with Hepatitis B is a common, incurable, and deadly infection. Despite inexpensive laboratory tests for diagnosis and management that have been established for decades, the worldwide rate of diagnosis is only ∼10%, and ∼5% of people are under treatment. Novel assays have been developed to improve linkage to care by providing more flexible approaches to determine a patient's health status. Other assays have been established to better investigate intrahepatic host-virus interactions to support clinical trials for cure research. This review outlines the clinical and scientific challenges still to be solved and the upcoming methods used to address them.

HemoScreen hematology analyzer compared to Sysmex XN for complete blood count, white blood cell differential, and detection of leukocyte abnormalities

We compared a point-of-care HemoScreen hematology analyzer to an automated Sysmex XN analyzer for complete blood count (CBC) and white blood cell (WBC) differential, and evaluated its capacity to detect leukocyte abnormalities. A total of 100 K2-EDTA whole blood samples, median age 56 years (2 months to 92 years), were compared. For CBC and WBC differential we compared 74 samples with no confirmed abnormal leukocytes. For 26 samples both analyzers gave flagging regarding leukocytes and the accuracy of the flagging was compared. Abnormal leukocytes were confirmed with manual microscopy (200 cells). HemoScreen CBC and WBC differential were highly comparable to Sysmex XN for most of the essential parameters (r = 0.909-0.975). More variation was seen for basophil and monocyte counts (r = 0.452 and 0.753, respectively). Sysmex XN gave more false WBC abnormal flagging (n = 15 altogether) compared to HemoScreen. In addition, Sysmex XN, as well as HemoScreen, gave false WBC flagging for eight samples confirmed normal. The samples verified by microscopy review to truly contain leukocyte abnormalities (n = 18) were flagged abnormal with both analyzers. The specificity for analyzer flagging was 72% and 88% for Sysmex XN and HemoScreen, respectively. HemoScreen hematology analyzer is essentially comparable to Sysmex XN for CBC and WBC differential analysis. Most importantly, HemoScreen detected all the samples confirmed to include abnormal leukocytes. HemoScreen was less prone for false WBC flagging compared to Sysmex XN, thereafter requiring less microscopy review. These abilities increase its utility in small health care units. Studies with a larger number of abnormal leukocyte samples are needed to confirm HemoScreen performance.

Point-of-care microvolume cytometer measures platelet counts with high accuracy from capillary blood

Background

Point-of-care (PoC) testing of platelet count (PLT) provides real-time data for rapid decision making. The goal of this study is to evaluate the accuracy and precision of platelet counting using a new microvolume (8 μL), absolute counting, 1.5 kg cytometry-based blood analyzer, the rHEALTH ONE (rHEALTH) in comparison with the International Society of Laboratory Hematology (ISLH) platelet method, which uses a cytometer and an impedance analyzer.

Methods

Inclusion eligibility were healthy adults (M/F) ages 18–80 for donation of fingerprick and venous blood samples. Samples were from a random N = 31 volunteers from a single U.S. site. Samples were serially diluted to test thrombocytopenic ranges. Interfering substances and conditions were tested, including RBC fragments, platelet fragments, cholesterol, triglycerides, lipids, anti-platelet antibodies, and temperature.

Results

The concordance between the rHEALTH and ISLH methods had a slope = 1.030 and R² = 0.9684. The rHEALTH method showed a correlation between capillary and venous blood samples (slope = 0.9514 and R² = 0.9684). Certain interferents changed platelet recovery: RBC fragments and anti-platelet antibodies with the ISLH method; platelet fragments and anti-platelet antibodies on the rHEALTH; and RBC fragments, platelets fragments, triglycerides and LDL on the clinical impedance analyzer. The rHEALTH’s precision ranged from 3.1–8.0%, and the ISLH from 1.0–10.5%.

Conclusions

The rHEALTH method provides similar results with the reference method and good correlation between adult capillary and venous blood samples. This demonstrates the ability of the rHEALTH to provide point-of-care assessment of normal and thrombocytopenic platelet counts from fingerprick blood with high precision and limited interferences.

Comparison between blood hemoglobin concentration determined by point-of-care device and complete blood count in adult patients with dengue

Background

Hematocrit measurement has been an indispensable tool for monitoring plasma leakage and bleeding in dengue patients. However, hematocrit measurement by automated methods is hampered by frequent venipunctures. Utility of point-of-care hemoglobin (POC-Hb) test for monitoring dengue patients has not been established. We evaluated the relationship between hemoglobin measured by POC-Hb testing and hematocrit measured by the automated method in adult dengue patients.

Methodology and principal findings

Adult dengue patients were recruited at two university hospitals in Thailand from October 2019 to December 2020. POC-Hb test was performed using capillary blood simultaneously with venipuncture to obtain whole blood for an automated complete blood count (CBC) analysis. The correlation of hemoglobin and hematocrit measurement was evaluated. A total of 44 dengue patients were enrolled. Twenty-nine patients (65.9%) were female, with a median age of 31 years (interquartile range 22–41). Of the enrolled patients, 30 (68.2%), 11 (25.0%), and 3 (6.8%) were classified as dengue without warning signs, with warning signs, and severe dengue, respectively. Seven patients (15.9%) had hemoconcentration, and five patients (11.3%) had bleeding. A total of 216 pairs of POC-Hb and CBC were evaluated. A significant positive correlation was observed between hemoglobin measured by POC-Hb testing and hematocrit measured by an automated CBC (r = 0.869, p <0.001). Bland-Altman analysis between hemoglobin measured by POC-Hb testing and an automated CBC showed a bias of -0.43 (95% limit of agreement of -1.81 and 0.95). Using the cutoff of POC-Hb ≥20% as a criteria for hemoconcentration, the sensitivity and specificity of hemoconcentration detected by POC-Hb device were 71.4% and 100.0%, respectively.

Conclusions

Hemoglobin measurement by POC-Hb testing has a strong correlation with hematocrit in adult patients with dengue fever. However, the sensitivity in detecting hemoconcentration is fair. The adjunct use of capillary POC-Hb testing can decrease the frequency of venipuncture. Further study in children is encouraged.

The natural history of dengue has the unique characteristic of plasma leakage that results in hemoconcentration as well as vasculopathy and thrombocytopenia that result in bleeding. Therefore, hematocrit monitoring is a crucial tool to guide management in dengue patients. Microhematocrit adjunct with a complete blood count (CBC) to monitor dengue patients were traditionally performed to decrease the frequency of venipuncture. However, microhematocrit is currently less preferred to the point-of-care hemoglobin monitoring tools to measure red cells in other diseases. There has been no study investigating the feasibility of using point-of-care hemoglobin (POC-Hb) to monitor dengue patients. We studied the correlation of hemoglobin measured by POC-Hb testing and hematocrit measured by an automated CBC in adult dengue patients. We were able to show a strong positive correlation between the two measurements (r = 0.869, p <0.001). Using the rise of POC-Hb value of ≥20% above the convalescent value as the criteria for detecting hemoconcentration by POC-Hb testing, measurement of hemoglobin using POC-Hb has a sensitivity of 71.4% for detecting hemoconcentration compared to the traditional hematocrit criteria. Our findings support the use of POC-Hb testing adjunct with a complete blood count to guide fluid management in dengue patients.

Evaluation of the analytical performance of the PC100 platelet counter

Introduction

Platelet count can be altered in various diseases and treatments and measuring it may provide better insight into the expected outcome. So far, quantification of platelet count is done within laboratory conditions by using established hematology analyzers, whereas a point-of-care device could be used for this purpose outside of the clinical laboratories.

Aim

Our aim was to assess the closeness of agreement between a newly developed point-of-care PC100 platelet counter and two reference methods (Sysmex® XP-300, Sysmex® XN-9000) in measuring platelet counts in whole blood and platelet-rich-plasma (PRP).

Method

Whole blood was obtained from 119 individuals, of which 74 were used to prepare PRP samples. Whole blood platelet count was measured by the two reference methods and the PC100 platelet counter. PRP was prepared from the whole blood and platelet count was adjusted to the range of 250–3600 × 10³/μl and measured with the PC100 platelet counter and Sysmex® XP-300.

Results

A median difference of − 1.35% and − 2.98% occurred in whole blood platelet count between the PC100 platelet counter and the Sysmex® XP-300 and Sysmex® XN-9000, respectively. A strong linear correlation (r ≥ 0.98) was seen in both cases and regression equations indicated neither a constant nor a proportional bias between the methods. Direct comparison of the two reference methods revealed a median difference of − 1.15% and a strongly linear relationship (r = 0.99). Platelet count in PRP resulted in a median difference of 1.42% between the PC100 platelet counter and the reference method, Sysmex® XP-300. While the difference between two methods increased with concentration of platelets in PRP, a strong linear relationship remained throughout the whole measuring interval indicated by the high correlation coefficient (r = 0.99). Assessment of the predicted bias at predefined platelet counts showed that the bias in platelet counts falls within the acceptance criterion for both whole blood and PRP measurements.

Conclusions

Our results show that the PC100 platelet counter can be used interchangeably with the reference methods for determining platelet counts.

A Novel Approach to Hematology Testing at the Point of Care

Background

The need for rapid point-of-care (POC) diagnostics is now becoming more evident due to the increasing need for timely results and improvement in healthcare service. With the recent COVID-19 pandemic outbreak, POC has become critical in managing the spread of disease. Applicable diagnostics should be readily deployable, easy to use, portable, and accurate so that they fit mobile laboratories, pop-up treatment centers, field hospitals, secluded wards within hospitals, or remote regions, and can be operated by staff with minimal training. Complete blood count (CBC), however, has not been available at the POC in a simple-to-use device until recently. The HemoScreen, which was recently cleared by the FDA for POC use, is a miniature, easy-to-use instrument that uses disposable cartridges and may fill this gap.

Content

The HemoScreen’s analysis method, in contrast to standard laboratory analyzers, is based on machine vision (image-based analysis) and artificial intelligence (AI). We discuss the different methods currently used and compare their results to the vision-based one. The HemoScreen is found to correlate well to laser and impedance-based methods while emphasis is given to mean cell volume (MCV), mean cell hemoglobin (MCH), and platelets (PLT) that demonstrate better correlation when the vision-based method is compared to itself due to the essential differences between the underlying technologies.

Summary

The HemoScreen analyzer demonstrates lab equivalent performance, tested at different clinical settings and sample characteristics, and might outperform standard techniques in the presence of certain interferences. This new approach to hematology testing has great potential to improve quality of care in a variety of settings.