Acceptable Limits Of Agreement Research Articles

Validation of EGOS-600 Near Infrared Spectroscopy to Measure Cerebral Oxygen Saturation by Comparing to NIRO-200nx In Vitro and In Vivo

Objective: Near-infrared spectroscopy (NIRS) has been increasingly used to monitor regional cerebral oxygen saturation (rScO2) during cardiac surgery and intensive care. NIRO-200nx (Hamamatsu Phototonics, Japan) is one of widely used NIRS devices. EGOS-600 is a new device developed by Tsinghua University in China. We validated EGOS-600 by comparing to NIRO-200nx in laboratory and clinical settings. Materials and methods: Laboratory test : A liquid tissue model was made consisting of 40 ml of human whole blood, 25 ml intralipid-20% and 935 ml buffer solution. Oxygen saturation (SO2) levels ranging 20-100% were made by inflating oxygen or adding sodium hydrosulfite. Eleven pairs of measures were obtained using the two oximeters. Clinical test: 31 children (aged 0.7-61 months, median 11 months) and 20 adults (aged 18-73 years, median 59 years) were enrolled within one week after cardiac surgery. One probe of each device was sequentially placed at the middle of patient’s forehead to measure rScO2 at 2-3 hour intervals. One hundred pairs of rScO2 were obtained in each group. Bland-Altman method was used for data analysis. Results: Laboratory test showed a bias of-2% and limits of agreement 20 to-24% with a trend of overestimating SO2 by EGOS-600 when average SO2>50% and underestimating when <50%. This trend disappeared in patients. The bias was-5.9% in children and-4.1% in adults. The limits of agreement were 1.3 to-13.1% in children, and 3.3 to-11.5% in adults. Conclusions: EGOS-600 introduces a small underestimation of rScO2 when compared to NIRO-200nx, with acceptable limits of agreement. The new device is applicable in clinical settings in both children and adults.

10-m Shuttle Ride Test in Youth With Osteogenesis Imperfecta Who Use Wheelchairs: Feasibility, Reproducibility, and Physiological Responses.

Physical fitness levels in youth with osteogenesis imperfecta (OI) who use wheelchairs are unknown. The 10-m Shuttle Ride Test (SRiT) has recently been introduced as a field test to determine cardiorespiratory fitness in children with cerebral palsy who self-propel a wheelchair. The purpose of this study was to investigate the feasibility and reproducibility of the SRiT, as well as the physiological responses to the SRiT, in youth with moderate-to-severe OI between 8 and 25 years of age who self-propel a wheelchair at least for long distances. A test-retest design was used. Thirteen patients with OI (8 boys, 5 girls; mean±SD values for age=15.5±6.4 years) using a manual wheelchair performed 2 SRiTs within 2 weeks. Adverse events, reached stage, peak heart rate (HRpeak), peak respiratory exchange ratio (RERpeak), peak oxygen uptake (V̇o2peak), and peak minute ventilation (V̇epeak) were the main outcome parameters. All participants performed a maximal effort at both SRiTs (mean±SD values for HRpeak of 195±9 beats per minute [bpm], RERpeak of 1.32±0.16, V̇o2peak of 25.4±5.6 mL·kg(-1)·min(-1), and V̇epeak of 47.9±18.6 L·min(-1)), without adverse events. The intraclass correlation coefficient of the reached stage showed excellent reliability (.95). Limits of agreement (LoA) analysis revealed acceptable LoA for reached stage (mean bias=-0.58, range=-2.50 to +1.35). There was a low correlation between reached stage and V̇o2peak (r=.61 and r=.45 for the first and second SRiTs, respectively). The influence of wheelchair properties and individually adjusted wheelchair designs was not examined. The SRiT appears to be a feasible, safe, and reproducible maximal field test in youth with OI using wheelchairs at least for long distances. This field test might be useful to provide an indication of physical fitness and to assess the efficacy of interventions on physical fitness in these patients.

Computed tomography volume measurements of the liver using a liver segmentation and analysis package: an intra- and inter-rater reliability study

Introduction: Recent advances in technology have seen the introduction of software assisted image post-processing (SAIP)tools to calculate the volume of the liver from Computed Tomography (CT) images. One such SAIP tool is the semi-automatedPhilips liver segmentation and analysis package (Endhoven, The Netherlands). The intra- and inter-rater reliability of the livervolumes of 16 participants calculated using this tool was assessed. Methods: Two CT Technologists accessed Abdominal CT data sets and calculated the volume of the liver using the Philips liversegmentation and analysis package. One technologist repeated their calculation. Results: Results demonstrated high intra-rater reliability (ICC 0.9997) and high inter-rater reliability (ICC 0.99994). Analysiswith Bland Altman plots showed the mean bias for both intra- and inter-rater reliability to be close to zero with acceptable limitsof agreement. Conclusions: This study has shown that liver volume measurements using the Philips SAIP (Endhoven, The Netherlands) can betaken reliably by CT technologists, with confidence that the same results would be obtained between different CT technologists.

Accuracy and Test-Retest Reproducibility of Two-Dimensional Knowledge-Based Volumetric Reconstruction of the Right Ventricle in Pulmonary Hypertension.

BackgroundRight heart function is the key determinant of symptoms and prognosis in pulmonary hypertension (PH), but the right ventricle has a complex geometry that is challenging to quantify by two-dimensional (2D) echocardiography. A novel 2D echocardiographic technique for right ventricular (RV) quantitation involves knowledge-based reconstruction (KBR), a hybrid of 2D echocardiography–acquired coordinates localized in three-dimensional space and connected by reference to a disease-specific RV shape library. The aim of this study was to determine the accuracy of 2D KBR against cardiac magnetic resonance imaging in PH and the test-retest reproducibility of both conventional 2D echocardiographic RV fractional area change (FAC) and 2D KBR.MethodsTwenty-eight patients with PH underwent same-day echocardiography and cardiac magnetic resonance imaging. Two operators performed serial RV FAC and 2D KBR acquisition and postprocessing to assess inter- and intraobserver test-retest reproducibility.ResultsBland-Altman analysis (mean bias ± 95% limits of agreement) showed good agreement for end-diastolic volume (3.5 ± 25.0 mL), end-systolic volume (0.9 ± 19.9 mL), stroke volume (2.6 ± 23.1 mL), and ejection fraction (0.4 ± 10.2%) measured by 2D KBR and cardiac magnetic resonance imaging. There were no significant interobserver or intraobserver test-retest differences for 2D KBR RV metrics, with acceptable limits of agreement (interobserver end-diastolic volume, −0.9 ± 21.8 mL; end-systolic volume, −1.3 ± 25.8 mL; stroke volume, −0.2 ± 24.2 mL; ejection fraction, 0.7 ± 14.4%). Significant test-retest variability was observed for 2D echocardiographic RV areas and FAC.ConclusionsTwo-dimensional KBR is an accurate, novel technique for RV volumetric quantification in PH, with superior test-retest reproducibility compared with conventional 2D echocardiographic RV FAC.

Strain assessment in the carotid artery wall using ultrasound speckle tracking: validation in a sheep model

The aim of this study was to validate carotid artery strain assessment in-vivo using ultrasound speckle tracking. The left carotid artery of five sheep was exposed and sonomicrometry crystals were sutured onto the artery wall to obtain reference strain. Ultrasound imaging was performed at baseline and stress, followed by strain estimation using an in-house speckle tracking algorithm tuned for vascular applications. The correlation between estimated and reference strain was r = 0.95 (p < 0.001) and r = 0.87 (p < 0.01) for longitudinal and circumferential strain, respectively. Moreover, acceptable limits of agreement were found in Bland–Altman analysis (longitudinally: −0.15 to 0.42%, circumferentially: −0.54 to 0.50%), which demonstrates the feasibility of estimating carotid artery strain using ultrasound speckle tracking. However, further studies are needed to test the algorithm on human in-vivo data and to investigate its potential to detect subclinical cardiovascular disease and characterize atherosclerotic plaques.

Validation of a food frequency questionnaire using 7 day weighed food diaries in an elderly population with arthritis

Currently there are 10 million people with symptoms of age-related arthritis in the UK, and there is continuing research in relieving symptoms of this condition with diet. The Arthritic Association is a charity dedicated to supporting people with arthritis by helping them to manage their condition with diet and lifestyle advice. This involves the individual assessment and monitoring of dietary intake (using a 7 day food record) by a registered dietitian. The charity commissioned London Metropolitan University to develop and validate a new dietary assessment tool to assess absolute energy and macronutrient intake, which was less burdensome on an elderly population and could also be used in future research. A semi-quantitative food frequency questionnaire (FFQ) was developed using a food list of common foods consumed by the membership from previously completed 7 day food records. The FFQ was piloted and then finalised with a total of 17 food groups, with an additional section for supplements and foods not listed. The self-administered FFQ, used household portion sizes was completed over a seven day period. The FFQ was validated against the reference measure of the 7 day weighed diary (7WD). The Arthritic Association advertised the study and asked for volunteers through their quarterly newsletter. Altogether 65 participants agreed to participate, of whom 60 completed the food frequency and 50 (83% response rate) also completed the 7 day weighed diaries. Nutrient intakes obtained from the FFQ were higher than those obtained from the 7WD (Table 1) although the level of under-reporting was similar (7WD 30%, FFQ 32%). Spearman correlations for macronutrients and most micronutrients were within the acceptable range r = 0·5–0·7 ( 2 ) for both crude and energy-adjusted values. The ranking for the macronutrients ranged from 73–88% within the same or adjacent quartile, with only 0–8% in the extreme quartile. Bland-Altman plots comparing the FFQ with the 7WD for energy, fat, protein, carbohydrate and fibre (NSP) were within acceptable limits of agreement (±1·96 SD). The newly developed FFQ was thus deemed a valid tool to assess dietary intake in this population.

The validity of Actiwatch2 and SenseWear armband compared against polysomnography at different ambient temperature conditions

There were no validation studies on portable sleep devices under different ambient temperature, thus this study evaluated the validity of wrist Actiwatch2 (AW2) or SenseWear armband (SWA) against polysomnography (PSG) in different ambient temperatures. Nine healthy young participants (6 males, aged 23.3±4.1y) underwent nine nights of study at ambient temperature of 17°C, 22°C and 29°C in random order, after an adaptation night. They wore the AW2 and SWA while being monitored for PSG simultaneously. A linear mixed model indicated that AW2 is valid for sleep onset latency (SOL), total sleep time (TST) and sleep efficiency (SE) but significantly overestimated wake after sleep onset (WASO) at 17°C and 22°C. SWA is valid for WASO, TST and SE at these temperatures, but severely underestimates SOL. However, at 29°C, SWA significantly overestimated WASO and underestimated TST and SE. Bland–Altman plots showed small biases with acceptable limits of agreement (LoA) for AW2 whereas, small biases and relatively wider LoA for most sleep variables were observed in SWA. The kappa statistic showed a moderate sleep–wake epoch agreement, with a high sensitivity but poor specificity; wake detection remains suboptimal. AW2 showed small biases for most of sleep variables at all temperature conditions, except for WASO. SWA is reliable for measures of TST, WASO and SE at 17–22°C but not at 29°C, and SOL approximates that of PSG only at 29°C, thus caution is needed when monitoring sleep at different temperatures, especially in home sleep studies, in which temperature conditions are more variable.

Automatic characterization of thoracic aortic aneurysms from CT images

Accurate determination of the diameter is an important step for diagnosis and follow-up of aortic abnormalities such as aneurysms, caused by dilation of the vessel lumen. In this work we focus on the development of an automatic method for measuring the calibre of the thoracic aorta. The method is based on the application of principal component analysis on normal planes extracted from the aorta to establish the main axis of each section of the vessel.Two experiments were performed in order to test the accuracy and the rotational invariance of the developed method. Accuracy was determined by using a database of 15 clinical cases, where our method and a commercial software, which was considered as the gold standard, were compared. For the rotational invariance check, phantom images in different orientations were obtained and the diameter was measured with the proposed method.For clinical cases, a good agreement was observed between our method and the gold standard. The Bland Altman plots indicated that all of the values were within the acceptable limits of agreement with a bias of 0.2mm between both methods. For phantom cases, an ANOVA test revealed that the results achieved for the data sets acquired for the different orientations were not statistically different (F=1.88, p=0.153), which demonstrates the robustness of the method for rotations.The proposed method is applicable for measuring the diameter in all tested cases, and the results achieved underscored the capability of our approach for automatic characterization of thoracic aortic aneurysms.

Strain measurement by cardiovascular magnetic resonance in pediatric cancer survivors: validation of feature tracking against harmonic phase imaging

Left ventricular strain may be a more sensitive marker of left ventricular dysfunction than ejection fraction in pediatric cancer survivors after anthracycline therapy, but there is limited validation of strain measurement by feature tracking on cardiovascular magnetic resonance (MR) images. To compare left ventricular circumferential and radial strain by feature tracking vs. harmonic phase imaging analysis (HARP) in pediatric cancer survivors. Twenty-six patients (20.2 ± 5.6years old) underwent cardiovascular MR at least 5years after completing anthracycline therapy. Circumferential and radial strain were measured at the base, midventricle and apex from short-axis myocardial tagged images by HARP, and from steady-state free precession images by feature tracking. Left ventricular ejection fraction more closely correlated with global circumferential strain by feature tracking (r = -0.63, P = 0.0005) than by HARP (r = -0.39, P = 0.05). Midventricular circumferential strain did not significantly differ by feature tracking or HARP (-20.8 ± 3.4 vs. -19.5 ± 2.5, P = 0.07), with acceptable limits of agreement. Midventricular circumferential strain by feature tracking strongly correlated with global circumferential strain by feature tracking (r = 0.87, P < 0.0001). Radial strain by feature tracking had poor agreement with HARP, particularly at higher values of radial strain. Intraobserver and interobserver reproducibility was excellent for feature tracking circumferential strain, but reproducibility was poor for feature tracking radial strain. Midventricular circumferential strain by feature tracking is a reliable and reproducible measure of myocardial deformation in patients status post anthracycline therapy, while radial strain measurements are unreliable. Further studies are necessary to evaluate potential relation to long-term outcomes.

Intra‐ and interobserver reliability of levator ani muscle biometry and avulsion using three‐dimensional endovaginal ultrasonography

To test intra- and interobserver reliability of assessment of levator ani muscle (LAM) biometry and avulsion using antenatal and postnatal three-dimensional (3D) endovaginal ultrasonography (EVUS), and to determine levator-urethra gap (LUG) values on EVUS. Primigravid women were scanned prior to delivery, early postpartum and 3 months postpartum, with EVUS performed at rest using a standardized protocol. During post-processing, measurements were taken in the plane of minimal hiatal dimensions by two independent investigators blinded to the clinical information and each other's results. LAM attachment to the pubic bone was assessed at the pubococcygeus and puborectalis levels using a score system: (1) intact; (2) partial avulsion (< 50%); (3) partial avulsion (≥ 50%); and (4) complete avulsion. Intraclass correlation coefficients (ICCs) and limits of agreement (LOAs) were calculated for each time point, with intraobserver analysis conducted in a random sample of 20 women scanned 3 months following delivery. One hundred and sixty-nine antenatal scans, 83 early postpartum scans and 75 scans at 3 months postpartum were performed. The intra- and interobserver ICCs, respectively, were 0.95 and 0.86-0.88 for hiatal area, 0.90 and 0.16-0.74 for hiatal transverse diameter, 0.91 and 0.73-0.80 for hiatal anteroposterior diameter, 0.50 and 0.32-0.52 for LAM thickness at the '9 o'clock position' and 0.55 and 0.33-0.45 for LAM thickness at the '3 o'clock position'. Both intra- and interobserver analysis revealed acceptable LOAs for hiatal measurements, but the LOAs were wide for thickness measurements. The correlation of LAM avulsion score was excellent on intra- and interobserver analysis. Antenatal mean ± SD LUGs were 18.8 ± 2.4 mm and 19.2 ± 2.3 mm on right and left sides, respectively; the intraobserver ICC was 0.82-0.91 but LOAs were wide, while interobserver ICC was 0.13-0.68 and also had wide LOAs. 3D-EVUS is a reliable tool for the assessment of hiatal measurements and LAM avulsion in women during pregnancy and after delivery, but performs less well for measurements of LAM thickness and LUG. EVUS can therefore be used in research studies involving childbirth and recurrent prolapse.

Test–retest reliability and comparability of paper and computer questionnaires for the Finnish version of the Tampa Scale of Kinesiophobia

ObjectivesTo estimate the internal consistency, test–retest reliability and comparability of paper and computer versions of the Finnish version of the Tampa Scale of Kinesiophobia (TSK-FIN) among patients with chronic pain. In addition, patients’ personal experiences of completing both versions of the TSK-FIN and preferences between these two methods of data collection were studied. DesignTest–retest reliability study. Paper and computer versions of the TSK-FIN were completed twice on two consecutive days. ParticipantsThe sample comprised 94 consecutive patients with chronic musculoskeletal pain participating in a pain management or individual rehabilitation programme. The group rehabilitation design consisted of physical and functional exercises, evaluation of the social situation, psychological assessment of pain-related stress factors, and personal pain management training in order to regain overall function and mitigate the inconvenience of pain and fear-avoidance behaviour. ResultsThe mean TSK-FIN score was 37.1 [standard deviation (SD) 8.1] for the computer version and 35.3 (SD 7.9) for the paper version. The mean difference between the two versions was 1.9 (95% confidence interval 0.8 to 2.9). Test–retest reliability was 0.89 for the paper version and 0.88 for the computer version. Internal consistency was considered to be good for both versions. The intraclass correlation coefficient for comparability was 0.77 (95% confidence interval 0.66 to 0.85), indicating substantial reliability between the two methods. ConclusionBoth versions of the TSK-FIN demonstrated substantial intertest reliability, good test–retest reliability, good internal consistency and acceptable limits of agreement, suggesting their suitability for clinical use. However, subjects tended to score higher when using the computer version. As such, in an ideal situation, data should be collected in a similar manner throughout the course of rehabilitation or clinical research.

Reliability and concurrent criterion validity of a novel technique for analyzing hip kinematics during running

Excessive frontal plane hip kinematics during running has been associated with numerous running pathologies. Traditionally, assessment of hip kinematics during running required expensive and complex equipment and procedures making objective running assessment difficult for practicing clinicians. The aim of this study was to establish the reliability and validity of a novel technique designed for clinicians that allows for objective assessment of frontal plane hip kinematics during running. Hip angles and excursions were measured using videos and jpeg images of 10 subjects (five males and five females) running. A 2-D motion analysis system and computer algorithm served as reference measures. Six raters (three licensed physical therapists and three student physical therapists) took measures on two instances. Reliability was examined using intraclass correlation coefficients (ICC). Validity was investigated with ICCs, 95% limits of agreement (LA), and mean absolute differences (MAD) by comparing each rater's 2-trial average to the criterion reference values. The ICCs for interrater and intrarater reliability for angle and excursion measures ranged from 0.82 to 0.99. The validity ICCs of all measures ranged from 0.89 to 0.99 with acceptable LA. The MAD ranged from 0.5°–1.5°. These results indicate that this novel technique is reliable and valid for measuring hip kinematics compared to the reference measures making it suitable for broad-based clinical use.

Performance of Multiplex Commercial Kits to Quantify Cytokine and Chemokine Responses in Culture Supernatants from Plasmodium falciparum Stimulations

BackgroundCytokines and chemokines are relevant biomarkers of pathology and immunity to infectious diseases such as malaria. Several commercially available kits based on quantitative suspension array technologies allow the profiling of multiple cytokines and chemokines in small volumes of sample. However, kits are being continuously improved and information on their performance is lacking.Methodology/Principal FindingsDifferent cytokine/chemokine kits, two flow cytometry-based (eBioscience® FlowCytomix™ and BD™ Cytometric Bead Array Human Enhanced Sensitivity) and four Luminex®-based (Invitrogen™ Human Cytokine 25-Plex Panel, Invitrogen™ Human Cytokine Magnetic 30-Plex Panel, Bio-Rad® Bio-Plex Pro™ Human Cytokine Plex Assay and Millipore™ MILLIPLEX® MAP Plex Kit) were compared. Samples tested were supernatants of peripheral blood mononuclear cells of malaria-exposed children stimulated with Plasmodium falciparum parasite lysates. Number of responses in range that could be detected was determined and reproducibility of duplicates was evaluated by the Bland-Altman test. Luminex® kits performed better than flow cytometry kits in number of responses in range and reproducibility. Luminex® kits were more reproducible when magnetic beads were used. However, within each methodology overall performance depended on the analyte tested in each kit. Within the Luminex® kits, the Invitrogen™ with polystyrene beads had the poorer performance, whereas Invitrogen™ with magnetic beads had the higher percentage of cytokines/chemokines with both readings in range (40%), followed by Bio-Rad® with magnetic beads (35%). Regarding reproducibility, the Millipore™ kit had the highest percentage (60%) of cytokines/chemokines with acceptable limits of agreement (<30%), followed by the Invitrogen™ with magnetic beads (40%) that had tighter limits of agreement.Conclusions/SignificanceCurrently available kits for cytokine and chemokine quantification differ in reproducibility and concentration range of accurate detection. Luminex®-based kits with magnetic beads perform the best. Data highlights the importance of testing different kits before each study to choose the most appropriate, depending on the priority of the cytokines assessed.

Measurement of Left Atrial Volume from Transthoracic Three-Dimensional Echocardiographic Datasets Using the Biplane Simpson’s Technique

Although left atrial volume (LAV) by two-dimensional (2D) echocardiography provides prognostic information, the misalignment of the 2D cutting plane of the left atrium could make the measurements inaccurate. The aim of this study was to test the hypothesis that LAV measurement from three-dimensional (3D) echocardiographic data sets using the biplane Simpson's technique is a more reliable approach for measuring LAV. The accuracy of 3D echocardiographic LAV measurements was retrospectively determined in 20 patients using multidetector computed tomography as a reference. LAV indexed to body surface area (LAVI) was measured using 2D and 3D echocardiography in 200 other subjects. LAV determination by 2D echocardiography was performed using the biplane Simpson's method. A 3D determination of LAV was performed using quantitative software and the biplane Simpson's method using the anterior-posterior and medial-lateral 2D views extracted from the 3D data sets. Although LAV using the 3D volumetric method (mean, 98 ± 24 mL) was slightly but significantly lower than LAV on multidetector computed tomography (mean, 103 ± 23 mL), a significant correlation between the two methods (r= 0.97, P < .001) with acceptable limits of agreement was noted. The left atrial short-axis image extracted from the 3D data sets revealed an ellipsoid shape. Although a good correlation for LAVI was noted between the 2D biplane Simpson's method and the 3D volumetric method (r= 0.96, P < .001), the mean value of 2D echocardiographic LAVI was significantly greater compared with 3D echocardiographic LAVI, with a mean bias of 4.7 mL/m(2). An excellent correlation was noted between the 3D biplane Simpson's and 3D volumetric methods (r= 0.99, P < .001), with a lower bias (0.54 mL/m(2)) and limits of agreement of ±5.8 mL/m(2). The time required for LAV analysis was significantly shorter with the 2D (mean, 82 ± 7 sec) and 3D (mean,94±11 sec) biplane Simpson's methods (P < .01 vs 2D biplane Simpson's method) compared with the 3D volumetric methods (mean, 135 ± 24 sec) (P < .01 vs 2D and 3D biplane Simpson's methods). The 2D biplane Simpson's method overestimates LAV because of the misalignment of the 2D cutting plane, and the 3D biplane Simpson's method is a practical and more reliable way to accurately determine LAV.

Abbreviated Injury Scale: Not a reliable basis for summation of injury severity in trauma facilities?

BackgroundInjury severity is most frequently classified using the Abbreviated Injury Scale (AIS) as a basis for the Injury Severity Score (ISS) and the New Injury Severity Score (NISS), which are used for assessment of overall injury severity in the multiply injured patient and in outcome prediction. European trauma registries recommended the AIS 2008 edition, but the levels of inter-rater agreement and reliability of ISS and NISS, associated with its use, have not been reported. MethodsNineteen Norwegian AIS-certified trauma registry coders were invited to score 50 real, anonymised patient medical records using AIS 2008. Rater agreements for ISS and NISS were analysed using Bland–Altman plots with 95% limits of agreement (LoA). A clinically acceptable LoA range was set at ±9 units. Reliability was analysed using a two-way mixed model intraclass correlation coefficient (ICC) statistics with corresponding 95% confidence intervals (CI) and hierarchical agglomerative clustering. ResultsTen coders submitted their coding results. Of their AIS codes, 2189 (61.5%) agreed with a reference standard, 1187 (31.1%) real injuries were missed, and 392 non-existing injuries were recorded. All LoAs were wider than the predefined, clinically acceptable limit of ±9, for both ISS and NISS. The joint ICC (range) between each rater and the reference standard was 0.51 (0.29,0.86) for ISS and 0.51 (0.27,0.78) for NISS. The joint ICC (range) for inter-rater reliability was 0.49 (0.19,0.85) for ISS and 0.49 (0.16,0.82) for NISS. Univariate linear regression analyses indicated a significant relationship between the number of correctly AIS-coded injuries and total number of cases coded during the rater's career, but no significant relationship between the rater-against-reference ISS and NISS ICC values and total number of cases coded during the rater's career. ConclusionsBased on AIS 2008, ISS and NISS were not reliable for summarising anatomic injury severity in this study. This result indicates a limitation in their use as benchmarking tools for trauma system performance.

Real Time Three‐Dimensional Echocardiographic Assessment of Left Ventricular Function in Heart Failure Patients: Underestimation of Left Ventricular Volume Increases with the Degree of Dilatation

Accurate quantification of left ventricular (LV) volumes and ejection fraction (EF) is of critical importance. Cardiac magnetic resonance (CMR) is considered as the reference and three-dimensional echocardiography (3DE) is an accurate method, but only few data are available in heart failure patients. We therefore sought to compare the accuracy of real time three-dimensional echocardiography (RT3DE) and two-dimensional echocardiography (2DE) for quantification of LV volumes and EF, relative to CMR imaging in an unselected population of heart failure patients. We studied 24 patients (17 men, age 58 ± 15 years) with history of heart failure who underwent echocardiographic assessment of LV function (2DE, RT3DE) and CMR within a period of 24 hours. Mean LV end-diastolic volume (LVEDV) was 208 ± 109 mL (121 ± 64 mL/m(2) ) and mean LVEF was 31 ± 12.8%. 3DE data sets correlate well with CMR, particularly with respect to the EF (r: 0.8, 0.86, and 0.95; P < 0.0001 for LVEDV, LVESV, and EF, respectively) with small biases (-55 mL, -44 mL, 1.1%) and acceptable limits of agreement. RT3DE provides more accurate measurements of LVEF than 2DE (z= 2.1, P = 0.037) and lower variability. However, 3DE-derived LV volumes are significantly underestimated in patients with severe LV dilatation. In patients with LVEDV below 120 mL/m(2) , RT3DE is more accurate for volumes and EF evaluation. Compared with CMR, RT3DE is accurate for evaluation of EF and feasible in all our heart failure patients, at the expense of a significant underestimation of LV volumes, particularly when LVEDV is above 120 mL/m(2) .

The Validity of Temperature-Sensitive Ingestible Capsules for Measuring Core Body Temperature in Laboratory Protocols

The human core body temperature (CBT) rhythm is tightly coupled to an endogenous circadian pacemaker located in the suprachiasmatic nucleus of the anterior hypothalamus. The standard method for assessing the status of this pacemaker is by continuous sampling of CBT using rectal thermometry. This research sought to validate the use of ingestible, temperature-sensitive capsules to measure CBT as an alternative to rectal thermometry. Participants were 11 young adult males who had volunteered to complete a laboratory protocol that extended across 12 consecutive days. A total of 87 functional capsules were ingested and eliminated by participants during the laboratory internment. Core body temperature samples were collected in 1-min epochs and compared to paired samples collected concurrently via rectal thermistors. Agreement between samples that were collected using ingestible sensors and rectal thermistors was assessed using the gold-standard limits of agreement method. Across all valid paired samples collected during the study (n = 120,126), the mean difference was 0.06°C, whereas the 95% CI (confidence interval) for differences was less than ±0.35°C. Despite the overall acceptable limits of agreement, systematic measurement bias was noted across the initial 5 h of sensor-transit periods and attributed to temperature gradations across the alimentary canal. (Author correspondence: david.darwent@unisa.edu.au)

Validation of cardiac output measurement with the LiDCOTM pulse contour system in patients with impaired left ventricular function after cardiac surgery*

After cardiac surgery, patients with low left ventricular ejection fraction probably benefit the most from accurate monitoring of continuous cardiac output. Thirty patients with impaired ventricular function were studied, and intermittent bolus thermodilution and continuous pulse contour (LiDCO plus™) cardiac output compared. Following lithium dilution calibration, a total of 220 paired results were recorded. Thermodilution and LiDCO measurements ranged from 2.3 to 11.0 and 2.6 to 10.8 l.min(-1), respectively. Corresponding means (SD) were 6.1 (1.6) and 6.2 (1.9) l.min(-1), with coefficients of variance of 26 and 31%, respectively. The correlation coefficient was 0.82, bias 0.28 l.min(-1) with upper and lower limits of agreement 1.96 and -1.41 l.min(-1); the percentage error was 27%. LiDCO showed good correlation, marginal bias and acceptable limits of agreement and percentage error. It could therefore potentially replace thermodilution as a means of measuring cardiac output in the ICU, particularly when determination of pulmonary artery pressure is not required.

Bias and Precision Statistics: Should We Still Adhere to the 30% Benchmark for Cardiac Output Monitor Validation Studies?

Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong. hcritchley@cuhk.edu.hkIt was with great interest that I read Peyton and Chong's meta-analysis of papers comparing minimally invasive cardiac output monitors to thermodilution,1particularly as much of the discussion centered around a much-cited paper by me and my late brother Julian Critchley.2Our 1999 paper made a number of important contributions to assessing cardiac output monitoring2: (1) it provided guidelines on how the results from validation studies should be presented; (2) it defined a standard statistical variable by which performance could be compared, the percentage error or limits of agreement; (3) it established that the error of the reference method, usually thermodilution, was also an important factor in validation studies; and (4) it set limits of acceptance of ± 30% based on a precision for the reference method of ± 20%. Peyton and Chong should be congratulated on providing a thorough and comprehensive meta-analysis of cardiac output validation studies published during the last decade.1However, I would like to take issue with two of their conclusions.Peyton and Chong make reference to the accuracy of thermodilution cardiac output.1I would agree that the true precision of the thermodilution method in many of these validation studies is unknown. Cecconi et al. have suggested that the precision of the reference method should be known before using Bland and Altman analysis in validation studies.3However, this is not easily done, and simply calculating the coefficient of variability from a series of readings is not the answer.4The precision of the thermodilution can vary quite considerably depending of the type of catheter and measurement system, as we have shown in a recent in vitro investigation.5However, I would have to take issue with Peyton and Chong in their assertion that precision is significantly worse during in vivo or clinical testing. I agree that cardiac output varies with respiration and other physiologic effects, but comparative measurements are made simultaneously, and the mean of several readings is used to average out these background physiologic effects.Peyton and Chong also suggest that our ± 30% limits of agreement are set too low and a more realistic benchmark would be ± 45%, which they base on reference and test precision errors of ± 30%, reset from our ± 20%. Good news for the manufacturers. However, our choice of a ± 20% error for the reference readings was not just based on data from papers by Stetz et al. and Mackenzie et al., 6,7as Peyton and Chong suggest. In Bland and Altman's 1986 paper,8the decision as to what were acceptable limits of agreement was left to the judgment of the clinician, and for cardiac output measurement, most authors at the time were suggesting a precision of less than 1 l/min, which for a mean cardiac output of 5 l/min was 20%.9,10Furthermore, increasing the limits ± 45% would give a false impression that many monitors are measuring cardiac output reliably, which simply is not true. Therefore, I would still recommend using ± 20% for our criteria.Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong. hcritchley@cuhk.edu.hk

Development and validation of a tool to recall alcoholic beverage and wine consumption over consumers’ lifetimes

Different past experiences are likely to influence current preferences and consumption through learning processes, such as evaluative conditioning, leading to different flavour preference developments. The ability to measure past experience of alcoholic beverage consumption would be useful in order to understand the drivers of current wine consumption. The developed and validated tool provides reliable data for both past alcohol consumption recall and current wine consumption. Intraclass correlation coefficients (ICC) and F-tests indicated reliability, specifically, high internal consistency (lifetime drinking history and current wine consumption), internal validity and acceptable limits of agreement (current wine consumption relative to a 7-day diary), especially for the most frequently consumed wine (red), demonstrating that the measures taken were reproducible over time. In contrast to previous lifetime alcohol consumption studies, the present study included measures of type of wine consumed. Results justify and encourage the administration of the developed tool on a larger sample, aiming to seek associations between ‘drinking histories’ in order to understand current wine consumption.