Intra-individual Agreement Research Articles

Agreement of objectively measured physical activity and sedentary time in preschool children

ObjectiveTo determine the intra-individual agreement for objectively measured physical activity (PA) and sedentary behavior (SED) over two subsequent weeks in preschool children.MethodNinety-one children aged 3 to 5 years (49% boys) from three preschools in Sogn og Fjordane, Norway, provided 14 consecutive days of accelerometer data (Actigraph GT3X +) during the autumn of 2014. Week-by-week reliability was assessed using intraclass correlation (ICC), Bland–Altman plots and 95% limits of agreement for different wear time criteria (≥ 6, 8 and 10 h/day and ≥ 3 and 5 days/week).ResultsThe week-by-week ICC was ≥ 0.75 for all variables across all wear criteria applied, except for absolute sedentary time (ICC 0.61–0.81). Using a ≥ 8 h/day and ≥ 3 days/week criterion (n = 78), limits of agreement were ± 209.5 cpm for overall PA, ± 68.6 min/day for SED, ± 43.8 min/day for light PA, ± 20.2 min/day for moderate-to-vigorous PA, and ± 55.9 min/day for light-to-vigorous PA, equaling 1.0–1.6 standard deviation units.ConclusionConsiderable week-by-week variability was found for all variables. Researchers need to be aware of substantial intra-individual variability in accelerometer-measurements and take necessary actions according to the hypothesis under study, as noise in any measurement will preclude researchers' ability to arrive at valid conclusions in epidemiology.

Assessing Sedentary Behavior with the GENEActiv

The Sedentary Sphere is a method for the analysis, identification, and visual presentation of sedentary behaviors from a wrist-worn triaxial accelerometer. This study aimed to introduce the concept of the Sedentary Sphere and to determine the accuracy of posture classification from wrist accelerometer data. Three samples were used: 1) free living (n = 13, ages 20-60 yr); 2) laboratory based (n = 25, ages 30-65 yr); and 3) hospital inpatients (n = 10, ages 60-90 yr). All participants wore a GENEActiv on their wrist and activPAL on their thigh. The free-living sample wore an additional GENEActiv on the thigh and completed the Multimedia Activity Recall for Children and Adults. The laboratory-based sample wore the monitors while seated at a desk for 7 h, punctuated by 2 min of walking every 20 min. The free-living and inpatient samples wore the monitors for 24 h. Posture was classified from wrist-worn accelerometry using the Sedentary Sphere concept. Sitting time did not differ between the wrist GENEActiv and the activPAL in the free-living sample and was correlated in the three samples combined (rho = 0.9, P < 0.001), free-living and inpatient samples (r ≃ 0.8, P < 0.01). Mean intraindividual agreement was 85% ± 7%. In the laboratory-based and inpatient samples, sitting time was underestimated by the wrist GENEActiv by 30 min and 2 h relative to the activPAL, respectively (P < 0.05). Posture classification disagreed during reading while standing, cooking while standing, and brief periods during driving. Posture allocation validity was excellent when the GENEActiv was worn on the thigh, evidenced by the near-perfect agreement with the activPAL (96% ± 3%). The Sedentary Sphere enables determination of the most likely posture from the wrist-worn GENEActiv. Visualizing behaviors on the sphere displays the pattern of wrist movement and positions within that behavior.

Perceptual evaluation of violins: A comparison of intra-individual agreement in playing vs. listening tasks for the case of richness

In previous studies by the authors, it was shown that there is a significant lack of agreement between violinists when evaluating different instruments in terms of perceived richness in free-playing tasks. A new experiment was designed to further investigate the perceptual evaluation of richness using both a constrained-playing task, which was recorded, and a subsequent listening task (using the previously recorded sounds). The goal was to compare the evaluation of richness from playing vs. listening tasks in order to better understand whether they are based more on auditory feedback or tactile and proprioceptive cues in the wider context of correlating audio features extracted from the recordings with richness judgments. Skilled violinists were asked to rank five different instruments by playing only certain notes on the G-string. Subsequently, the players were asked to listen to their recordings and rank the violins. Results appeared to show a higher inter-individual agreement relative to previous studies. Furthermore, the rankings in the playing task were generally different from those in the listening task, indicating that the evaluation of richness is based on different criteria in the two cases. Results from matching the tristimulus and spectral centroid of recorded tones to richness judgments will be presented at the conference.

Sighting versus sensory ocular dominance

Purpose An indication of the laterality of ocular dominance (OD) informs the clinical decision making process when considering certain ophthalmic refractive and surgical interventions. Can predictive reliance be assured regardless of OD technique or is the indication of a dominant eye method-dependent?

A pilot study of sampling subcutaneous adipose tissue to examine biomarkers of cancer risk.

Examination of adipose tissue biology may provide important insight into mechanistic links for the observed association between higher body fat and risk of several types of cancer, in particular colorectal and breast cancer. We tested two different methods of obtaining adipose tissue from healthy individuals. Ten overweight or obese (body mass index, 25-40 kg/m(2)), postmenopausal women were recruited. Two subcutaneous abdominal adipose tissue samples were obtained per individual (i.e., right and left lower abdominal regions) using two distinct methods (method A: 14-gauge needle with incision, versus method B: 16-gauge needle without incision). Gene expression was examined at the mRNA level for leptin, adiponectin, aromatase, interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in flash-frozen tissue, and at the protein level for leptin, adiponectin, IL-6, and TNF-alpha following short-term culture. Participants preferred biopsy method A and few participants reported any of the usual minor side effects. Gene expression was detectable for leptin, adiponectin, and aromatase, but was below detectable limits for IL-6 and TNF-alpha. For detectable genes, relative gene expression in adipose tissue obtained by methods A and B was similar for adiponectin (r = 0.64, P = 0.06) and leptin (r = 0.80, P = 0.01), but not for aromatase (r = 0.37,P = 0.34). Protein levels in tissue culture supernatant exhibited good intra-assay agreement [coefficient of variation (CV), 1-10%], with less agreement for intraindividual agreement (CV, 17-29%) and reproducibility, following one freeze-thaw cycle (CV, >14%). Subcutaneous adipose tissue biopsies from healthy, overweight individuals provide adequate amounts for RNA extraction, gene expression, and other assays of relevance to cancer prevention research.

Contrast-Enhanced MR Angiography Improves Detection of Carotid-T Occlusion by Acute Stroke MRI

Time-of-flight magnetic resonance angiography (TOF-MRA) is dependent on the inflow of spins into the imaged vessel section and, thus, on a minimum of residual blood flow. Proximal occlusion or high-grade stenosis of the internal carotid artery (ICA) may simulate an occluded distal intracranial ICA, which is known as carotid-T occlusion (CTO). An additional contrast-enhanced angiography (CE-MRA) was used to further differentiate between CTO and low-flow, but open intracranial ICA bifurcation in acute stroke patients. 28 patients with suspected CTO due to low TOF-MRA signal in the intracranial ICA were examined by a multiparametric stroke MRI protocol including CE-MRA within 6 h after symptom onset. Blinded occlusion site rating was performed by two experienced neuroradiologists using TOF- and CE-MRA separately. Final consensus rating revealed eleven patients suffering from CTO. Sensitivity to detect CTO by TOF-MRA was 64% versus 82%, specificity 65% versus 76%. Consensus of rating TOF-MRA was substantial (k = 0.71). Sensitivity for detecting CTO by CE-MRA was 100% versus 82% with 100% specificity for both raters. Interobserver agreement by CE-MRA was almost perfect (k = 0.85). Intraindividual agreement between the TOF-MRA versus CE-MRA examinations for one of the raters was slight (k = 0.27) and moderate for the other (k = 0.56). Additional CE-MRA improved overall accuracy in discriminating ICA stenosis versus CTO. CE-MRA should be the method of choice for the detection of CTO in case of flow reduction in the carotid artery. TOF-MRA alone is less accurate in these patients.

Validation of Magnetic Resonance Phase-Contrast Flow Measurements in the Main Pulmonary Artery and Aorta Using Perivascular Ultrasound in a Large Animal Model

Phase-contrast flow magnetic resonance imaging (pc-MRI) measurements are an established technique for noninvasive assessment of hemodynamics. However, in vivo validation data on the accuracy of pc-flow especially for nonphysiologic hemodynamic conditions are missing. The goal of our work was 1) to validate pc-flow with perivascular ultrasound in different hemodynamic conditions in the main pulmonary artery (MPA) and ascending aorta (AO) and 2) to investigate the relation between pc-MRI and invasive pressure measurements. Five healthy pigs with opened chest were investigated. Ultrasound measurements were performed outside the MRI unit using a detachable MR-table. Parallel to ultrasound flow measurements, invasive pressure measurements were performed. PC-MRI (1.5 T MRI) measurements were done using a FLASH 2-dimensional sequence. First the animals were examined in normotonia, followed by hypertension (infusion of Arterenol) and hypotension (infusion of Sodiumnitropussid). Flow measurements acquired in normotonia were 2.7 +/- 0.6 L/min (ultrasound) and 2.8 +/- 0.6 L/min for pc-MRI (not significantly different, P = 0.17). During hypertonia, the blood flow increased to 3.1 +/- 0.7 and 2.7 +/- 0.8 L/min, respectively (P = 0.01). During hypotension, the blood flow decreased to 1.7 +/- 0.5 and 1.7 +/- 0.5 L/min, respectively (P = 0.7). An excellent linear correlation (taking all measurements together) between the ultrasound and pc-MRI measurements was found (r = 0.89). 95% Limits of intraindividual agreement correspond to relative differences of -36 to 44%. Systolic pressure measurements in the AO were 91 mm Hg (normotonic), 111 mm Hg (hypertonic), and 64 mm Hg (hypotonic) and in the MPA 23 mm Hg (normotonic), 29 mm Hg (hypertonic), and 20 mm Hg (hypotonic). Systolic pressure measurements showed good linear correlation with pc-MRI average flow per minute and peak velocity (AO: r = 0.79, MPA: r = 0.66). MRI pc-flow measurements are a reliable tool for noninvasive assessment of blood flow. Hemodynamic parameters derived by MRI demonstrate good linear correlations with the pressure in the systemic and pulmonary arterial circulation.

Invasively Estimated International Continence Society Obstruction Classification Versus Noninvasively Assessed Bladder Outlet Obstruction Probability in Treatment Recommendation for LUTS Suggestive of BPH

To investigate the contribution of urodynamically proven presence or absence (International Continence Society classification) of bladder outlet obstruction (BOO) to treatment recommendations for lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia, and to investigate the impact of the replacement of the invasively estimated BOO classification with the noninvasively assessed BOO probability on treatment recommendations. Mandatory tests, recommended tests, and pressure-flow studies (with BOO classification) were performed in 150 consecutive men with LUTS suggestive of BPH. Three experienced urologists proposed, independently of each other, the treatment for each patient: watchful waiting, pharmacologic treatment, or surgery. After repeat randomization of the patients and replacement of the BOO classification with the BOO probability, the procedure was repeated 1 month later. A third treatment proposal was done after repeat randomization and after replacement of the BOO probability with the BOO classification. The symptom score and quality-of-life score were the most decisive in the treatment recommendations, followed by the BOO probability and BOO classification. The medical history, physical status, and duration of the complaints did not significantly affect the treatment recommendations. The intraindividual agreement between the judgments that included the BOO classification and the judgments that included the BOO probability was comparable to the agreement between both judgments that included BOO classification. The interindividual agreement between the judgments that included the BOO classification was not significantly different from that of the judgments that included the BOO probability. The symptom score and quality-of-life score were the most decisive in the medical treatment recommendations, followed by the BOO probability and BOO classification. The noninvasively assessed BOO probability was as valuable as the invasively estimated BOO classification in the medical treatment recommendations.

The intraindividual agreement of the bone density of the human proximal tibia

The interindividual variability in the biomechanical properties of cadaver bones has remained an unsolved problem in biomechanical investigation procedures. For this reason, it is postulated to use matched bone pairs from the same individual for comparative biomechanical tests. The rationale behind this procedure is based on the assumption that biomechanically similar behaviour is to be expected in an intraindividual rather than an interindividual comparison. Systematic studies confirming this thesis were performed on the human femur. However, investigations regarding the intraindividual properties of the proximal tibial metaphysis with respect to the underlying bone densities, have not yet been performed. In order to verify the hypothesis that matched proximal tibial metaphyses from the same donor imply corresponding bone density values, densitometric measurements (pQCT) were performed in 14 matched cadaver tibias (average age 61 years, 9 men, 5 women) which were fresh-frozen at -40 degrees C after removal. After statistical analysis of the bone density values, five tibial pairs were identified as differing on the basis of missing correlations and the existence of systematic differences within the pairwise data. In other words, only about 2/3 of the data in the random sample available was classified as comparable. As the bone density measured by pQCT technique significantly correlates with the biomechanical properties of the bone, it can be concluded from the test result available that matched human tibiae show no concurring bone density values in 1/3 of cases. Thus the pairing of corpse tibiae does not necessarily imply suitability for comparative biomechanical experiments.

OPTOELECTRONIC MOVEMENT ANALYSIS TO MEASURE MOTOR PERFORMANCE IN PATIENTS WITH CHRONIC LOW BACK PAIN: TEST OF RELIABILITY

To assess test-retest reliability of the Posturo-Locomotion-Manual(PLM) test in patients with chronic low back pain. A controlled study in which the PLM test was used repeatedly on patients with chronic low back pain and persons without back pain. Twelve patients with treatment-resistant chronic low back pain, selected by 2 orthopaedic spine surgeons and 12 age- and sex-matched individuals with no back pain history. An optoelectronic camera and a computer were used to quantify the performance during a simple test in which subjects picked up an object from the floor and transported it up to a shelf, thereby forcing the body through postural, locomotor and manual movements. The outcome measures were: movement time, simultaneity index and phase times for postural, locomotion and arm movement phases. Statistical analyses regarding intra-individual agreement between the measurements (reliability analysis) and changes over time were carried out. The effect of test movement habituation was minimized when the lowest mean value of any of 3 consecutive measures (tri-average) was used. In the control group, variation between test occasions was small. In the group of patients with chronic low back pain there was a random measurement error before intervention (sensory motor learning). After intervention the PLM test had the same precision in both groups. When the tri-average measure is used, the influence of test movement habituation is minimized and the optoelectronic PLM test is found to be reliable and responsive. It proved to be a useful tool to quantify dynamic performance in freely moving patients with chronic low back pain.

Perceptual analysis in different voice samples: agreement and reliability.

The objective of this study was to estimate the agreement and reliability of voice evaluation by a group of expert listeners using the central portion of a sustained vowel and a fragment of connected speech as voice samples. Ratings were made using Wilson's Buffalo III Voice Screening Profile. Analysis showed that intraindividual listeners' agreement presented variability in the evaluation of both voice samples. In the evaluation of the central portion of the sustained vowel, interindividual listener agreement was moderate for breathiness, hyponasal resonance, and overall voice rating; in connected speech, agreement was moderate for most voice qualities (breathy, rough, high/low pitch, and hyponasal resonance). Finally, Wilson's Buffalo III Voice Screening Profile presented good reliability values for both voice samples, with overall voice rating achieving higher values (.90) than any other voice-quality variable.

Development of an ADL instrument targeting elderly persons with age-related macular degeneration

Background: In order to estimate the needs of early intervention in a health education program, an ADL instrument measuring feelings of (in)security was needed. The instrument was intended to detect early signs of decline and to evaluate ADL performance among persons with AMD. An evaluative instrument must have a high level of responsiveness, which is the ability to detect true changes over time but must also show a high level of intra-individual agreement in a test-retest assessment. Purpose: The purpose of this study was to develop an ADL instrument for evaluative purposes and to establish the reliability and the responsiveness of the instrument. Method: The target group comprised all persons referred by an ophthalmologist for low vision rehabilitation, 65 years and older, living at home, with aged-related macular degeneration as the primary diagnosis and with distance visual acuity of the better eye with best correction not lower than 0.1. A nonparametric statistical method that is developed for paired ordered parametrical data was applied in order to measure the systematic and occasional intra-rater disagreement separately and to measure the responsiveness. Conclusion: The test-retest study showed that the ADL-instrument had a high level of test-retest stability, which is a condition for responsiveness. The instrument was found to be responsive. It could therefore detect true longitudinal changes and be used for evaluative purposes targeting elderly with AMD.

Assessment of DNA flow cytometry as a surrogate end point biomarker in a bladder cancer chemoprevention trial

Although conventional cytology represents the most widely performed cytometric analysis of bladder cancer cells, DNA flow cytometry has, over the past decade, been increasingly used to evaluate cell proliferation and DNA ploidy in cells from bladder washings. We have investigated whether DNA flow cytometry and conventional cytology of epithelial cells obtained from bladder washings provide reliable surrogate endpoint biomarkers in clinical chemoprevention trials. We used cytometric and clinical data from a chemoprevention trial of the synthetic retinoid Fenretinide on 99 patients with superficial bladder cancer. A total of 642 bladder washing specimens obtained from the patients at 4 month intervals was analyzed. Intra-individual agreement and correlation of flow cytometric DNA ploidy (diploid vs. aneuploid), DNA Index, Hyper-Diploid-Fraction (proportion of cells with DNA content higher than 2C), and conventional cytologic examination, as assessed by kappa statistics and Spearman's correlation test, were poor from baseline through 24 months. Moreover, no correlation was found between DNA ploidy and cytology at each time point. The same results were obtained when the analyses were stratified by treatment group. In addition, the association between the results of bladder washing (by either DNA flow cytometry or cytology) and concomitant tumor recurrence was significant only for abnormal cytology, while neither biomarker was predictive of tumor recurrence at the subsequent visit. During the time of this study only four patients progressed to muscle-invasive bladder cancer, indicating the "low-risk" features of the patient population. We conclude that DNA flow cytometry and conventional cytology on epithelial cells obtained from bladder washings do not appear to provide suitable surrogate endpoint biomarkers during the early stages of bladder carcinogenesis.

Validation of objective assessment methods for tonal noise from wind farms

The perceived impact of wind farm noise depends not only on the overall level of noise emitted, but also on the character of the noise. In particular, the presence of tonal components increases the subjective annoyance. Procedures for the detection of tonal components in the environmental noise and for the assessment of the annoyance due to these components have been proposed in national standards and legislation, e.g., German norm DIN 45681 (draft), Joint Nordic Method. To validate tonality calculation procedures, noises from a representative sample of nine wind turbines of German wind farm sites were recorded by means of a dummy head at the emission measuring point nearby the turbines. Together with a set of five synthesized pink noises with tonal components of different strengths, ten selected wind turbine noises were randomly presented at equal loudness over headphones. Sixteen subjects had to assess categorically the tonality of each noise, which occurred six times in two sessions. The resulting subjective answers showing high inter- and intraindividual agreement could serve as an excellent validation basis for eight selected tonality calculation procedures. It will be shown that the prominence ratio-based methods are the best in modeling subjective tonality assessments.

Studies on electrolyte and trace metal metabolism applying stable isotopes as tracers

Tracer-kinetic investigations provide a useful tool for the assessment of body composition regarding electrolytes and trace elements. This paper demonstrates the feasibility of stable isotopes as tracers in studies on calcium and iron metabolism in risk groups like children. By applying both radioisotopes and stable isotopes simultaneously, in adults, a good intra-individual agreement was obtained for the derived figures of intestinal absorption. Using only stable isotopes, intestinal calcium absorption in children with renal failure was found to follow a similar pattern to that in adult patients.

Critical evaluation of computerised x ray planimetry for the measurement of lung volumes.

Computerised x-ray planimetry has been advocated as an alternative to body plethysmography and helium dilution for measuring static lung volumes. The accuracy and reproducibility of this method has been assessed in comparison with these standard methods. Plethysmographic and planimetric measurements of total lung capacity (TLC) and functional residual capacity (FRC) were made in 10 normal subjects and in 12 patients with chronic obstructive pulmonary disease (COPD), with additional helium dilution measurements in the latter 12 patients. Mean lung volumes (TLC and FRC) for groups of subjects measured by planimetry and by plethysmography were similar in both groups and larger than the helium dilution measurement in patients with COPD. Intraindividual agreement between planimetry and plethysmography was poor, however, with a wide confidence interval (-2.2 to +2.31). The planimeter did not measure reliably changes in volume from TLC to FRC in individuals. Mean lung volumes measured by planimetry in a group of patients probably reflect a regression to the mean of the computer algorithm rather than accurate TLC estimation. The technique is not yet robust enough to replace the established techniques of helium dilution or plethysmography.