Assessing Inter-rater Agreement for Compositional Data

Compositional data are non-negative vectors whose elements sum to one (e.g., [0.1, 0.5, 0.4]). This type of data occurs in many research areas where the relative magnitudes between the vector’s elements are of primary interest. In this dissertation we propose novel methodology for assessing inter-rate agreement based on compositional data. This is needed because existing agreement measures either involve converting the vector to a univariate value, thereby losing information, or they fail to account for the sum-to-one restriction. We propose a novel Bayesian approach, enabled by Markov chain Monte Carlo, to investigate differences in the pattern of compositional vector scores. We extend our model to handle discrete compositional scores, comparisons involving more than two raters, and studies that involve replicate scores on the same subjects. Numerous simulation studies are used to demonstrate the validity of our model and the advantages of our approach. Both simulated data and a real scoring data set are analyzed to illustrate our method and compare it to traditional agreement indices. The application of this new methodology is focused on pathology, where pathologists rate immunohistochemistry (IHC) assays using compositional scores. To enhance the use of this methodology and help with the design of future agreement studies, an R Shiny package designed for the IHC agreement analysis is developed

Maximum Agreement Linear Prediction via the Concordance Correlation Coefficient

This paper examines distributional properties and predictive performance of the estimated maximum agreement linear predictor (MALP) introduced in Bottai, Kim, Lieberman, Luta, and Pena (2022) paper in The American Statistician, which is the linear predictor maximizing Lin's concordance correlation coefficient (CCC) between the predictor and the predictand. It is compared and contrasted, theoretically and through computer experiments, with the estimated least-squares linear predictor (LSLP). Finite-sample and asymptotic properties are obtained, and confidence intervals are also presented. The predictors are illustrated using two real data sets: an eye data set and a bodyfat data set. The results indicate that the estimated MALP is a viable alternative to the estimated LSLP if one desires a predictor whose predicted values possess higher agreement with the predictand values, as measured by the CCC

Reliability of transcranial magnetic stimulation evoked potentials to detect the effects of theta-burst stimulation of the prefrontal cortex

Background: Transcranial magnetic stimulation (TMS) with simultaneous electroencephalography (EEG) is a novel method for assessing cortical properties outside the motor region. Theta burst stimulation (TBS), a form of repetitive TMS, can non-invasively modulate cortical excitability and has been increasingly used to treat psychiatric disorders by targetting the dorsolateral prefrontal cortex (DLPFC). The TMS-evoked potentials (TEPs) and local mean field power (LMFP) analyses have been used to evaluate local cortical excitability changes after TBS. However, it remains unclear whether TEPs can detect the neuromodulatory effects of TBS. Objectives: To confirm the reliability of TEP components and LMFP within and between sessions and to measure changes in neural excitability induced by intermittent (iTBS) and continuous TBS (cTBS) applied to the left DLPFC. Methods: Test-retest reliability of TEPs/LMFP and TBS-induced changes in cortical excitability were assessed in twenty-four healthy participants by stimulating the DLPFC in five separate sessions, once with sham and twice with iTBS and cTBS. EEG responses were recorded of 100 single TMS pulses before and after TBS, and the reproducibility measures were quantified with the concordance correlation coefficient (CCC). Results: The N100 and P200 components presented substantial reliability within the baseline block (CCCs>0.8) and moderate concordance between sessions (CCCmax> 0.6). Both N40 and P60 TEP amplitudes showed little concordance between sessions. Similar results were achieved using LMFP responses. Changes in TEP amplitudes after iTBS were marginally reliable for N100 (CCCmax = 0.52), P200 (CCCmax = 0.47) and P60 (CCCmax = 0.40), presenting only fair levels of concordance at specific time points. LMFP changes showed poor reproducibility after iTBS and cTBS. Conclusions: The present findings show that only the N100 and P200 components had good concordance between sessions. The reliability of earlier TEP components and LMF responses may have been affected by a sub-optimal removal of TMS-related artefacts. The poor reliability in detecting changes in neural excitability induced by TBS indicates that TEPs/LMFP do not provide a precise estimate of the changes in excitability in the DLPFC or, alternatively, that TBS did not induce consistent changes in neural excitability

Reproducibility of Standing Posture for X-Ray Radiography: A Feasibility Study of the BalancAid with Healthy Young Subjects

Unreliable spinal X-ray radiography measurement due to standing postural variability can be minimized by using positional supports. In this study, we introduce a balancing device, named BalancAid, to position the patients in a reproducible position during spinal X-ray radiography. This study aimed to investigate the performance of healthy young subjects’ standing posture on the BalancAid compared to standing on the ground mimicking the standard X-rays posture in producing a reproducible posture for the spinal X-ray radiography. A study on the posture reproducibility measurement was performed by taking photographs of 20 healthy young subjects with good balance control standing on the BalancAid and the ground repeatedly within two consecutive days. We analyzed nine posterior–anterior (PA) and three lateral (LA) angles between lines through body marks placed in the positions of T3, T7, T12, L4 of the spine to confirm any translocations and movements between the first and second day measurements. No body marks repositioning was performed to avoid any error. Lin’s CCC test on all angles comparing both standing postures demonstrated that seven out of nine angles in PA view, and two out of three angles in LA view gave better reproducibility for standing on the BalancAid compared to standing on the ground. The PA angles concordance is on average better than that of the LA angles

Effects of environmental enrichment and behavioural style on stress responses in singly housed shelter cats (Felis catus)

Shelters are potentially stressful environments for singly housed cats. The behaviour and faecal glucocorticoid metabolite (FGM) responses were examined in six shelter cats caged singularly for 30 days. Raised faecal glucocorticoid metabolite (FGM) concentrations and Cat-Stress-Scores (CSS) together with increased grooming and reduced eating indicated a stress response that tended to decrease with time. Environmental enrichment (EE) of the cages may help reduce this stress. However, the efficacy of different types of EE may be reliant on whether a cat is bold or shy, and may be related to the EE preferences expressed. A test was developed to discriminate between bold and shy cats. Nine cats were tested for latency to emerge from a carrier, and percentage of time spent in a carrier during a 5-min test in an empty arena. These measures were found to be significantly different across individuals and not significantly different across time. Seventeen cats were then subjected to a similar test, with similar results. Combining these results, it was determined that latency to emerge from carrier with a cut-point of 10 s was the most appropriate test for discriminating between bold and shy cats in a shelter setting. It correctly classified a high percentage of cats overall, was quick and easy to administer, and best suited to correctly identify shy individuals, which were less represented in this population and arguably could derive greater benefit from identification and extra attention. A final behavioural style study subjected 84 cats to this test, which showed acceptable cross-context consistency and correctly classified a high percentage of cats. Cats’ visit frequency to and time allocation with different types of EE were assessed using a plus-shaped choice chamber, in which each external compartment contained a different type of EE. Entrance to each chamber was gained through a cat-flap door monitored remotely using a HOBO data-logger. Usage of the shelf compartment was not significantly different from any other compartment. A significantly higher percentage of time was allocated to the compartment containing the hiding box compared to the toy compartment and to the empty control compartment, suggesting a hiding box may be a valued resource. A final experiment housed 72 bold or shy cats singly in cages enriched with either a hiding box or a shelf, or in an empty control cage. The amount of food eaten and the percentage of time spent eating increased across time, and percentage of time spent grooming decreased over time. Cats in the hiding box group had significantly lower FGM and higher food intake than cats in the control group, indicating that the type of EE used most in the choice test reduced stress. Shy cats used the hiding box significantly more than bold cats, and had a significantly higher CSS until day 5. There was no evidence that bold and shy cats benefited from different types of EE. The results indicated that the stress of caging is experienced more intensely by shy cats, but it can be reduced by the inclusion of a hiding opportunity in cats expressing either mode of this behavioural style

Inference for Clustered Mixed Outcomes from a Multivariate Generalized Linear Mixed Model

Multivariate generalized linear mixed models (MGLMM) are used for jointly modeling the clustered mixed outcomes obtained when there are two or more responses repeatedly measured on each individual in scientific studies. The relationship among these responses is often of interest. In the clustered mixed data, the correlation could be present between repeated measurements either within the same observer or between different observers on the same subjects. This study proposes a series of in- dices, namely, intra, inter and total correlation coefficients, to measure the correlation under various circumstances of observations from a multivariate generalized linear model, especially for joint modeling of clustered count and continuous outcomes. Bayesian methods are widely used techniques for analyzing MGLMM. The need for noninformative priors arises when there is insufficient prior information on the model parameters. Another aim of this study is to propose an approximate uniform shrinkage prior for the random effect variance components in the Bayesian analysis for the MGLMM. This prior is an extension of the approximate uniform shrinkage prior. This prior is easy to apply and is shown to possess several nice properties. The methods are illustrated in terms of both a simulation study and a case example

Am J Clin Nutr

Background:An efficacy evaluation of the AutoAnthro system to measure child (0\u201359 months) anthropometry in the United States found 3D imaging performed as well as gold-standard manual measurements for biological plausibility and precision.Objectives:We conducted an effectiveness evaluation of the accuracy of the AutoAnthro system to measure 0- to 59-month-old children\u2019s anthropometry in population-based surveys and surveillance systems in households in Guatemala and Kenya and in hospitals in China.Methods:The evaluation was done using health or nutrition surveillance system platforms among 600 children aged 0\u201359 months (Guatemala and Kenya) and 300 children aged 0\u201323 months (China). Field team anthropometrists and their assistants collected manual and scan anthropometric measurements, including length or height, midupper arm circumference (MUAC), and head circumference (HC; China only), from each child. An anthropometry expert and assistant later collected both manual and scan anthropometric measurements on the same child. The expert manual measurements were considered the standard compared to field team scans.Results:Overall, in Guatemala, Kenya, and China, for interrater accuracy, the average biases for length or height were 120.3 cm, 121.9 cm, and 126.2 cm, respectively; for MUAC were 0.9 cm, 1.2 cm, and 120.8 cm, respectively; and for HC was 2.4 cm in China. The inter-technical errors of measurement (inter-TEMs) for length or height were 2.8 cm, 3.4 cm, 5.5 cm, respectively; for MUAC were 1.1 cm, 1.5 cm, and 1.0 cm, respectively; and for HC was 2.8 cm in China. For intrarater precision, the absolute mean difference and intra-TEM (interrater, intramethod TEM) were 0.1 cm for all countries for all manual measurements. For scans, overall, absolute mean differences for length or height were 0.4\u20130.6 cm; for MUAC were 0.1\u20130.1 cm; and for HC was 0.4 cm. For the intra-TEM, length or height was 0.5 cm in Guatemala and China and 0.7 cm in Kenya, and other measurements were 640.3 cm.Conclusions:Understanding the factors that cause the many poor scan results and how to correct them will be needed prior to using this instrument in routine, population-based survey and surveillance systems.CC999999/ImCDC/Intramural CDC HHSUnited States/2022-10-17T00:00:00Z35285874PMC957634112024vault:4339

Anthropometric prediction of DXA-measured percentage of fat mass in athletes with unilateral lower limb amputation

To date there is no anthropometric equation specific to athletes with unilateral lower limb amputation to estimate the percentage of fat mass (%FM). This study investigated the accuracy of a set of anthropometric equations validated on able-bodied populations to predict the %FM assessed by-means of dual-energy x-ray absorptiometry (DXA) in athletes with unilateral lower limb amputation. Furthermore, a predictive anthropometric equation specific to athletes with unilateral lower limb amputation was developed from skinfold thickness measurements using DXA as the reference method for the estimation of the %FM. Twenty-nine white male athletes with unilateral lower limb amputation underwent a DXA scan and an anthropometric assessment on the same day. The %FM, calculated through several existing anthropometric equations validated upon able-bodied populations, was compared with the DXA-measured %FM (%FM_DXA). Accuracy and agreement between the two methods was computed with two-tailed paired-sample t-test, concordance correlation coefficient, reduced major axis regression and Bland-Altman analysis. A stepwise multiple regression analysis with the %FM_DXA as the dependent variable and age and nine skinfold thicknesses as potential predictors was carried out and validated using a repeated 10-fold cross-validation. A linear regression analysis with the sum of nine skinfolds as the independent variable was also carried out and validated using a repeated 10-fold cross-validation. The results showed that the anthropometric equations validated on able-bodied populations are inaccurate in the estimation of %FM_DXA with an average bias ranging from 0.51 to -13.70%. Proportional bias was also found revealing that most of the anthropometric equations considered, tended to underestimate/overestimate the %FM_DXA as body fat increased. Regression analysis produced two statistically significant models (P < 0.001 for both) which were able to predict more than 93% of total variance of %FM_DXA from the values of four skinfold measurements (i.e., thigh, abdominal, subscapular and axillary skinfold measurements) or from the sum of 9 skinfolds. Repeated cross-validation analysis highlighted a good predictive performance of the proposed equations. The predictive equations proposed in this study represent a useful tool for clinicians, nutritionists, and physical conditioners to evaluate the physical and nutritional status of athletes with unilateral lower limb amputation directly in the field

ENHANCING KINEMATIC SHOULDER FUNCTION EVALUATION THROUGH A VALID, SIMPLE AND CLINICALLY APPLICABLE SCORE

Introduction Controversies surrounding Patient-Reported Outcome Measures (PROMs) and the cumbersome-nature of movement analysis-based (MAB) methods for shoulder function evaluation make the exploration of alternatives needed. Research aimed at the simplification of MAB outcome measures had demonstrated previously that the B-B Score, which relies on two movements only, was valid for out-of-laboratory evaluations of shoulder function. Nevertheless, further investigations were needed to optimise testing procedures, test the B-B Score’s capability of acquisition using a user-friendly device, and critically evaluate its measurement properties in comparison to current methods. Objective The aim of this thesis was to develop and assess the simplest possible MAB shoulder function scoring procedure for clinical measurement. Methods The research included four steps: 1) Optimisation of the B-B Score testing procedure (Phase 1 study [data-driven]), 2) Comparison of measurements using a smartphone or an inertial sensor system (Phase 2 study [data-driven]), 3) Validation in frequentlyoccurring pathologies (rotator cuff conditions, instability, fracture, capsulitis) (Phase 3 study [data-driven]), 4) Benchmarking of the new approach with concurrent MAB outcome measures and PROMs (literature review). Results Amongst the tested methods, the B-B score was optimised by using the mean of three replicates in the computation of the range of accelerations by angular velocities. The comparison of easily-used smartphone and reference device showed non-significant differences and excellent relationships between measurements (Intraclass Correlation Coefficient [ICC=0.97]). The smartphone’s B-B Score intra-rater and inter-rater reliability was excellent (ICC=0.92), but limits of agreement could reach up to ±19.4%. The score was responsive (area under the curve [AUC≥0.70]) and demonstrated excellent discriminative power between patients and controls (AUC≥0.90), except for shoulder instability (AUC=0.67). The correlations with PROMs were moderate to high. The benchmarking established that the measurement properties of the B-B Score compared equivalently with those of PROMs and MAB outcome measures, except for shoulder instability. Conclusion Shoulder function can be efficiently evaluated using a simple scoring procedure performed with a smartphone, which facilitates its objective assessment. Further research is needed to understand how best to reduce the effects of variability associated with single measurements in order to optimise clinical applicability and to explore the B-B Score’s properties in other situations requiring functional assessments of the shoulder. . Keywords: shoulder, shoulder function; outcome assessment; validation studies, reliability and validity; inertial sensors; smartphone sensors; body-worn sensors; kinematics; sensitivity and specificity