Intraclass Correlation Coefficient Difference Research Articles

Reproducibility and Intervendor Agreement of Left Ventricular Global Systolic Strain in Children Using a Layer-Specific Analysis

Speckle-tracking strain analysis provides additive data to the assessment of pediatric and congenital heart disease; however, the variety of strain analysis software platforms by different vendors and the lack of data on intervendor strain agreement in children have limited its utility. The purpose of this study is to evaluate the intervendor agreement of strain on two commonly used analysis platforms in pediatrics by layer of myocardium and data compression. This prospective study analyzed two-dimensional speckle-tracking strain on two software platforms in 53 children with normal cardiac segmental anatomy and varying function. Three standard apical views and one parasternal short-axis view were exported at their acquired frame rates to workstations with GE EchoPAC and TomTec software and then also to TomTec at compressed frame rates. Both software platforms had been updated with European Association of Cardiovascular Imaging/American Society of Echocardiography Task Force recommendations for left ventricular (LV) global strain. Intravendor and intervendor agreement between layer-specific comparisons were assessed using Bland-Altman analysis (limits of agreement and bias) and intraclass correlation coefficients. This study included subjects with normal LV function (n=38) and cardiomyopathy (n=15) with an age range of 1month to 18years. Intertechnique agreement by default vendor myocardial layer (GE mid-TomTec endocardial layer) was robust for both global longitudinal (GLS) and circumferential strain (GCS; higher for GLS than GCS). Intravendor (inter- and interreader) agreement was slightly higher than intervendor. Only small differences in intraclass correlation coefficients were present between various myocardial layers and acquired versus compressed TomTec data with narrow limits of agreement and small bias except in certain subgroup comparisons. Comparison of LV GLS and GCS between two commonly used software platforms after European Association of Cardiovascular Imaging/American Society of Echocardiography Industry Task Force recommendations demonstrated good to excellent agreement in pediatrics, regardless of the layer of analysis or the image format, although some degree of variability remains between vendor platforms. Overall, GLS agreement was more robust than GCS, and this difference is exaggerated in specific subanalyses. These data suggest that comparisons of strain values obtained on these two vendors will be reasonable, but caution should be used when the indication is the detection of small differences between serial echocardiograms.

Assessing the validity of proxy caregiver reporting for potential palliative care outcome measures in Parkinson’s disease

Background: There is increasing interest in applying palliative care approaches for patients with Parkinson’s disease. Methodological studies are needed to validate palliative care outcome measures for Parkinson’s disease to build this evidence base. As many patients with Parkinson’s disease have cognitive and/or communication issues, proxy outcome measures may improve the inclusivity and relevance of research. Aim: To assess the validity of proxy caregiver reports for several potential palliative care outcome measures. Design: A cross-sectional study of Parkinson’s disease patients and caregivers completed a battery of outcome measures relevant to palliative care including the Memorial Symptom Assessment Scale, Hospital Anxiety and Depression Scale, Prolonged Grief Questionnaire 12, Parkinson Disease Questionnaire 39, Functional Assessment of Chronic Illness Therapy–Spiritual Wellbeing, and Schwab and England. Intraclass correlation coefficients were used to assess agreement. Setting/participants: A total of 50 Parkinson’s disease patient and caregiver dyads recruited at an academic medical center, Veterans Affairs Medical Center, and community support groups. Results: There was moderate to good agreement for Schwab and England, Parkinson Disease Questionnaire 39 total, and majority of Parkinson Disease Questionnaire 39 subscales; moderate to good agreement for the Hospital Anxiety and Depression Scale, Functional Assessment of Chronic Illness Therapy–Spiritual Wellbeing, Prolonged Grief Questionnaire 12, and Memorial Symptom Assessment Scale; and poor to moderate agreement for the Parkinson Disease Questionnaire 39 stigma, social support, and bodily pain subscales. Caregivers tended to attribute higher symptom severity than patients. We did not detect differences in intraclass correlation coefficient based on cognitive status but patients with advanced illness had significantly lower intraclass correlation coefficients for several outcomes. Conclusions: Caution is indicated when considering caregiver proxy reporting for most outcomes assessed, particularly in Parkinson’s disease patients with advanced disease.

Dedicated Spine Measurement Software Quantifies Key Spino-Pelvic Parameters More Reliably Than Traditional Picture Archiving and Communication Systems Tools.

Measurement reliability study of adult spinal deformity (ASD) patient radiographs using intraclass correlation coefficients (ICC) and variance. The aim of the study was to compare picture archiving and communication systems (PACS) to dedicated spine measurement software (SMS). Accurate radiographic measurement of sagittal alignment is essential for evaluating ASD. PACS measurements often necessitate rudimentary techniques and estimations of anatomic landmarks and angles. Though SMS has been studied and validated, no studies directly compare PACS to SMS. Eleven independent observers (7 spine surgeons, 4 researchers) digitally measured 20 ASD radiographs for pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, thoracic kyphosis (TK), and sagittal vertical axis (SVA). Round 1 used PACS basic line/angle tools; Round 2 used a validated SMS that automatically calculates spino-pelvic parameters from 6 user-identified landmarks. Means, coefficient of variance (CV), and intraclass correlation coefficients (ICC) were analyzed. PACS measurements were significantly greater than SMS (PI, PT, PI-LL: P < 0.0001), though within clinical and measurement margins of error. Excluding TK, the variations in measurement (CV) were significantly greater for PACS (14-34%) vs. SMS (11-23%). Reliability was greater in SMS than PACS for PI, PT, PI-LL, LL, and SVA. The greatest differences in intraclass correlation coefficients (ICC) between PACS and SMS were in PI (PACS: 0.647; SMS: 0.810) and PI-LL (PACS: 0.921; SMS: 0.970). Among surgeons, the differences between PACS and SMS were augmented, and SMS had higher intraclass correlation coefficients (ICC) than PACS for all parameters (mean intraclass correlation coefficients [ICC] 0.931 vs. 0.861). Among surgeons, PI had the lowest reliability ( 0.505; SMS: 0.752) and SVA had the highest ( 0.985; SMS: 0.994). SMS provides significantly more reliable measurements than PACS, especially among surgeons. Consistent use of SMS in the evaluation and surgical planning of ASD patients appears necessary given the significant differences in values, variance, and reliability between PACS and SMS.

Reproducibility of in vivo corneal confocal microscopy as a novel screening test for early diabetic sensorimotor polyneuropathy

With the goal of identifying a valid biomarker of early diabetic sensorimotor polyneuropathy, we aimed to identify the most reliable in vivo corneal confocal microscopy (CCM) parameter for detection of abnormality of small nerve fibre morphology. Cross-sectional examination of 46 subjects (26 with Type 1 diabetes and 20 healthy volunteers) examined by corneal confocal microscopy for intra- and interobserver reproducibility by the intraclass correlation coefficient method. Corneal nerve fibre density, nerve branch density, nerve fibre length and tortuosity were measured on the same day that subjects underwent clinical and electrophysiological examination. The 26 subjects with Type 1 diabetes had mean age and diabetes duration 42.8 ± 16.9 and 22.7 ± 16.4 years, respectively. Twelve of those subjects (46%) did not meet criteria for diabetic sensorimotor polyneuropathy, while five (19%) had mild, three (12%) had moderate and six (23%) had severe diabetic sensorimotor polyneuropathy. None of the healthy volunteers (mean age 41.4 ± 17.3 years) had polyneuropathy. Re-examination of selected corneal confocal microscopy images or sets of 40 images yielded very good to excellent intraclass correlation coefficients for all parameters. However, only one parameter (corneal nerve fibre length) emerged with consistently very good reproducibility using a clinically relevant 'study-level' protocol of subject re-examination (intra-observer intraclass correlation coefficient 0.72; interobserver intraclass correlation coefficient 0.73). Despite no differences in intraclass correlation coefficient between subgroups, corneal nerve fibre length was significantly lower (14.76 vs. 16.15 mm/mm(2), P = 0.04) in those with diabetes. Development of corneal confocal microscopy may need to focus on the measurement of corneal nerve fibre length, as it appears to have superior reliability in comparison with other parameters, and as evidence exists for its potential as a clinical biomarker of early diabetic sensorimotor polyneuropathy.

Competing sources of earnings inequality: A comparison of variance components

Using data from the National Longitudinal Survey of Youth, this study partitions competing sources of earnings variation into four components: a component for individual-level factors, a component for transitory factors, a component for occupational factors, and a component for geographic factors. From these variance components intraclass correlation coefficients are calculated and compared within and across seven ascriptive statuses: non-Hispanic white, non-Hispanic black, Latino, women, men, foreign-born and U.S. born statuses. Among those of age 25 to middle adulthood, the results indicate that the transitory component is the largest source of variation in earnings, followed by individual-level factors. Occupational factors and geographic factors combined account for nearly the amount of earnings variation as individual-level factors. The omission of these socio-structural factors inflates the size of the individual-level variance component by over 35 percent. Counter to expectations, the variance profiles are remarkably similar across ascriptive statuses. Indeed, the variance profiles for whites and blacks are nearly identical. Modest differences in intraclass correlation coefficients are found between men and women. Relative to men, less of the variation in earnings for women is attributed to individual-level factors, and slightly more of the variation in earnings for women is attributed to occupational factors and transitory factors. This research draws attention to universal theories of earnings inequality.