Bland-Altman Research Articles

Agreement of Automated Oscillometric Blood Pressure Measurement Device with the Manual Mercury Sphygmomanometer

Abstract The usage of the manual mercury sphygmomanometer to measure blood pressure (BP) is universally regarded as the gold standard, but its use has decreased globally due to concerns about potential mercury toxicity. Automated BP devices have become more popular, though their accuracy in detecting hypertension hasn’t been studied extensively. This cross-sectional study was conducted on 301 adult female students of the University of Delhi with the aim to assess the degree of agreement between standard manual mercury sphygmomanometer and automated BP monitor (Omron JPN1). Three consecutive BP readings were taken on the left arm by a certified medical doctor using both instruments. Bland Altman plots were created to assess the degree of agreement between the two BP devices and to test the accuracy of automated BP monitor in detecting hypertensive adults. The automated BP monitor underestimated the systolic BP measurement by 4 mmHg and diastolic BP measurement by 7 mmHg as determined by Bland Altman plot. Based on international validation protocols, a mean difference of < 5 ± 8 mmHg was established to assess the level of agreement between the two devices. The automatic BP monitor did not show complete agreement with the “gold standard” mercury sphygmomanometer. With growing restrictions on the use of mercury sphygmomanometers, its replacement with an equivalent mercury-free validated device is urgently needed.

Opportunistic osteoporosis screening in intraoperative CT can accurately identify patients with low volumetric bone mineral density and osteoporosis during spine surgery.

To evaluate the accuracy of opportunistic measurements of volumetric bone mineral density (vBMD) in intraoperative multi-detector CT (MDCT) scans, using preoperative MDCT as the reference. This retrospective, single-center study included 105 patients (mean age: 73 ± 12.6 years, 53 women) who underwent spine surgery for various indications. All patients had preoperative MDCT with/without intravenous contrast and unenhanced intraoperative scans. VBMD of thoracolumbar vertebrae was automatically extracted using a convolutional neural network (CNN)-based framework with asynchronous calibration and contrast-phase correction. Vertebrae affected by artifacts, fractures, or severe degenerations were excluded. Root-mean-square errors (RMSEs) for associations between pair-wise vertebrae from preoperative and intraoperative vBMD values were calculated in linear regression models. Mean bias and 95%-limits of agreement (LOA) were calculated in Bland-Altman plots. Strong associations between preoperative and intraoperative vBMD values were observed in the thoracic (R2 = 0.94) and lumbar spine (R2 = 0.96). Intraoperative vBMD values showed high accuracy in reference to preoperative measurements with a mean bias of -1.3mg/cm3 for the thoracic spine (LOA: -18.7 to 16.1mg/cm3) and - 3.0mg/cm3 for the lumbar spine (LOA: -17.4 to 11.3mg/cm3). RMSEs between preoperative and intraoperative vBMD values slightly increased for contrast-enhanced scans (RMSEthoracic: 8.42 vs. 10.1mg/cm3; RMSElumbar: 7.75 vs. 8.87mg/cm3). Opportunistic osteoporosis screening with the presented approach is feasible and demonstrates high accuracy in reference to preoperative MDCT scans. This could enable the identification of patients with low bone mass during surgery, allowing surgeons to take measures (e.g., adapted techniques) that prevent postoperative complications and improve patient outcomes.

Objective Grading of Tonography Tracings for the Measurement of Outflow Facility.

Tonography is the standard method for non-invasive measurement of aqueous humor outflow facility. However, assessment of tonography tracing quality is currently subjective, and acceptance of poor-quality data or inappropriately discarding valid data can bias results. The purpose of this study was to develop an objective method for assessing the quality of tonography tracings. Pneumatonography tracings were obtained from glaucoma and ocular hypertension patients as part of an ongoing multicenter study of aqueous humor dynamics. Intraocular pressure (IOP) was captured digitally at 40Hz over 2minutes. Root mean square error (RMSE) of a linear best-fit line was obtained for each tracing. Each tracing was also graded by seven experienced tonographers using a scale of 1 (worst) to 10 (best) for quality (Expert score). A Reference set of 35 tracings was used to determine the relationship between RMSE values and Expert scores using a logarithmic curve. This relationship was used to calculate a predicted score in a second Test set of 20 tracings. A logarithmic curve was used to account for the fixed range of Expert scores and unbounded upper range for RMSE values. The differences between the predicted scores and the Expert scores were evaluated using Bland-Altman analysis. There was a very strong correlation between predicted and Expert scores (R = 0.94). The mean difference between Expert and predicted scores was -1.01 ± 0.84, and the limits of agreement were between -2.65 and +0.63. Objective assessment of pneumatonography tracings can be performed using RMSE of a fitted line and calculation of a predicted quality score that closely matches scores given by expert graders. Tonography tracing quality can now be objectively assessed.

Interchangeability of the Polar Team Pro system in determining match load and intensities in semi-professional rugby union players

ABSTRACT This study assessed the interchangeability of the 10-Hz Polar and Catapult GPS during competitive matches. The agreement between data from both GPS units worn simultaneously and processed with the manufacturer’s individual GPS-filtered software was also assessed. Thirty players competing in the Currie Cup first division competition were monitored using two different tracking systems across six matches. To determine the interchangeability between systems, player movement variables including total distance (TD), low-speed running (LSR, 0.0–14.4 km/h), high-speed running (HSR, 14.4–18.9 km/h), very high-speed running (VHSR, >18.9 km/h), acceleration efforts > 2.5 m/s2 (ACC), deceleration efforts <-2.5 m/s2 (DEC) and maximum velocity reached during each half were compared. The two systems showed good to excellent agreement (CCC = 0.83–0.98) during all selected variables. During the entire match, Polar had, on average, higher values than Catapult, except for LSR and HSR. The percentage differences between systems were 3.6% TD, 1.9% maximum velocity, −4.7% LSR, −4.6% HSR, 16.5% VHSR, 13.7% ACC and 11.9% DEC. In addition, Bland-Altman plots showed a low average difference for TD (129.1; 90.1 m), maximum velocity (0.5; 0.5 km/h), LSR (138.2; 80.9 m), HSR (21.3; 5.4 m), VHSR (35.7; 22.3 m), ACC (1.6; 1.8 efforts) and DEC (2.0; 1.2 efforts).

Estimation of aerobic fitness of underground coal mine workers and development of a predictive equation to determine their VO2max.

This study aims to evaluate the aerobic fitness of miners and develop a predictive equation to assess their maximum oxygen uptake (VO2max), which is crucial for ensuring their safety and health in harsh working conditions. Measurement of VO2max via indirect calorimetry is costly and requires skilled personnel; developing a predictive equation is a viable alternative. Existing predictive equations, e.g., Hunt, Kline and Dolgener equations, were tested using the Pearson correlation coefficient, constant error, standard error of estimate and total error. The aerobic fitness of shearer operators, bolters miners, jackhammer drillers and road header operators was very low. Bland-Altman analysis revealed that predicted VO2max measurements of all three equations had a total error of >10%, which is unacceptable for usage. Therefore, a new predictive equation was developed with a total error of 9.78%. The developed predictive equation is useful to evaluate miners' functional capacity with higher precision and assist in allocating work.

Evaluation of SARS-CoV-2 Antibody Response Between Paired Fingerprick (HemaPEN®) and Venepuncture Collected Samples in Children and Adults

Serological surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies is important to monitor population COVID-19 immunity. Dried blood spots (DBS) are a valuable method for serosurveys, particularly in remote settings and in children. We compared the measurement of SARS-CoV-2 spike-specific IgG in paired blood samples collected using standard venepuncture (serum) and the hemaPEN® microsampling DBS device from children and adults. A total of 83 participants (10 months to 65 years of age), comprising COVID-positive and -negative participants, were recruited. Paired serum and DBS samples were assayed for SARS-CoV-2 receptor-binding domain (RBD) and Spike (S1) antibodies using an established in-house ELISA. RBD and S1 IgG concentrations of paired hemaPEN DBS eluates and serum samples were compared using a non-parametric Wilcoxon matched-pairs signed ranked test. A Pearson’s correlation was used for RBD and S1 IgG concentrations and the level of agreement between the hemaPEN DBS eluates and serum samples was assessed by Bland–Altman analysis. A total of N = 41 adults (36 COVID-positive and 5 COVID-negative), and N = 42 children (37 COVID-positive, and 5 COVID-negative) have paired serum and DBS assayed. We found moderate to strong correlations between paired hemaPEN DBS eluates and serum SARS-CoV-2 IgG antibodies for RBD (r = 0.9472, p &lt; 0.0001) and S1 proteins (r = 0.6892, p &lt; 0.0001). Similar results were observed in both adult and paediatric populations. No significant differences in S1-specific IgG levels were observed in hemaPEN DBS samples stored for up to 35 weeks at room temperature. Eluted hemaPEN samples showed high specificity and sensitivity (100% and 89.89%, respectively) compared with serum. The use of the microsampling hemaPEN device for DBS sample collection is a feasible approach for assessing SARS-CoV-2 antibodies for serosurveillance studies, particularly in remote settings and in children.

Validation of a Swedish version of the National Institute of Health - Chronic Prostatitis Symptom Index.

Chronic primary prostate pain syndrome (PPPS), usually referred to as chronic prostatitis with chronic pelvic pain syndrome (CP/CPPS), affects approximately 10% of all men. The National Institute of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) was developed for clinical assessment and research evaluation of this patient category. The objective of this study was to translate the NIH-CPSI into Swedish, including cross-cultural adaptation and testing it for validity and reliability. Material and methods: Fifty men with chronic PPPS participated in the testing of a new Swedish questionnaire. The initial translation included forward and backward translation followed by a comprehensive review by anexpert committee. The preliminary Swedish translation was tested for face validity and test-retest reliability. In all steps of the translation, both medical experts and laymen participated. Results: The Swedish translation showed a high degree of consistency with the original version. A few cultural adaptations were jointly agreed upon. The questionnaire was assessed to be clear to understand and having good face validity. The test-retest reliability showed an intraclass correlation (ICC) of 0.89 (95% confidence interval [CI] = 0.82-0.94) which indicates good to excellent reliability. The standard error of measurement and minimal detectable change were 2.5 and 7.0 respectively. A Bland Altman plot showed no systematic difference between test-retest. Conclusion: This study brings to health care providers and researchers a Swedish version of the internationally recognised NIH-CPSI questionnaire having good validity and reliability, a beneficial addition in the management of men suffering from chronic PPPS in Sweden.

Assessment of Biological Age With Conventional Ultrasound Imaging as an Alternative to X-Ray-A Pilot Study in Youth Soccer.

The aim of the study was to evaluate conventional ultrasound (US) as a radiation-free alternative to X-ray for determining biological age (BA; indicated by skeletal age). BA, was determined in 24 healthy, male, elite youth soccer goalkeepers around peak height velocity (11-16years of age) using both X-ray and conventional US scans of the left hand. X-ray scans were evaluated using the Tanner-Whitehouse 2 method. Conventional US scans served to determine BA via ossification ratios of 13 hand and wrist bones. The new conventional US method showed very strong correlation with X-ray r=0.90 (p<0.05). However, the agreement for the difference in BA and CA, which accounts for age-related variance, was classified poor (ICC=0.48, p<0.05). Additionally, linear regression analysis and the Bland-Altman plot suggested the presence of a systematic and proportional overestimation of BA in younger players and an underestimation of BA in older players. Furthermore, Cohen's kappa showed a moderate agreement between players' classification into maturity groups for the two assessment methods. In conclusion, our study has shown that using US-derived ossification ratios did not deliver valid results compared to X-ray when determining BA in youth soccer goalkeepers.

Real-world smartphone-based point-of-care diagnostics in primary health care to monitor HbA1c levels in people with diabetes

BackgroundThe lack of accurate and affordable monitoring of glycated hemoglobin (HbA1c) is a common issue among patients with diabetes in low- and middle-income countries. We aimed to test a tablet- and smartphone-based point-of-care (TSB POC) device against a local laboratory-based measure of HbA1c for monitoring diabetes under real-world conditions.MethodsFor this cross-sectional clinical method applicability study, capillary and venous blood was collected in duplicate and analyzed at local primary health care centers. For a heterogeneity test, the tests were performed by an expert, and by a team of local nurses. The study was conducted in a multicenter design in rural and urban Aceh, Indonesia in 2019, and included a total of 533 adults. We mainly used Bland-Altman plots to assess the number of readings within the 95%-limits of agreement (LoA) and Deming regressions.ResultsThe results show a mean difference between capillary HbA1c on the test device and the reference method of −0.54 [CI0.95 = −1.6933; 0.6048] with 5.21% of measurements outside the LoA and a Pearson’s r = 0.91 in the Deming Regression. There is no significant difference in test concordance between local nurses and the expert (4.23% versus 5.13% results outside the LoA [CI0.95 = −0.0331; 0.0511]).ConclusionsTSB POC for analysis of HbA1c is an acceptable alternative for accessible monitoring of diabetes patients under these conditions. This method could provide access to high-quality diagnostic decisions through regular and cost-effective HbA1c monitoring directly in healthcare facilities, thus providing better access to essential health services.

In Vivo Bone Mineral Density Assessment With Spectral Localizer Radiographs From Photon-Counting Detector CT

Purpose The aim of this study was to determine in a prospective patient study the accuracy of areal bone mineral density (aBMD) measurements with spectral localizer radiographs obtained with a clinical photon-counting detector computed tomography (PCD-CT) scanner in comparison with dual-energy x-ray absorptiometry (DXA). Methods In this institutional review board–approved, prospective study, 41 patients (15 females, 26 males; mean age 61.3 years, age range 35–78 years) underwent PCD-CT of the abdomen with a spectral localizer radiograph (tube voltage 140 kVp, tube current 30 mA) and DXA within a median of 45 days. aBMD values were derived for lumbar vertebrae L1–L4 from both methods and were compared with linear regression, Pearson correlation, intraclass correlation coefficients (ICCs), and Bland-Altman plots. T-scores were calculated on a patient level and were compared between methods. Results DXA and spectral localizer radiographs showed strong correlation in aBMD measurements (R = 0.97, P &lt; 0.001) and patient level T-scores (R = 0.99, P &lt; 0.001). There was a strong agreement between aBMD from both methods (ICC, 0.96; 95% CI, 0.94–0.97). Bland-Altman analysis revealed a very small mean difference in aBMD between methods (mean absolute error 0.019 g/cm2) with narrow limits of agreement (−0.083 g/cm2 to 0.121 g/cm2). Similarly, there were small differences in regard to the T-score (mean absolute error 0.156) with narrow limits of agreement (−0.422 to 0.734) between methods. ICCs indicated an excellent agreement between T-scores from DXA and spectral localizer radiographs (ICC, 0.98; 95% confidence interval, 0.95–0.99). Conclusions Our prospective patient study indicates that spectral localizer radiographs obtained with a clinical PCD-CT system enable accurate quantification of the lumbar bone areal mineral density. This opens up the opportunity for opportunistic screening of osteoporosis in patients who undergo CT for other indications.

Reference values for the 1-minute sit-to-stand test to assess functional capacity and short-term mortality in people with idiopathic pulmonary fibrosis and fibrotic connective tissue related interstitial lung diseases: a prospective real-world cohort study

BackgroundEarly identification of functional decline in fibrotic interstitial lung disease (F-ILD) is crucial for timely treatment and improved survival. While the 6-minute walk test (6MWT) is the standard for functional evaluation, it has practical limitations. The 1-minute sit-to-stand test (1MSTS) offers a simpler alternative; however, its correlation with the 6MWT in F-ILD patients remains unclear. This study aims to establish reference values for the 1MSTS in assessing functional capacity, evaluate its correlation with the 6MWT, and explore its utility in predicting 18-month mortality in F-ILD patients.MethodsThis prospective study enrolled participants diagnosed with F-ILD based on multidisciplinary team discussions. Assessments included the 1MSTS, 6MWT, pulmonary function test (PFT), GAP score, mMRC scale, and Charlson Comorbidity Index (CCI). The association between 1MSTS repetitions and other variables was calculated using Spearman’s rho. Bland-Altman plots assessed the agreement between 1MSTS repetitions and the 6MWT. Predictors of 18-month mortality were evaluated using ROC curve and Kaplan-Meier curve.ResultsOf the 150 F-ILD patients, 37 (24.6%) had idiopathic pulmonary fibrosis (IPF), and 113 (75.4%) had connective tissue disease-related ILD (CTD-ILD). Using ≤ 23 repetitions as the cutoff for functional impairment in 1MSTS, 74 (47.3%) patients were classified as impaired. The 1MSTS significantly predicted 18-month mortality and demonstrated moderate correlations with GAP score (rs = -0.49), mMRC scale (rs = -0.47), and 6MWT distance (rs = 0.65). Bland-Altman analysis indicated agreement between 1MSTS repetitions and 6MWT distance. Using ≤ 23 repetitions as the cutoff value for the 1MSTS to predict 18-month mortality, the mortality rate was 76.4%, with an AUC of 0.81.ConclusionsThe findings suggest that ≤ 23 repetitions in the 1MSTS can serve as an indicator of functional impairment, demonstrate a good correlation with 6MWT distance, and effectively predict 18-month mortality in patients with F-ILD.Clinical trial numberNot applicable.

Chemical shift and relaxation regularization improve the accuracy of 1H MR spectroscopy analysis.

Accurate analysis of metabolite levels from 1H MRS data is a significant challenge, typically requiring the estimation of approximately 100 parameters from a single spectrum. Signal overlap, spectral noise, and common artifacts further complicate the analysis, leading to instability and reports of poor agreement between different analysis approaches. One inconsistently used method to improve analysis stability is known as regularization, where poorly determined parameters are partially constrained to take a predefined value. In this study, we examine how regularization of frequency and linewidth parameters influences analysis accuracy. The accuracy of three MRS analysis methods was compared: (1) ABfit, (2) ABfit-reg, and (3) LCModel, where ABfit-reg is a modified version of ABfit incorporating regularization. Accuracy was assessed on synthetic MRS data generated with random variability in the frequency shift and linewidth parameters applied to each basis signal. Spectra ( ) were generated across a range of SNR values (10, 30, 60, 100) to evaluate the impact of variable data quality. Comparison between ABfit and ABfit-reg demonstrates a statistically significant (p < 0.0005) improvement in accuracy associated with regularization for each SNR regime. An approximately 10% reduction in the mean squared metabolite errors was found for ABfit-reg compared to LCModel for SNR >10 (p < 0.0005). Furthermore, Bland-Altman analysis shows that incorporating regularization into ABfit enhances its agreement with LCModel. Regularization is beneficial for MRS fitting and accurate characterization of the frequency and linewidth variability in vivo may yield further improvements.

Comparative analysis of ocular biometrics using spectral domain optical coherence tomography with Purkinje image and optic nerve head alignments in mice

BackgroundMice are an emerging model for experimental myopia. Due to their small eye size, non-invasive optical coherence tomography is essential for evaluating ocular biometrics. There is currently no universally accepted protocol for those measurements. This study aims to compare ocular biometric measurements using two methods: Purkinje image-based alignment and optic nerve head alignment, utilizing spectral domain optical coherence tomography. Gaining an understanding of the implications of these methods in determining axial elongation in the normal growing eyes of wild-type C57BL/6J mice would offer valuable insight into their relevance for the experimental myopia model.MethodsOcular dimensions and refractive development were measured on postnatal days P21 (n = 10), P28 (n = 15), and P35 (n = 8). The Purkinje image-based alignment (P1) was determined using a photorefractor and aligned perpendicular to the corneal apex using SD-OCT. In comparison, due to the absence of a fovea in the mouse retina, the optic nerve head (ONH) alignment was used. Variance analysis, regression analysis, and Bland–Altman analysis were performed to compare the differences between alignment methods as well as the replication by another operator.ResultsMice developed hyperopic ametropia under normal visual conditions. The photorefractor measured a technical variation of 3.9 D (95% CI, n = 170, triplicates). Bland–Altman analysis revealed a shorter (mean ± SD) axial length (− 26.4 ± 18.1 μm) and vitreous chamber depth (− 39.9 ± 25.4 μm) in the Purkinje image-based alignment. There was a significant difference in the relative growth trend in VCD (linear regression, p = 0.02), which was relatively stable and showed shortening when measured with ONH alignment from postnatal age 21 to 35 days.ConclusionsSD-OCT allowed precise in-vivo measurement and segmentation of ocular dimensions, regardless of the methods adopted. P1 alignment consistently resulted in significantly shorter VCD and AL compared to ONH alignment at most time points. When considering temporal changes from P21 to P35, both methods showed similar results, with significant elongation of ACD, LT, and AL as expected. However, our findings revealed a significant shortening of VCD over time with the adoption of ONH alignment, while the change in P1 alignment was relatively stable. Therefore, AL provides a better measure for evaluating ocular growth in mice using optical coherence tomography than VCD for myopia research.

Accuracy of Visual Estimation of Left Ventricular Ejection Fraction Compared With Echocardiography in Children.

This study compared visual assessments of left ventricular systolic function in children by pediatric physicians with quantitative measurements using the Simpson method. This was a transverse, cohort study conducted between January and June 2023. Patient's echocardiography were performed by a certified pediatric cardiologist in the presence of 2 pediatricians: a senior pediatric intensivist (S.Z.) and a pediatric resident (A.D.). Both pediatricians had prior training in cardiac ultrasound. Following the visual assessment of the echocardiography, each pediatrician records their evaluation of the left ventricular ejection fraction (LVEF) as a percentage. We compared the visual assessment of LVEF with that obtained with quantitative measurements using the Simpson method by the pediatric cardiologist. Bland-Altman analysis was performed between the pediatrician and the cardiologist's LVEF evaluation. Besides the correlation coefficients (r) were calculated. A total of 136 patients, aged between 0 and 18 years, were enrolled. The mean LVEF measured by the cardiologist was 65.05±14.15. The mean LVEF estimated by the senior pediatrician and the pediatric resident was 64.48±13.59 and 64.87±13.17, respectively. Strong correlations were found between visual estimates by both pediatricians and 2-dimensional LVEF (r=0.832 and r=0.763 respectively, P<0.001). The bland-Altman plot showed that the mean difference of LVEF determined by 2-dimensional LVEF and eyeballing by a senior pediatric intensivist and the junior pediatrician was 0.57±3.64% and 0.18±4.37%, respectively. The study suggests that visual assessment of LVEF in children is reliable when conducted by experienced pediatricians familiar with echocardiography. However, the results of this study are primarily applicable to the assessment of normal or near-normal left ventricular function.

Agreement and Diagnostic Accuracy of New Linear Deflection Oscillometry and Doppler Devices for Hypotension Detection Compared to Invasive Blood Pressure in Anesthetized Dogs

Blood pressure (BP) monitoring is essential during anesthesia to maintain cardiovascular stability and detect hypotension. This study evaluated the agreement and diagnostic accuracy of linear deflection oscillometry (LDO) and Doppler compared to invasive blood pressure (IBP) in anesthetized dogs. Eleven healthy dogs were anesthetized, and BP measurements were taken using LDO, Doppler, and IBP methods under normotensive and hypotensive conditions. The LDO device demonstrated superior agreement, assessed using Bland–Altman analysis, with IBP, especially in hypotensive conditions, compared to the Doppler method. LDO showed bias and standard deviation in the hypotensive state, with a mean and systolic arterial pressure (MAP and SAP) of −5.1 ± 7.9 and −5.6 ± 12.5 mmHg, respectively. Conversely, Doppler measurements tended to overestimate SAP during hypotension, presenting a bias of −13 ± 15.45 mmHg. The LDO achieved an area under the curve (AUC) of 0.809 for hypotension detection, with an MAP cutoff of ≤72 mmHg (sensitivity: 90%, specificity: 63%). Meanwhile, the best threshold for Doppler measurements was an AUC of 0.798, SAP ≤ 100 mmHg (sensitivity: 77.8%, specificity: 81.8%). These results indicate that LDO is a reliable method for hypotension detection in anesthetized dogs, with potential applications for real-time monitoring. In contrast, the Doppler method may help confirm hypotension diagnoses.

Repeatability and reproducibility of a new spectral-domain optical coherence tomography biometer and agreement with swept-source optical coherence tomography based biometer.

To assess the repeatability and reproducibility of the Colombo IOL biometer (Moptim, China), which utilizes spectral-domain optical coherence tomography (SD-OCT), in measuring ocular parameters of normal subjects and to compare its agreement with the swept-source optical coherence tomography (SS-OCT)-based IOLMaster 700 biometer (Carl Zeiss Meditec AG, Germany). This prospective study included 91 eyes from 91 normal subjects. The evaluated parameters were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), lens thickness (LT), flattest and steepest meridian keratometry (Kf and Ks), mean keratometry (Km), astigmatism (AST) magnitude, white-to-white (WTW) distance, and pupil diameter (PD). The within-subject standard deviation (Sw), test-retest repeatability (TRT), coefficient of variation (CoV), and intraclass correlation coefficient (ICC) were calculated to determine the repeatability and reproducibility. Paired t-tests and Bland-Altman plots with 95% limits of agreement (LoA) were employed to assess the agreement. With respect to intraobserver repeatability, the Sw and TRT values of all evaluated parameters were low. Except J45 and PD, the ICCs were all higher than 0.928. The reproducibility Sw and TRT values of Colombo IOL were also low, and ICCs were not lower than 0.900. Comparing Colombo IOL and IOLMaster 700, the 95% LoA of AL, CCT, AQD, ACD, LT, Kf, Ks, Km, AST, J0, J45, WTW and PD ranged from - 0.08 to 0.03mm, - 21.58 to 5.09μm, 0.01 to 0.15mm, - 0.01 to 0.14mm, - 0.05 to 0.10mm, - 0.14 to 0.59 D, - 0.31 to 0.40 D, - 0.13 to 0.40 D, - 0.68 to 0.32 D, - 0.09 to 0.34 D, - 0.07 to 0.25 D, 0.11 to 1.47mm, and - 0.97 to 2.31mm, respectively. The new SD-OCT-based Colombo IOL biometer demonstrates excellent repeatability and reproducibility. Moreover, it generally agrees well with the SS-OCT-based IOLMaster 700, except for the WTW and PD measurements.

Development and validation of an LC-MS/MS multiplex assay for the quantification of bedaquiline, n-desmethyl bedaquiline, linezolid, levofloxacin, and clofazimine in dried blood spots.

Dried blood spot (DBS) assays to quantify novel and repurposed drugs for the treatment of rifampicin-resistant tuberculosis (RR-TB) would facilitate pharmacokinetic studies and therapeutic drug monitoring in low-middle income settings, considering their ease of application and simple sample storage requirements. We describe a DBS method for the simultaneous quantification of bedaquiline and metabolite N-desmethyl bedaquiline, linezolid, levofloxacin, and clofazimine. The analytes were extracted from the matrix and isolated by solid-phase extraction. Two LC-MS/MS systems were used, optimized for the separate analysis of the more polar compounds (linezolid and levofloxacin), and less polar compounds (bedaquiline, N-desmethyl bedaquiline, and clofazimine), employing gradient elution. Electrospray ionization and multiple reaction monitoring were used to quantify the analytes on a Sciex API3200 and an API5500 triple quadrupole mass spectrometer, for the more polar and less polar analytes, respectively. Isotopically labelled internal standards were used to compensate for variability in the quantification of each analyte. The method was validated according to international guidelines and applied to samples from a clinical trial. We performed correlation and agreement analysis of the DBS assay and in-house plasma methods using Deming regressions and Bland-Altman plots. Coefficients of correlation between measured plasma and DBS concentrations ranged from 0.866 (95% CI: 0.817-0.902) to 0.989 (95% CI: 0.985-0.992). More than 67% of the samples showed a difference between the observed and estimated plasma concentrations within 20% of their means, meeting EMA requirements for method reproducibility and demonstrating the interchangeability of our DBS and plasma LC-MS/MS methods.

Actigraphy validation in behavioral variant frontotemporal dementia.

Actigraphy is increasingly being used to assess sleep in patients with neurodegenerative diseases. However, information on its accuracy relative to polysomnography (PSG) in this clinical population remains scarce. This study investigates the performance of actigraphy compared to PSG in patients with behavioral variant frontotemporal dementia (bvFTD), which is the leading form of early-onset dementia. Eighteen patients with bvFTD (10 males, mean age 70.50±8.48 years) underwent overnight, in-home PSG while concurrently wearing an actigraph on their non-dominant wrist. Actigraphy performance was assessed through discrepancy analysis, Bland-Altman plots, and epoch-by-epoch analysis (EBE). Analyses were conducted separately for the Cole-Kripke and UCSD scoring algorithms. Discrepancy analysis highlighted that the Cole-Kripke and UCSD algorithms overestimate total sleep time (by 43 and 60min, respectively) and sleep efficiency (by 7.13% and 10.33%, respectively). The Cole-Kripke algorithm also overestimates sleep onset latency (by 7.75min). Wake after sleep onset (WASO) showed a negative proportional bias for both algorithms, indicating that actigraphy underestimates WASO for subjects with longer PSG-measured WASO. In the EBE analysis, the Cole-Kripke algorithm shows an accuracy of 84% (sensitivity 93%, specificity 62%) and the UCSD algorithm an accuracy of 85% (sensitivity 96%, specificity 57%). In patients with bvFTD, actigraphy significantly overestimates total sleep time, sleep latency, and sleep efficiency, while underestimating WASO. Clinicians and researchers using actigraphy to study sleep in bvFTD must carefully consider these measurement biases and correct for them based on the results of previous comparison studies.

Prediction models of basal energy expenditure in children and adolescents across the BMI spectrum based on room calorimetry: a cross-sectional cohort study.

Existing equations for prediction of basal energy expenditure (BEE) may not be accurate in children with overweight or obesity (OW/OB). We aimed to develop BEE prediction equations applicable to children and adolescents across a wide BMI spectrum using gold standard room calorimetry. We measured weight, height, waist and hip circumferences, body composition (DXA), and BEE (whole room calorimetry) in a cross-sectional cohort of 1155 healthy children, 5-19 years of age. 67% of the males and 51% of the females were classified as OW/OB. We applied multiple linear regression analyses to develop BEE prediction models for each sex. Using relevant predictors, we developed models with fat-free mass (FFM); waist and hip circumference; weight and height only; and weight only. A representative sample of participants (83 males, 125 females) served as a validation dataset to test model performance. The models' performance in predicting BEE was compared to existing models in the literature. Model fits (R2) for the new BEE prediction models were = 0.84 (P < 0.0001). Our BEE prediction models performed equally in children with normal weight and OW/OB, with <1.5% difference between the measured versus predicted BEE in the validation dataset for both sexes. In Bland-Altman analysis, our BEE prediction models were superior to existing prediction models, especially for children with higher BEEs. New BEE prediction models developed and tested in cohorts representative of children with normal weight and OW/OB had superior performance compared with existing models. The BEE prediction equations based on simple anthropometrics or body composition provided improved accuracy and precision for children with NW or OW/OB, ages 5 to 19. More accurate estimates of BEE should allow for better estimates of energy requirements of children.

Quality in Question: Assessing the Accuracy of Four Heart Rate Wearables and the Implications for Psychophysiological Research.

Heart rate (HR) and heart rate variability (HRV) are two key measures with significant relevance in psychophysiological studies, and their measurement has become more convenient due to advances in wearable technology. However, photoplethysmography (PPG)-based wearables pose critical validity concerns. In this study, we validated four PPG wearables: three consumer-grade devices (Kyto2935, Schone Rhythm 24, and HeartMath Inner Balance Bluetooth) and one research-grade device (Empatica EmbracePlus, successor to the widely-used but discontinued Empatica E4). All devices were worn simultaneously by 40 healthy participants who underwent conditions commonly used in laboratory research (seated rest, arithmetic task, recovery, slow-paced breathing, a neuropsychological task, posture manipulation by standing up) and encountered in ambulatory-like settings (slow walking and stationary biking), compared against a criterion electrocardiography device, the Vrije Universiteit Ambulatory Monitoring System (VU-AMS). We determined the signal quality, the linear strength through regression analysis, the bias through Bland-Altman analysis, and the measurement error through mean arctangent absolute percentage error for each condition against the criterion device. We found that the research-grade device did not outperform the consumer-grade devices in laboratory conditions. It also showed low agreement with the ECG in ambulatory-like conditions. In general, devices captured HR more accurately than HRV. Finally, conditions that deviated from baseline settings and involved slight to high movement, negatively impacted the agreement between PPG devices and the criterion. We conclude that PPG devices, even those advertised and designed for research purposes, may pose validity concerns for HRV measurement in conditions other than those similar to resting states.