scholarly journals Capillary blood tests may overestimate ketosis: triangulation between three different measures of β-hydroxybutyrate

2020 ◽  
Vol 318 (2) ◽  
pp. E184-E188 ◽  
Author(s):  
Jakob Norgren ◽  
Shireen Sindi ◽  
Anna Sandebring-Matton ◽  
Ingemar Kåreholt ◽  
Ulrika Akenine ◽  
...  

The ketone body β-hydroxybutyrate (BHB), assessed by a point-of-care meter in venous whole blood (BHBv), was used as the main outcome in a study on nutritional ketosis in healthy older adults. Two other BHB measures were also used in the study for validation and exploratory purposes, and here we report findings on correlation and agreement between those three methods. Ketosis in the range of 0–1.5 mmol/L was induced in 15 healthy volunteers by intake of medium-chain fatty acids after a 12-h fast. BHBv was assessed at 12 time points for 4 h. The same point-of-care meter was also used to test capillary blood (BHBc) at three time points, and a laboratory test determined total ketones (TK) in plasma (BHBp + acetoacetate) at four time points. A total of 180 cases included simultaneous data on BHBv, BHBc, BHBp, and TK. TK correlated with BHBp (Pearson’s r = 0.99), BHBv ( r = 0.91), and BHBc ( r = 0.91), all P < 0.0001. BHBv and BHBp had good agreement in absolute values. However, the slope between BHBc and BHBv, measured with the same device, was in the range of 0.64–0.78 in different regression models, indicating substantially higher BHB concentrations in capillary versus venous blood. We conclude that all three methods are valid to detect relative changes in ketosis, but our results highlight the importance of method considerations and the possible need to adjust cutoffs, e.g., in the management of ketoacidosis and in the evaluation and comparison of dietary interventions.

2020 ◽  
Vol 9 ◽  
Author(s):  
Alessandra da Silva Pereira ◽  
Inês Rugani Ribeiro de Castro ◽  
Flávia Fioruci Bezerra ◽  
José Firmino Nogueira Neto ◽  
Ana Carolina Feldenheimer da Silva

Abstract Portable haemoglobinometers have been used in order to estimate the prevalence of anaemia in diverse settings. However, few studies have been conducted to evaluate their performance in children of different age groups in distinct epidemiological contexts. To evaluate the reproducibility and reliability of a portable haemoglobinometer for the diagnosis of anaemia in children <5 years Hb was measured in the venous blood of 351 children <5 years by an automated system (standard method) and in three capillary blood samples, using a portable haemoglobinometer (HemoCue®; test method). The reproducibility of the device and of the test method was evaluated using the intraclass correlation coefficient (ICC) (Hb in its continuous form), κ and prevalence-adjusted bias-adjusted κ (PABAK) (categorised variable: anaemia: yes/no). For test method validation, Bland–Altman analyses were performed and sensitivity, specificity, accuracy rate, positive predictive value (PPV) and negative predictive values (NPV) were calculated. The haemoglobinometer presented good device reproducibility (ICC = 0·79) and reasonable method reproducibility (puncture, collection and reading) (ICC = 0·71). Superficial and fair agreement (κ) and good agreement (PABAK) were observed among the diagnoses obtained through the test method. The prevalence of anaemia was 19·1 and 19·7 % using the standard and the test method, respectively, with no statistically significant differences. The test method presented higher specificity (87·7 %) and NPV (88·3 %) than sensitivity (50·7 %) and PPV (49·3 %), and intermediary accuracy rate (57·8 %). HemoCue® showed good device reproducibility and reasonable method reproducibility, as well as good performance in estimating the prevalence of anaemia. Nevertheless, it showed a fair reliability and low individual diagnostic accuracy.


2008 ◽  
Vol 99 (06) ◽  
pp. 1097-1103 ◽  
Author(s):  
Karina Black ◽  
Mary Massicotte ◽  
Michelle Bauman ◽  
Stefan Kuhle ◽  
Susan Howlett-Clyne ◽  
...  

SummaryPoint-of-care INR (POC INR) meters can provide a safe and effective method for monitoring oral vitamin K antagonists (VKAs) in children. Stollery Children’s Hospital has a large POC INR meter loan program for children requiring oral VKAs. Our protocol requires that POC INR results be compared to the standard laboratory INR for each child on several consecutive tests to ensure accuracy of CoaguChek XS® (Roche Diagnostics, Basel Switzerland) meter. It was the objective of the study to determine the accuracy of the CoaguChek XS by comparing whole blood INR results from the CoaguChek XS to plasma INR results from the standard laboratory in children. POC INR meter validations were performed on plasma samples from two time points from 62 children receiving warfarin by drawing a venous blood sample for laboratory prothrombin (PT)-INR measurements and simultaneous INR determinations using the POC-INR meter. Agreement between CoaguChek XS INR and laboratory INR was assessed using Bland-Altman plots. Bland-Altman's 95% limits of agreement were 0.11 (-0.20; 0.42) and 0.13 (-0.22; 0.48) at the two time points, respectively. In conclusion, the CoaguChek XS meter appraisal generates an accurate and precise INR measure in children when compared to laboratory INR test results.


Author(s):  
Samantha Wilkinson ◽  
Tiago Chiavegatti ◽  
Benedicte Nauche ◽  
Given Names Deactivated Family Name Deactivated ◽  
Nitika Pant Pai

Background: Timely detection, staging, treatment initiation are pertinent to controlling HIV Infection. CD4+ cell-based point-of-care (POC) devices offer the potential to rapidly stage patients, and decide on initiating treatment, but a comparative evaluation of their performance has not yet been performed. With this in mind, we conducted a systematic review and meta-analyses. Methods: For the period Jan 2000 to April 2015, 19 databases were systematically searched, 6619 citations retrieved, and 25 articles selected. Diagnostic performance was compared across devices (i.e., PIMA, CyFlow, miniPOC, MBioCD4 System) and across specimens (i.e., capillary blood vs. venous blood). A Bayesian approach was used to meta-analyze the data. The primary outcome, the Bland-Altman (BA) mean bias (which represents agreement between cell counts from POC device and flow cytometry), was analyzed with a Bayesian hierarchical normal model. Findings: We performed a head-to-head comparison of two point-of-care devices, PIMA and PointCareNOW CD4. PIMA appears to perform better vs. PointCareNOW with venous samples (BA mean bias: -9.5 cells/μL; 95% CrI:-37.71 to 18.27 vs. 139.3 cells/μL; 95% CrI:-0.85 to 267.4, mean difference = 148.8, 95% CrI: 11.8, 285.8); however, PIMA’s best performed when used with capillary samples (BA mean bias: 2.2 cells/μL; 95% CrI:-19.32 to 23.6). Sufficient data was available to allow pooling of sensitivity and specificity data only at the 350 cells/μL cutoff. For PIMA device sensitivity 91.6 (84.7 to 95.5) and specificity was 94.8 (90.1 to 97.3) respectively. There was not sufficient data to allow comparisons between any other devices. Conclusions: PIMA device was comparable to flow cytometry. The estimated differences between the CD4+ cell counts of the device and the reference was small and best estimated in capillary blood specimens. As the evidence stands, the PointCareNOW device will need to improve prior to widespread use and more data on MBio and MiniPOC are needed. Findings inform implementation of PIMA and improvements in other CD4 POC device prior to recommending widespread use.


2014 ◽  
Vol 3 (4) ◽  
pp. 233-242 ◽  
Author(s):  
Benjamin Paul Green ◽  
Javier Thomas Gonzalez ◽  
Kevin Thomas ◽  
Emma Stevenson ◽  
Penny Louise Sheena Rumbold

This study examined the agreement between fingertip-capillary and antecubital-venous measures of appetite-related peptides. Simultaneous fingertip-capillary and antecubital-venous blood samples were collected from 19 participants. The samples were obtained at baseline, 30, 60, 90, and 120 min following breakfast for the determination of plasma GLP17–36, glucagon, insulin and leptin. Between-day reproducibility of fingertip-capillary-derived estimates was assessed in 18 participants. Deming regression, limits of agreement (LOA) and typical error as a coefficient of variation (CV) were used to quantify agreement (CVa) and reproducibility (CVr). Deming regression revealed no systematic bias for any of the analytes studied, but for insulin there was evidence of a proportional difference at higher concentrations. Measures of GLP17–36 (CVa=24.0%, LOA ±2.5 pg m/l per h), leptin (CVa=9.0%, LOA ×/÷1.19) and glucagon (CVa=21.0%, LOA, ±31.5 pg m/l per h) revealed good agreement between methodological approaches. Fingertip-capillary glucagon was highly reproducible between days (CVr=8.2%). GLP17–36 and leptin demonstrated modest reproducibility (CVr=22.7 and 25.0% respectively). For insulin, agreement (CVa=36.0%, LOA ×/÷1.79) and reproducibility were poor (CVr=36.0%). Collectively, the data demonstrate that fingertip-capillary blood sampling provides a comparable and reproducible alternative to antecubital-venous blood sampling for the quantification of glucagon, and to a lesser extent for GLP17–36 and leptin. Caution should be exercised when utilising fingertip-capillary blood sampling for insulin quantification, and consequently should not be employed interchangeably with antecubital-venous blood sampling.


2021 ◽  
pp. 026988112199156
Author(s):  
David Taylor ◽  
Matthew Atkins ◽  
Robert Harland ◽  
Irina Baburina ◽  
James H MacCabe ◽  
...  

Background: The use of clozapine demands regular monitoring of clozapine plasma concentrations and of white blood cell parameters. The delay between sending blood samples for analysis and receiving the results hinders clinical care. Point-of-care testing (POCT) can provide drug assay results within a few minutes. Aim: This study aimed to investigate the utility of a novel point-of-care device that can measure clozapine concentrations using capillary blood samples collected via a finger stick. Method: During a five-week period starting in June 2019 eligible patients were asked to provide a finger-stick capillary sample in addition to their usual venous blood sample. Samples were analysed by the novel point-of-care device and by the standard laboratory method. Capillary blood samples were tested by the MyCare™ Insite POCT analyser, and a quantitative measurement of clozapine concentration was provided within six minutes. Results: A total of 309 patients agreed to measurements by the two methods. Analysis revealed clozapine concentrations in venous blood as determined by the laboratory method ranged from 20 to 1310 ng/mL and by POCT from 7 to 1425 ng/mL. There was a strong positive correlation ( R = 0.89) between the results from the venous and the capillary sample methods. The slope of the association between standard assay and MyCare™ Insite was 1.0 with an intercept of –21 ng/mL, indicating minimal bias. Conclusion: Clozapine concentrations can be accurately measured at the point of care using capillary blood samples collected via a finger stick. This approach may be more acceptable than venous sampling to patients and, with almost instant results available, more useful to clinicians.


2021 ◽  
pp. 1-27
Author(s):  
Teena Dasi ◽  
Ravindranadh Palika ◽  
Raghu Pullakhandham ◽  
Little Flower Augustine ◽  
Naveen K. Boiroju ◽  
...  

Abstract Population-based surveys commonly use point-of-care (POC) methods with capillary blood samples for estimating haemoglobin (Hb) concentrations; these estimates need to be validated by comparison with reference methods using venous blood. In a cross-sectional study in 748 participants (17-86y, 708 women, Hb: 5.1 to 18.2 g/dL) from Hyderabad, India, we validated Hb measured from a pooled capillary blood sample by a POC autoanalyser (Horiba ABX Micros 60OT, Hb-C-AA) by comparison with venous blood Hb measured by two reference methods: POC autoanalyser (Hb-V-AA) and cyanmethemoglobin method (Hb-V-CM). These comparisons also allowed estimation of blood sample related and equipment related differences in the Hb estimates. We also conducted a longitudinal study in 426 participants (17-21y) to measure differences in the Hb response to iron folate treatment by the capillary blood POC method compared to the reference methods. In the cross-sectional study, Bland Altman analyses showed trivial differences between source of blood (Hb-C-AA and Hb-V-AA; mean difference, limits of agreement: 0.1, -0.8 to 1.0 g/dL) and between analytical methods (Hb-V-AA and Hb-V-CM; mean difference, limits of agreement :< 0.1, −1.8 to 1.8 g/dL). Cross-sectional anaemia prevalence estimated using Hb-C-AA did not differ significantly from Hb-V-CM or Hb-V-AA. In the longitudinal study, the Hb increment in response to IFA intervention was not different when using Hb-C-AA (1.6 ± 1.7 g/dL) compared to Hb-V-AA (1.7± 1.7g/dL) and Hb-V-CM (1.7± 1.7 g/dL). The pooled capillary blood–autoanalyzer method (Hb-C-AA) offers a practical and accurate way forward for POC screening of anaemia.


2019 ◽  
Vol 34 (05) ◽  
pp. 506-509
Author(s):  
Jessica Topping ◽  
Matthew Reardon ◽  
Jake Coleman ◽  
Brian Hunter ◽  
Haruka Shojima-Perera ◽  
...  

AbstractBackground:Blood glucose level (BGL) is routinely assessed by paramedics in the out-of-hospital setting. Most commonly, BGL is measured using a blood sample of capillary origin analyzed by a hand-held, point-of-care glucometer. In some clinical circumstances, the capillary sample may be replaced by blood of venous origin. Given most point-of-care glucometers are engineered to analyze capillary blood samples, the use of venous blood instead of capillary may lead to inaccurate or misleading measurements.Hypothesis/Problem:The aim of this prospective study was to compare mean difference in BGL between venous and capillary blood from healthy volunteers when measured using a capillary-based, hand-held, point-of-care glucometer.Methods:Using a prospective observational comparison design, 36 healthy participants provided paired samples of blood, one venous and the other capillary, taken near simultaneously. The BGL values were similar between the two groups. The capillary group had a range of 4.3mmol/l, with the lowest value being 4.4mmol/l and 8.7mmol/l the highest. The venous group had a range of 2.7mmol/l, with the lowest value being 4.1mmol/l and 7.0mmol/l the highest.For the primary research question, the mean BGL for the venous sample group was 5.3mmol/l (SD = 0.6), compared to 5.6mmol/l (SD = 0.8) for the capillary group. This represented a statistically significant difference of 0.3mmol/l (P = .04), but it did not reach the a priori established point of clinical significance (1.0mmol/l). Pearson’s correlation coefficient for capillary versus venous indicated moderate correlation (r = 0.42).Conclusion:In healthy, non-fasted people in a non-clinical setting, a statistically significant, but not clinically significant, difference was found between venous- and capillary-derived BGL when measured using a point-of-care, capillary-based glucometer. Correlation between the two was moderate. In this context, using venous samples in a capillary-based glucometer is reasonable providing the venous sample can be gathered without exposure of the clinician to risk of needle-stick injury. In clinical settings where physiological derangement or acute illness is present, capillary sampling would remain the optimal approach.


2014 ◽  
Vol 138 (7) ◽  
pp. 962-966 ◽  
Author(s):  
Ron B. Schifman ◽  
Tan T. Nguyen ◽  
Susan T. Page

Context.—Point-of-care glucose (POCG) testing on capillary blood specimens is central to maintaining glycemic control in patients with diabetes. Although there are known performance issues with POCG methods, especially for maintaining tight glucose control, there is little information about the accuracy of results in the critical ranges that may involve life-threatening conditions. Objectives.—To evaluate the reliability of POCG measurements in critical, high (&gt;600 mg/dL) and low (&lt;40 mg/dL) ranges. Design.—One-year retrospective analysis of POCG (ACCU-CHEK glucose meter, Roche Diagnostics Corporation, Indianapolis, Indiana) results for routine patient care were obtained. The frequency and accuracy of repeat testing after critical POCG results was analyzed. A convenience sample of noncritical capillary POCG measurements retested on venous blood specimens by another point-of-care device (RAPIDPoint 405 analyzer, Siemens Medical Solutions USA, Malvern, Pennsylvania) was also evaluated. Results.—Critical values were observed in 2.4 per 1000 POCG tests (256 of 105,928; 0.24%), with the highest rate (76 of 2289; 3.32%) from the emergency department. Twice as many critical high values as critical low values were seen. Nearly 80% of critical POCG tests (204 of 256) were repeated within 10 minutes. Of these 204 repeat measurements, 112 (54.9%) met accuracy criteria (±15 mg/dL of low and ±20% of high initial values). Accuracy was significantly higher when retesting was performed on the same meter or by the same operator (P ≤ .05). Comparison of capillary and venous POCG testing of noncritical results showed no significant difference (P = .95), with 89.8% (125 of 139) meeting accuracy criteria. Conclusions.—POCG measurements in the critical range are frequently erroneous, which is likely caused by preanalytic factors associated with sampling capillary blood. POCG testing practices should include retesting to confirm critical results.


2020 ◽  
Author(s):  
Lisa Nwankwo ◽  
Kate McLaren ◽  
Jackie Donovan ◽  
Melody Zhifang Ni ◽  
Alberto Vidal-Diaz ◽  
...  

Background In a tertiary respiratory centre, large cohorts of patients are managed in an outpatient setting and require blood tests to monitor disease activity and organ toxicity. This requires either visits to tertiary centres for phlebotomy and physician review or utilisation of primary care services. Objectives This study aims to validate remote capillary blood testing in an outpatient setting and analyse impact on clinical pathways. Methods A single-centre prospective cross-sectional validation and parallel observational study was performed. Remote finger prick capillary blood testing was validated compared to local standard venesection using comparative statistical analysis: paired t-test, correlation and Bland-Altman. Capillary was considered interchangeable with venous samples if all 3 criteria were met: non-significant paired t-test (i.e. p>0.05), Pearson's correlation coefficient (r) >0.8 and 95% of tests within 10% difference through Bland-Altman (Limits of agreement). In parallel, current clinical pathways including phlebotomy practice was analysed over 4 weeks to review test predictability. A subsequent pilot cohort study analysed potential impact of remote capillary blood sampling on shared decision making and outpatient clinical pathways. Results 117 paired capillary and venous blood samples were prospectively analysed. Interchangeability with venous blood was seen with HbA1c (%), total protein and CRP. Further tests, although not interchangeable, are likely useful to enable longitudinal remote monitoring (e.g. liver function, total IgE, and vitamin D). 65% of outpatient clinic blood tests were predictable with 16% of patients requiring further contact due to actions required. Pilot implementation of remote capillary sampling showed patient and clinician-reported improvement in shared decision-making given contemporaneous blood test results. Conclusions Remote capillary blood sampling can be used accurately for specific tests to monitor chronic disease, and when incorporated into an outpatient clinical pathway can improve shared decision making and patient experience. Further research is required to determine health-economic impact and applicability within telemedicine-based outpatient care.


2021 ◽  
Vol 11 ◽  
pp. 204512532110008
Author(s):  
Matthew Atkins ◽  
Philip McGuire ◽  
Bhirundra Balgobin ◽  
Pravinkumar Patel ◽  
David Taylor

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.


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