Tag: statistics

Br J Math Stat Psychol. 2021 Feb 25. doi: 10.1111/bmsp.12238. Online ahead of print.

ABSTRACT

Principal covariate regression (PCOVR) is a method for regressing a set of criterion variables with respect to a set of predictor variables when the latter are many in number and/or collinear. This is done by extracting a limited number of components that simultaneously synthesize the predictor variables and predict the criterion ones. So far, no procedure has been offered for estimating statistical uncertainties of the obtained PCOVR parameter estimates. The present paper shows how this goal can be achieved, conditionally on the model specification, by means of the bootstrap approach. Four strategies for estimating bootstrap confidence intervals are derived and their statistical behaviour in terms of coverage is assessed by means of a simulation experiment. Such strategies are distinguished by the use of the varimax and quartimin procedures and by the use of Procrustes rotations of bootstrap solutions towards the sample solution. In general, the four strategies showed appropriate statistical behaviour, with coverage tending to the desired level for increasing sample sizes. The main exception involved strategies based on the quartimin procedure in cases characterized by complex underlying structures of the components. The appropriateness of the statistical behaviour was higher when the proper number of components were extracted.

PMID:33629738 | DOI:10.1111/bmsp.12238

Biom J. 2021 Feb 25. doi: 10.1002/bimj.202000227. Online ahead of print.

ABSTRACT

Shrinkage estimation in a meta-analysis framework may be used to facilitate dynamical borrowing of information. This framework might be used to analyze a new study in the light of previous data, which might differ in their design (e.g., a randomized controlled trial and a clinical registry). We show how the common study weights arise in effect and shrinkage estimation, and how these may be generalized to the case of Bayesian meta-analysis. Next we develop simple ways to compute bounds on the weights, so that the contribution of the external evidence may be assessed a priori. These considerations are illustrated and discussed using numerical examples, including applications in the treatment of Creutzfeldt-Jakob disease and in fetal monitoring to prevent the occurrence of metabolic acidosis. The target study’s contribution to the resulting estimate is shown to be bounded below. Therefore, concerns of evidence being easily overwhelmed by external data are largely unwarranted.

PMID:33629749 | DOI:10.1002/bimj.202000227

J Magn Reson Imaging. 2021 Feb 25. doi: 10.1002/jmri.27578. Online ahead of print.

ABSTRACT

BACKGROUND: Although contrast agents would be beneficial, they are seldom used in four-dimensional (4D) flow magnetic resonance imaging (MRI) due to potential side effects and contraindications.

PURPOSE: To develop and evaluate a deep learning architecture to generate high blood-tissue contrast in noncontrast 4D flow MRI by emulating the use of an external contrast agent.

STUDY TYPE: Retrospective.

SUBJECTS: Of 222 data sets, 141 were used for neural network (NN) training (69 with and 72 without contrast agent). Evaluation was performed on the remaining 81 noncontrast data sets.

FIELD STRENGTH/SEQUENCES: Gradient echo or echo-planar 4D flow MRI at 1.5 T and 3 T.

ASSESSMENT: A cyclic generative adversarial NN was trained to perform image translation between noncontrast and contrast data. Evaluation was performed quantitatively using contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), structural similarity index (SSIM), mean squared error (MSE) of edges, and Dice coefficient of segmentations. Three observers performed a qualitative assessment of blood-tissue contrast, noise, presence of artifacts, and image structure visualization.

STATISTICAL TESTS: The Wilcoxon rank-sum test evaluated statistical significance. Kendall’s concordance coefficient assessed interobserver agreement.

RESULTS: Contrast in the regions of interest (ROIs) in the NN enhanced images increased by 88%, CNR increased by 63%, and SNR improved by 48% (all P < 0.001). The SSIM was 0.82 ± 0.01, and the MSE of edges was 0.09 ± 0.01 (range [0,1]). Segmentations based on the generated images resulted in a Dice similarity increase of 15.25%. The observers managed to differentiate between contrast MR images and our results; however, they preferred the NN enhanced images in 76.7% of cases. This percentage increased to 93.3% for phase-contrast MR angiograms created from the NN enhanced data. Visual grading scores were blood-tissue contrast = 4.30 ± 0.74, noise = 3.12 ± 0.98, and presence of artifacts = 3.63 ± 0.76. Image structures within and without the ROIs resulted in scores of 3.42 ± 0.59 and 3.07 ± 0.71, respectively (P < 0.001).

DATA CONCLUSION: The proposed approach improves blood-tissue contrast in MR images and could be used to improve data quality, visualization, and postprocessing of cardiovascular 4D flow data. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 1.

PMID:33629795 | DOI:10.1002/jmri.27578

Gerontol Geriatr Educ. 2021 Feb 25:1-10. doi: 10.1080/02701960.2021.1891417. Online ahead of print.

ABSTRACT

Background/Objectives: To develop and evaluate a post-acute care simulation-based mastery learning (SBML) continuing medical education (CME)/maintenance of certification (MOC) procedure course.Design: Pretest-posttest study of the SBML intervention.Setting: A 2-day post-acute care procedures course.Participants: Sixteen practicing clinicians (5 physicians,11 advanced practice providers). Participants engaged in a skills pretest on knee aspiration/injection, gastrostomy tube removal/replacement, tracheostomy tube exchange, and basic suturing using a checklist created for each procedure. Participants received a didactic on each procedure followed by deliberate practice with feedback. Using the same checklists, participants completed a skills posttest and were required to meet a minimum passing standard (MPS) to obtain CME/MOC credit.Measurements: The MPS for each skills checklist was determined by a multidisciplinary panel of 11 experts. Participants completed surveys on procedure self-confidence and a course evaluation.Results: There was statistically significant improvement between pre- and posttests for all four procedures (p < .001). All participants were able to meet or exceed the MPS for each skill during the 2-day course. Participants’ self-confidence regarding each procedure improved significantly (p < .001).Conclusion: An SBML training course granting CME/MOC credit for post-acute care providers significantly improves performance of knee aspiration/injection, gastrostomy tube removal/replacement, tracheostomy tube exchange, and basic suturing.

PMID:33629646 | DOI:10.1080/02701960.2021.1891417

Mil Med. 2021 Feb 25:usab085. doi: 10.1093/milmed/usab085. Online ahead of print.

ABSTRACT

INTRODUCTION: Weight status perception (WSP) is the subjective assessment of one’s own body weight. It is not correlated with the body mass index (BMI). People practicing sports, including overweight people, tend to perceive themselves as normal weight. The military is in a paradoxical position between the need to gain muscle mass for professional purposes while respecting BMI standards. Using body composition might be more advantageous than using BMI as part of an individual approach in making a decision about fitness to serve. However, measuring body composition is not easy in current practice, and a bridge between WSP and body composition would make it possible to develop a simple assessment tool.

MATERIALS AND METHODS: This was a prospective, descriptive, cross-sectional study. We collected sociodemographic data, anthropometric data, and WSP.

RESULTS: Thirty-eight subjects were included. Among them, 71.1% were male. Mean age was 31.2 years (SD 8.9). The BMI was greater than 25 for 15 (39.5%) subjects. Twenty-four (63.2%) defined themselves as being overweight. Thirteen were overweight according to fat percentage (Fat%). A significant association (P = .008) was found between WSP and Fat%.

CONCLUSION: We were able to show a statistically significant association between WSP and Fat%. Such an association may be of great interest because the measurement of the Fat%, whatever the method used, is not easy in current practice. A replication of the study in the general population would be of great interest, especially since Fat% is closely associated with the incidence of cardiovascular diseases and many cancers.

PMID:33629720 | DOI:10.1093/milmed/usab085

Cereb Cortex. 2021 Feb 25:bhab029. doi: 10.1093/cercor/bhab029. Online ahead of print.

ABSTRACT

The posterior superior temporal sulcus (pSTS) is a brain region characterized by perceptual representations of human body actions that promote the understanding of observed behavior. Increasingly, action observation is recognized as being strongly shaped by the expectations of the observer (Kilner 2011; Koster-Hale and Saxe 2013; Patel et al. 2019). Therefore, to characterize top-down influences on action observation, we evaluated the statistical structure of multivariate activation patterns from the action observation network (AON) while observers attended to the different dimensions of action vignettes (the action kinematics, goal, or identity of avatars jumping or crouching). Decoding accuracy varied as a function of attention instruction in the right pSTS and left inferior frontal cortex (IFC), with the right pSTS classifying actions most accurately when observers attended to the action kinematics and the left IFC classifying most accurately when observed attended to the actor’s goal. Functional connectivity also increased between the right pSTS and right IFC when observers attended to the actions portrayed in the vignettes. Our findings are evidence that the attentive state of the viewer modulates sensory representations in the pSTS, consistent with proposals that the pSTS occupies an interstitial zone mediating top-down context and bottom-up perceptual cues during action observation.

PMID:33629729 | DOI:10.1093/cercor/bhab029

Expert Rev Pharmacoecon Outcomes Res. 2021 Feb 25. doi: 10.1080/14737167.2021.1895753. Online ahead of print.

ABSTRACT

Background: Hidradenitis suppurativa (HS) is a potentially disabling, chronic inflammatory skin disease affecting up to 1% of the population in Europe. This study aims to assess the cost-of-illness of HS from a societal perspective in Hungary, and to analyse the predictors of costs.Methods: A multicentre, cross-sectional cost-of-illness study was performed among 200 adult HS patients. We evaluated direct medical (physician consultations, inpatient admissions, medical and surgeries), direct non-medical (transportation and caregiving) and indirect costs (productivity loss).Results: The mean annual cost-of-illness of HS was €6,791 per patient. The main cost components were productivity loss (53.3%), biological treatment (21.5%) and informal care (9.2%). Patients missed, on average, 26 and 63 days from work annually due to absenteeism and presenteeism, respectively. Male sex, more severe disease, gluteal involvement and coexisting inflammatory bowel disease were associated with higher direct medical costs, while lower education level and worse quality-of-life outcomes predicted higher indirect costs.Conclusions: This is the first study to assess both direct and indirect costs in HS patients. HS imposes a substantial burden on patients and society, predominantly arising from productivity loss and biological therapy. Resource utilization data and cost-of-illness estimates provide valuable inputs into cost-effectiveness analyses of health interventions in HS.

PMID:33629618 | DOI:10.1080/14737167.2021.1895753

Scand J Rheumatol. 2021 Feb 25:1-9. doi: 10.1080/03009742.2020.1846778. Online ahead of print.

ABSTRACT

Objective: The aim of the study was to assess the development of widespread non-joint pain (WNP) in a cohort of patients with early rheumatoid arthritis (RA), the associated health-related quality of life (HRQoL), and clinical and demographic risk factors for WNP.Method: Incident cases with RA, from the Swedish population-based study Epidemiological Investigation of Rheumatoid Arthritis (EIRA), with a follow-up of at least 3 years, constituted the study population. WNP was defined as pain outside the joints in all four body quadrants and was assessed at the 3 year follow-up. Patients who reported WNP were compared to patients without WNP regarding HRQoL, measured by the Short Form-36, at 3 years, and clinical and demographic characteristics at the time of RA diagnosis.Results: A total of 749 patients constituted the study sample, of whom 25 were excluded after reporting already having severe pain before RA diagnosis. At the 3 year follow-up, 8% of the patients reported having WNP as well as statistically significant worse HRQoL. At the time of RA diagnosis, the patients with WNP had worse pain and pain-related features, while no difference was seen in the inflammatory parameters.Conclusion: WNP occurs in a substantial subset of patients with RA, also early in the course of the disease, and the HRQoL for these patients is significantly reduced. Patients who develop WNP at 3 years are already distinguishable at the time of diagnosis by displaying more pronounced pain ratings together with an average level of inflammatory disease activity.

PMID:33629632 | DOI:10.1080/03009742.2020.1846778

Q J Exp Psychol (Hove). 2021 Feb 25:17470218211001547. doi: 10.1177/17470218211001547. Online ahead of print.

ABSTRACT

The application of framing effects in the field of moral judgment has offered a golden opportunity to assess the reliability of people’s moral judgments and decisions. To date, however, these studies are still scarce and they suffer from multiple methodological issues. Therefore, the present study aims to provide further insights into the reliability of moral judgments while fixing these methodological shortcomings. In the current study, we employed the classic trolley dilemma moral decision-making paradigm to determine the extent to which moral decisions are susceptible to framing effects. A total of 1040 participants were included in the study. The data revealed that choices of participants did not significantly differ between the two frames. Equivalence tests confirmed that the associated effect size was very small. Further exploratory analyses revealed an unplanned interaction between the framing effect and the target of the framing manipulation. This result became from marginally statistically significant to insignificant following different sensitivity analyses. The implications and limitations of these findings and directions for future research are discussed.

PMID:33629641 | DOI:10.1177/17470218211001547

Asia Pac J Clin Oncol. 2021 Feb 25. doi: 10.1111/ajco.13523. Online ahead of print.

ABSTRACT

AIM: Recent surgical de-escalation of the axilla in breast cancer management has led to reduced number of immediate and delayed axillary lymph node dissections (ALND) after sentinel lymph node biopsies (SLNBs). We aim to assess the postoperative impact of SLNB versus immediate and delayed ALND on arm lymphoedema and morbidity.

METHODS: A retrospective analysis from a prospectively collected institutional database was performed reviewing the rates of lymphoedema and arm morbidity in terms of shoulder restriction and patient-reported functional deficit in women undergoing axillary surgery for breast cancer between 2013 and 2018.

RESULTS: In this 776 patient cohort (564 SLNBs, 192 immediate ALNDs and 20 delayed ALNDs), at 12 months after surgery, the results are as follows: lymphoedema rate: SLNB (4.62%), immediate ALND (19.51%), delayed ALND (15.00%); axillary cording rate: SLNB (3.08%), immediate ALND (10.65%), delayed ALND (5.00%); new functional deficit: SLNB (5.58%), immediate ALND (13.66%) and delayed ALND (20%); pain SLNB (14.02%), immediate ALND (15.97%), delayed ALND (17.65%); shoulder flexion/abduction restrictions: SLNB (8.14%/5.14%), immediate ALND (16.45%/15.79%) and delayed ALND (17.65%/20.00%). ALND was associated with increased risk of developing lymphoedema, shoulder dysfunction and development of more than one morbidity. No statistically significant difference in lymphoedema and morbidity outcome was observed between immediate and delayed ALND.

CONCLUSION: Immediate and delayed ALND have comparable outcomes, but both are associated with increased postoperative arm lymphoedema and morbidity outcomes compared to SLNB alone. Preoperative appropriate selection of patients for axillary surgery treatment may improve lymphoedema outcomes in breast cancer patients.

PMID:33629541 | DOI:10.1111/ajco.13523