Evaluation of the performance of a point-of-care method for total and differential white blood cell count in clozapine users

Point-of-care self-testing for measuring total white blood cells and C-reactive protein - a pilot study for future home-monitoring of patients during antibiotic treatment at home

BACKGROUND

During home treatment with antibiotics, patients' laboratory results of total white blood cell count (WBC) with neutrophil counts and C-reactive protein (CRP) are drawn and monitored at the hospital. The aim of the study was to examine the feasibility and analytical accuracy of hospitalized patients 18 years or older self-testing using two point-of-care tests (POCT).

METHODS

The pilot study included 41 hospitalized patients. A subjective judgment of the patients' ability to conduct the self-testing was made along with a comparison of the POCT measurements of WBC, neutrophil counts and CRP with standard laboratory measurements. Correlation between the POCTs and laboratorial values was assessed by coefficient of determination and the level of agreement between the means was assessed by Bland Altman test.

RESULTS

Of the 38 patients conducting self-testing, 78% were men and the mean age was 61.8 years. 28 patients (73.7%) successfully performed self-testing on the first try while, 10 (26.3%) 'HemoCue WBC DIFF' measurements showed an error code. All the patients successfully performed the 'QuickRead go CRP' self-test. Comparison of the 'HemoCue WBC DIFF' results with the laboratory results of WBC and neutrophil counts showed good agreement. On the other hand, 'QuickRead go CRP' results showed a small but significant systematic disagreement compared to the laboratory results.

CONCLUSION

Our results showed that the POCTs can be used by some patients and factors influencing the patient participation included psychological and physical limitations. Both POCTs appeared to have an acceptable clinical level of accuracy.

Detection of COVID-19-related biomarkers by electrochemical biosensors and potential for diagnosis, prognosis, and prediction of the course of the disease in the context of personalized medicine

As a more efficient and effective way to address disease diagnosis and intervention, cutting-edge technologies, devices, therapeutic approaches, and practices have emerged within the personalized medicine concept depending on the particular patient's biology and the molecular basis of the disease. Personalized medicine is expected to play a pivotal role in assessing disease risk or predicting response to treatment, understanding a person's health status, and, therefore, health care decision-making. This work discusses electrochemical biosensors for monitoring multiparametric biomarkers at different molecular levels and their potential to elucidate the health status of an individual in a personalized manner. In particular, and as an illustration, we discuss several aspects of the infection produced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a current health care concern worldwide. This includes SARS-CoV-2 structure, mechanism of infection, biomarkers, and electrochemical biosensors most commonly explored for diagnostics, prognostics, and potentially assessing the risk of complications in patients in the context of personalized medicine. Finally, some concluding remarks and perspectives hint at the use of electrochemical biosensors in the frame of other cutting-edge converging/emerging technologies toward the inauguration of a new paradigm of personalized medicine.

Paper-Based Cytometer for the Detection and Enumeration of White Blood Cells According to Their Immunophenotype

Total and differential white blood cell (WBC) counts are vital metrics used routinely by clinicians to aid in the identification of diseases. However, the equipment necessary to perform WBC counts restricts their operation to centralized laboratories, greatly limiting their accessibility. Established solutions for the development of point-of-care assays, namely lateral flow tests and paper-based microfluidic devices, are inherently limited in their ability to support the detection of WBCs─the pore sizes of materials used to fabricate these devices (e.g., membranes or chromatography papers) do not permit passive WBC transport via wicking. Herein, we identify a material capable of the unimpeded transport of WBCs in both lateral and vertical directions: a coffee filter. Through in situ labeling with an enzyme-labeled affinity reagent, our paper-based cytometer detects WBCs according to their immunophenotype. Using two cultured leukocyte lines (Jurkat D1.1 T cells and MAVER-1 B cells), we demonstrate the specific, colorimetric enumeration of each target cell population across the expected physiological range for total lymphocytes, 1000-4000 cells μL^-1. Additionally, we highlight a potential application of this type of device as a screening tool for detecting abnormal cell counts outside the normal physiological range and in subclasses of cell types, which could aid in the identification of certain diseases (e.g., CD4+ T lymphocytes, an important biomarker for HIV disease/AIDS). These results pave the way for a new class of paper-based devices─those capable of controlled white blood cell transport, labeling, capture, and detection─thus expanding the opportunities for low-cost, point-of-care cytometers.

Point-of-care testing technologies for the home in chronic kidney disease: a narrative review

Point-of-care testing (POCT) performed by the patient at home, paired with eHealth technologies, offers a wealth of opportunities to develop individualized, empowering clinical pathways. The non-dialysis-dependent chronic kidney disease (CKD) patient who is at risk of or may already be suffering from a number of the associated complications of CKD represents an ideal patient group for the development of such initiatives. The current coronavirus disease 2019 pandemic and drive towards shielding vulnerable individuals have further highlighted the need for home testing pathways. In this narrative review we outline the evidence supporting remote patient management and the various technologies in use in the POCT setting. We then review the devices currently available for use in the home by patients in five key areas of renal medicine: anaemia, biochemical, blood pressure (BP), anticoagulation and diabetes monitoring. Currently there are few devices and little evidence to support the use of home POCT in CKD. While home testing in BP, anticoagulation and diabetes monitoring is relatively well developed, the fields of anaemia and biochemical POCT are still in their infancy. However, patients' attitudes towards eHealth and home POCT are consistently positive and physicians also find this care highly acceptable. The regulatory and translational challenges involved in the development of new home-based care pathways are significant. Pragmatic and adaptable trials of a hybrid effectiveness-implementation design, as well as continued technological POCT device advancement, are required to deliver these innovative new pathways that our patients desire and deserve.

Evaluation of the LeukoScope for Point-of-Care Measurement of White Blood Cell and Neutrophil Counts in Malawi

White blood cell (WBC) and neutrophil counts are important laboratory tests used by clinicians to assess a variety of conditions. However, current methods to measure WBC and neutrophil counts are difficult to perform at the point of care, being either cost or labor prohibitive. To meet this need, we developed the LeukoScope: a portable, imaging-based system to measure WBC and neutrophil counts from a drop of blood. Here, we present the performance of the LeukoScope in 136 pediatric and 164 neonatal subjects at a central hospital in Malawi. For pediatric patients, 95.4, 66.7, and 80.0% of samples with normal, low, and high WBC counts, respectively, were correctly identified, and 88.6, 100.0, and 89.3% of samples with normal, low, and high neutrophil counts, respectively, were correctly identified. Accuracy was lower overall for neonatal samples; 92.1, 64.3, and 26.7% of samples with normal, low, and high WBC counts, respectively, were correctly identified, and 73.2 and 78.6% of samples with normal and high neutrophil counts, respectively, were correctly identified. Results of this study show that the LeukoScope can help meet need for point-of-care measurement of WBC counts in pediatric patients and highlight the challenges of point-of-care assessment of WBC counts in neonatal patients.

Prescription attitudes and practices regarding clozapine among Serbian psychiatrists: results of a nationwide survey

OBJECTIVE

Despite clozapine being the most effective treatment for treatment-resistant schizophrenia (TRS), a clear explanation as to why it is underutilized and why its initiation is delayed remains unclear. The first aim of the study was to conduct a nation-wide assessment of both the psychiatrists' attitudes of the obstacles for prescribing clozapine as well as their prescription practices. The second aim was to make recommendations, based on the results obtained, for improving the Serbian clozapine guidelines.

METHODS

A questionnaire was conducted consisting of two parts. One regarded the clinical characteristics of the psychiatrists, while the second contained questions about indications for clozapine initiation, clozapine prescribing tendencies, and barriers to clozapine use. The questionnaire was sent to 302 Serbian psychiatrists.

RESULTS

With 161 out of the 302 psychiatrists returning the questionnaires, the response rate was 53.3%. Nearly 60% of the psychiatrists treated 10 or more patients with clozapine, with TRS being the most common indication. Only four psychiatrists (2.5%) had no patients currently on clozapine. Psychiatrists indicated that their fear of agranulocytosis (68%) constituted the greatest obstacle for clozapine prescription, followed closely by weight gain (56%), and sedation (39%). Despite their fear of agranulocytosis, only 83.9% of the psychiatrists monitored leukocytes regularly.

CONCLUSION

In general, psychiatrists in Serbia seem to be confident in prescribing clozapine, even in the absence of clear monitoring guidelines and the possibility of therapeutic drug monitoring. In order to reduce obstacles for clozapine prescription, monitoring laxity, and an overreliance on personal experience, we recommend three modifications of the existing clozapine guideline.

Using a fingerstick test for haematological monitoring in patients treated with clozapine

BACKGROUND

Treatment with clozapine requires regular blood monitoring in order to minimise the risk of agranulocytosis. The demands on patients and clinicians associated with monitoring may be reduced by using point-of-care, as opposed to lab-based assessments. We assessed the utility of a device that can measure white blood cell (WBC) and neutrophil counts by capillary fingerstick blood.

METHOD

The performance of a small, portable device (HemoCue® WBC DIFF System) was compared with that of a widely used laboratory analyser (ADVIA® 2120i) for measuring WBC and neutrophil counts. Patients with schizophrenia who were being treated with clozapine (n = 201) provided a fingerstick capillary sample and a venous sample for the respective assays.

RESULTS

WBC counts and neutrophil counts from venous blood as determined by ADVIA 2120i, ranged from 3.0 × 10⁹/l to 19.5 × 10⁹/l, and 1.2 × 10⁹/l to 15.9 × 10⁹/l, respectively. There was a strong correlation between the results from venous and the capillary sample methods (WBC: R = 0.89, neutrophil: R = 0.92). By Passing-Bablok regression analysis, the slope of the association between ADVIA^® 2120i and HemoCue WBC DIFF for WBC was 1.0 [95% confidence interval (CI) 0.944-1.086], with intercept at -0.9 (95% CI -1.43 to -0.45). For neutrophils, the slope was 0.870 (95% CI 0.817-0.923), with intercept at -0.19 (95% CI -0.43 to 0.02). Overall, mean biases of -0.95 × 10⁹/l for WBC, and -0.91 × 10⁹/l for neutrophils were observed for the capillary blood method compared with the venous blood method. Below the clinical cutoff intervals for clozapine monitoring WBC (<3.5 × 10⁹/l) and neutrophils (<1.5 × 10⁹/l) these biases were -1.1 × 10⁹/l for WBC, and -0.25 × 10⁹/l for neutrophils.

CONCLUSION

Results from the capillary blood HemoCue WBC DIFF analyser compared well with the venous blood ADVIA 2120i analyser for determining WBC and neutrophil counts. There was a slight overall bias, with the capillary method reporting lower values for both measures. Fingerstick point-of-care analysis is suitable for monitoring blood counts in patients on clozapine, although confirmatory standard venous testing is recommended for test results falling below accepted thresholds.

A Rational Use of Clozapine Based on Adverse Drug Reactions, Pharmacokinetics, and Clinical Pharmacopsychology

Using Richardson and Davidson's model and the sciences of pharmacokinetics and clinical pharmacopsychology, this article reviewed the: (1) poor life expectancy associated with treatment-resistant schizophrenia (TRS), which may be improved in patients who adhere to clozapine; (2) findings that clozapine is the best treatment for TRS (according to efficacy, effectiveness and well-being); and (3) potential for clozapine to cause vulnerabilities, including potentially lethal adverse drug reactions such as agranulocytosis, pneumonia, and myocarditis. Rational use requires: (1) modification of the clozapine package insert worldwide to include lower doses for Asians and to avoid the lethality associated with pneumonia, (2) the use of clozapine levels for personalizing dosing, and (3) the use of slow and personalized titration. This may make clozapine as safe as possible and contribute to increased life expectancy and well-being. In the absence of data on COVID-19 in clozapine patients, clozapine possibly impairs immunological mechanisms and may increase pneumonia risk in infected patients. Psychiatrists should call their clozapine patients and families and explain to them that if the patient develops fever or flu-like symptoms, the psychiatrist should be called and should consider halving the clozapine dose. If the patient is hospitalized with pneumonia, the treating physician needs to assess for symptoms of clozapine intoxication since halving the dose may not be enough for all patients; consider decreasing it to one-third or even stopping it. Once the signs of inflammation and fever have disappeared, the clozapine dose can be slowly increased to the prior dosage level.

Impact of point-of-care testing for white blood cell count on triage of patients with infection in the remote Northern Territory of Australia

In Australia's Northern Territory (NT), acute infections are highly prevalent within Indigenous remote communities and difficulties in diagnosing the aetiology of infection are exacerbated by limited access to diagnostic tests. The objective of this study was to investigate the clinical effectiveness of point-of-care (POC) testing for total and 5-part differential white blood cell (WBC DIFF) counts for the triage of patients with possible acute infection. The HemoCue WBC DIFF POC device was introduced into 13 remote health clinics over a 6 month period. A retrospective clinical audit of patient cases meeting the selection criteria for three acute infections (sepsis, respiratory infection and appendicitis) were examined by four registrars in duplicate; one with POC test results available and the other with POC test results removed to determine if WBC DIFF results changed or assisted in patient triage. The number of changed outcomes provided a preliminary cost-benefit analysis. Sixty (23%) patient cases met the selection criteria for the clinical effectiveness analysis. POC test results changed the triage decision for 24 (41%) patients, of which 20 (34%) led to the prevention of an unnecessary medical retrieval and four (7%) indicated the patient had an acute infection which required a medical retrieval. POC test results assisted decision making for a further 13 (22%) patients. Cost savings related to avoiding unnecessary medical retrievals were estimated to be AU$481,440. Extrapolated NT-wide cost savings are projected to be AU$5.33 million per annum. POC testing for WBC DIFF counts aided clinical decision making for triaging patients with three common acute infections.

Clinical training and validation of the LeukoScope: a low-cost, point-of-care device to perform white blood cell and neutrophil counts

We present a novel, point-of-care method to perform WBC and neutrophil counts with a drop of blood and portable reader.

Development of point-of-care testing devices to improve clozapine prescribing habits and patient outcomes

Although clozapine has demonstrated superior efficacy in patients with schizophrenia and other serious mental health illness, drug utilization rates are significantly low due to safety concerns and administration challenges. Previous research indicates that current barriers to clozapine use include lack of confidence and knowledge by prescriber, therapeutic monitoring requirements, lack of support and infrastructure to for adequate monitoring and patient adherence, and inadequate understanding of clozapine's benefit-risk profile by policy makers and payers. One potential solution to optimizing clozapine therapy and improving clinical outcomes is the use of point-of-care testing (POCT) devices. Although the drug development process for currently used therapeutics is widely acknowledged, little is known regarding the development of POCT devices by the clinical community. The aim of this review is to provide a summary of the regulatory approval process and current availability of POCT devices for monitoring clozapine therapeutics. The potential role of POCT devices in clinical trials to inform personalized dosing strategies and improve patient outcomes will also be discussed.

Preliminary Results from a Prospective Study Comparing White Blood Cell and Neutrophil Counts from a Laboratory to Those Measured with a New Device in Patients with Breast Cancer

BACKGROUND/AIM

If blood tests were performed at home, unnecessary trips of patients for chemotherapy could be avoided. The HemoCue® WBC DIFF device was tested at home by 14 patients with breast cancer.

MATERIALS AND METHODS

A total of 42 measurements of white blood cell (WBC) and neutrophil counts with the device at home were compared to laboratory measurements performed within 3 hours. Bland-Altman plots were created for limits of agreement that should be less than 1.0×10⁹/l for WBC and 0.5×10⁹/l for neutrophils to indicate a similar grade of intensity.

RESULTS

Limits of agreement were -1.61×10⁹/l and +2.34×10⁹/l for WBC and -1.15×10⁹/l and +1.39×10⁹/l for neutrophils. All patients considered the device advantageous, particularly because they did not have to travel or wait for results. Most patients experienced problems with the lancet when taking blood samples.

CONCLUSION

Disagreement of WBC and neutrophil counts between methods appeared clinically relevant. Findings need to be verified in a larger cohort, including the use of a different type of lancet.

Point-of-care blood eosinophil count in a severe asthma clinic setting

BACKGROUND

One of the main severe asthma phenotypes is severe eosinophilic or eosinophilic refractory asthma for which novel biologic agents are emerging as therapeutic options. In this context, blood eosinophil counts are one of the most reliable biomarkers.

OBJECTIVE

To evaluate the performance of a point-of-care peripheral blood counter in a patients with severe asthma.

METHODS

The blood eosinophil counts of 76 patients with severe asthma were evaluated by point-of-care and standard analyzers.

RESULTS

A significant correlation between blood eosinophils assessed by the 2 devices was found (R² = 0.854, P < .001); similar correlations were found also for white blood cells, neutrophils, and lymphocytes. The point-of-care device had the ability to predict blood eosinophil cutoffs used to select patients for biologic treatments for severe eosinophilic asthma and the ELEN index, a composite score useful to predict sputum eosinophilia.

CONCLUSION

The results of our study contribute to the validation of a point-of-care device to assess blood eosinophils and open the possibility of using this device for the management of severe asthma management.

The HemoCue WBC DIFF system could be used for leucocyte and neutrophil counts but not for full differential counts

AIM

The aim of this study was to evaluate the HemoCue WBC DIFF system for point of care testing of fingerstick samples from paediatric patients.

METHODS

We analysed 158 white blood cell counts on both the point of care HemoCue WBC DIFF instrument and the Cell Dyn Sapphire cell counter used by our central laboratory and compared the results. The measurements were performed using fingerstick samples drawn by nurses working in paediatric emergency and paediatric oncology units.

RESULTS

There was good agreement between the two instruments for white blood cell and neutrophil counts. The correlation was weaker for lymphocytes, and the correlations were poor for monocytes and eosinophils. The HemoCue WBC DIFF flagged 56 of the 148 capillary drawn samples as abnormal, but none of the 10 venously collected samples. Only two of the flagged samples differed significantly between the instruments, with regard to the cell counts.

CONCLUSION

The correlations between the white blood cell counts and neutrophil counts in this real-life study were good enough to diagnose children in emergency department and oncology unit settings. However, the high number of pathological flags from fingerstick samples, which made reruns necessary, limited the usefulness of the instrument.