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A procedure to detect general association based on concentration of ranks.

ABSTRACT: In modern high-throughput applications, it is important to identify pairwise associations between variables, and desirable to use methods that are powerful and sensitive to a variety of association relationships. We describe RankCover, a new non-parametric association test of association between two variables that measures the concentration of paired ranked points. Here 'concentration' is quantified using a disk-covering statistic similar to those employed in spatial data analysis. Considerations from the theory of Boolean coverage processes provide motivation, as well as an R²-like quantity to summarize strength of association. Analysis of simulated and real datasets demonstrate that the method is robust and often powerful in comparison to competing general association tests.

SUBMITTER: Rudra P

PROVIDER: S-EPMC5616165 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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A procedure to detect general association based on concentration of ranks.

Rudra Pratyaydipta P Zhou Yihui Y Wright Fred A FA

Stat (International Statistical Institute) 20170216 1

In modern high-throughput applications, it is important to identify pairwise associations between variables, and desirable to use methods that are powerful and sensitive to a variety of association relationships. We describe RankCover, a new non-parametric association test of association between two variables that measures the concentration of paired ranked points. Here 'concentration' is quantified using a disk-covering statistic similar to those employed in spatial data analysis. Consideration ...[more]

PMID: 28966789

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Project description:ImportanceSeveral lines of evidence support low plasma transthyretin concentration as an in vivo biomarker of transthyretin tetramer instability, a prerequisite for the development of both wild-type transthyretin cardiac amyloidosis (ATTRwt) and hereditary transthyretin cardiac amyloidosis (ATTRm). Both ATTRm and ATTRwt cardiac amyloidosis may manifest as heart failure (HF). However, whether low plasma transthyretin concentration confers increased risk of incident HF in the general population is unknown.ObjectiveTo evaluate whether low plasma transthyretin concentration is associated with incident HF in the general population.Design, setting, and participantsThis study included data from 2 similar prospective cohort studies of the Danish general population, the Copenhagen General Population Study (CGPS; n = 9582) and the Copenhagen City Heart Study (CCHS; n = 7385). Using these data, first, whether low concentration of plasma transthyretin was associated with increased risk of incident HF was tested. Second, whether genetic variants in TTR associated with increasing tetramer instability were associated with lower transthyretin concentration and with higher risk of HF was tested. Data were collected from November 2003 to March 2017 in the CGPS and from November 1991 to June 1994 in the CCHS; participants from both studies were observed for survival time end points until March 2017. Data were analyzed from March to June 2019.ExposuresTransthyretin concentration at or below the 5th percentile, between the 5th and 95th percentile (reference), and greater than the 95th percentile; genetic variants in TTR.Main outcome and measureIncident HF identified using the Danish National Patient Registry.ResultsOf 9582 individuals in the CGPS, 5077 (53.0%) were women, and the median (interquartile range [IQR]) age was 56 (47-65) years. Of 7385 individuals in the CCHS, 4452 (60.3%) were women, and the median (IQR) age was 59 (46-70) years. During a median (IQR) follow-up of 12.6 (12.3-12.9) years and 21.7 (11.6-23.8) years, 441 individuals (4.6%) in the CGPS and 1122 individuals (15.2%) in the CCHS, respectively, developed HF. Baseline plasma transthyretin concentrations at or below the 5th percentile were associated with incident HF (CGPS: hazard ratio [HR], 1.6; 95% CI, 1.1-2.4; CCHS: HR, 1.4; 95% CI, 1.1-1.7). Risk of HF was highest in men with low transthyretin levels. Compared with p.T139M, a transthyretin-stabilizing variant, TTR genotype was associated with stepwise lower transthyretin concentrations for wild-type TTR (-16.5%), p.G26S (-18.1%), and heterozygotes for other variants (p.V142I, p.H110N, and p.D119N; -30.8%) (P for trend <.001). The corresponding HRs for incident HF were 1.14 (95% CI, 0.57-2.28), 1.29 (95% CI, 0.64-2.61), and 2.04 (95% CI, 0.54-7.67), respectively (P for trend = .04).Conclusions and relevanceIn this study, lower plasma and genetically determined transthyretin concentrations were associated with a higher risk of incident HF, suggesting a potential mechanistic association between low transthyretin concentration as a marker of tetramer instability and incident HF in the general population.

Project description:IntroductionSelf-review of recorded surgical procedures offers new opportunities for trainees to extend technical learning outside the operating-room. Valid tools for self-assessment are required prior to evaluating the effectiveness of video-review in enhancing technical learning. Therefore, we aimed to contribute evidence regarding the validity of intraoperative performance assessment tools for video-based self-assessment by general surgery trainees when performing laparoscopic cholecystectomies.Methods and proceduresUsing a web-based platform, general surgery trainees in a university-based residency program submitted recorded laparoscopic cholecystectomy procedures where they acted as the supervised primary surgeon. Attending surgeons measured operative performance at the time of surgery using general and procedure-specific assessment tools [Global Operative Assessment of Laparoscopic Skills (GOALS) and Operative Performance Rating System (OPRS), respectively] and entrustability level (O-SCORE). Trainees self-evaluated their performance from video-review using the same instruments. The validity of GOALS and OPRS for trainee self-assessment was investigated by testing the hypotheses that self-assessment scores correlate with (H1) expert assessment scores, (H2) O-SCORE, and (H3) procedure time and that (H4) self-assessment based on these instruments differentiates junior [postgraduate year (PGY) 1-3] and senior trainees (PGY 4-5), as well as (H5)simple [Visual Analogue Scale (VAS) ≤ 4] versus complex cases (VAS > 4). All hypotheses were based on previous literature, defined a priori, and were tested according to the COSMIN consensus on measurement properties.ResultsA total of 35 videos were submitted (45% female and 45% senior trainees) and self-assessed. Our data supported 2 out of 5 hypotheses (H1 and H4) for GOALS and 3 out of 5 hypotheses (H1, H4 and H5) for OPRS, for trainee self-assessment.ConclusionsOPRS, a procedure-specific assessment tool, was better able to differentiate between groups expected to have different levels of intraoperative performance, compared to GOALS, a general assessment tool. Given the interest in video-based learning, there is a need to further develop valid procedure-specific tools to support video-based self-assessment by trainees in a range of procedures.

Dataset Information

A procedure to detect general association based on concentration of ranks.

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A procedure to detect general association based on concentration of ranks.

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