Bland-Altman Test Research Articles

A qualitative, quantitative and dosimetric evaluation of a machine learning-based automatic segmentation method in treatment planning for gastric cancer.

To investigate the performance of a machine learning-based segmentation method for treatment planning of gastric cancer. Eighteen patients planned to be irradiated for gastric cancer were studied. The target and the surrounding organs-at-risk (OARs) were manually delineated on CT scans. A machine learning algorithm was used for automatically segmenting the lungs, kidneys, liver, spleen and spinal cord. Two radiation oncologists evaluated these contours and performed the required editing. The accuracy of the auto-segmented contours relative to manual outlines was evaluated by calculating the dice similarity coefficient (DSC), Jaccard score (JS), sensitivity and precision. VMAT plans were initially created on manual contours (MCPlans) and, then, on edited and unedited auto-segmented contours (ACedPlans). Dose parameters of the OARs and target volume derived from the different treatment plans were statistically compared. The 24.6% of the auto-segmented contours were acceptable and 40.5% needed changes related to stylistic deviations. Minor editing was applied in 34.1% of these contours. The mean values of the DSC, JS, sensitivity and precision associated with the comparison of the manual outlines and the contour set including edited and unedited auto-segmented contours were 0.91-0.97, 0.84-0.94, 0.92-0.97 and 0.91-0.97, respectively. No significant differences were found for fifteen out of eighteen examined dosimetric parameters derived from MCPlans and ACedPlans (p>0.05). These parameters from the MCPlans agreed well with those from ACedPlans based on the Bland-Altman test. The qualitative, quantitative and dosimetric analysis highlighted the clinical acceptability of a machine learning-based segmentation method for radiotherapy of gastric cancer.

Reliability and Accuracy of the Fitbit Charge 4 Photoplethysmography Heart Rate Sensor in Ecological Conditions: Validation Study.

Wrist-worn photoplethysmography (PPG) sensors allow for continuous heart rate (HR) measurement without the inconveniences of wearing a chest belt. Although green light PPG technology reduces HR measurement motion artifacts, only a limited number of studies have investigated the reliability and accuracy of wearables in non-laboratory-controlled conditions with actual specific and various physical activity movements. The purpose of this study was to (1) assess the reliability and accuracy of the PPG-based HR sensor of the Fitbit Charge 4 (FC4) in ecological conditions and (2) quantify the potential variability caused by the nature of activities. We collected HR data from participants who performed badminton, tennis, orienteering running, running, cycling, and soccer while simultaneously wearing the FC4 and the Polar H10 chest belt (criterion sensor). Skin tone was assessed with the Fitzpatrick Skin Scale. Once data from the FC4 and criterion data were synchronized, accuracy and reliability analyses were performed, using intraclass correlation coefficients (ICCs), Lin concordance correlation coefficients (CCCs), mean absolute percentage errors (MAPEs), and Bland-Altman tests. A linear univariate model was also used to evaluate the effect of skin tone on bias. All analyses were stratified by activity and pooled activity types (racket sports and running sports). A total of 77.5 hours of HR recordings from 26 participants (age: mean 21.1, SD 5.8 years) were analyzed. The highest reliability was found for running sports, with ICCs and CCCs of 0.90 and 0.99 for running and 0.80 and 0.93 for orienteering running, respectively, whereas the ICCs and CCCs were 0.37 and 0.78, 0.42 and 0.88, 0.65 and 0.97, and 0.49 and 0.81 for badminton, tennis, cycling, and soccer, respectively. We found the highest accuracy for running (bias: 0.1 beats per minute [bpm]; MAPE 1.2%, SD 4.6%) and the lowest for badminton (bias: -16.5 bpm; MAPE 16.2%, SD 14.4%) and soccer (bias: -16.5 bpm; MAPE 17.5%, SD 20.8%). Limit of agreement (LOA) width and artifact rate followed the same trend. No effect of skin tone was observed on bias. LOA width, bias, and MAPE results found for racket sports and soccer suggest a high sensitivity to motion artifacts for activities that involve "sharp" and random arm movements. In this study, we did not measure arm motion, which limits our results. However, whereas individuals might benefit from using the FC4 for casual training in aerobic sports, we cannot recommend the use of the FC4 for specific purposes requiring high reliability and accuracy, such as research purposes.

Study on heart rate recovery index to predict maximum oxygen uptake in healthy adults aged 30 to 60 years old.

To explore the feasibility of post-exercise heart rate recovery indicators for predicting maximum oxygen uptake (VO2max) in healthy adults aged 30-60years. 260 healthy adults who did not perform regular exercise were randomly recruited and divided into a model group (n = 200) and a verification group (n = 60). Measure body fat percentage, weight, height and other indicators, and complete a cardiopulmonary exercise test as required to measure VO2max and heart rate recovery (HRR1, HRR2) in the first and second minutes after exercise. Equations are established through stepwise regression method, and the selected optimal equation is tested for back substitution. The optimal equation is: . Analysis of variance, goodness-of-fit test, VIF test, Shapiro-Wilk test, and Durbin-Watson test indicate that the equation is more reliable; Pearson product-moment correlation analysis, paired t test, and Bland-Altman consistency test indicate that the equation is more valid good. The regression equation established through heart rate recovery after exercise can be used to predict VO2max in healthy adults aged 30-60years.

Interobserver Variability in Manual Versus Semi-Automatic CT Assessments of Small Lung Nodule Diameter and Volume.

This study aimed to assess the interobserver variability of semi-automatic diameter and volumetric measurements versus manual diameter measurements for small lung nodules identified on computed tomography scans. The radiological patient database was searched for CT thorax examinations with at least one noncalcified solid nodule (∼3-10 mm). Three radiologists with four to six years of experience evaluated each nodule in accordance with the Fleischner Society guidelines using standard diameter measurements, semi-automatic lesion diameter measurements, and volumetric assessments. Spearman's correlation coefficient measured intermeasurement agreement. We used descriptive Bland-Altman plots to visualize agreement in the measured data. Potential discrepancies were analyzed. We studied a total of twenty-six nodules. Spearman's test showed that there was a much stronger relationship (p < 0.05) between reviewers for the semi-automatic diameter and volume measurements (avg. r = 0.97 ± 0.017 and 0.99 ± 0.005, respectively) than for the manual method (avg. r = 0.91 ± 0.017). In the Bland-Altman test, the semi-automatic diameter measure outperformed the manual method for all comparisons, while the volumetric method had better results in two out of three comparisons. The incidence of reviewers modifying the software's automatic outline varied between 62% and 92%. Semi-automatic techniques significantly reduced interobserver variability for small solid nodules, which has important implications for diagnostic assessments and screening. Both the semi-automatic diameter and semi-automatic volume measurements showed improvements over the manual measurement approach. Training could further diminish observer variability, given the considerable diversity in the number of adjustments among reviewers.

Comparison of Corneal Keratometry Measured by Three Different Methods

To compare and evaluate the interchangeability and agreement between corneal keratometry measurements (flattest-steepest keratometry, mean keratometry and corneal astigmatism) using partial coherence interferometry reflectometry optical biometry (Nidek AL Scan, 2.4–3.3 mm zones, Nidek Technologies, Gamagori, Japan), corneal aberrometer/topographer (Nidek OPD Scan II, Nidek Technologies, Gamagori, Japan) and standard autorefractokeratometer (Topcon KR 8900, Topcon Inc., Tokyo, Japan) a total of 360 right eyes of 360 healthy volunteers with a mean age of 24.37±3.91 years were enrolled in this prospective comparative study. Paired t-tests were used to evaluate pairwise comparisons. The Bland–Altman test with 95% limits of agreement was used to evaluate the agreement between the three devices. There were no statistically significant differences between all keratometric values of the Nidek AL Scan obtained in the 2.4 and 3.3 mm zones (p&gt;0.05). There were no statistically significant differences in AstK values between the Nidek AL Scan (2.4 -3.3 mm zone) and the Nidek OPD Scan II pairwise comparisons (p&gt;0.05). When the K1, K2, and Kmean values measured with the Nidek OPD Scan II and Topcon KR 8900 were compared with the Nidek AL Scan (2.4 -3.3 mm zone), a statistically significant difference was found (p

Agreement between Two Biometers for Central Corneal Thickness Measurement in High Myopia Patients

Background In refractive surgery, the measurement of Central Corneal Thickness (CCT) is a critical factor in the preparation and screening of surgery to correct myopia. CCT measurements can be measured by optical biometers, including the Scheimpflug camera and Swept-source Optical Coherence Tomography (SS-OCT). Aim This study aimed to compare the Central Corneal Thickness (CCT) measurements made with Swept-source Optical Coherence Tomography (SS-OCT)-based biometers and the Scheimpflug camera in patients with high myopia. Methods An analytical cross-sectional study was performed to evaluate the agreement between Central Corneal Thickness (CCT) values obtained using Swept-source Optical Coherence Tomography (SS-OCT) and the Scheimpflug camera. We included a total of 28 individuals with high myopia, including 44 eyes, for our study. These patients underwent Central Corneal Thickness (CCT) tests using both Swept-source Optical Coherence Tomography (SS-OCT) and the Scheimpflug camera. The Bland-Altman test was used to assess the agreement between the two devices. Results Forty-four eyes with axial lengths ranging from 26.05 to 34.02 mm based on SS-OCT examinations were included in this study. The mean CCT was 527.59 ± 35.710 (p &lt;0.05) μm and 525.64 ± 35.421 μm (p &lt;0.05), based on SS-OCT and the Scheimpflug camera, respectively. The Bland-Altman plot revealed good agreement between both devices, with a mean difference of 2.3409 μm; however, a 95% limit of agreement demonstrated a wide range, ranging from -8.48509 to 12.39400 μm at a 95% confidence interval. Conclusion CCT measurements using SS-OCT and the Scheimpflug camera differed significantly among patients with high myopia. Our findings have suggested that CCT measurements made with either device should be interpreted with caution and not be used interchangeably.

Validation of the Affordable, Portable International Visionkeys System for Visual Acuity and Stereopsis.

A new, portable computerized distance vision testing (screen plus remote) system called VisionKeys has been developed by the missions equipment developer EyeMobil so we validated it compared to conventional research testing devices. Using a standardized protocol of surround HOTV optotype presentation, the VisionKeys was compared to M&S for patched monocular distance visual acuity. A different VisionKeys function with anaglyph spectacle distance stereopsis was compared to near stereo on Titmus circles with Polaroid goggles and PDI Check on an autostereoscopic screen. Raw scores were converted to logarithm and compared with non-parametric and Bland Altman tests. We recruited 145 ethnically diverse patients with range of acuity -0.4 to 2.6 (NLP) logMAR from a pediatric eye and adult strabismus practice showing median logMAR acuity of 0.0 with VisionKeys significantly finer resolution than 0.1 for M&S (Mann-Whitney z=2.6, p=0.01, n=290). VisionKeys acuity correlated very well with M&S and children under age 7 scored coarser than teens and young adults. Median distance log arc seconds stereo on VisionKeys (2.00) differed from near Titmus circles (1.78) and PDI Check (1.89, Kruskal-Wallis X2(2)=9.8, p=0.007) however they all correlated well by Bland Altman. The new, portable VisionKeys system gives valid distance visual acuity with slightly finer estimate compared to M&S and the distance stereo compared well with near Titmus and PDI Check. As such, it should be valuable for testing children and adults in remote locations.

Clinical evaluation of a digital stethoscope with simultaneous phonocardiography and electrocardiography in cats.

A smartphone-based technology combining a digital stethoscope (DS) with simultaneous phonocardiography (PCG) and 1-lead electrocardiogram (ECG) is available. The aim of the present study was to evaluate the sensitivity and specificity of the DS for the detection of heart disease in cats considering transthoracic echocardiography as gold standard. The study is prospective and observational inlcuding 42 client-owned cats. All cases underwent auscultation with a conventional stethoscope (CS), recording with the DS, 6-lead ECG and echocardiography. All the recordings were blindly reviewed. The agreement with standard methods was assessed using the Cohen's kappa and the Bland-Altman test. The Fisher's exact test was used to test the effect of shaving on tracings' quality. Intraoperator and interoperator variability were assessed with Cohen's k and Fleiss' k, respectively. Audio recordings obtained with DS were interpretable in 100% of the cats. The agreement between DS and echocardiography in detecting heart disease was substantial (k = 0.714), while between CS and echocardiography the agreement was moderate (k = 0.571). Intraoperator and interoperator agreement was almost perfect (k = 0.904; k = 0.867, respectively). The ECG tracings recorded with the DS were interpretable in 83% of the cats and the device was reliable in assessing basic ECG measurements. No significant differences were found in the quality of the audio and ECG tracings in relation to the shaving condition. Based on the efficacy of detecting cardiac murmurs and gallop sound, the DS can be considered a reliable tool for cardiac auscultation in cats, producing good quality audio and ECG tracings also suitable for possible remote interpretation.

Comparison of the early childhood oral health impact scale (ECOHIS-4D) and EuroQol-5D-Y for measuring oral health-related quality of life utility in children.

The psychometric properties of the Early Childhood Oral Health Impact Scale (ECOHIS-4D), an oral health-related quality-of-life tool for children, and EuroQol 5D-Young (EQ-5D-Y), a commonly used generic quality-of-life tool for children, were compared across a clinical severity index to determine which tool is better for measuring oral health-related quality of life in children. Delayed and filled surfaces score (dfs) was calculated for under six-year-old children at the recruitment and one year later. ECOHIS-4D and EQ-5D were filled out on both occasions. The following properties were examined: (i) Content validity by comparing mean utility values using the Wilcoxson Signed Rank Test and Bland Altman Test, (ii) Construct validity (ability to discriminate between groups of different clinical severity) by examining effect size between severity groups (iii) Responsiveness (for changes in health status) using floor and ceiling effect, standard response mean and linear regression (iv) Correlation between the utilities and dfs. Respectively, 287 and 189 children were examined at the baseline and follow-up. Mean utility estimates from the tools were significantly different. All items of EQ-5D-Y showed high ceiling effects compared to items of ECOHIS-4D. Only the utility scores of ECOHIS-4D showed a significant association with the dfs score (β=-0.003, 95%CI=-0.004 to -0.002) in the linear regression models. Utility values form ECOHIS-4D, but not EQ-5D-Y correlated with the dfs (spearman's r=-0.33, 95%CI -0.43 to -0.23). ECOHIS-4D performs better than EQ-5D-Y in assessing young children's oral health-related quality of life.

Quantitative evaluation of adalimumab and anti-adalimumab antibodies in sera using a surface plasmon resonance biosensor

ObjectivesMonitoring of therapeutic antibody adalimumab (ADL) and of anti-adalimumab antibodies (AAA) in autoimmune diseases patients' sera has achieved increased attention since several studies showed a correlation between AAA levels and treatment failure. We evaluated a new surface plasmon resonance (SPR)-based method that, with slight changes in the analysis condition and in the ligand immobilized on the chip surface, allows to monitor both AAA and ADL. This new label-free method does not require sample pretreatments, and it is fully automated, only requiring the preparation of the chip, which can be used for multiple analysis, and the preparation of the sample sets. Design & MethodsSera from ADL-treated patients (n = 47) and controls (n = 13) were included in this study. Quantitative analysis of AAA and ADL were performed separately using a new SPR-biosensor, and a commercially available ELISA kit. Agreement was defined by overall, positive, and negative agreement. Wilson Score was used to calculate confidence intervals (CI) on binomial probability and Spearman’s rho and Bland-Altman test were used to assess correlations. ResultsELISA and SPR-based assay were able to identify circulating AAA in ADL-treated patients, with the percentage of positivity varying among the methods, with an overall agreement of 79%. AAA were detected in 18 (38 %) out of the 47 treated patients by the ELISA whereas SPR-based assay detected 10 (21 %) out of 47 samples. ConclusionsReal-time label free SPR-based protocol for both AAA and ADL quantification has been set-up. Although quantitative differences were observed when compared with ELISA, the agreement among methodologies was high, particularly for ADL quantification within the therapeutic window of the drug.

Use of Artificial Intelligence in Cobb Angle Measurement for Scoliosis: Retrospective Reliability and Accuracy Study of a Mobile App.

Scoliosis is a spinal deformity in which one or more spinal segments bend to the side or show vertebral rotation. Some artificial intelligence (AI) apps have already been developed for measuring the Cobb angle in patients with scoliosis. These apps still require doctors to perform certain measurements, which can lead to interobserver variability. The AI app (cobbAngle pro) in this study will eliminate the need for doctor measurements, achieving complete automation. We aimed to evaluate the reliability and accuracy of our new AI app that is based on deep learning to automatically measure the Cobb angle in patients with scoliosis. A retrospective analysis was conducted on the clinical data of children with scoliosis who were treated at the Pediatric Orthopedics Department of the Children's Hospital affiliated with Fudan University from July 2019 to July 2022. Three measurers used the Picture Archiving and Communication System (PACS) to measure the coronal main curve Cobb angle in 802 full-length anteroposterior and lateral spine X-rays of 601 children with scoliosis, and recorded the results of each measurement. After an interval of 2 weeks, the mobile AI app was used to remeasure the Cobb angle once. The Cobb angle measurements from the PACS were used as the reference standard, and the accuracy of the Cobb angle measurements by the app was analyzed through the Bland-Altman test. The intraclass correlation coefficient (ICC) was used to compare the repeatability within measurers and the consistency between measurers. Among 601 children with scoliosis, 89 were male and 512 were female (age range: 10-17 years), and 802 full-length spinal X-rays were analyzed. Two functionalities of the app (photography and photo upload) were compared with the PACS for measuring the Cobb angle. The consistency was found to be excellent. The average absolute errors of the Cobb angle measured by the photography and upload methods were 2.00 and 2.08, respectively. Using a clinical allowance maximum error of 5°, the 95% limits of agreement (LoAs) for Cobb angle measurements by the photography and upload methods were -4.7° to 4.9° and -4.9° to 4.9°, respectively. For the photography and upload methods, the 95% LoAs for measuring Cobb angles were -4.3° to 4.6° and -4.4° to 4.7°, respectively, in mild scoliosis patients; -4.9° to 5.2° and -5.1° to 5.1°, respectively, in moderate scoliosis patients; and -5.2° to 5.0° and -6.0° to 4.8°, respectively, in severe scoliosis patients. The Cobb angle measured by the 3 observers twice before and after using the photography method had good repeatability (P<.001). The consistency between the observers was excellent (P<.001). The new AI platform is accurate and repeatable in the automatic measurement of the Cobb angle of the main curvature in patients with scoliosis.

Comparison of angiography-derived index of microcirculatory resistance measurements between low and high frame-rate acquisitions: the prospective ADMIRAL-study

Abstract Background Angiography-derived index of microcirculatory resistance (angio-IMR) is a novel, wire-free, angiography-based method (QFR-IMR®) to assess coronary microvascular dysfunction. If a frame-rate of 15 frames per second (fps) is recommended, there is an interest in decreasing this frame-rate to reduce X-ray exposure. However, the impact of frame-rate reduction on angio-IMR quantification has not been investigated. Purpose To compare angio-IMR at 7.5 fps (angio-IMRlow) to angio-IMR at 15 fps (angio-IMRhigh) in a multicentric study. Methods From October 2023 to February 2024, we conducted a multicentre prospective study including consecutive patients referred for an invasive coronary angiogram with a final diagnosis of ischemia with no obstructive coronaries arteries (INOCA) (positive stress test with normal coronary angiogram) or acute coronary syndrome (ACS). Main exclusion criteria were creatinine clearance&amp;lt;45ml/kg/1.73m2, factors that might substantially impact the coronary angiograms quality (e.g: aortic stenosis, supraventricular tachycardia), and TIMI flow &amp;lt;3. In ACS patients, angio-IMR was measured after revascularisation. The same two acquisitions with different angles (≥25°) were recorded at a rate of 7.5 fps and a rate of 15 fps to measure angio-IMR in the selected vessel (culprit coronary vessel in ACS patients or left anterior descending artery in patients with INOCA). Angio-IMR was measured with dedicated software (QFR-IMR® RE, Medis Medical Imaging). Correlation between angio-IMRlow and angio-IMRhigh was assessed by linear regression and Bland-Altman test. The diagnostic accuracy of angio-IMRlow to predict microcirculatory dysfunction (defined as angio-IMRhigh≥ 25 for INOCA and ≥ 40 for ACS) was also assessed. Statistical significance was awarded by p≤0.05. Results Of 87 consecutive eligible patients, 75 were included in the study, comprising 57 with ACS and 18 with INOCA (mean age 61±12 years, 72% male). Angio-IMRlow (median=35; [IQR:28-48]) was slightly but significantly higher (p=0.04) than angio-IMRhigh (median=34; [IQR:25-45]). Angio-IMRlow and angio-IMRhigh were significantly correlated (r=0.90; p&amp;lt;0.0001) (Figure 1). Using Bland-Altman analysis, mean difference between the two measurements was 2.2 (95% CI 0.1-4.4) with a significant higher value with angio-IMRlow (p=0.04). Moreover, as value of Angio-IMRhigh increases, the difference between angio-IMRlow and angio-IMRhigh becomes more significant (Figure 2). Using angio-IMRhigh to diagnose microcirculatory dysfunction as reference, angio-IMRlow achieved positive and negative predictive values of 83% and 85% respectively with 6 false positives, and 6 false negatives. Conclusion Correlation between angio-IMRhigh and angio-IMRlow is acceptable. Lowering frame acquisition rate reduces radiation exposure without relevantly impact on the diagnostic accuracy of angio-IMR, which can contribute to a widespread use of angio-IMR.Correlation between angioIMRlow and highBland-Altman plot

Validation of a hand-held ultrasound device in the evaluation of aortic stenosis

Abstract Introduction Hand-held Ultrasound devices (HHUD) are increasingly used in routine clinical practice, although until recently they did not have continuous Doppler. There is no evidence on the usefulness of an HHUD for the assessment of aortic stenosis (AS) in real life. Objective To validate the use of a new HHUD device in a real-life scenario. Material and methods Observational, single-center and prospective study, including patients diagnosed with AS with a previous standard echocardiography. Patients were randomly recruited from a tertiary cardiac imaging laboratory. Immediately after the reference echocardiography performed by an imaging expert, a Cardiology trainee with ASE level II repeated the study blindly with an HHUD. Agreement between the two tests was evaluated by measuring the mean aortic valve gradient (mAG). An intraclass correlation coefficient (ICC) test, linear regression, and Bland-Altman test were performed to compare the two methods. Results 101 patients were recruited. The reference test calculated a mAG of 29 mmHg (19.8 - 42.2) versus a mAG of 27.2 mmHg (16.2 - 43.9) in HHUD. The statistical analysis showed a good correlation between both tests (ICC: 0.87 (95% CI: 0.79 -0.94) and r=0.89 (95% CI: 0.85-0.94) (Figure). The Bland-Altman test showed a non-significant underestimation (1.61 ± 0.9 mmHg; p= 0.09). The HHUD classified 29 cases as severe or major AS compared to 31 in the reference test (kappa= 0.81; 95% CI: 0.68 - 0.94). The HHUD showed an excellent agreement for classification of AS in at least severe AS grade. The kappa analysis had a value of 0.81 (95% CI 0.68 – 0.94) with a global agreement of 92.1%. The positive predictive value was 89.6%. The negative predictive value was 93.1%. Sensitivity and specificity were 83.8% and 95.7%. The rest of the variables evaluated showed poorer agreement. In those patients with obesity, worse acoustic window, atrial fibrillation and critical AS, the agreement was worse. Conclusions The new HHUD evaluated by an operator with limited experience showed good agreement with the reference echocardiographic device in determining the mean aortic gradient.Central picture

Accuracy of a Smart Diaper System for Nursing Home Residents for Automatically Detecting Voided Volume: Instrument Validation Study.

Diapers are commonly used by older patients with urination disorders. A smart diaper system (SDS) may be able to estimate the weight of urine comparably to conventional measurements made by weighing diapers. The aim of the current research is to determine the degree of accuracy of an SDS technology specifically designed for the management of urination routines and the use of incontinence pads in older adults. From January to December 2022, 97 older patients with at least 1 chronic disease from 3 nursing homes were included. In this study, the SDS was used for 1 month per patient after obtaining their consent; all patients originally used traditional diapers in the nursing home. The index test measured the change in electrical resistance of the SDS and the reference test measured the change in actual urine weight. When measuring the actual urine weight, the degree of absorption was directly confirmed with the naked eye because the expression value varied according to pressure changes caused by the user's movement or position. The Pearson correlation was used to determine the correlation between the 2 test methods, the intraclass correlation coefficient (ICC) was used to check the degree of agreement between the evaluators, and the Bland-Altman test was used to confirm whether there was a significant difference between the 2 test methods. The average age of the 97 participants was 86.48 (SD 6.26) years, with 10 men and 87 women. There were 73 patients (75%) with hypertension, 86 patients (88%) with dementia, and 86 patients (88%) with 2 or more comorbidities, accounting for the majority. The Pearson correlation coefficient and ICC were 0.971 and 0.985 (P<.001). In the Bland-Altman figure, the difference in the mean between the 2 tests was evenly scattered without showing a specific pattern, indicating that the SDS and actual urine weight were very consistent. The difference between the mean of the 2 tests was -0.045 of the standardized mean difference, and all measurements were located within the 95% CI, so this confirms that the 2 test methods are equivalent. Our study showed a fairly high correlation coefficient and ICC for all patient groups, which reveals that the 2 tests were very consistent and that the SDS can replace traditional diapers, even in a real clinical setting. This study shows the possibility that heath care professionals could be alerted by the SDS to the need for pad replacement due to incontinence, thus avoiding the development of dermatological complications.

Heart rate variability: Obtaining the stress score from SDNN values

BACKGROUND: Heart Rate Variability (HRV) is a non-invasive method of assessing the autonomic nervous system response during exercise and fatigue. OBJECTIVE: The aim of the study was to analyze the validity and feasibility of the stress score index (SS) calculated from SDNN values during exercise. METHODS: 18 Men performed 2 running tests: 1) incremental exercise test; 2) 10-minute constant load test. Subjects underwent HRV analysis during the constant load test, before both tests, and afterward in a seated position at 3 intervals (0’–5’, 5’–10’, 10’–15’). The relationship between SDNN and SD2 was analyzed before, during, and after the test. SS was calculated as 1/SD2*1000. The Bland-Altman test analyzed the reliability of ESS. The bias, limits of agreement (LoA), standard deviation of difference, intraclass correlation (ICC), and person coefficient were calculated. RESULTS: The bias was 0.15 ± 2.54 (UperLOA: 2.54; LowerLOA: -2.23). In all conditions, SD2 and SDNN showed a positive linear relationship (r2 = 0.986); SS and ESS were correlated; and SS and ESS described a positive linear relationship (r2 = 0.993). CONCLUSIONS: The SS index calculation from SDNN is a reliable alternative during exercise.

B-318 Serum PSA in Extracellular Vesicles: Immunoreactivity to Commercial Kits and Elimination Kinetics

Abstract Background Prostate Specific Antigen (PSA) also circulates in blood bound to extracellular vesicles (EVs), and observed higher ratio of PSA in EVs respect total serum PSA when serum concentrations are &amp;lt;4 μg/L, and can represent up to 59% of total circulating PSA. Moreover, this molecular form of PSA (ev-PSA) is recognized and can be quantified with commercial methodologies designed for serum quantification. We aimed to characterize ev-PSA studying its immunoreactivity to different commercial assays and analyzing its presence in international standards used for assays standardization. Serum half-life and elimination kinetics of ev-PSA were also studied. Methods Serum EVs from 32 prostate cancer (PCa) patients were isolated by ultracentrifugation (100,000xg, 90 minutes). PSA was assessed in serum (srm-), serum supernatant free of EVs (sn-) and EVs (ev-) with total PSA (T-PSA) commercial immunoassays (Elecsys® from Roche Diagnostics and Immulite® 2000 from Siemens Healthineers), and Immulite/Elecsys ratio was calculated in all samples. The analysis of the differences between methods was performed with Bland-Altman test, representing the percentage of the difference respect the mean. WHO 96/670 PSA Standard was ultracentrifuged and analyzed by Nanoparticle Tracking Analysis (NTA) in a NanoSight LM20.For half-life estimation, serum samples from 10 localized PCa patients were collected basal and 2 days after radical prostatectomy, and EVs were isolated by Size Exclusion Chromatography using Exo-spinTM kit (Cell Guidance System). The Research Ethic Committee approved the study. Results Significant differences were observed between Elecsys and Immulite immunoassays in ev-T-PSA (p&amp;lt;0.001) concentrations. ev-T-PSA was quantified in all samples with Elecsys (median: 0.134 μg/L; Q1-Q3: 0.033-0.391 μg/L), but only in 22 patients (68.75%) with Immulite (median: 0.206 μg/L; Q1-Q3: 0.074-0.340 μg/L). In those 22 quantifiable patients, the median Immulite/Elecsys ratio was similar (p=0.057) between sn-T-PSA and srm-T-PSA (0.96 and 0.92, respectively), but much lower for ev-T-PSA (0.77; p&amp;lt;0.001). Bland-Altman graphical analysis showed that Elecsys overestimates the concentrations of T-PSA in all samples compared to Immulite, being this overestimation more marked in the case of PSA contained in EVs, and amplified at lower PSA concentrations. Besides, NTA analysis of WHO 96/670 PSA Standard showed that it does not contain EVs, and therefore, ev-PSA. The percentage of remnant PSA calculated in samples obtained post-surgery respect to baseline concentration in prostatectomized patients, was significantly higher for ev-T-PSA compared to soluble srm-T-PSA (p=0.014) and srm-F-PSA (p=0.002). The elimination half-life of ev-T-PSA was 3.99 days, much higher than those estimated for serum T-PSA and F-PSA, that were 1.76 days and 0.64 days, respectively. Conclusions The quantification of ev-PSA is affected by the different immunoreactivity of the diverse commercial assays. Thus, Elecsys T-PSA immunoassay shows higher immunoreactivity compared to Immulite technique, being this different reactivity more marked at lower PSA concentrations. ev-PSA is not considered in the International WHO 96/670 PSA Standard used for methods standardization. PSA bound to EVs remains longer in circulation than soluble serum PSA.

Prediction of the maximum oxygen consumption (VO2max) for young Saudi females using exercise parameters.

Maximum oxygen consumption (VO2max), an essential indicator of integrated function of the cardiovascular, respiratory, and muscular systems, is an excellent predictor of all-cause morbidity and mortality. Direct measurement is a sophisticated procedure which for some individuals is difficult to perform. The use of international formulae leads to overestimation or underestimation of values. Therefore, the present study aimed to generate a best-fit VO2max prediction formula for young Saudi females. One hundred and two randomly selected young healthy Saudi females (19-25 years) with normal body mass index (18.5-24.99 kg m-2) and sedentary lifestyle underwent maximum cardiopulmonary exercise testing on cycle ergometer when using breath-by-breath analyzing system. Hemodynamic and ventilatory parameters were assessed before and during the maximum exercise. Significantly correlated exercise and nonexercise parameters enterd in multiple linear regression analysis to find the best-fit model, and used to generate a VO2max prediction formula. The mean measured VO2max was 1449.1 ± 233.92 ml min-1. The VO2max prediction formula was 1304.193 ± 17.902 × body weight + 43.857 × time until exhaustion - 6.83 × maximum heart rate. The mean calculated VO2max was 1449.14 ± 143.97 ml min-1. No statistically significant difference was observed between the measured and calculated VO2max. The Bland-Altman test for the limit of agreement was performed and showed good agreement between the two values with a minute proportional bias. The standard error of the estimate was 156.34, which is approximately 10.6% of the mean measured VO2max. Reliability analysis yielded a Cronbach's alpha of 0.709. This study presents a reliable and valid VO2max prediction formula for young Saudi females. This nationally generated formula is far more representative of the VO2max value than international formulae. We recommend the implementation of this formula and an investigation of its validity in other Saudi population groups.

Methods established for the detection of mineral levels in whole blood by the dried blood spot technique

Mineral are intimately related to human health and disease, and detection of mineral content in the body is of great significance for the diagnosis and prevention of diseases. In this study, we validated the method developed to detect magnesium (Mg), copper (Cu), iron (Fe), zinc (Zn), and selenium (Se) levels in dried blood spots (DBS). In accordance with the requirements of the guidelines for the Bioanalytical Method Validation Guidance for Industry, we evaluate the linearity, sensitivity, precision, accuracy and selectivity of the developed methods. In addition, Mg, Cu, Fe, Zn and Se were quantified in 195 older adults using DBS technique, and its accuracy was assessed by comparing the results to those detected by inductively coupled plasma-mass spectrometry (ICP-MS). The method has excellent sensitivity and linear range to cover the concentration range of mineral elements in the general population with the required precision, accuracy and selectivity. The correlation coefficients of Mg, Cu, Fe, Zn and Se levels in blood detected by the DBS technique and ICP-MS were 0.638, 0.823, 0.463, 0.728 and 0.751, respectively (all P < 0.05), which indicated that there was a strong correlation between the detection results of the two methods. More than 95 % of the sample results in the Bland-Altman consistency test were within the acceptable limits of agreement (LOA) range, indicating that they had good consistency. DBS technique has good accuracy and reliability in detecting blood mineral levels in the elderly, suggesting potential in the quantification of mineral level in blood.

The Cayor Atlas: a black Senegalese dental atlas for permanent tooth formation.

Many aspects of tooth development have been documented, particularly in Caucasian populations. However, dental development has not been extensively studied in West Africa. The present study was designed to provide information on the sequences of tooth calcification in West African black Senegalese children and to compare the results with those of other populations, notably the London Atlas. A total of 556 orthopantomograms (OPGs) from 289 males and 266 females with a mean age of 11.34 ± 3.84years were analyzed. Demirjian A-H staging was applied to record the stages of tooth development. Tables of tooth development stages for each tooth were generated separately for age cohorts and by sex. The most common stage of tooth formation (modal) was the characteristic age stage of development. Differences between boys and girls and between maxillary and mandibular teeth were also analyzed using chi-squares. Accuracy was assessed by comparing the age estimated by the Dental Development Atlas for this population (Cayor Atlas) and the London Atlas tooth with chronological age using the Bland-Altman test. There was no significant difference in tooth development between girls and boys, p > 0.05. Maxillary teeth had similar dental development to mandibular teeth, p > 0.05. The Pearson correlation test showed a strong correlation between chronological age and the age estimated by the Cayor atlas, p < 0.001. The Bland-Altman test also showed greater accuracy than the London Atlas. These results show dental calcification sequences different from those of the London Atlas Tooth and the Witts Atlas (Atlas of Black South African Subjects).

Same-Day Repeatability and 28-Day Reproducibility of Xenon MRI Ventilation in Children With Cystic Fibrosis in a Multi-Site Trial.

MRI with xenon-129 gas (Xe MRI) can assess airflow obstruction and heterogeneity in lung diseases. Specifically, Xe MRI may represent a sensitive modality for future therapeutic trials of cystic fibrosis (CF) therapies. The reproducibility of Xe MRI has not yet been assessed in the context of a multi-site study. To determine the same-day repeatability and 28-day reproducibility of Xe MRI in children with CF. Four-center prospective, longitudinal. Thirty-eight children (18 females, 47%), median interquartile range (IQR) age 12 (9-14) years old, with mild CF (forced expiratory volume in 1 second (FEV1) ≥85% predicted). 3-T, two-dimensional (2D) gradient-echo (GRE) sequence. Xe MRI, FEV1, and nitrogen multiple-breath wash-out for lung-clearance index (LCI2.5) were performed. To assess same-day reproducibility, Xe MRI was performed twice within the first visit, and procedures were repeated at 28 days. Xe hypoventilation was quantified using ventilation-defect percentage (VDP) and reader-defect volume (RDV). For VDP, hypoventilated voxels from segmented images were identified using a threshold of <60% mean whole-lung signal and expressed as a percentage of the lung volume. For RDV, hypoventilation was identified by two trained readers and expressed as a percentage. Inter-site comparisons were conducted using Kruskal-Wallis nonparametric tests with Dunn's multiple-comparisons tests. Differences for individuals were assessed using Wilcoxon matched-pairs tests. Bland-Altman tests were used to evaluate same-day repeatability, 28-day reproducibility, and inter-reader agreement. A P-value ≤0.05 was considered significant. Median FEV1 %-predicted was 96.8% (86%-106%), and median LCI2.5 was 6.6 (6.3-7.4). Xe MRI had high same-day reproducibility (mean VDP difference 0.12%, 95% limits of agreement [-3.2, 3.4]; mean RDV difference 0.42% [-2.5, 3.3]). At 28 days, 26/31 participants (84%) fell within the same-day 95% limits of agreement. Xe MRI may offer excellent same-day and short-term reproducibility. 2 TECHNICAL EFFICACY: Stage 2.