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Concept: Covariance and correlation


PURPOSE: Existing patient self-reported shoulder scoring systems fail to express physicians' points of view, and understanding the wording can sometimes lead to confusion in Easterners. We sought to develop a valid, reliable, and responsive shoulder scoring system that combines the points of view of physicians and patients and is easily understood for worldwide applicability. METHODS: Six steps were followed to develop the scale: (1) investigation, identification of a specific population, and patient and physician interviews; (2) item generation, according to existing shoulder scales, a literature review, and patient and physician interviews; (3) item reduction, by combining and adjusting items; (4) formatting of the questionnaire, designed using both subjective and objective scales, with a 100-point score range; (5) pretesting, to eliminate confusion and misunderstanding of items, and (6) preliminary evaluation. Pearson correlation coefficients were calculated to assess validity (compared with American Shoulder and Elbow Surgeons, Constant-Murley, and University of California, Los Angeles scores), intraclass correlation coefficients were calculated to assess reliability (with a 2-week test-retest interval), and the standardized response mean was calculated to assess responsiveness (comparing preoperative and postoperative scores in patients). RESULTS: The final scoring system was designed to have a 100-point score range, with higher scores indicating better function. It consisted of self-report assessment by patients (61 points in total) and objective assessment by physicians (39 points in total). Updated scales, including a night pain subscale, patient-physician satisfaction, and 2-dimensional visual analog scale tool, were incorporated in our system. Compared with the other 3 scoring systems (American Shoulder and Elbow Surgeons, Constant-Murley, and University of California, Los Angeles scores), the new scoring system has shown favorable validity, with a Pearson correlation coefficient greater than 0.7. In addition, the intraclass correlation coefficient was greater than 0.9 during a 2-week test-retest interval, indicating high reliability, and the standardized response mean of the new system was greater than that of the other 3 scoring systems, indicating sensitive responsiveness. CONCLUSIONS: A new shoulder scoring system has been developed based on patients' and physicians' points of view and worldwide applicability and was verified to be valid, reliable, and responsive. The new scoring system includes a 2-dimensional visual analog scale, night pain subscale, and patient-physician satisfaction scale, which are not included in the existing scoring systems. LEVEL OF EVIDENCE: Level III, development of diagnostic criteria.

Concepts: Spearman's rank correlation coefficient, Physician, Assessment, Psychometrics, Correlation and dependence, Reliability, Pearson product-moment correlation coefficient, Covariance and correlation


The purpose of this prospective study was to establish the ultrasonographic characteristics of the dimension of the right pancreatic lobe with that of the associated anatomic landmarks in healthy dogs. Ultrasonographic examinations were performed on 25 dogs. The thickness of the right pancreatic lobe was compared with that of mural thickness of duodenum, diameters of duodenum, pancreatic duct, abdominal aorta, portal vein, caudal vena cava, and length and width of the right kidney and right adrenal gland. The correlation between each pancreatic parameter and the dimensions of the anatomical landmarks were assessed using linear regression analysis and Pearson’s correlation coefficient ® test. Significant, but weak linear correlations were observed between thickness of right pancreatic lobe with that of duodenum mural thickness (r=0.605, R(2)=0.339, P=0.001); duodenum diameter (r=0.573, R(2)=0.299, P=0.003); and right adrenal gland length (r=0.508, R(2)=0.052, P=0.01). There was no significant dimensional relationship with other selected anatomic landmarks. The ratio between the thickness of right pancreatic lobe and the mural thickness of duodenum, diameter of duodenum and length of right adrenal gland were 2.88 ± 0.53, 1.27 ± 0.27, and 0.81 ± 0.15, respectively. Calculating the ratio of thickness of the right pancreatic lobe with the dimension of significantly correlated anatomic landmarks is a useful and simple method for evaluating the size of the right pancreatic lobe in dogs in clinical practice.

Concepts: Kidney, Pancreas, Spearman's rank correlation coefficient, Abdominal aorta, Correlation and dependence, Pearson product-moment correlation coefficient, Covariance and correlation, Adrenal gland


This study examines the distributional equity of urban tree canopy (UTC) cover for Baltimore, MD, Los Angeles, CA, New York, NY, Philadelphia, PA, Raleigh, NC, Sacramento, CA, and Washington, D.C. using high spatial resolution land cover data and census data. Data are analyzed at the Census Block Group levels using Spearman’s correlation, ordinary least squares regression (OLS), and a spatial autoregressive model (SAR). Across all cities there is a strong positive correlation between UTC cover and median household income. Negative correlations between race and UTC cover exist in bivariate models for some cities, but they are generally not observed using multivariate regressions that include additional variables on income, education, and housing age. SAR models result in higher r-square values compared to the OLS models across all cities, suggesting that spatial autocorrelation is an important feature of our data. Similarities among cities can be found based on shared characteristics of climate, race/ethnicity, and size. Our findings suggest that a suite of variables, including income, contribute to the distribution of UTC cover. These findings can help target simultaneous strategies for UTC goals and environmental justice concerns.

Concepts: Regression analysis, Spearman's rank correlation coefficient, Correlation and dependence, Pearson product-moment correlation coefficient, Least squares, Covariance and correlation, Statistical dependence, Household income in the United States


Purpose To demonstrate the feasibility of the use of a rapid, noninvasive, in vivo imaging method to measure fatty acid fractions of breast adipose tissue during diagnostic breast magnetic resonance (MR) examinations and to investigate associations between fatty acid fractions in breast adipose tissue and breast cancer status by using this method. Materials and Methods The institutional review board approved this retrospective HIPAA-compliant study and informed consent was waived. Between July 2013 and September 2014, multiple-echo three-dimensional gradient-echo data were acquired for 89 women. Spectra were generated and used to estimate fractions of monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), and saturated fatty acid (SFA) in the breast adipose tissue. Analysis of covariance and exact Mann-Whitney tests were used to compare groups and the Spearman rank correlation coefficient was used to characterize the association of each imaging measure with each attribute. Results For postmenopausal women, MUFA was lower (0.38 ± 0.06 vs 0.46 ± 0.10; P < .05) and SFA was higher (0.31 ± 0.07 vs 0.19 ± 0.11; P < .05) for women with invasive ductal carcinoma than for those with benign tissue. No correlation was found between body mass index (BMI) and fatty acid fractions in breast adipose tissue. In women with benign tissue, postmenopausal women had a higher PUFA (0.35 ± 0.06 vs 0.27 ± 0.05; P < .01) and lower SFA (0.19 ± 0.11 vs 0.30 ± 0.12; P < .05) than premenopausal women. Conclusion There is a possible link between the presence of invasive ductal carcinoma and fatty acid fractions in breast adipose tissue for postmenopausal women in whom BMI values are not correlated with the fatty acid fractions. (©) RSNA, 2016 Online supplemental material is available for this article.

Concepts: Nutrition, Fatty acids, Spearman's rank correlation coefficient, Fat, Body mass index, Covariance and correlation, Statistical dependence, Unsaturated fat


Purpose: the Thai PPS Adult Suandok tool was translated from the Palliative Performance Scale (PPSv2) and had been used in Chiang Mai, Thailand for several years. Aim: to test the reliability and validity of the Thai translation of PPSv2. Design: a set of 22 palliative cases were used to determine a PPS score on Time-1, and repeated two weeks later as Time-2. A survey questionnaire was also completed for qualitative analysis. Participants: a total of 70 nurses and physicians from Maharaj Nakorn Hospital in Chiang Mai participated. Results: The Time-1 intraclass correlation coefficient (ICC) for absolute agreement is 0.911 (95% CI 0.86-0.96) and for consistency is 0.92 (95% CI 0.87-0.96). The Time-2 ICC for agreement is 0.905 (95% CI 0.85-0.95) and for consistency is 0.912 (95% CI 0.86-0.96). These findings indicate good agreement among participants and also were somewhat higher in the Time-2 re-test phase. Cohen’s kappa score is 0.55, demonstrating a moderate agreement. Thematic analysis from the surveys showed that 91% felt PPS to be a valuable clinical tool overall, with it being ‘very useful’ or ‘useful’ in several areas, including care planning (78% and 20%), disease monitoring (69% and 27%) and prognostication (61% and 31%), respectively. Some respondents noted difficulty in determining appropriate scores in paraplegic patients or those with feeding tubes, while others found the instructions long or difficult. Conclusion: the Thai PPS Adult Suandok translated tool has good inter- and intra-rater reliability and can be used regularly for clinical care.

Concepts: Psychometrics, Reliability, Covariance and correlation, Thailand, Cohen's kappa, Inter-rater reliability, Translation, Chiang Mai


Fatigue is a frequent symptom during ankylosing spondylitis (AS) often under estimated which needs to be measured properly with respect to its intensity by appropriate measures, such as the multidimensional assessment of fatigue (MAF). The aims of this study were to translate into the classic Arabic version of the MAF questionnaire and to validate its use for assessing fatigue in Moroccan patients with AS. The MAF contains 16 items with a global fatigue index (IGF). The MAF was translated and back-translated to arabic, pretested and reviewed by a committee following the Guillemin criteria (J Clin Epidemiol 46:1417-1432, 1993). It was then validate on 110 Moroccan patients with AS. Reliability for the 3-day test-retest was assessed using internal consistency by Cronbach’s alpha coefficient and the intra-class correlation coefficient (ICC). External construct validity was assessed by correlation with pain, activity of disease and other keys variable. The reproducibility of the 15 items was satisfactory with a kappa statistics of agreement superior to 0.6. The ICC for IGF score reproducibility was good and reached 0.98 (IC 95%, 0.96-0.99). The internal consistency was at 0.991 with Cronbach’s alpha coefficient. The construct validity showed a positive correlation between MAF and the axial (r = 0.34) and peripheral (r = 0.32) visual analogical scale, the Bath ankylosing spondylitis disease activity index (BASDAI) (r = 0.77), the first item of BASDAI (r = 0.85), the functional disability by the Bath ankylosing spondylitis functional index (r = 0.64), the erythrocyte sedimentation rate (r = 0.43) and the C reactive protein (r = 0.30) (for all P < 0.001). There was no statistical correlation between MAF and the other variables. The Arabic version of the MAF has good comprehensibility, internal consistency, reliability and validity for the evaluation of Arabic speaking patients with AS.

Concepts: Psychometrics, Correlation and dependence, Reliability, Pearson product-moment correlation coefficient, Covariance and correlation, C-reactive protein, Cronbach's alpha, Ankylosing spondylitis


BACKGROUND AND PURPOSE:: The Tinetti Performance-Oriented Mobility Assessment (POMA) is commonly used to measure balance ability in older adults. The purpose of this study was to determine the test-retest reliability and minimal detectable change (MDC) of the POMA and explore its cross-sectional and longitudinal construct validity for use in people early after stroke. METHODS:: Participants were recruited if they had a first documented stroke and were receiving physical therapy during inpatient rehabilitation. The POMA, gait speed, and motor Functional Independence Measure (FIM) scores were collected at admission and at discharge from inpatient rehabilitation. A second trial of the POMA was conducted 1 day after the first trial for reliability analysis. Correlations (Spearman ρ) between raw scores of admission and discharge outcome measures, as well as change in scores between admission and discharge, were used to explore the construct validity of the POMA. RESULTS:: Fifty-five people, with average age of 75 ± 11 years, who had experienced first documented stroke participated in the study and began inpatient physical therapy at a mean of 8 ± 5 days poststroke. Test-retest reliability intraclass correlation coefficient (ICC2,1) was 0.84 and MDC was 6 points. The POMA scores were moderately correlated to motor FIM and gait speed scores at admission (rs = 0.55 and 0.70) and discharge (rs = 0.55 and 0.82.) Change scores of all 3 measures had a fair correlation (rs = 0.28-0.51). DISCUSSION AND CONCLUSIONS:: Test-retest reliability and MDC of the POMA in people with stroke is similar to previous research in older adult long-term care residents. Results support cross-sectional and longitudinal construct validity of the POMA in persons early after stroke and demonstrate validity and reliability to measure balance ability in this population. VIDEO ABSTRACT AVAILABLE: (see Video, Supplemental Digital Content 1, for more insights from the authors.

Concepts: Spearman's rank correlation coefficient, Psychometrics, Correlation and dependence, Reliability, Pearson product-moment correlation coefficient, Covariance and correlation, Statistical dependence, Test-retest


Children with developmental coordination disorder (DCD) have deficits in working memory, but little is known about the everyday memory of these children in real-life situations. We investigated the everyday memory function in children with DCD, and explored the specific profile of everyday memory across different domains. Nineteen children with DCD and 19 typically developing (TD) children participated in the study. Their everyday memory performance was evaluated using the Rivermead Behavioral Memory Test for Children, which showed that 52.6% of the children with DCD had everyday memory deficits. The overall everyday memory scores of the DCD group were significantly lower than those of the controls, particularly in the verbal and visual memory domains. Pearson correlation analysis indicated significant associations between verbal intelligence and memory scores. Analysis of covariance with verbal intelligence as a covariate showed no significant differences between groups in memory scores. Mediator analysis supported the notion that everyday memory deficits in children with DCD were fully mediated through verbal intelligence. We provide evidence of everyday memory deficits in most of the children with DCD, and hypothesize that language abilities are their underlying cause. The clinical implications of these findings and recommendations for additional research are discussed.

Concepts: Psychology, Memory, Child, Developmental psychology, Pearson product-moment correlation coefficient, Covariance and correlation, Analysis of variance, Karl Pearson


BACKGROUND: -Accurate measures are critical when attempting to distinguish normal from pathological changes in cardiac function during exercise, yet imaging modalities have seldom been assessed against invasive exercise standards. We sought to validate a novel method of biventricular volume quantification by cardiac magnetic resonance imaging (CMR) during maximal exercise. METHODS AND RESULTS: -CMR was performed on 34 subjects during exercise and free-breathing using an ungated real-time CMR (“RT-ungated”) sequence. ECG and respiratory movements were retrospectively synchronized enabling compensation for cardiac cycle and respiratory phase. Feasibility of RT-ungated imaging was compared with standard exercise CMR imaging with ECG gating (“gated”), Accuracy of RT-ungated CMR was assessed against an invasive standard (direct Fick) and reproducibility was determined following a second bout of maximal exercise. Ventricular volumes were able to be analyzed more frequently during high-intensity exercise using RT-ungated as compared with gated CMR (100% vs. 47%, p<0.0001) and with better inter-observer variability for RT-ungated (coefficient of variation CV=1.9% and 2.0% for left and right ventricular stroke volumes, respectively) than gated (CV=15.2% and 13.6%), p <0.01. Cardiac output determined by RT-ungated CMR proved accurate against the direct Fick method with excellent agreement (intraclass correlation coefficient R=0.96) which was highly reproducible during a second bout of maximal exercise (R=0.98). CONCLUSIONS: -By combining real-time ungated CMR with post-hoc analysis incorporating compensation for respiratory motion, highly reproducible and accurate biventricular volumes can be measured during maximal exercise.

Concepts: Scientific method, Cardiology, Heart, Nuclear magnetic resonance, Magnetic resonance imaging, Cardiac output, Covariance and correlation, Fick principle


Aim  The aims of this study were to examine whether objective measurements of the 10-minute drooling quotient (DQ10) and the 5-minute drooling quotient (DQ5) are interchangeable; to assess agreement between the measurements and their accuracy in classifying drooling severity; and to develop a time-efficient clinical assessment. Method  The study cohort included 162 children (61 females, 101 males; mean age 11y 6mo, SD 4y 5mo, range 3y 9mo-22y 1mo) suffering from moderate to profuse drooling. One hundred and twenty-four had cerebral palsy and 38 had other developmental disabilities. Seventy-four of the participants were ambulant and 88 non-ambulant. The original DQ10 was recalculated into a 5-minute score (DQ5). Assessments were undertaken while the participants were in a rest situation (DQ® ) and while they were active (DQ(A) ). Agreement in scores was quantified using intraclass correlations and Bland-Altman plots. To classify drooling, area under the receiver operating characteristic curve analysis was used to compare accuracy of the DQ10 and DQ5 at rest and during activity. Results  Agreement between DQ10A, and DQ5(A) , and between DQ10® and DQ5® was high (intraclass correlation coefficient >0.90). Moderate agreement existed between DQ(A) and DQ® . DQ(A) scores were more accurate in classifying children’s drooling behaviour. For DQ5(A) , a cut-off point of 18 or more (drooling episodes/observation time) might indicate ‘constant drooling’. Interpretation  The DQ10 and DQ5 can be used interchangeably. DQ(A) is most discriminative for drooling severity. For evaluating treatment efficiency the cut-off point can be used. For clinical and research purposes, the DQ5 is time efficient and cost saving while validity, and intrarater and interrater reliability are preserved.

Concepts: Evaluation, Assessment, Psychometrics, Correlation and dependence, Pearson product-moment correlation coefficient, Covariance and correlation, Receiver operating characteristic, Inter-rater reliability