Gold Standard Measure Research Articles

Cystatin C provides substantially higher glomerular filtration rate estimates than creatinine in a subset of Black people with HIV on current antiretroviral regimens

Background In African populations, estimated glomerular filtration rate by cystatin C (eGFRcys) is better aligned with gold-standard GFR measurements than eGFR by creatinine (eGFRcr). Moreover, eGFRcys is unaffected by the effects of antiretroviral therapy (ART) on tubular secretion and may thus provide better estimates of GFR in people with HIV on ART. Setting Observational cohort study of people of African ancestry living with suppressed HIV RNA on ART in London, United Kingdom. Methods Cross sectional analysis of 360 paired serum creatinine and cystatin C measurements. Participants whose eGFRcys substantially (>10%) exceeded eGFRcr were identified, and factors associated with this outcome identified in logistic regression analysis. Results The median age was 52 years, 56% were female, and 82% born in Africa or the Caribbean. The eGFRcys substantially exceeded eGFRcr in 42% of participants in the overall cohort, and in 68% of those with eGFRcr 45-75 mL/min/1.73m2. In multivariable analysis, a higher eGFRcr was associated with lower odds (0.59 [0.50, 0.68] per 10 mL/min/1.73m2 increase) of eGFRcys substantially exceeding eGFRcr; a higher BMI was also associated with this outcome while ART regimens inhibiting tubular secretion of creatinine were not predictive. Of the 22 participants with eGFRcr 45-60 mL/min/1.73m2, 16 (73%) had eGFRcys >60 mL/min/1.73m2. Conclusion: We report substantially higher eGFRcys than eGFRcr in a subset of people of African ancestry with suppressed HIV, particularly among those with eGFRcr 45-75 mL/min/1.73m2. In this population, eGFRcys provides clinically useful information irrespective of ART regimen.

Invasive validation of central blood pressure measurements using a suprasystolic monitor

Abstract Interest in the assessment of Central Blood Pressure (cBP) is steadily growing since it is a better predictor of myocardial infarction, stroke, or death than Peripheral Blood Pressure (pBP). However, pBP remains the first line for the diagnosis of hypertension (HTN) due to the ease and speed of the measurement. We sought to validate a new method to estimate cBP from brachial sphygmomanometer measurements. We estimated cBP using a sphygmomanometer that can record, after conventional pBP measurements, the pressure in the cuff maintained at a constant suprasystolic pressure. cBP is calculated using a method based on applying a physics-based model of the left subclavian artery to the brachial arterial branch to the suprasystolic brachial artery pressure waveforms. We compared this noninvasive estimated cBP to an invasive gold-standard measurement during cardiac catheterization. After clinically indicated cardiac catheterization requiring a haemodynamic assessment of a moderate coronary artery stenosis by Fractional Flow Reserve (FFR), the wire that incorporates a high fidelity electronic pressure transducer was positioned into the guiding catheter left in the ascending aorta. Simultaneous measurements were performed with a cuff placed on the patient's left arm. The output signals were recorded in a custom-based acquisition system. The comparison was obtained on the same 10 seconds recorded by the cuff and the pressure wire. The goal will be to reach 85 patients as recommended by the ARTERY Society Task Force. It recommends as an accuracy criterion to achieve a mean difference ≤ 5 mmHg with a standard deviation (SD) ≤ 8 mmHg, which are the standards adopted for this study. Patients with aortic stenosis, atrial fibrillation, or frequent (supra)ventricular extrasystoles were excluded. A total of 197 pairs of measured-estimated cBP were analysed in 78 patients with a mean age of 63 ± 8 yo, 75% of whom were men, 70% had hypertension, 26% fdiabetes, 93% dyslipidemia, 41% were tobacco users and 14% suffered from clinical peripheral artery diseases without history of revascularization. The median (InterQuartiles 25-75%) pBP was 123 [112 134] / 70 [64 77] mmHg. Measured cBP was 102 [92 11] / 78 [70 84] mmHg with a central augmentation index of 34 [23 44] %. The mean difference between estimated and measured systolic cBP was 4.9 ± 6.5 mmHg, while it was -3.9 ± 5.8 mmHg for diastolic cBP, meeting the prespecified accuracy criteria. In conclusion, our approach based on an exact matching and comparison of non-invasive suprasystolic arm cuff measurements and high-fidelity aortic BP validates that an estimation of central aortic blood pressure that can be easily carried out in daily practice and might improve HTN management. It remains to be demonstrated that more cardiovascular complications will be avoided by guiding the antihypertensive therapy with cBP instead of pBP measurements.Bland-Altman of estimated - measured cBP

Instrument for Evaluation and Training of Decision Making in Dual Tasks in Soccer: Validation and Application.

Training in team sports such as soccer requires advanced technical and tactical skills for effective decision-making, particularly when executing a shot. This study validates an innovative instrument, a training platform (TP), designed to measure and enhance decision-making in dual-task scenarios. The TP aims to improve visual-motor reactions in multitask environments that simulate real game conditions. Equipped with an LED panel, main circuitry, ball sensor, and targets, the TP challenges players to kick the ball in response to the illumination of the final LED array on the panel while hitting a designated target. The study evaluated three parameters: reaction time (RT), ball speed (BS) and accuracy. To validate the TP against a gold standard (GS), we conducted correlation analyses. The results exhibited very strong correlations for both RT (r = 0.997) and BS (r = 0.994). The mean differences between TP and GS measurements were 13 ± 15 ms for RT and 0.1 ± 0.5 km/h for BS. Bland-Altman plots revealed trend lines obtained by a simple linear regression of r = -0.507, p = 0.307 for RT and r = 0.134, p = 0.077 for BS. The TP effectively simulates game scenarios, offering advantages such as low-cost components, installation flexibility, test variability, instant feedback, and integration of physical and cognitive components of sports performance.

Reliability of Glomerular Filtration Rate Estimated by Creatinine-Based Formulas in Moderate to Severe Proteinuria.

Creatinine-based Glomerular Filtration rate (GFR) formulas introduce a substantial bias in GFR estimations in patients with frank nephrotic syndrome. The bias and accuracy of creatinine-based GFR estimates (eGFR) in patients with non-nephrotic proteinuria need better characterization. We utilized data from the Ramipril in non-diabetic renal failure (REIN 1) and REIN 2 trials involving non-diabetic chronic kidney disease (CKD) patients with proteinuria to compare eGFRs derived from the CKD Epidemiology Consortium (CKD-EPI)formulas (with and without race), and the European Kidney Function Consortium (EKFC) equations with iohexol clearance (a gold-standard GFR measure, measured glomerular filtration rate [mGFR]). Bias was defined as the median difference between eGFR and mGFR, while accuracy was assessed using P30 and P15 metrics, which represent the percentage of eGFR values within ±30% and ±15% of mGFR, respectively. The median bias of the three formulas being compared did not differ, being minimal and in a strict range (0.04 to 0.05 ml/ml/min/1.73m2) in the REIN 1 study and (-0.04 to -0.03 ml/min/1.73 m2) in the REIN 2 study. These findings were confirmed in analyses stratified by age and mGFR. The global accuracy of the three formulas regarding P30% showed sufficient accuracy (P30 >75%) in REIN 1 and all strata in REIN 2, but the mGFR stratum <15 ml/min/1.73m2. The CKD-EPI (with and without race), and EKFC equations show no significant bias and sufficient accuracy in patients with proteinuria. These formulas can be safely applied to non-diabetic CKD patients with moderate to severe proteinuria.

A refined TTC assay precisely detects cardiac injury and cellular viability in the infarcted mouse heart

Histological analysis with 2,3,5-triphenyltetrazolium chloride (TTC) staining is the most frequently used tool to detect myocardial ischemia/reperfusion injury. However, its practicality is often challenged by poor image quality in gross histology, leading to an equivocal infarct-boundary delineation and potentially compromised measurement accuracy. Here, we introduce several crucial refinements in staining protocol and sample processing, which enable TTC images to be analyzed with light microscopy. The refined protocol involves a two-step TTC staining process (perfusion and immersion) and subsequent Zamboni fixation to differentiate myocardial viability and necrosis, and use of Coomassie brilliant blue to label area-at-risk. After the duo-staining steps were completed, the heart sample was embedded and sliced transversally by a cryostat into a series of thin sections (50 µm) for microscopic analysis. The refined TTC (redTTC) assay yielded remarkably high-quality images with striking color intensity and sharply defined boundaries, permitting unambiguous and reliable delineation of the infarct and area-at-risk. In the same animals, the redTTC assay showed good agreement with the in-vivo gold standard measurements (LGE and MEMRI). Meanwhile, redTTC imaging allows tracking of viable cardiomyocytes at cellular resolution, and with this enhanced capability, we convincingly demonstrated the pro-survival action of stem cells based-therapy. Therefore, the redTTC assay represents a significant technical advance that permits precise detection of the true extent of cardiac injury and cardiomyocyte viability. This approach is cost-effective and may be adapted for use in diverse applications, making it highly appealing to many laboratories performing ischemia/reperfusion injury experiments.

A Psychometric Evaluation of the Body Image Questionnaire Child and Adolescent Version.

Body dysmorphic disorder (BDD) typically develops during adolescence, but there has been little research evaluating assessment tools for BDD in youth. This study sought to provide a comprehensive psychometric evaluation of a brief self-report questionnaire of BDD symptoms, the Body Image Questionnaire Child and Adolescent version (BIQ-C), in both clinical and non-clinical adolescent samples. Properties of the BIQ-C were examined in 479 adolescents recruited through schools and 118 young people with BDD attending a specialist clinic. Sensitivity to change was additionally examined in a subgroup of the clinical sample who received treatment (n = 35). Exploratory factor analysis indicated that a two-factor structure provided the best fit for the data in the non-clinical sample. The two-factor solution was corroborated through confirmatory factor analysis as the best solution in the clinical sample, although it did not fulfil predefined fit thresholds The first factor encompassed preoccupation and repetitive behaviours, while the second included items assessing functional impairment. The BIQ-C showed good internal consistency across both samples, and convergent validity with other measures of BDD. Among those in the clinical sample who received treatment, BIQ-C scores decreased significantly, and BIQ-C change scores were highly correlated with change scores on the gold-standard clinician-rated measure of BDD symptom severity. These findings indicate that the BIQ-C is a suitable tool for assessing BDD symptoms in young people and measuring change during treatment.

An alternate to accumulated oxygen deficit (AOD) for measuring anaerobic contribution: 'AOD_alt' is valid in normoxia and hypoxia.

The gold standard measure of anaerobic contribution is accumulated oxygen deficit (AOD). The purpose of this study was to investigate the validity of an alternate measure, AOD_alt. AOD_alt is the sum of the phosphocreatine and glycolytic contributions, which are estimated from post-exercise oxygen uptake and blood lactate concentration, respectively. In Study One, six women and three men performed 6-min bouts of heavy intensity cycle ergometer exercise, once in normoxia (FIO2 ~ 21%) and twice under hypoxic conditions (FIO2 ~ 15% and ~ 12%). In Study Two, four women and two men performed severe intensity tests to exhaustion, once in normoxia (~ 10min) and twice in hypoxia (FIO2 ~ 15% and ~ 10%). Physiological responses were measured during exercise and 7min of recovery. In 6min of heavy exercise, Study One, the alternate and criterion measures of anaerobic contribution (AOD_alt and AOD) were correlated, in normoxia and in hypoxia. In exhaustive severe exercise, Study Two, AOD_alt and AOD were correlated (r = 0.77) and similar, in normoxia and at FIO2 ~ 15%. However, AOD_alt and AOD values were neither correlated (r = 0.27) nor similar (57 ± 5mL·kg-1 vs 51 ± 7mL·kg-1) at FIO2 ~ 10%. These results confirm the validity of AOD_alt as a measure of anaerobic capacity in severe intensity exercise, demonstrate its validity in heavy exercise, and assert its validity in conditions of hypoxia (FIO2 ~ 12%).

Phenotypes based on respiratory drive and effort to identify the risk factors when P0.1 fails to estimate ∆PES in ventilated children.

Monitoring respiratory effort and drive during mechanical ventilation is needed to deliver lung and diaphragm protection. Esophageal pressure (∆PES) is the gold standard measure of respiratory effort but is not routinely available. Airway occlusion pressure in the first 100ms of the breath (P0.1) is a readily available surrogate for both respiratory effort and drive but is only modestly correlated with ∆PES in children. We sought to identify risk factors for P0.1 over or underestimating ∆PES in ventilated children. Secondary analysis of physiological data from children and young adults enrolled in a randomized controlled trial testing lung and diaphragm protective ventilation in pediatric acute respiratory distress syndrome (PARDS) (NCT03266016). ∆PES (∆PES-REAL), P0.1 and predicted ∆PES (∆PES-PRED = 5.91*P0.1) were measured daily to identify phenotypes based upon the level of respiratory effort and drive: one passive (no spontaneous breathing), three where ∆PES-REAL and ∆PES-PRED were aligned (low, normal, and high effort and drive), two where ∆PES-REAL and ∆PES-PRED were mismatched (high underestimated effort, and overestimated effort). Logistic regression models were used to identify factors associated with each mismatch phenotype (High underestimated effort, or overestimated effort) as compared to all other spontaneous breathing phenotypes. We analyzed 953 patient days (222 patients). ∆PES-REAL and ∆PES-PRED were aligned in 536 (77%) of the active patient days. High underestimated effort (n = 119 (12%)) was associated with higher airway resistance (adjusted OR 5.62 (95%CI 2.58, 12.26) per log unit increase, p < 0.001), higher tidal volume (adjusted OR 1.53 (95%CI 1.04, 2.24) per cubic unit increase, p = 0.03), higher opioid use (adjusted OR 2.4 (95%CI 1.12, 5.13, p = 0.024), and lower set ventilator rate (adjusted OR 0.96 (95%CI 0.93, 0.99), p = 0.005). Overestimated effort was rare (n = 37 (4%)) and associated with higher alveolar dead space (adjusted OR 1.05 (95%CI 1.01, 1.09), p = 0.007) and lower respiratory resistance (adjusted OR 0.32 (95%CI 0.13, 0.81), p = 0.017). In patients with PARDS, P0.1 commonly underestimated high respiratory effort particularly with high airway resistance, high tidal volume, and high doses of opioids. Future studies are needed to investigate the impact of measures of respiratory effort, drive, and the presence of a mismatch phenotype on clinical outcome. NCT03266016; August 23, 2017.

Respiratory Rate Estimation from Thermal Video Data Using Spatio-Temporal Deep Learning.

Thermal videos provide a privacy-preserving yet information-rich data source for remote health monitoring, especially for respiration rate (RR) estimation. This paper introduces an end-to-end deep learning approach to RR measurement using thermal video data. A detection transformer (DeTr) first finds the subject's facial region of interest in each thermal frame. A respiratory signal is estimated from a dynamically cropped thermal video using 3D convolutional neural networks and bi-directional long short-term memory stages. To account for the expected phase shift between the respiration measured using a respiratory effort belt vs. a facial video, a novel loss function based on negative maximum cross-correlation and absolute frequency peak difference was introduced. Thermal recordings from 22 subjects, with simultaneous gold standard respiratory effort measurements, were studied while sitting or standing, both with and without a face mask. The RR estimation results showed that our proposed method outperformed existing models, achieving an error of only 1.6 breaths per minute across the four conditions. The proposed method sets a new State-of-the-Art for RR estimation accuracy, while still permitting real-time RR estimation.

Non-invasive surrogates for right Ventricular-Pulmonary arterial coupling: a systematic review and Meta-Analysis.

Right ventricle-pulmonary artery (RV-PA) coupling describes the energetic relationship between RV contractility and its afterload. The gold standard for assessment of this relationship requires invasive pressure-volume (PV) loop measurements. Non-invasive surrogates of RV-PA coupling have been developed, such as the echocardiographic tricuspid annular plane systolic excursion to pulmonary artery systolic pressure ratio (TAPSE/PASP), but their performance has not been systematically assessed. We sought to assess performance of TAPSE/PASP ratio compared to PV loop-defined RV-PA coupling. A systematic search was conducted. Studies were included if PV loop derived RV-PA coupling metrics were compared to echocardiographic or magnetic resonance imaging surrogates. We conducted a meta-analysis of TAPSE/PASP correlation to PV loop-defined RV-PA coupling. 1452 studies were identified in the initial search, of which ten met inclusion criteria. Five studies allowed for pooled analysis of TAPSE/PASP to Ees/Ea correlation (r = 0.52, 95% confidence interval 0.36-0.65). There was moderate heterogeneity across the pooled studies. Despite the common use of Non-invasive surrogates of RV-PA coupling, there is only moderate correlation with gold standard measurements. These metrics do not inform on the individual components of RV-PA coupling, limiting their use in the management of patients with RV dysfunction.

Smartphone automated motor and speech analysis for early detection of Alzheimer's disease and Parkinson's disease: Validation of TapTalk across 20 different devices.

Smartphones are proving useful in assessing movement and speech function in Alzheimer's disease and other neurodegenerative conditions. Valid outcomes across different smartphones are needed before population-level tests are deployed. This study introduces the TapTalk protocol, a novel app designed to capture hand and speech function and validate it in smartphones against gold-standard measures. Twenty different smartphones collected video data from motor tests and audio data from speech tests. Features were extracted using Google Mediapipe (movement) and Python audio analysis packages (speech). Electromagnetic sensors (60Hz) and a microphone acquired simultaneous movement and voice data, respectively. TapTalk video and audio outcomes were comparable to gold-standard data: 90.3% of video, and 98.3% of audio, data recorded tapping/speech frequencies within±1Hz of the gold-standard measures. Validation of TapTalk across a range of devices is an important step in the development of smartphone-based telemedicine and was achieved in this study. TapTalk evaluates hand motor and speechfunctions across a wide range of smartphones.Data showed 90.3% motor and 98.3% speech accuracy within +/-1Hz of gold standards.Validation advances smartphone-based telemedicine for neurodegenerative diseases.

Wireless matrix metalloproteinase-9 sensing by smart wound dressing with controlled antibacterial nanoparticles release toward chronic wound management

Chronic wounds cause serious health and economic burdens on patients and society. Herein, a wireless and flexible smart wound dressing was developed for matrix metalloproteinase-9 (MMP-9) monitoring and antimicrobial treatment toward chronic wound management. The highly sensitive radio frequency MMP-9 sensor was realized based on a bioresponsive hydrogel with bioactive sequences of the arginyl-glycyl-aspartic acid peptide. Taking advantage of the flexible inductive-capacitive (LC) circuit and bioresponsive hydrogel, the wireless and wearable smart wound dressing offered an efficient strategy for in-situ wound analysis. Besides, the controlled release of silver nanoparticles (AgNPs) from the degradable hydrogel exhibited significant antimicrobial efficacy against typical bacteria in wound infection including Escherichia coli and Staphylococcus aureus. The analysis of MMP-9 in wound exudate from diabetic foot ulcer (DFU) patients demonstrated good accuracy cross-validated with gold-standard fluorescent measurements, providing great potential for personalized wound management.

Asymmetric right ventricular myocardial work correlates with gold standard measurements of cardiac function in pulmonary hypertension

AbstractRight ventricular (RV) (dys)function determines outcomes in pulmonary hypertension (PH). We previously found that asymmetric RV myocardial work (MW) corresponds with inefficient RV function in experimental PH models. We therefore aimed to investigate regional distribution of RV MW and its correlation with catheter hemodynamics in children with PH. RV MW was calculated by longitudinal strain and simultaneous catheter pressure measurements in 14 patients with PH. Wasted MW was defined as the ratio of inappropriate myocardial lengthening to favorable shortening work. Segment‐wise and averaged MW and wasted MW were evaluated at baseline and during pulmonary vasodilation therapy with oxygen and nitric oxide, and their relationship to hemodynamic measurements was analyzed. We found that MW was higher for the lateral wall than the septum: 1013 ± 374 mmHg · % versus 532 ± 190 mmHg · % at baseline. Wasted MW ratio did not differ significantly between wall regions. Pulmonary vasodilators slightly reduced mean pulmonary artery pressure and was accompanied by a more symmetrical MW distribution. Averaged MW correlated with the rate of RV pressure development (dP/dt maximum) and decay (dP/dt minimum) at all conditions (p 0.047). The results suggest that MW contribute to, and may be used as a marker of, systolic and diastolic efficiency in the PH RV.

Effect of aortic valve replacement on myocardial perfusion and exercise capacity in patients with severe aortic stenosis

Aortic valve replacement (AVR) leads to reverse cardiac remodeling in patients with aortic stenosis (AS). The aim of this secondary pooled analysis was to assess the degree and determinants of changes in myocardial perfusion post AVR, and its link with exercise capacity, in patients with severe AS. A total of 68 patients underwent same-day echocardiography and cardiac magnetic resonance imaging with adenosine stress pre and 6–12 months post-AVR. Of these, 50 had matched perfusion data available (age 67 ± 8 years, 86% male, aortic valve peak velocity 4.38 ± 0.63 m/s, aortic valve area index 0.45 ± 0.13cm2/m2). A subgroup of 34 patients underwent a symptom-limited cardiopulmonary exercise test (CPET) to assess maximal exercise capacity (peak VO2). Baseline and post-AVR parameters were compared and linear regression was used to determine associations between baseline variables and change in myocardial perfusion and exercise capacity. Following AVR, stress myocardial blood flow (MBF) increased from 1.56 ± 0.52 mL/min/g to 1.80 ± 0.62 mL/min/g (p < 0.001), with a corresponding 15% increase in myocardial perfusion reserve (MPR) (2.04 ± 0.57 to 2.34 ± 0.68; p = 0.004). Increasing severity of AS, presence of late gadolinium enhancement, lower baseline stress MBF and MPR were associated with a greater improvement in MPR post-AVR. On multivariable analysis low baseline MPR was independently associated with increased MPR post-AVR. There was no significant change in peak VO2 post-AVR, but a significant increase in exercise duration. Change in MPR was associated with change in peak VO2 post AVR (r = 0.346, p = 0.045). Those with the most impaired stress MBF and MPR at baseline demonstrate the greatest improvements in these parameters following AVR and the magnitude of change in MPR correlated with improvement in peak VO2, the gold standard measure of aerobic exercise capacity.

Model based fitting of pattern reversal visually evoked potentials provides a reliable characterization of waveform components

ObjectiveTo introduce a novel approach to analyzing pattern reversal visual evoked potentials (prVEPs) using a difference-of-gammas model-based fitting method. MethodsprVEP was recorded from uninjured youth ages 11–19 years during pre- or post-season sports evaluation. A difference-of-gammas model fit was used to extract the amplitude, peak time, and peak width of each of four gamma components. The within session reliability and stability of fits across a 6-month period were determined. To demonstrate an application of this analysis, changes in parameters across age were determined. ResultsA difference-of-gammas model consisting of four gamma functions was fit to the prVEP of 151 youth. Peak times and amplitudes of functions corresponded to standard measures of the N75, P100, and N135 components respectively, and a late gamma peak (mean peak time 219 ms). We extracted the peak width, which increased with each subsequent temporal peak. Parameter fits were reliable within sessions (correlation coefficient > 0.92 for all measured parameters; good agreement on Bland-Altman calculation) and were stable between sessions separated by less than 6 months (correlation coefficient > 0.90). Standard peak analysis metrics extracted from the difference-of-gamma model fits were largely consistent with gold-standard peak analysis measurements. ConclusionsThe difference-of-gammas model provides a stable and reliable within-participant representation of the global temporal variability of prVEP waveforms across a large sample of youth. SignificanceUsing difference-of-gammas model to characterize the global temporal variability of the prVEP waveform offers a promising direction to enhance analysis for identifying and following subtle changes in neurologic conditions.

Automated visual acuity estimation by optokinetic nystagmus using a stepped sweep stimulus.

To describe an automatic system for objective measurement of visual acuity (VA) using optokinetic nystagmus (OKN). This pilot study tested the system's sensitivity and specificity for detecting reduced VA in healthy adults by comparing VA-OKN to VA with an Early Treatment of Diabetic Retinopathy Study (ETDRS) chart (VA-ETDRS). Adult participants (age 30 ± 12 years) with either reduced VA (n = 11, VA-ETDRS > 0.20 logMAR) or normal VA (n = 12, VA-ETDRS ≤ 0.20 logMAR) completed monocular VA-OKN measurements in each eye. The VA-OKN stimulus was an array of drifting (5°/s) vanishing discs presented in descending/ascending size order (0.00-1.00 logMAR in 0.10 steps). The stimulus was stepped every 2 s, and 10 sweeps were shown per eye (five ascending and five descending). Eye-tracking data determined when OKN activity ceased (descending sweep) or began (ascending sweep), which was used to determine VA-OKN for each sweep. The estimates were averaged across sweeps to produce an automated VA-OKN. The automated sweeps were then provided in randomised order to a reviewer blinded to the VA-ETDRS findings who determined a final VA-OKN for an eye. A single randomly selected eye from each observer was used for analysis. The sensitivity and specificity of VA-OKN using the same 0.20 logMAR threshold as VA-ETDRS was 100%. Comparisons between the VA-OKN and VA-ETDRS measures were made for participants in the reduced VA group. There was no significant difference between VA-OKN and VA-ETDRS (p = 0.55) and the two measures produced comparable values (r2 = 0.84, 95% limits of agreement = 0.19 logMAR, intra-class correlation coefficient = 0.90 [95% CI:0.68-0.97]). Visual acuity using optokinetic nystagmus correctly identified a VA deficit in adults and for those with a VA deficit, VA-OKN was strongly correlated with the gold-standard clinical measure of VA. OKN is a promising method which has the potential for use in cognitively impaired adults and pre-verbal children.

Associations between accurate measures of adiposity and fitness, blood proteins, and insulin sensitivity among South Asians and Europeans.

South Asians (SAs) may possess a unique predisposition to insulin resistance (IR). We explored this possibility by investigating the relationship between 'gold standard' measures of adiposity, fitness, selected proteomic biomarkers, and insulin sensitivity among a cohort of SAs and Europeans (EURs). A total of 46 SAs and 41 EURs completed 'conventional' (lifestyle questionnaires, standard physical exam) as well as 'gold standard' (dual energy X-ray absorptiometry scan, cardiopulmonary exercise test, and insulin suppression test) assessments of adiposity, fitness, and insulin sensitivity. In a subset of 28 SAs and 36 EURs, we also measured the blood-levels of eleven IR-related proteins. We conducted Spearman correlation to identify correlates of steady-state plasma glucose (SSPG) derived from the insulin suppression test, followed by multivariable linear regression analyses of SSPG, adjusting for age, sex and ancestral group. Sixteen of 30 measures significantly associated with SSPG, including one conventional and eight gold standard measures of adiposity, one conventional and one gold standard measure of fitness, and five proteins. Multivariable regressions revealed that gold standard measures and plasma proteins attenuated ancestral group differences in IR, suggesting their potential utility in assessing IR, especially among SAs. Ancestral group differences in IR may be explained by accurate measures of adiposity and fitness, with specific proteins possibly serving as useful surrogates for these measures, particularly for SAs.

Comparison of spatiotemporal gait parameter measurements across various emulated foot strike patterns between the Tekscan® Strideway™ pressure sensitive walkway and gold-standard marker-based motion capture

Spatiotemporal gait parameters are commonly used to quantify physical functioning including in populations with atypical foot strike patterns. The current gold standard measurement system for gait analysis is marker-based motion capture and floor-mounted force plates, but it can be expensive and cumbersome to set up. Pressure sensitive walkways are more affordable, quicker to set up, and more portable. Currently available walkways have not been compared to marker-based motion capture when measuring atypical foot strike patterns. The recently developed Tekscan® Strideway pressure sensitive walkway system has not been compared to any gold standard. This study compared measurements of step width, step length, and step time from the Strideway™ system against a gold standard marker-based motion capture (Vicon® Vantage™) and floor-mounted force plate (AMTI®) system. Ten typically ambulating adults, free of injury, emulated five different foot strike patterns recording two-hundred footsteps for each. Results indicate that the Strideway™ compares well to the gold standard especially under typical foot strike patterns. The errors were highest for step width and near-zero for step time. However, the user needs to be aware that errors can substantially increase with certain foot strike patterns such as when the heel does not make contact with the walkway. The results of this study will help inform users about potential limitations when using a pressure sensitive walkway like the Strideway™ for testing populations with typical and atypical strike patterns.

Evaluation of a Novel Virtual Reality Simulated Alternate Cover Test to Assess Strabismus: A Prospective, Masked Study

A sensorimotor examination is the gold standard for strabismus diagnosis and quantification but requires a highly skilled examiner and may be limited by a child's cooperation. Virtual reality (VR) employs eye-tracking technology to monitor eye position and may be able to measure strabismus. The aim of this study was to assess a prototype VR-simulated alternate cover test to detect and measure strabismus. Prospective, masked diagnostic test study. Patients aged 5-18 years with visual acuity of 20/80 or better were prospectively enrolled to undergo strabismus measurements using a VR simulated alternate cover test (Olleyes, Inc., Summit, NJ) followed by an alternate cover test performed by a masked pediatric ophthalmologist or orthoptist. The main outcome measure was correlation between gold standard and VR-obtained strabismus measurements (in prism diopters [PD]) in primary gaze at near using Pearson correlation coefficients and Bland-Altman analysis with limits of agreement (LOA). A secondary measure was the diagnostic accuracy for the VR headset to detect strabismus. A total of 85 participants were enrolled, mean ± standard deviation age was 10.8 ± 3.8 years, 45.9% (39/85) male. 40.0% (34/85) had strabismus: 17.7% (15/85) esotropia, 22.4% (19/85) exotropia, and 5.9% (5/85) vertical strabismus. 52.9% (18/34) of strabismus was intermittent. The overall correlation between VR and gold standard strabismus measurements was moderate but significant (r = 0.42, 95% CI 0.22, 0.58, P < .001), and correlation was strong for esotropia and constant deviations (r = 0.74, 95% CI 0.38, 0.91, P = .001 and r = 0.74, 95% CI 0.39, 0.91, P < .001, respectively). In participants with horizontal strabismus, Bland-Altman analysis showed a mean difference between standard and VR measurements of 3.55 ± 8.33 PD for esotropia (upper and lower LOA 19.89, -12.78 PD) and 17.15 ± 11.20 PD for exotropia (LOA 39.09 and -4.79 PD). Sensitivity for detecting strabismus was low: 27.6% (95% CI 12.7, 47.2), but specificity was high: 87.5% (95% CI 75.9, 94.8). A prototype VR simulated alternate cover test showed a moderate but significant correlation with the gold standard sensorimotor examination and correlation was strong in those with esotropia and constant deviations. While the level of agreement demonstrated by this novel VR technology is promising, further improvements are needed before clinical deployment. However, this study demonstrates that VR has the potential to expand our ability to detect, measure, and monitor strabismus.

Associations among motor competence, health-related fitness, and physical activity in children: A comparison of gold standard and field-based measures

ABSTRACT This study compared the associations among motor competence, health-related fitness, and physical activity measured by gold standard and field-based methods in children. A total of 248 first-grade children (153 boys) aged 6–7 years participated in the study. Motor competence was assessed using the Test of Gross Motor Development, Second Edition (TGMD −2). Gold standard measures were percent body fat using dual-energy X-ray absorptiometry, peak oxygen uptake per weight using a gas analyser, and moderate-to-vigorous physical activity using accelerometers. Field-based measures were body mass index, maximum speed during progressive running on a treadmill, and a physical activity questionnaire. Multiple regression analysis adjusted for age and sex was used to examine the associations of motor competence with one of the health-related variables and compared differences by measurement method. The results indicated that field-based measures models showed lower associations (R2 = 0.02–0.17) than the gold standard (R2 = 0.21–0.27) and lower standardised regression coefficients for sex and motor competence, except for maximum speed. In conclusion, gold standard measures resulted in stronger associations between motor competence, and health-related fitness and physical activity in children. Examining the contribution of motor competence in children’s health using field-based tests can underestimate it.