Similar Limits Of Agreement Research Articles

Validation of basal metabolic rate equations in persons with innervated and denervated chronic spinal cord injury.

Basal metabolic rate (BMR) measurement is time consuming and requires specialized equipment. Prediction equations allow clinicians and researchers to estimate BMR; however, their accuracy may vary across individuals with chronic spinal cord injury (SCI). The objective of this study was to investigate the validity of SCI-specific equations as well as able-bodied (AB) prediction equations in individuals with upper motor neuron (UMN), lower motor neuron (LMN), and females with SCI. Twenty-six men and women with chronic SCI (n = 12 innervated males, n = 6 innervated females, n = 8 denervated males) participated in this cross-sectional study. BMR values were measured by indirect calorimetry. Body composition (dual-energy X-ray absorptiometry and anthropometrics) assessment was conducted. AB-prediction equations [Cunningham, Nelson, Owen, Harris and Benedict, Mifflin, Schofield, Henry] and SCI-specific equations [Chun and Nightingale & Gorgey] were used to estimate and validate BMR. The accuracy of AB-specific FFM equations in predicting BMR was evaluated using Bland-Altman plots, paired t-tests, and error metrics. Measured BMR for innervated males, females, and denervated males was 1436 ± 213 kcal/day, 1290 ± 114, and 1597 ± 333 kcal/day, respectively. SCI-specific equations by Chun etal., Nightingale & Gorgey, and AB-specific FFM equations accurately predicted BMR for innervated males. For the denervated males, Model 4 equation by Nightingale & Gorgey was not different (p = 0.18), and Bland-Altman analyses showed negative mean bias but similar limits of agreement between measured and predicted BMR for the SCI-specific equations and AB-specific FFM equations. We demonstrated that SCI-specific equations accurately predicted BMR for innervated males but underpredicted it for denervated males. The Model 4 equation by Nightingale & Gorgey accurately estimated BMR in females with SCI. Findings from the current study will help to determine caloric needs in different sub-groups of SCI.

Prediction of fat-free mass in young children using bioelectrical impedance spectroscopy

BackgroundBioimpedance devices are practical for measuring body composition in preschool children, but their application is limited by the lack of validated equations.ObjectivesTo develop and validate fat-free mass (FFM) bioimpedance prediction equations among New Zealand 3.5-year olds, with dual-energy X-ray absorptiometry (DXA) as the reference method.MethodsBioelectrical impedance spectroscopy (SFB7, ImpediMed) and DXA (iDXA, GE Lunar) measurements were conducted on 65 children. An equation incorporating weight, sex, ethnicity, and impedance was developed and validated. Performance was compared with published equations and mixture theory prediction.ResultsThe equation developed in ~70% (n = 45) of the population (FFM [kg] = 1.39 + 0.30 weight [kg] + 0.39 length2/resistance at 50 kHz [cm2/Ω] + 0.30 sex [M = 1/F = 0] + 0.28 ethnicity [1 = Asian/0 = non-Asian]) explained 88% of the variance in FFM and predicted FFM with a root mean squared error of 0.39 kg (3.4% of mean FFM). When internally validated (n = 20), bias was small (40 g, 0.3% of mean FFM), with limits of agreement (LOA) ±7.6% of mean FFM (95% LOA: –0.82, 0.90 kg). Published equations evaluated had similar LOA, but with marked bias (>12.5% of mean FFM) when validated in our cohort, likely due to DXA differences. Of mixture theory methods assessed, the SFB7 inbuilt equation with personalized body geometry values performed best. However, bias and LOA were larger than with the empirical equations (–0.43 kg [95% LOA: –1.65, 0.79], p < 0.001).ConclusionsWe developed and validated a bioimpedance equation that can accurately predict FFM. Further external validation of the equation is required.

P–319 Measuring intraobserver and intermethod reliability of endometriotic cyst volumes: a comparison between MRI and 3D transvaginal ultrasound

Abstract Study question Are three-dimensional imaging techniques, MRI and three-dimensional transvaginal ultrasound reliable for the volume measurement of endometriotic cysts? Summary answer MRI and XI VOCAL 3D-transvaginal ultrasound both provide a very good intraobserver reliability. The imaging techniques are however not advised to be used interchangeably. What is known already Two-dimensional transvaginal ultrasound (2D-TVUS) and MRI are commonly used in endometriosis care. However, three-dimensional ultrasound (3D-US) has gained more attention in recent years. The use of 3D-US, more specifically VOCAL and XI VOCAL software has proven to be a reliable tool in the measurement of volumes such as splenic volumes and uterine niche volumes. Up to date, 3D-TVUS has not been evaluated for volume measurements in endometrioma. Study design, size, duration A prospective case-control study was performed in an academic endometriosis centre. In total, 23 endometriosis cysts from 16 patients were included. Participants/materials, setting, methods Women diagnosed with endometriosis through laparoscopy with histological confirmation presenting with uni- or bilateral endometrioma on TVUS were included in this study. All women had a regular menstrual cycle (28 days ± 3 days). Women were seen for examinations at two time points during one menstrual cycle: on cycle day 2–4 (T0) and cycle day 20–22 (T1). At both time points a 2D and 3D TVUS and an MRI at 1,5T were performed. Main results and the role of chance The intraclass correlation for intraobserver reliability is good to very good for all three techniques ranging from the lowest value of 0.953 to the highest of 1.000. MRI has the most narrow limits of agreement (–3.93 to 4.53), followed by XI VOCAL (–5.16 – 5.65) while VOCAL has the widest limits of agreement (–10.22 to 11.39). Intraclass correlations are poor in the comparison of XI VOCAL to MRI, moderate between VOCAL and XI VOCAL, and good for the comparison between VOCAL and MRI. The limits of agreement are widest for XI VOCAL versus MRI (–36.96 –10.54). Similar limits of agreement are found between VOCAL versus XI VOCAL (–7.80 –23.40) as between VOCAL versus MRI (–18.27–8.96). Limitations, reasons for caution No absolute volume measurements were obtained during subsequent surgery to compare the imaging data to. This makes it more difficult to determine an acceptable error margin for the 3D imaging techniques used. Wider implications of the findings: Being able to determine (small) volumetric changes in endometrioma can give more insight into the development and circumstances under which endometrioma grow or decrease in size. For reliable and accurate follow up of endometrioma a single measuring technique must be used as three-dimensional imaging techniques are not interchangeable. Trial registration number Trial NL2106 (NTR2223)

Abstract 15302: Cardiac MRI Assessment of Cardiac Output Agrees With Simultaneous Fick Assessment in Pediatric Heart Transplant Patients

Introduction: Systemic cardiac output (Qs) and pulmonary blood flow (Qp) can be measured by cardiac magnetic resonance (CMR) and invasive oximetry, with studies showing good agreement between the two modalities. CMR-guided right heart catheterization (MR-RHC) collects simultaneous CMR and oximetry measurements permitting direct comparison. This study assessed agreement between CMR and Fick measurements of cardiac output in the pediatric heart transplant (HT) population. Methods: Twenty-three pediatric HT patients (body surface area range 0.6-2 m 2 ) with 53 MR-RHC between 2014 -2020 were reviewed. One outlier was excluded due to erroneous pulmonary vein saturation, leaving 52 MR-RHC for analysis. Measurements of un-indexed Qs and Qp from both CMR phase contrast and invasive oximetry using Fick were collected. Bland-Altman (BA) statistical and graphical analyses compared CMR versus Fick estimates of Qs and Qp. Results: BA limits of agreement (LOA) and corresponding concordance plot demonstrate good agreement between CMR and Fick (Figure 1). Panels A and B are the BA and concordance plots for Qs, respectively. Panels C and D are the BA and concordance plots for Qp, respectively. The 95% confidence interval LOA are -1.0 to +1.8 for Qs and -1.0 to +1.7 for Qp. Average bias and Lin correlation are similar for Qs and Qp at +0.36 L/min and 0.8, respectively. Conclusions: CMR and Fick measurements of Qs and Qp are similar in pediatric HT patients, with a tendency for slightly higher values by Fick estimates and similar LOA to previously published results. CMR acquired hemodynamics offer a radiation-free modality to reduce overall radiation exposure for pediatric HT patients.

Magnetic resonance phase contrast velocity mapping for flow quantification in irregular heart rhythms using radial k-space ultrashort echo time imaging

BackgroundPhase contrast velocity mapping sequences utilising ultrashort echo time (UTE) radial k-space sequences have been used to reduce intravoxel dephasing at high velocities. We evaluated the accuracy of the UTE flow sequence for mitral regurgitation (MR) quantification, including patients with atrial fibrillation. MethodsForty patients underwent cardiac MRI for indirect MR quantification by assessment of aortic flow using a UTE phase contrast sequence (TE 0.65 ms) combined with left ventricular stroke volume. Retrospective ECG-gating was used in sinus rhythm (30 patients), prospective ECG-triggering in atrial fibrillation (10). MR was also quantified by a standard phase contrast sequence (TE 2.85 ms, standard flow method) and by comparing stroke volumes (volumetric method). ResultsUTE flow-derived MR measurement showed modest agreement in sinus rhythm (95% limits of agreement: ±38.2 ml; ±29.8%) and atrial fibrillation (±33.7 ml; ±30.3%) compared to standard flow assessment. There was little systematic bias in sinus rhythm (mean offset −4.4 ml /−3.5% compared to standard flow assessment), but a slight bias towards greater regurgitation in atrial fibrillation (+15.2 ml /+14.0%). There were wider limits of agreement between the UTE flow method and volumetric method than between the regular flow method and the volumetric method in sinus rhythm (±48.4 ml; ±36.4%; mean offset: −12.2 ml /−9.0%) and similar limits of agreement in atrial fibrillation (±29.6 ml; 25.8%; +12.0 ml /+10.3%). ConclusionsUTE flow imaging is inferior to conventional flow techniques for MR assessment in patients with sinus rhythm as well as atrial fibrillation. However, the number of atrial fibrillation patients in this initial study is small.

Can EOS Imaging Substitute for Conventional Radiography in Measurement of Acetabular Morphology in the Young Dysplastic Hip?

EOS imaging offers a low-radiation alternative to conventional radiography (CR) and has little to no magnification effects. However, it is unclear how radiographic measures may be affected using EOS. The present study aims to determine the reproducibility of measures of acetabular morphology on EOS images as compared with CR, and to directly compare the 2 imaging modalities. A total of 21 consecutive patients (66.7% female; 14.4±4.7 y) indicated for an open hip preservation procedure with both an anterior-posterior pelvis radiograph and EOS image performed preoperatively were included. Three orthopaedic surgeons measured Tönnis angle, lateral center edge angle (LCEA), acetabular depth-width ratio (ADR), and extrusion index (EI). Measurements were performed twice, 2 weeks apart. Reliability between observers and time points was measured using intraclass correlation coefficients, and agreement between time points and modalities was measured using Bland-Altman analysis. On EOS images, inter-rater reliability was 0.86 for Tönnis angle, 0.86 for LCEA, 0.74 for ADR, and 0.93 for EI. On CR, inter-rater reliability was 0.86 for Tönnis anlge, 0.90 for LCEA, 0.82 for ADR, and 0.84 for EI. In the agreement analysis, biases between imaging modalities were observed. On average, raters measured Tönnis angle and EI higher on EOS images than CR (2.22 degrees, 1.09%, respectively); and LCEA and ADR lower on EOS images than CR (1.54 degrees, 1.14% respectively). Limits of agreement (LOA) between modalities were similar to that of LOA observed in intra-rater analysis. Measures of acetabular morphology performed on EOS images have similarly high intra-rater and inter-rater reliability compared with CR. Measures performed on EOS also have similar intra-rater agreement as compared with CR. Intermodality agreement had similar LOA as intra-rater agreement on either individual imaging modality. Small biases between imaging modalities were detected. Level I-diagnostic study: investigating a diagnostic test.

Think Globally, Act Locally: The Importance of Population-Specific Bioelectrical Impedance Analysis Prediction Equations for Muscle Mass Assessment.

Bioelectrical impedance analysis (BIA) is a convenient muscle assessment method, but its accuracy highly depends on population-specific aspects of the adopted equation. We aimed to develop appendicular lean mass (ALM) prediction models for older South Americans and to compare their performances to those of reference equations in the same sample. Cross-sectional evaluation of 192 community-dwelling Brazilian subjects ≥60 years old from the COMO VAI? Using measurements from single-frequency and multifrequency devices (BIASF and BIAMF, respectively), new ALM prediction equations were developed (reference method: dual-energy x-ray absorptiometry [DXA]). Validity was assessed by bootstrapping. Four previously established equations were also tested, and the performances were compared using Bland-Altman analysis. Stepwise variable selection produced the following equations: ALMSF-BIA = (2.08 × sex) + (0.04 × weight) + (0.24 × RI50 ) + (0.07 × Xc50 ) - 0.16; ALMMF-BIA = (1.85 × sex) + (0.03 × weight) + (0.31 × RI50 ) + (0.04× Xc50 ) + (0.01 × Z5 ) - 8.16, where ALM is estimated in kg; female sex = 0 and male sex = 1; weight is measured in kg; RI50 is the resistance index at 50 kHz measured in cm2 /Ω); Xc50 is the reactance at 50 kHz measured in Ω; and Z5 is impedance at 5 kHz measured in Ω. The equations explained, respectively, 89% and 90% of the variability of ALMDXA in our sample, and their estimates were not significantly different from DXA measurements. Bland-Altman analysis revealed accurate and unbiased performances for both models, with similar limits of agreement (BIASF : ±2.58 kg; BIAMF : ±2.48 kg), and their validity was considered adequate by the bootstrap method. The reference equations, however, systematically overestimated ALM in our sample. The proposed equations might represent practical options to estimate ALM in older noninstitutionalized South Americans. Further external validation, though, is required to verify the reproducibility of our findings.

Measured and predicted resting energy expenditure in wheelchair rugby athletes

Objective: Report measured resting energy expenditure (REE) in wheelchair rugby athletes and evaluate agreement between REE and the prediction models of Chun, Cunningham, Harris-Benedict, Mifflin, Nightingale and Gorgey, and Owen.Design: Cohort-based validation study.Setting. Paralympic team training camp.Participants: Fourteen internationally competitive athletes who play wheelchair rugby, 13 of whom had cervical spinal cord injuries (SCI).Outcome Measures: A portable metabolic analyzer was used to measure REE following an overnight fast and dual-energy X-ray absorptiometry (DXA) was used to assess lean body mass for the prediction equations.Results: REE in the current sample was 1735 ± 257 kcal × day−1 ranging from 1324 to 2068 kcal × day−1. Bland–Altman analyses revealed negative mean bias but similar limits of agreement between measured REE and scores predicted by Chun, Cunningham, Mifflin, Nightingale and Gorgey, and Owen models in elite athletes who play wheelchair rugby.Conclusion: Prediction models regressed on persons with and without SCI under-predicted REE of competitive wheelchair rugby athletes. This outcome may be explained by the higher REE/fat-free mass (FFM) ratio of current athletes compared to less active samples. Findings from the current study will help practitioners to determine nutrient intake needs on training days of varied intensity.

Comparison of Cardiac Output of Both 2 and 3 Dimensional Transoesophageal Echocardiography With Transpulmonary Thermodilution During Cardiac Surgery

Purpose: Transpulmonary thermodilution (TD) is the gold standard for cardiac output (CO) monitoring during cardiac surgery but is feasible with TOE, but 2D TOE underestimates CO due to assumption of a circular LVOT, when 3D TOE demonstrates it is ovoid. The aim of this study is to determine if 3D TOE correlates better with TD than 2-D TOE. Methodology: After ethics approval, 50 adult patients without more than mild valvular regurgitation or A who were scheduled for bypass cardiac surgery were recruited prospectively at two institutions. CO was measured simultaneously by TD and TOE (2D/3D) before and after CPB. CO was calculated using the continuity method (product of VTI, area and heart rate) using the modal and outer-edge trace of the LVOT VTI. The aortic valve area was estimated with planimetry by both 2D and 3D TOE. Agreement analysis was performed using the Deming model II regression analysis and Bland-Altman technique (TD as the reference method). Results: Proportional but not fixed bias was present for the VTI modal method but not for any other method. Correlation for LVOT modal was poor (0.40) and CO was underestimated (mean bias = -1.59 L.min-1), but the limits of agreement were similar to other methods. Tracing the edge of the LVOT VTI rather than the modal line reduced the bias (-0.59 L.min-1), and improved correlation (0.92). 3D planimetry of the AV and continuous wave Doppler had the best agreement with TD. The mean bias approached zero for the 3D methods but with similar limits of agreement. Conclusion: For 2D measurements, tracing around the LVOT VTI rather than through the modal line improved precision. The other 2D and 3D measurements of CO showed absence of bias, and reasonable agreement with TD.

The redevelopment of the Kay picture test of visual acuity

Aims: To validate the design of updated optotypes to be used in the Kay picture acuity tests to improve the resolution acuity, recognition, repeatability and comparisons with gold standard logMAR acuity assessments. Methods: The study was completed in four phases. Inball phases the pictures were presented on a monitor as a single crowded optotype, with five optotypes at each visual acuity (VA) level. Phase one assessed the resolution acuity for 25 pictures, eight Landolt Csband five ETDRS letters. The recognition phase (phasebtwo) assessed children (18 months to 5 years) to determine which pictures were most commonly identified. During phase three, the resolution acuity of a reduced number of pictures and the Landolt C were reassessed to ensure that fatigue had not influenced the initial results. Phase four compared the new Kay pictures with LEA symbols and the ETDRS (part a), and repeatability of the Kay pictures and the ETDRS chart (part b). Results: Phase one (resolution acuity): 50 adult subjects were tested. The mean (±SD) acuity scores achieved using each of the 25 pictures ranged from -0.123 ±0.124 to -0.308 ±0.105. The mean (±SD)bacuity for the eight Landolt C orientations was -0.059 ±0.120, and -0.128 ±0.101 for the ETDRS letters. Following this analysis, three pictures were removed. Phase two (Recognition): 420 children were assessed (54% male) using the remaining 22 pictures. Analysis resulted in the removal of 10 pictures based on the recognition levels. Phase three (resolution acuity): 43 adult subjects were tested with the remaining 12 pictures. The picture selection was reduced to six based on a combination of similar mean bias levels, recognition levels in all children and recognition levels in the youngest children. Phase four (a) (comparability): 113 adult subjects were tested. The mean bias indicated similar results between the tests. The limits of agreement for ETDRS versus Lea symbols were slightly wider than for ETDRS versus Kay pictures. Phase four (b) (repeatability): 100 adult subjects were tested. Paired t-test analysis demonstrated no significant difference between tests in either ETDRS ( p = 0.1) or Kay pictures ( p = 0.1). Mean bias for both tests was 0.01 logMAR with similar limits of agreement. Conclusion: The newly designed Kay picture optotypes have been shown to be reliably recognised by a paediatric population. In a six-picture test format the newly designed optotypes with single picture presentation and crowding bars have been shown to be a reliable and repeatable VA test in an adult population with good agreement with current gold standard VA assessment methods. Normative data in a paediatric population are now required.

Accuracy of a combined heart rate and motion sensor for assessing energy expenditure in free-living adults during a double-blind crossover caffeine trial using doubly labeled water as the reference method.

A combined heart rate (HR) and motion sensor (Actiheart) has been proposed as an accurate method for assessing total energy expenditure (TEE) and physical activity energy expenditure (PAEE). However, the extent to which factors such as caffeine may affect the accuracy by which the estimated HR-related PAEE contribution will affect TEE and PAEE estimates is unknown. Therefore, we examined the validity of Actiheart in estimating TEE and PAEE in free-living adults under a caffeine trial compared with doubly labeled water (DLW) as reference criterion. Using a double-blind crossover trial (Clinicaltrials.gov ID: #NCT01477294) with two conditions (4-day each with a 3-day-washout period), randomly ordered as caffeine (5 mg/kg per day) and placebo (malt-dextrine) intake, TEE was measured by DLW in 17 physically active men (20-38 years) who were non-caffeine users. In each condition, resting energy expenditure (REE) was assessed by indirect calorimetry and PAEE was calculated as (TEE-(REE+0.1 TEE)). Simultaneously, PAEE and TEE were estimated by Actiheart using an individual calibration (ACC+HRstep). Under caffeine, ACC+HRstep explained 76 and 64% of TEE and PAEE from DLW, respectively; corresponding results for the placebo condition were 82 and 66%. No mean bias was found between ACC+HRstep and DLW for TEE (caffeine:-468 kJ per day; placebo:-407 kJ per day), although PAEE was slightly underestimated (caffeine:-856 kJ per day; placebo:-1147 kJ per day). Similar limits of agreement were observed in both conditions ranging from -2066 to 3002 and from -3488 to 1776 kJ per day for TEE and PAEE, respectively. Regardless of caffeine intake, the combined HR and motion sensor is valid for estimating free-living energy expenditure in a group of healthy men but is less accurate for an individual assessment.

Convergent Validity of the One-Mile Run and PACER VO2MAX Prediction Models in Middle School Students

FITNESSGRAM uses an equating method to convert Progressive Aerobic Cardiovascular Endurance Run (PACER) laps to One-mile run/walk (1MRW) times to estimate aerobic fitness (VO2MAX) in children. However, other prediction models can more directly estimate VO2MAX from PACER performance. The purpose of this study was to examine the convergent validity and relative accuracy between 1MRW and various PACER models for predicting VO2MAX in middle school students. Aerobic fitness was assessed on 134 students utilizing the 1MRW and PACER on separate testing days. Pearson correlations, Bland–Altman plots, kappa statistics, proportion of agreement, and prediction error were used to assess associations and agreement among models. Correlation coefficients were strong ( r ≥ .80, p &lt; .001) and error estimates were similar between comparisons. Bland–Altman plots yielded similar Limits of Agreement between 1MRW and PACER models. Fitness Zone agreement with 1MRW was moderate-to-excellent with kappa &gt; .40 and agreement &gt; .90. The results support that PACER models contain convergent validity and strong relative accuracy with the 1MRW model.

Test–retest reliability and validity of normative cut-offs of the two devices measuring touch threshold: Weinstein Enhanced Sensory Test and Pressure-Specified Sensory Device

Introduction Touch threshold screening instruments must accurately distinguish normal versus abnormal sensation to screen nerve pathology. This study was conducted to find out whether two touch threshold measuring devices (i.e. Weinstein Enhanced Sensory Test (WEST) and Pressure-Specified Sensory Device (PSSD) provide consistent results and indicators of “normal” sensation, and secondarily what rules best define normality. Methods The study design was a cross-sectional reliability and validity assessment with 23 healthy participants. Instruments were applied in random order on the pulp of the middle and little fingers of both hands; with five applications on each digit. Cut-offs of 3, 4, and 5 correct responses were used to classify the response as being normal. Weighted kappa and percent agreement were used to indicate test–retest reliability of the WEST, and validity was determined by calculating the percentage of normal controls that achieved a normal score. The Bland–Altman method was used to characterize the retest reliability of PSSD, and validity was determined by whether the mean of the score is different from the normative scores. Results The agreement between test and retest of WEST (detection level = 3/5) was almost perfect ( k = 1). The average percentages of normal detection of the WEST on two test/retest were 93% and 97% (detection level = 4/5) and 82% and 85% (detection level = 5/5). All mean PSSD tests values were found within the predetermined normal range. The Bland–Altman plot demonstrated a minimal mean difference between test occasions and similar limits of agreement across the four test locations. Discussion The study found that more than 90% of the tests with healthy young participants were reliable and valid in relation to their ability to detect a normal WEST filament or PSSD within a normal force range. Our study was limited by a small sample with healthy participants.

A hybrid approach for quantification of aortic valve stenosis using cardiac magnetic resonance imaging and echocardiography:

We replaced Doppler-derived stroke volume in the continuity equation (method A) by either right heart catheterization-derived stroke volume (method B) or cardiovascular magnetic resonance-derived stroke volume (method C) to calculate aortic valve area in 20 consecutive patients with moderate or severe aortic stenosis. Comparison of both hybrid methods (methods B and C) by Bland-Altman analysis showed a mean difference near zero, a spread within two standard deviations and very similar limits of agreement. More importantly, all patients were classified into the same category of severity by both methods.