Generalized Spearman rank correlation coefficient and its application

It is desirable to adjust Spearman's rank correlation for covariates, yet existing approaches have limitations. For example, the traditionally defined partial Spearman's correlation does not have a sensible population parameter, and the conditional Spearman's correlation defined with copulas cannot be easily generalized to discrete variables. We define population parameters for both partial and conditional Spearman's correlation through concordance-discordance probabilities. The definitions are natural extensions of Spearman's rank correlation in the presence of covariates and are general for any orderable random variables. We show that they can be neatly expressed using probability-scale residuals (PSRs). This connection allows us to derive simple estimators. Our partial estimator for Spearman's correlation between X and Y adjusted for Z is the correlation of PSRs from models of X on Z and of Y on Z, which is analogous to the partial Pearson's correlation derived as the correlation of observed-minus-expected residuals. Our conditional estimator is the conditional correlation of PSRs. We describe estimation and inference, and highlight the use of semiparametric cumulative probability models, which allow preservation of the rank-based nature of Spearman's correlation. We conduct simulations to evaluate the performance of our estimators and compare them with other popular measures of association, demonstrating their robustness and efficiency. We illustrate our method in two applications, a biomarker study and a large survey.

This study aims to compare the diagnostic reliability of ICDAS-II visual criteria, light-induced fluorescence (using the VistaCam iX, Dürr Dental, Bietigheim-Bissingen, Germany), and laser-induced fluorescence (using the DIAGNOdent Pen, KaVo, Biberach, Germany) on occlusal caries. Permanent and temporary molars were selected according to the inclusion criteria. Out of 160 teeth that met the inclusion criteria, 139 were chosen and examined by two previously trained and calibrated examiners. The kappa value was 0.95 for both VistaCam iX and DIAGNOdent Pen. Results from visual examination and the readings of the two fluorescence devices were computed, lesions being divided into non-cavitated, enamel lesions, and lesions extended to dentin. All statistical analyses were performed using R (version 4.2.2). Spearman's rank correlation was computed to assess the relationship between the scores of diagnostics reliabilities of the three methods mentioned above. There was a positive, statistically significant Spearman's rank correlation coefficient, ρ = 0.25, between VistaCam iX and ICDAS II, and a positive, not statistically significant Spearman's rank correlation coefficient, ρ = 0.11, between DiagnoDent Pen and ICDAS II. Considering the temporary teeth, there was a positive, statistically significant Spearman's rank correlation coefficient, ρ = 0.52, between VistaCam iX and DiagnoDent Pen; a positive, statistically significant Spearman's rank correlation coefficient, ρ = 0.35, between VistaCam iX and ICDAS II; and the lowest, not statistically significant Spearman's rank correlation coefficient, ρ = 0.16, between DiagnoDent Pen and ICDAS II. Conclusions: In conclusion, ICDAS II and light-induced fluorescence are better diagnostic methods than the laser-induced fluorescence devices for detecting occlusal caries. Clinical Significance: This study may support clinicians in selecting the most efficient tool for diagnosing carious lesion in the earliest stages possible. Furthermore, such technologies raise the availability for more preventive approaches, as opposed to invasive procedures.

Yttrium-90 ((90)Y)-microspheres administered via the hepatic artery has been used for the treatment of unresectable primary or metastatic cancer in the liver. Prior to (90)Y therapy, however, the (90)Y administered activity and the percent shunting to lungs must be determined, most commonly by gamma camera imaging of technetium-99m ((99m)Tc)-macroaggregated albumin (MAA). The purpose of the current study was to identify and evaluate an objective measure of the correlation of (90)Y and MAA activity distributions and thus assess the reliability of MAA imaging for evaluation of (90)Y administered activity and tumor and liver radiation doses. The MAA study consisted of two acquisitions. After administration of 185 MBq of MAA, a partial-body or so-called breakthrough scan was performed in order to determine the percent shunting to lungs. Immediately after a breakthrough scan, a combined single-photon emission computed tomography (SPECT)/transmission computed tomography (CT) scanner was used to image MAA distribution in order to derived the prescribed (90)Y administered activity based on tumor and liver dosimetry. (90)Y SPECT/CT was performed 2-4 weeks later and activities used were in the range of 777-2,442 MBq. In order to compare (90)Y and MAA SPECT images, first the respective CT image sets were registered using a transform based on normalized mutual information. The transform thus derived was used to align the 90Y and MAA SPECT image sets, and the Spearman's (rho) rank correlation as well as image distance (L2-norm) between the registered SPECT images were then calculated. The Spearman's rank correlation values ranged from 0.451 to 0.818 and the L2 distances from 0.626 to 2.889. Based on visual inspection, the registration of the (90)Y and MAA SPECT images appeared reasonably accurate. The regression coefficient (r) between visual scoring and the Spearman's rank correlation was 0.65 and between visual scoring and L2 distance 0.61. The Spearman's rank correlation thus appears to be more reliable than the image distance for assessing the correlation of the (90)Y and MAA images.

9116 Background: Although there are many perceptual voice evaluation scales available but to date there is no scale available for speech evaluation in HNC patients. The aim of this study was to develop and validate first ever speech-specific scale for perceptual evaluation of speech in HNC patients. Methods: Based on an extensive literature review and discussion in a multidisciplinary setting 5 speech parameters (intelligibility, articulation, speech rate, nasality and asthenia) and overall grade of speech impairment were selected and evaluated for the development and validation of this scale. Speech samples of 117 subjects (65 HNC patients and 52 age and sex matched healthy volunteers) were recorded using a standard protocol consisting reciting specific words and a standard text passage. All samples were independently judged and rated by 3 experienced raters (speech and language therapists) and were re-rated 12 weeks apart for establishing test-retest reliability. Internal consistency, test-retest reliability and Inter-rater reliability of different parameters of this scale and overall grade were determined using Cronbach's alpha and Spearman's rank correlation coefficients. Construct validity was tested using Spearman's rank correlation coefficient. Group validity was tested by Mann-Whitney U-test. Results: The Cronbach's alpha coefficients for internal consistency ranged from 0.87-0.90 for connected speech and 0.79-0.84 for words. The Spearman's correlation coefficients for test-retest reliability of these parameters for connected speech varied between 0.38-0.87 while for words the values ranged between 0.50-0.71. These values for inter-rater reliability of connected speech were between 0.55-0.99, while for words they ranged between 0.40-0.57. For construct validity, the Spearman's correlation coefficient between overall grade of connected speech and overall speech question of SHI, Speech domain of SHI and speech question of UWQOL ranged between 0.35- 0.55. Conclusions: GAAIN-R scale is a valid and reliable tool for speech evaluation in HNC patients. This scale may be used in other groups of patients' as well especially those with neurological diseases. No significant financial relationships to disclose.

A sunflower testing network that included 25 commercial hybrids and 26 sites in Serbia was analyzed by the sites regression biplot based on grain yield data in 2006 and 2007. The scientific aims of our study were to determine the representativeness and discriminating ability of the test sites and to identify good test sites for selecting generally and specifically adapted sunflower hybrids. Correlations among test sites, revealed by biplot and with Spearman's nonparametric rank correlation coefficients for each pair of test sites, were compared. Discriminating but nonrepresentative test sites in our study were represented by Aleksa Santic (18.8 degrees C average temperature, 72.0 mm precipitation, and 269.2 h of sunshine) and Rimski Sancevi (18.4 degrees C average temperature, 79.2 mm precipitation, and 252.1 h of sunshine), based on a biplot analysis of the 2006 testing network. Sombor (20.1 degrees C average temperature, 52.5 mm precipitation, and 304.7 h of sunshine) was also a discriminating but nonrepresentative test site, based on a biplot analysis of the 2007 testing network. A test site that was both discriminating and representative was Kikinda (20.2 degrees C average temperature, 63.3 mm precipitation, and 313.7 h of sunshine), based on a 2007 biplot analysis. Sombor and Kikinda could be suitable test sites for selecting specifically and generally adapted hybrids of sunflower, respectively, for dry and hot areas and seasons, since 2007 had less precipitation and a higher mean temperature in comparison to 2006. The presence of close association between test sites Rimski Sancevi and Kikinda, based on the 2006, 2007, and combined data, and on biplot and Spearman's correlations, suggested that the same information about the genotypes could be obtained from either of these 2 test sites, and consequently testing costs could be reduced. The relationships among test sites revealed by biplot did not always coincide with Spearman's rank correlation coefficients for site pairs.

AB1149 A Simple Assessment of Psychological Distress in Rheumatoid Arthritis Patients Using Multidimensional Health Assessment Questionnaire (MDHAQ): A Validation Study of Psychological MDHAQ

Bedriddenness Rank (BR) and Cognitive Function Score (CFS), issued by the Ministry of Health, Labour and Welfare, Japan, are easy-to-use and widely used in the medical and long-term care insurance systems in Japan. This study aims to clarify the criterion-related validity of the CFS with the Mini-Mental State Examination (MMSE) and ABC Dementia Scale (ABC-DS), and to re-evaluate the criterion-related validity of BR with the Barthel Index (BI) or Katz Index (KI) in more appropriate settings and a larger population compared with the previous study. A single-center prospective observational study was conducted in an acute care hospital in a suburban city in Japan. All inpatients aged 20 years or older admitted from October 1, 2018 to September 30, 2019. The relationship between BR and the BI and KI, and the relationship between CFS and the MMSE and ABC-DS were analyzed using Spearman's correlation coefficients. We enrolled 3,003 patients. Of these, 1,664 (56%) patients exhibited normal BR. The median (interquartile range) values of the BI and KI were 100 (65-100) and 6 (2-6), respectively. Spearman's rank correlation coefficients between BR and the BI and KI were -0.891 (p < 0.001) and -0.877 (p < 0.001), respectively. Of the patients, 1,967 (65.5%) showed normal CFS. The median (interquartile range) MMSE of 951 patients with abnormal CFS and ABC-DS of all patients were 15 (2-21) and 117 (102-117), respectively. Spearman's rank correlation coefficients between CFS and MMSE and ABC-DS were -0.546 (p < 0.001) and -0.862 (p < 0.001), respectively. BR and CFS showed significant criterion-related validity with well-established but complicated objective scales for assessing activities of daily living and cognitive functions, respectively. These two scales, which are easy to assess, are reliable and useful in busy clinical practice or large-scale screening settings.

Aim. The question of the identity or difference of both the matrices of characteristics of different accessions and the matrices of their correlation coefficients and path coefficients is important. We carried out a comparative analysis of correlation matrices and matrices of path coefficients between productivity and its components for pea varieties bred by the Institute of Plant Production na V.Ya. Yuryev National Academy of Sciences (Ukraine) in 2002-2018.
 Materials and methods. The field trials were carried out in the years 2014-2016 in the scientific crop rotation of the Institute of Plant Production na V.Ya. Yuryev (PPI) in the Kharkiv region. 14 varieties of peas own breeding of PPI and included in the State Register of Plant Varieties which are suitable for distribution in the Ukraine were used as research material.
 The path correlation coefficients were calculated in accordance with the description of Dewey and Lu. The Spearman's rank coefficient sensu Rao G. Nageswara was used for the assessment of the series identity of both genotypic and path coefficients. The table of critical values of Spearman's coefficient was used for the assessment of significance.
 Result and discussion. Highly reliable genotypic correlation coefficients with strong association were recorded for the trait "number of seeds per plant": 10 out of 14 varieties. To determine the consistency of the correlation matrix for the researched varieties, Spearman's correlation coefficient was calculated. Reliable values of Spearman's coefficients were found for 66 pairs of comparisons out of a total of 182. All the Spearman's correlation coefficients for the matrix of varieties in Hajduk were low and not significant.
 There was no unidirectional influence of any trait on productivity in the analysis of direct and indirect effect indicators for the varieties in the sample. Only the trait "number of seeds per plant" had the highest positive values of direct effect. In other cases, differences in the productivity of the varieties studied are confirmed by both positive and negative high values of direct effects.
 Spearman's correlation coefficients, calculated to determine agreement between path coefficient correlation matrices for varieties in the sample, were significant in only 16 pairwise comparisons (for direct and indirect effects) of the total calculated. Spearman's correlation coefficients for direct effects ranged from rs = 0.92 to rs = -0.78 and for indirect effects from rs = 0.82 to rs = -0.70 in pairwise comparisons.
 Thus, differences in the strength and direction of the relationships between the characteristic matrices of the samples can be assessed using Spearman's correlation coefficient.
 The differences in the characteristics determining the direct effects between our results and those of the cited publications can be explained both by the different genetic nature of the research objects and by the influence of meteorological conditions during the growth period and plant cultivation technologies. Note that most researchers tend to correlate morphological traits in aggregated samples. This leads to a generalised description of the relationship without the need for individualisation.
 Conclusions. Correlation coefficients, path analysis and Spearman's rank correlation coefficients allow determination not only of the general trend of interaction between traits in the population, but also of the significance of differences between genotypes.

Computing the nonnull asymptotic variance and the asymptotic relative efficiency of Spearman's rank correlation

Coexistence of species requires equalizing mechanisms that minimize fitness differences, which are balanced by stabilizing mechanisms that enhance negative intraspecific interactions versus interspecific ones. Here, we develop a simple theoretical framework that allows measuring the relative strength of intraspecific versus interspecific competition in dominance hierarchies. We use it to evaluate mechanisms promoting coexistence between two congeneric charr that compete for foraging positions, which strongly influence density-dependent growth and survival. Agonistic interactions (n=761) among 71 Dolly Varden Salvelinus malma and whitespotted charr Salvelinus leucomaenis were measured by snorkelling in two pools in the sympatric zone of a Hokkaido stream during two summers. Interspecific dominance hierarchies, analysed using three methods, were closely correlated with fish length but the species treated each other equally. Ranks for the most dominant fish in each pool, determined directly by knockout experiments, were also virtually identical to ranks by length. Similarly, exponential random graph modelling of the social networks provided no evidence that either species was dominant over the other. Instead, larger fish were more likely to win contests, especially over fish of the next lower ranks. These results demonstrated that the two species were nearly ecological equivalents in accessing key resources in this sympatric zone. Nearly identical growth and stable densities over 4years further supported this inference, although Dolly Varden were a minority (29% of the assemblage), a sign of some fitness difference. Detailed foraging observations coupled with two concurrent studies revealed an effective stabilizing mechanism. Dolly Varden shifted to feeding directly from the benthos when drifting invertebrates declined, a behaviour enhanced by morphological character displacement, thereby partitioning food resources and enhancing intraspecific competition while avoiding agonistic encounters with whitespotted charr. The plurality of evidence indicates that fitness differences between these ecologically equivalent species are small in this local assemblage, and balanced by resource partitioning, a modest stabilizing mechanism that promotes coexistence. The theoretical framework presented here is a useful tool to evaluate the strength of interspecific versus intraspecific competition, which combined with information on trade-offs in ecological performance can contribute to a mechanistic understanding of species coexistence.

[Background]: Maintenance of cerebral blood flow during cardiopulmonary resuscitation (CPR) is a critical factor affecting the neurological outcome of patients after cardiac arrest. However, dynamic indicator of cerebral blood flow during CPR is not established. Near infrared spectroscopy (NIRS) is a non-invasive technique capable of detecting changes in cerebral blood volume continuously. The aim of this study is to compare cerebral perfusion during CPR obtained by continuous measure of carotid blow flow (CBF) using flow sensor with continuous cerebral perfusion indices (CPI) assessment by NIRS in a porcine model of ventricular fibrillation (VF) cardiac arrest. [Methods]: CBF during CPR were measured in 21 swine (25± 3 kg) using extra-vascular flow probes positioned around the common carotid arteries. The optodes of the NIRS were attached to the skull bone. Following baseline measurements, VF was electrically induced. After the interval of untreated VF, CPR was continued for 25 min, during which mechanical and manual CPR was alternated at every 5 min intervals. CBF and CPI were measured continuously during CPR. The mean volume of CBF and CPI was calculated average 10 beats in each phase. Correlations between CBF volume and CPI were analyzed by Spearman's rank correlation. [Results]: The followability of CBF and CPI during CPR was good. The Spearman's rank correlation coefficient between CBF volume and CPI was different by sections and it was suggested that the CBF volume was too small to assess the correlation in many sections. If the sections with CBF volume>0.4 ml were extracted and reanalyzed, the rate of sections correlated between CBF volume and CPI were increased (Spearman’s correlation coefficient≧0.4 was 41.3%, Spearman’s correlation coefficient≧0.7 was 17.5%).(Table) [Conclusions]: It was suggested that CPI by NIRS can reflect the CBF during CPR in the sections where enough CBF is.

Variability in the correlation between nicotine and PM2.5 as airborne markers of second-hand smoke exposure

Neuroradiology diagnostic errors at a tertiary academic centre: effect of participation in tumour boards and physician experience

To collect preliminary functional data on ataxia telangiectasia and create a disease specific scale: the Ataxia Telangiectasia Functional Scale (ATFS). Retrospective information on patients with ataxia telangiectasia referred to the Assistive Technology Unit was included. Functional mobility scales (the Gross Motor Function Classification System [GMFCS] and the Functional Mobility Scale [FMS]-5, FMS-50, FMS-500) and activities of daily living [ADL] parameters were recorded. We created a 51-point ATFS, that consisted of three ambulation items adapted for ataxia telangiectasia in the frame of FMS (home, school, outdoors), five ADL items, and one schooling item. Twenty-seven participants (17 males, 10 females; mean age 10y 8mo [SD 5y 1mo], range 1y 9mo-25y 6mo), were enrolled; 168 measurements were recorded. Patients walked at a mean age of 1year 4months (SD 5y 4mo) and lost ambulatory capacity at 8years 8months (SD 2y 1mo). GMFCS level and FMS-5, FMS-50, FMS-500 assessments correlated with age (Spearman's correlations r=0.555, -0.617, -0.639, -0.662 respectively, p<0.01 for all), but plateaued after 12years of age. ATFS mean score was 37.46 (SD 7.88) and increased with age (Spearman's correlation r=0.585, p<0.01). The scale showed threestages of disease progression. In this pilot study we show longitudinal functional data of ambulation and ADL skills in ataxia telangiectasia, and created a framework for a functional scale. This functional scale closely approximated disease course, but further validation is required. The Gross Motor Function Classification System and the Functional Mobility Scale are ill-suited for ataxia telangiectasia assessments. Three functional mobility scales (home, school, outdoors) suited to ataxia telangiectasiawere created. The Ataxia Telangiectasia Functional Scale (ATFS) combines mobility and items of activities of daily living. The ATFS closely approximates the three-stage progression of the disorder.

Comparison of Magnetic Resonance Imaging Versus Doppler Echocardiography for the Evaluation of Left Ventricular Diastolic Function in Patients With Cardiac Amyloidosis