Assessing agreement between point of care and laboratory results for lipid testing from a clinical perspective

Improving the accuracy of bone mineral density using a multisource CBCT

Multisource cone beam computed tomography CBCT (ms-CBCT) has been shown to overcome some of the inherent limitations of a conventional CBCT. The purpose of this study was to evaluate the accuracy of ms-CBCT for measuring the bone mineral density (BMD) of mandible and maxilla compared to the conventional CBCT. The values measured from a multi-detector CT (MDCT) were used as substitutes for the ground truth. An anthropomorphic adult skull and tissue equivalent head phantom and a homemade calibration phantom containing inserts with varying densities of calcium hydroxyapatite were imaged using the ms-CBCT, the ms-CBCT operating in the conventional single source CBCT mode, and two clinical CBCT scanners at similar imaging doses; and a clinical MDCT. The images of the anthropomorphic head phantom were reconstructed and registered, and the cortical and cancellous bones of the mandible and the maxilla were segmented. The measured CT Hounsfield Unit (HU) and Greyscale Value (GV) at multiple region-of-interests were converted to the BMD using scanner-specific calibration functions. The results from the various CBCT scanners were compared to that from the MDCT. Statistical analysis showed a significant improvement in the agreement between the ms-CBCT and MDCT compared to that between the CBCT and MDCT.

Volumetric computed tomography with carbon nanotube X-ray source array for improved image quality and accuracy

Cone beam computed tomography (CBCT) is widely used in medical and dental imaging. Compared to a multidetector CT, it provides volumetric images with high isotropic resolution at a reduced radiation dose, cost and footprint without the need for patient translation. The current CBCT has several intrinsic limitations including reduced soft tissue contrast, inaccurate quantification of X-ray attenuation, image distortions and artefacts, which have limited its clinical applications primarily to imaging hard tissues and made quantitative analysis challenging. Here we report a multisource CBCT (ms-CBCT) which overcomes the short-comings of the conventional CBCT by using multiple narrowly collimated and rapidly scanning X-ray beams from a carbon nanotube field emission source array. Phantom imaging studies show that, the ms-CBCT increases the accuracy of the Hounsfield unit values by 60%, eliminates the cone beam artefacts, extends the axial coverage, and improves the soft tissue contrast-to-noise ratio by 30-50%, compared to the CBCT configuration.

Unmet need for hypercholesterolemia care in 35 low- and middle-income countries: A cross-sectional study of nationally representative surveys

BACKGROUND

As the prevalence of hypercholesterolemia is increasing in low- and middle-income countries (LMICs), detailed evidence is urgently needed to guide the response of health systems to this epidemic. This study sought to quantify unmet need for hypercholesterolemia care among adults in 35 LMICs.

METHODS AND FINDINGS

We pooled individual-level data from 129,040 respondents aged 15 years and older from 35 nationally representative surveys conducted between 2009 and 2018. Hypercholesterolemia care was quantified using cascade of care analyses in the pooled sample and by region, country income group, and country. Hypercholesterolemia was defined as (i) total cholesterol (TC) ≥240 mg/dL or self-reported lipid-lowering medication use and, alternatively, as (ii) low-density lipoprotein cholesterol (LDL-C) ≥160 mg/dL or self-reported lipid-lowering medication use. Stages of the care cascade for hypercholesterolemia were defined as follows: screened (prior to the survey), aware of diagnosis, treated (lifestyle advice and/or medication), and controlled (TC <200 mg/dL or LDL-C <130 mg/dL). We further estimated how age, sex, education, body mass index (BMI), current smoking, having diabetes, and having hypertension are associated with cascade progression using modified Poisson regression models with survey fixed effects. High TC prevalence was 7.1% (95% CI: 6.8% to 7.4%), and high LDL-C prevalence was 7.5% (95% CI: 7.1% to 7.9%). The cascade analysis showed that 43% (95% CI: 40% to 45%) of study participants with high TC and 47% (95% CI: 44% to 50%) with high LDL-C ever had their cholesterol measured prior to the survey. About 31% (95% CI: 29% to 33%) and 36% (95% CI: 33% to 38%) were aware of their diagnosis; 29% (95% CI: 28% to 31%) and 33% (95% CI: 31% to 36%) were treated; 7% (95% CI: 6% to 9%) and 19% (95% CI: 18% to 21%) were controlled. We found substantial heterogeneity in cascade performance across countries and higher performances in upper-middle-income countries and the Eastern Mediterranean, Europe, and Americas. Lipid screening was significantly associated with older age, female sex, higher education, higher BMI, comorbid diagnosis of diabetes, and comorbid diagnosis of hypertension. Awareness of diagnosis was significantly associated with older age, higher BMI, comorbid diagnosis of diabetes, and comorbid diagnosis of hypertension. Lastly, treatment of hypercholesterolemia was significantly associated with comorbid hypertension and diabetes, and control of lipid measures with comorbid diabetes. The main limitations of this study are a potential recall bias in self-reported information on received health services as well as diminished comparability due to varying survey years and varying lipid guideline application across country and clinical settings.

CONCLUSIONS

Cascade performance was poor across all stages, indicating large unmet need for hypercholesterolemia care in this sample of LMICs-calling for greater policy and research attention toward this cardiovascular disease (CVD) risk factor and highlighting opportunities for improved prevention of CVD.

The validity of activity trackers is affected by walking speed: the criterion validity of Garmin Vivosmart® HR and StepWatch™ 3 for measuring steps at various walking speeds under controlled conditions

Introduction

The use of activity trackers has increased both among private consumers and in healthcare. It is therefore relevant to consider whether a consumer-graded activity tracker is comparable to or may substitute a research-graded activity tracker, which could further increase the use of activity trackers in healthcare and rehabilitation. Such use will require knowledge of their accuracy as the clinical implications may be significant. Studies have indicated that activity trackers are not sufficiently accurate, especially at lower walking speeds. The present study seeks to inform decision makers and healthcare personnel considering implementing physical activity trackers in clinical practice. This study investigates the criterion validity of the consumer-graded Garmin Vivosmart^® HR and the research-graded StepWatch^™ 3 compared with manual step count (gold standard) at different walking speeds under controlled conditions.

Methods

Thirty participants, wearing Garmin Vivosmart^® HR at the wrist and StepWatch^™ 3 at the ankle, completed six trials on a treadmill at different walking speeds: 1.6 km/h, 2.4 km/h, 3.2 km/h, 4.0 km/h, 4.8 km/h, and 5.6 km/h. The participants were video recorded, and steps were registered by manual step count. Medians and inter-quartile ranges (IQR) were calculated for steps and differences in steps between manually counted steps and the two devices. In order to assess the clinical relevance of the tested devices, the mean absolute percentage error (MAPE) was determined at each speed. A MAPE ≤3% was considered to be clinically irrelevant. Furthermore, differences between manually counted steps and steps recorded by the two devices were presented in Bland-Altman style plots.

Results

The median of differences in steps between Garmin Vivosmart^® HR and manual step count ranged from -49.5 (IQR = 101) at 1.6 km/h to -1 (IQR = 4) at 4.0 km/h. The median of differences in steps between StepWatch^™ 3 and manual step count were 4 (IQR = 14) at 1.6 km/h and 0 (IQR = 1) at all other walking speeds. The results of the MAPE showed that differences in steps counted by Garmin Vivosmart^® HR were clinically irrelevant at walking speeds 3.2-4.8 km/h (MAPE: 0.61-1.27%) as the values were below 3%. Differences in steps counted by StepWatch^™ 3 were clinically irrelevant at walking speeds 2.4-5.6 km/h (MAPE: 0.08-0.35%).

Conclusion

Garmin Vivosmart^® HR tended to undercount steps compared with the manual step count, and StepWatch^™ 3 slightly overcounted steps compared with the manual step count. Both the consumer-graded activity tracker (Garmin Vivosmart^® HR) and the research-graded (StepWatch^™ 3) are valid in detecting steps at selected walking speeds in healthy adults under controlled conditions. However, both activity trackers miscount steps at slow walking speeds, and the consumer graded activity tracker also miscounts steps at fast walking speeds.

A short-term religious "fast" from animal products has a minimal impact on cardiometabolic health biomarkers irrespective of concurrent shifts in distinct plant-based food groups

BACKGROUND

Plant-based diets may help improve measures of body fat, blood cholesterol, glucose metabolism, and inflammation. However, limited evidence suggests that the health effects of reducing animal products may depend on the quality of plant-based foods consumed as caloric replacements.

OBJECTIVE

This study examined how temporarily restricting consumption of meat, dairy, and egg (MDE) products for religious purposes influences cardiometabolic health biomarkers and whether any effects of MDE restriction on biomarkers are modified by concurrent shifts in calories, fish, and distinct plant-based foods.

DESIGN

This study followed a sample of 99 individuals in the United States with varying degrees of adherence to Orthodox Christian (OC) guidance to abstain from MDE products during Lent, the 48-d period prior to Easter. Dietary composition was estimated from FFQs and 7-d food records; measures of body fat, blood lipids, glucose metabolism, and inflammation were collected prior to and at the end of Lent.

RESULTS

Each serving decrease in MDE products was associated with an average -3.7% (95% CI: -5.5%, -2.0%; P < 0.0001) and -3.6% (95% CI: -5.8%, -1.3%; P = 0.003) change in fasting total and LDL blood cholesterol, respectively, which were partly explained by minor weight loss. However, the total/HDL cholesterol ratio did not significantly decrease due to an average -3.2% (95% CI: -5.8%, -0.6%; P = 0.02) change in HDL cholesterol. No associations between MDE restrictions and shifts in measures of body fat, glucose, insulin, or C-reactive protein were observed. The data could not provide evidence that changes in cardiometabolic health biomarkers in relation to MDE restriction were modified by concurrent shifts in calories, fish, or plant-based foods.

CONCLUSION

Temporary MDE restrictions practiced by this sample of OCs in the United States during Lent had minimal effects on cardiometabolic disease risk factors. Further research among larger samples of OCs is needed to understand how nutritionally distinct and complex combinations of plant-based foods may modify the health effects of religious fasting from MDE products.

Comparison between Mother, ActiGraph wGT3X-BT, and a hand tally for measuring steps at various walking speeds under controlled conditions

Introduction

Walking is endorsed as health enhancing and is the most common type of physical activity among older adults. Accelerometers are superior to self-reports when measuring steps, however, if they are to be used by clinicians the validity is of great importance. The aim of this study was to investigate the criterion validity of Mother and ActiGraph wGT3X-BT in measuring steps by comparing the devices to a hand tally under controlled conditions in healthy participants.

Methods

Thirty healthy participants were fitted with a belt containing the sensor of Mother (Motion Cookie) and ActiGraph. Participants walked on a treadmill for two minutes at each of the following speeds; 3.2, 4.8, and 6.4 km/h. The treadmill walking was video recorded and actual steps were subsequently determined by using a hand tally. Wilcoxon’s signed ranks test was used to determine whether Mother and ActiGraph measured an identical number of steps compared to the hand tally. Intraclass correlation coefficients were calculated to determine the relationship and Root Mean Square error was calculated to investigate the average error between the devices and the hand tally. Percent differences (PD) were calculated for between-instrument agreement (Mother vs. the hand tally and ActiGraph vs. the hand tally) and PDs below 3% were interpreted as acceptable and clinically irrelevant.

Results

Mother and ActiGraph under-counted steps significantly compared to the hand tally at all walking speeds (p < 0.001). Mother had a median of total differences of 9.5 steps (IQR = 10) and ActiGraph 59 steps (IQR = 77). Mother had smaller PDs at all speeds especially at 3.2 km/h (2.5% compared to 26.7%). Mother showed excellent ICC values ≥0.88 (0.51–0.96) at all speeds whilst ActiGraph had poor and fair to good ICC values ranging from 0.03 (−0.09–0.21) at a speed of 3.2 km/h to 0.64 (0.16–0.84) at a speed of 6.4 km/h.

Conclusion

Mother provides valid measures of steps at walking speeds of 3.2, 4.8, and 6.4 km/h with clinically irrelevant deviations compared to a hand tally while ActiGraph only provides valid measurements at 6.4 km/h based on the 3% criterion. These results have significant potential for valid objective measurements of low walking speeds. However, further research should investigate the validity of Mother in patients at even slower walking speeds and in free-living conditions.

Evaluation of the point of care Afinion AS100 analyser in a community setting

Background

A ‘one stop shop’ model for multifactorial risk factor management in a culturally sensitive environment may improve cardiovascular disease and diabetes prevention. A full biochemical profile for cardiovascular disease risk assessment includes a lipid profile, glucose, glycated haemoglobin and urine albumin creatinine ratio measurements. This may require the use of more than one point of care testing instrument.

Methods

Individuals who attended a community cardiovascular disease risk screening or an audit programme of the diabetic care pathway in the community were sampled. Bland–Altman and Deming regression plots were used to assess agreement between methods for total cholesterol, high-density lipoprotein cholesterol, triglycerides, glycated haemoglobin and urine albumin creatinine ratio.

Results

There was good agreement between the Afinion AS100 analyser, Cholestech LDX and the laboratory methods for total cholesterol, high-density lipoprotein cholesterol and triglycerides ( n = 232). The Afinion AS100 agreed well with the laboratory method for glycated haemoglobin ( n = 255) and urine albumin creatinine ratio ( n = 176). There was statistically significant bias ( p = 0.03 to <0.0001) for several measurements. However, these were judged not to be clinically relevant. Specifically for the total cholesterol and high-density lipoprotein cholesterol values, we obtained good agreement (weighted kappa: 0.91 and 0.94 for the Afinion AS100 vs. Cholestech LDX and Afinion AS100 vs. laboratory method, respectively) for cardiovascular disease risk calculation using QRISK2.

Conclusions

Point of care testing can support a ‘one stop shop’ approach by providing rapid, reliable results. The Afinion AS100 analyser provides a multi-analyte platform and compares well with laboratory-based methods and another well-established point of care testing analyser.

Assessing the accuracy of a point-of-care analyzer for hyperlipidaemia in western Kenya

OBJECTIVES

The prevalence of hyperlipidaemia, along with other non-communicable diseases, is on the rise in low- and middle-income countries. CardioChek PA is a point-of-care lipid measuring device, which seeks to overcome laboratory-based diagnostic barriers by providing immediate results without dependency on significant laboratory infrastructure. However, it has not been validated in Kenya. In this study, we assess the accuracy of CardioChek PA with respect to the gold standard laboratory-based testing.

METHODS

In Webuye, Kenya, two blood samples were collected from 246 subjects to simultaneously measure the lipid levels via both CardioChek PA and the gold standard. All subjects were adults, and geographic stratified sampling methods were applied. Statistical analysis of the device's accuracy was based on per cent bias parameters, as established by the United States National Institutes of Health (NIH). The NIH recommends that per cent bias be ≤±3% for low-density lipoprotein (LDL) cholesterol, ≤±5% for high-density lipoprotein (HDL) cholesterol, ≤±5% for total cholesterol (TC) and ≤±4% for triglycerides (TG). Risk group misclassification rates were also analysed.

RESULTS

The CardioChek PA analyzer was substantially inaccurate for LDL cholesterol (-25.9% bias), HDL cholesterol (-8.2% bias) and TC (-15.9% bias). Moreover, those patients at higher risk of complications from hyperlipidaemia were most likely to be misclassified into a lower risk category.

CONCLUSION

CardioChek PA is inaccurate and not suitable for our clinical setting. Furthermore, our findings highlight the need to validate new diagnostic tools in the appropriate setting prior to scale up regardless of their potential for novel utility.

Nucleic-acid testing, new platforms and nanotechnology for point-of-decision diagnosis of animal pathogens

Accurate disease diagnosis in animals is crucial for animal well-being but also for preventing zoonosis transmission to humans. In particular, livestock diseases may constitute severe threats to humans due to the particularly high physical contact and exposure and, also, be the cause of important economic losses, even in non-endemic countries, where they often arise in the form of rapid and devastating epidemics. Rapid diagnostic tests have been used for a long time in field situations, particularly during outbreaks. However, they mostly rely on serological approaches, which may confirm the exposure to a particular pathogen but may be inappropriate for point-of-decision (point-of-care) settings when emergency responses supported on early and accurate diagnosis are required. Moreover, they often exhibit modest sensitivity and hence significantly depend on later result confirmation in central or reference laboratories. The impressive advances observed in recent years in materials sciences and in nanotechnology, as well as in nucleic-acid synthesis and engineering, have led to an outburst of new in-the-bench and prototype tests for nucleic-acid testing towards point-of-care diagnosis of genetic and infectious diseases. Manufacturing, commercial, regulatory, and technical nature issues for field applicability more likely have hindered their wider entrance into veterinary medicine and practice than have fundamental science gaps. This chapter begins by outlining the current situation, requirements, difficulties, and perspectives of point-of-care tests for diagnosing diseases of veterinary interest. Nucleic-acid testing, particularly for the point of care, is addressed subsequently. A range of valuable signal transduction mechanisms commonly employed in proof-of-concept schemes and techniques born on the analytical chemistry laboratories are also described. As the essential core of this chapter, sections dedicated to the principles and applications of microfluidics, lab-on-a-chip, and nanotechnology for the development of point-of-care tests are presented. Microdevices already applied or under development for application in field diagnosis of animal diseases are reviewed.

A combined laboratory and field evaluation of the Cholestech LDX and CardioChek PA point-of-care testing lipid and glucose analysers

Background

Combined lipid and glucose point-of-care testing (POCT) devices could facilitate widespread population screening for cardiovascular disease (CVD) and diabetes as part of the NHS Vascular Risk Assessment and Management Program (NHS Health Checks). An evaluation of the Cholestech LDX and CardioChek PA POCT analysers was performed in collaboration with the Wolverhampton City Primary Care Trust (PCT).

Methods

Intra-/inter-batch imprecision, between-analyser variation and the effect of haematocrit and ascorbic acid assay interference were investigated. Accuracy of the POCT capillary whole blood total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-C) and glucose measurements was estimated by comparison with those from the laboratory analysis of paired venous samples. POCT usability and clinical governance were also assessed.

Results

The LDX exhibited lower intra- and inter-batch imprecision and external quality assessment (EQA) scheme between-analyser variation for the measurement of TC, HDL-C and glucose when compared to the CardioChek. Ascorbic acid negatively interfered in all three assays on both POCT analysers and results reported by the CardioChek were influenced by the specimen haematocrit. The LDX displayed closer agreement with the laboratory methods for the measurement of TC and HDL-C but both the LDX and the CardioChek displayed positive bias for the measurement of glucose.

Conclusions

POCT has clear advantages for delivering NHS Health Checks over the laboratory-based approach although device performance does differ. Users should also be aware of the potential clinical governance and interference issues associated with these devices.

Reproducibility, accuracy and concordance of Accutrend Plus for measuring circulating lipid concentration in adults

INTRODUCTION

The determination of lipid biomarkers by capillary sampling may be useful in the screening, diagnosis and/or personal management of hyperlipidemia and cardiovascular risk. It remains unclear whether the use of the Accutrend Plus system is appropriate. This study aimed to assess its reproducibility, accuracy and concordance for blood lipid profiling in adults.

MATERIALS AND METHODS

Fasting capillary total cholesterol (TC) and triglyceride (TG) concentration on Accutrend Plus were compared with their venous analogues obtained by a laboratory reference method in sixty-one adults (27 men and 34 women, aged 33.0 years). Supplementary capillary sampling was performed at two consecutive days taking into account macro-nutrient intake.

RESULTS

The day-to-day reproducibility of the Accutrend Plus system proved to be high for TC (ICC = 0.85, P < 0.001), but moderate for TG (ICC = 0.68, P < 0.001). Strong correlations (r > or = 0.80, P < 0.001) with the reference method were found for TC and TG. Mean difference (limits of agreement) were: 0.26 mmol/L (-0.95, 1.47) for TC, and -0.16 mmol/L (-1.29, 0.98) for TG. The concordance for subject classification according to the National Cholesterol Education Program (NCEP) guidelines was significant (P < 0.001), with substantial agreement for TC (K(w) = 0.67), and moderate agreement for TG (K(w) = 0.50).

CONCLUSIONS

Day-to-day reproducibility of the Accutrend Plus device for TC and TG is not optimal and lacks accuracy when compared to the reference laboratory method. The concordance between both methods for classifying subjects according to the NCEP is inadequate. Accutrend Plus device should not be interchangeably used as a substitution for the standard laboratory methods in the diagnosis of hyperlipidemia.

Point-of-care testing (POCT): Current techniques and future perspectives

Point-of-care testing (POCT) is a laboratory-medicine discipline that is evolving rapidly in analytical scope and clinical application. In this review, we first describe the state of the art of medical-laboratory tests that can be performed near the patient. At present, POCT ranges from basic blood-glucose measurement to complex viscoelastic coagulation assays. POCT shortens the time to clinical decision-making about additional testing or therapy, as delays are no longer caused by transport and preparation of clinical samples, and biochemical-test results are rapidly available at the point of care. Improved medical outcome and lower costs may ensue. Recent, evolving technological advances enable the development of novel POCT instruments. We review the underlying analytical techniques. If new instruments are not yet in practical use, it is often hard to decide whether the underlying analytical principle has real advantage over former methods. However, future utilization of POCT also depends on health-care trends and new areas of application. But, even today, it can be assumed that, for certain applications, near-patient testing is a useful complement to conventional laboratory analyses.

Point of care testing is appropriate for National Health Service health check

BACKGROUND

The Department of Health launched a cardiovascular disease risk assessment initiative with particular reference to reducing health inequalities in ethnic minorities. Collaboration between HEART UK, Royal Free Hampstead NHS Trust and Hindu Temples resulted in vascular screening in North London.

METHODS

Subjects of South Asian origin were screened. A full lipid profile and glucose were measured using a point of care testing (POCT) Cholestech LDX analyser (LDX). Venous samples were analysed in our hospital laboratory.

RESULTS

The results (215 men; 191 women) were divided into tertiles and Bland-Altman plots were used to assess agreement. At high-density lipoprotein cholesterol (HDL-C) concentrations < 1.0 mmol/L the LDX underestimated values by -0.2 mmol/L (P<0.0001). At HDL-C concentrations >1.3 mmol/L this bias disappeared. For total cholesterol the concentration-dependent negative bias was evident at concentrations of < 4.1 mmol/L (P < 0.0001). This bias was less evident at higher concentrations. A similar pattern was seen for low-density lipoprotein cholesterol. There were also small variations in glucose and triglyceride values. However, there was excellent agreement in calculated cardiovascular disease risk using kappa analysis for JBS2, QRISK2, ETHRISK and Framingham (κ = 0.86, 0.92, 0.94 and 0.88, respectively). This was a high-risk population since 9.7-19.4% had a ≥ 20% 10-y probability of a vascular event depending on the risk engine and assay method used. The corresponding values for intermediate risk (11-19%) were 18.6-25.7%.

CONCLUSIONS

There was a minimum mismatch irrespective of the type of risk calculator used. POCT measurements are adequate for the National Health Service Health Check.