Revealing subgroup-specific mechanisms of change via moderated mediation: A meditation intervention example

OBJECTIVE

Effective psychosocial interventions exist for numerous mental health conditions. However, despite decades of research, limited progress has been made in clarifying the mechanisms that account for their beneficial effects. We know that many treatments work, but we know relatively little about why they work. Mechanisms of change may be obscured due to prior research collapsing across heterogeneous subgroups of patients with differing underlying mechanisms of response. Studies identifying baseline individual characteristics that predict differential response (i.e., moderation) may inform research on why (i.e., mediation) a particular subgroup has better outcomes to an intervention via tests of moderated mediation.

METHOD

In a recent randomized controlled trial comparing a 4-week meditation app with a control condition in school system employees (N = 662), we previously developed a "Personalized Advantage Index" (PAI) using baseline characteristics, which identified a subgroup of individuals who derived relatively greater benefit from meditation training. Here, we tested whether the effect of mindfulness acquisition in mediating group differences in outcome was moderated by PAI scores.

RESULTS

A significant index of moderated mediation (IMM = 1.22, 95% CI [0.30, 2.33]) revealed that the effect of mindfulness acquisition in mediating group differences in outcome was only significant among those individuals with PAI scores predicting relatively greater benefit from the meditation app.

CONCLUSIONS

Subgroups of individuals may differ meaningfully in the mechanisms that mediate their response to an intervention. Considering subgroup-specific mediators may accelerate progress on clarifying mechanisms of change underlying psychosocial interventions and may help inform which specific interventions are most beneficial for whom. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Consequences and Control of Multiscale Order/Disorder in Chiral Magnetic Textures

Transition metal intercalated transition metal dichalcogenides (TMDs) are promising platforms for next-generation spintronic devices based on their wide range of electronic and magnetic phases, which can be tuned by varying the host lattice or intercalant's identity, stoichiometry, or spatial order. Some of these compounds host a chiral magnetic phase in which the helical winding of magnetic moments propagates along a high-symmetry crystalline axis. Previous studies have demonstrated that variation in intercalant concentrations can have a dramatic effect on the formation of chiral domains and ensemble magnetic properties. However, a systematic and comprehensive study of how atomic-scale order and disorder impact these chiral magnetic textures is so far lacking. Here, we leverage a combination of imaging modes in the (scanning) transmission electron microscope (S/TEM) to directly probe (dis)order across multiple length scales and show how subtle changes in the atomic lattice can tune the mesoscale spin textures and bulk magnetic response in Cr1/3NbS2, with direct implications for the fundamental understanding and technological implementation of such compounds.

Comparative Electronic Structures of the Chiral Helimagnets Cr1/3NbS2 and Cr1/3TaS2

Magnetic materials with noncollinear spin textures are promising for spintronic applications. To realize practical devices, control over the length and energy scales of such spin textures is imperative. The chiral helimagnets Cr1/3NbS2 and Cr1/3TaS2 exhibit analogous magnetic-phase diagrams with different real-space periodicities and field dependence, positioning them as model systems for studying the relative strengths of the microscopic mechanisms giving rise to exotic spin textures. Although the electronic structure of the Nb analogue has been experimentally investigated, the Ta analogue has received far less attention. Here, we present a comprehensive suite of electronic structure studies on both Cr1/3NbS2 and Cr1/3TaS2 using angle-resolved photoemission spectroscopy and density functional theory. We show that bands in Cr1/3TaS2 are more dispersive than their counterparts in Cr1/3NbS2, resulting in markedly different Fermi wavevectors. The fact that their qualitative magnetic phase diagrams are nevertheless identical shows that hybridization between the intercalant and host lattice mediates the magnetic exchange interactions in both of these materials. We ultimately find that ferromagnetic coupling is stronger in Cr1/3TaS2, but larger spin-orbit coupling (and a stronger Dzyaloshinskii-Moriya interaction) from the heavier host lattice ultimately gives rise to shorter spin textures.

Validation of a Biomechanical Injury and Disease Assessment Platform Applying an Inertial-Based Biosensor and Axis Vector Computation

Inertial kinetics and kinematics have substantial influences on human biomechanical function. A new algorithm for Inertial Measurement Unit (IMU)-based motion tracking is presented in this work. The primary aims of this paper are to combine recent developments in improved biosensor technology with mainstream motion-tracking hardware to measure the overall performance of human movement based on joint axis-angle representations of limb rotation. This work describes an alternative approach to representing three-dimensional rotations using a normalized vector around which an identified joint angle defines the overall rotation, rather than a traditional Euler angle approach. Furthermore, IMUs allow for the direct measurement of joint angular velocities, offering the opportunity to increase the accuracy of instantaneous axis of rotation estimations. Although the axis-angle representation requires vector quotient algebra (quaternions) to define rotation, this approach may be preferred for many graphics, vision, and virtual reality software applications. The analytical method was validated with laboratory data gathered from an infant dummy leg's flexion and extension knee movements and applied to a living subject's upper limb movement. The results showed that the novel approach could reasonably handle a simple case and provide a detailed analysis of axis-angle migration. The described algorithm could play a notable role in the biomechanical analysis of human joints and offers a harbinger of IMU-based biosensors that may detect pathological patterns of joint disease and injury.

How Accurate and Consistent Are Score-Based Assessment Decisions? A Procedure Using the Linear Factor Model

When scales or tests are used to make decisions about individuals (e.g., to identify which adults should be assessed for psychiatric disorders), it is crucial that these decisions be accurate and consistent. However, it is not obvious how to assess accuracy and consistency when the scale was administered only once to a given sample and the true condition based on the latent variable is unknown. This article describes a method based on the linear factor model for evaluating the accuracy and consistency of scale-based decisions using data from a single administration of the scale. We illustrate the procedure and provide R code that investigators can use to apply the method in their own data. Finally, in a simulation study, we evaluate how the method performs when applied to discrete (vs. continuous) items, a practice that is common in published literature. The results suggest that the method is generally robust when applied to discrete items.

A novel approach to estimate moderated treatment effects and moderated mediated effects with continuous moderators

Moderation analysis is used to study under what conditions or for which subgroups of individuals a treatment effect is stronger or weaker. When a moderator variable is categorical, such as assigned sex, treatment effects can be estimated for each group resulting in a treatment effect for males and a treatment effect for females. If a moderator variable is a continuous variable, a strategy for investigating moderated treatment effects is to estimate conditional effects (i.e., simple slopes) via the pick-a-point approach. When conditional effects are estimated using the pick-a-point approach, the conditional effects are often given the interpretation of "the treatment effect for the subgroup of individuals…." However, the interpretation of these conditional effects as subgroup effects is potentially misleading because conditional effects are interpreted at a specific value of the moderator variable (e.g., +1 SD above the mean). We describe a simple solution that resolves this problem using a simulation-based approach. We describe how to apply this simulation-based approach to estimate subgroup effects by defining subgroups using a range of scores on the continuous moderator variable. We apply this method to three empirical examples to demonstrate how to estimate subgroup effects for moderated treatment and moderated mediated effects when the moderator variable is a continuous variable. Finally, we provide researchers with both SAS and R code to implement this method for similar situations described in this paper. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Bridging Structure, Magnetism, and Disorder in Iron-Intercalated Niobium Diselenide, FexNbSe2, below x = 0.25

Transition-metal dichalcogenides (TMDs) intercalated with magnetic ions serve as a promising materials platform for developing next-generation, spin-based electronic technologies. In these materials, one can access a rich magnetic phase space depending on the choice of intercalant, host lattice, and relative stoichiometry. The distribution of these intercalant ions across given crystals, however, is less well defined-particularly away from ideal packing stoichiometries-and a convenient probe to assess potential longer-range ordering of intercalants is lacking. Here, we demonstrate that confocal Raman spectroscopy is a powerful tool for mapping the onset of intercalant superlattice formation in Fe-intercalated NbSe₂ (Fe_xNbSe₂) for 0.14 ≤ x < 0.25. We use single-crystal X-ray diffraction to confirm the presence of longer-range intercalant superstructure and employ polarization-, temperature-, and magnetic field-dependent Raman measurements to examine both the symmetry of emergent phonon modes in the intercalated material and potential magnetoelastic coupling. Magnetometry measurements further indicate a correlation between the onset of magnetic ordering and the relative degree of intercalant superlattice formation. These results show Raman spectroscopy to be an expedient, local probe for mapping intercalant ordering in this class of magnetic materials.

Summary Intervals for Model-Based Classification Accuracy and Consistency Indices

When scores are used to make decisions about respondents, it is of interest to estimate classification accuracy (CA), the probability of making a correct decision, and classification consistency (CC), the probability of making the same decision across two parallel administrations of the measure. Model-based estimates of CA and CC computed from the linear factor model have been recently proposed, but parameter uncertainty of the CA and CC indices has not been investigated. This article demonstrates how to estimate percentile bootstrap confidence intervals and Bayesian credible intervals for CA and CC indices, which have the added benefit of incorporating the sampling variability of the parameters of the linear factor model to summary intervals. Results from a small simulation study suggest that percentile bootstrap confidence intervals have appropriate confidence interval coverage, although displaying a small negative bias. However, Bayesian credible intervals with diffused priors have poor interval coverage, but their coverage improves once empirical, weakly informative priors are used. The procedures are illustrated by estimating CA and CC indices from a measure used to identify individuals low on mindfulness for a hypothetical intervention, and R code is provided to facilitate the implementation of the procedures.

Analysis of microbiota-host communication mediated by butyrate in Atlantic Salmon

Butyrate is a microbiota-produced metabolite, sensed by host short-chain fatty acid receptors FFAR2 (Gpr43), FFAR3 (Gpr41), HCAR2 (Gpr109A), and Histone deacetylase (HDAC) that promotes microbiota-host crosstalk. Butyrate influences energy uptake, developmental and immune response in mammals. This microbial metabolite is produced by around 79 anaerobic genera present in the mammalian gut, yet little is known about the role of butyrate in the host-microbiota interaction in salmonid fish. To further our knowledge of this interaction, we analyzed the intestinal microbiota and genome of Atlantic salmon (Salmo salar), searching for butyrate-producing genera and host butyrate receptors. We identified Firmicutes, Proteobacteria, and Actinobacteria as the main butyrate-producing bacteria in the salmon gut microbiota. In the Atlantic salmon genome, we identified an expansion of genes orthologous to FFAR2 and HCAR2 receptors, and class I and IIa HDACs that are sensitive to butyrate. In addition, we determined the expression levels of orthologous of HCAR2 in the gut, spleen, and head-kidney, and FFAR2 in RTgutGC cells. The effect of butyrate on the Atlantic salmon immune response was evaluated by analyzing the pro and anti-inflammatory cytokines response in vitro in SHK-1 cells by RT-qPCR. Butyrate decreased the expression of the pro-inflammatory cytokine IL-1β and increased anti-inflammatory IL-10 and TGF-β cytokines. Butyrate also reduced the expression of interferon-alpha, Mx, and PKR, and decreased the viral load at a higher concentration (4 mM) in cells treated with this molecule before the infection with Infectious Pancreatic Necrosis Virus (IPNV) by mechanisms independent of FFAR2, FFAR3 and HCAR2 expression that probably inhibit HDAC. Moreover, butyrate modified phosphorylation of cytoplasmic proteins in RTgutGC cells. Our data allow us to infer that Atlantic salmon have the ability to sense butyrate produced by their gut microbiota via different specific targets, through which butyrate modulates the immune response of pro and anti-inflammatory cytokines and the antiviral response.

Virtual Group-based Walking Intervention for Persons with Schizophrenia: A Pilot Randomized Controlled Trial

Persons with schizophrenia have reduced cardiorespiratory fitness (CRF), a predictor of all-cause mortality. Exercise is effective for improving CRF; however, motivational challenges affecting those with schizophrenia impact exercise engagement and maintenance. Virtual Physical Activity Can Enhance Life (Virtual PACE-Life), a multicomponent walking intervention guided by self-determination theory (SDT), was developed to target CRF in this population while addressing motivational difficulties. Virtual PACE-Life includes live video-delivered group walking sessions, Fitbit activity tracking, recommendations for home-based walking sessions, goal setting, and if-then plans. The present study was a 16-week pilot randomized controlled trial that evaluated the impact of Virtual PACE-Life against Fitbit Alone in a sample of 37 participants with schizophrenia on intermediate targets (competence, autonomy, and relatedness satisfaction, autonomous motivation), proximal outcomes (Fitbit-measured steps/day and minutes spent walking), and the primary outcome (CRF using the 6-minute walk test). Blinded research staff completed assessments at baseline, midpoint, posttest, and one-month follow-up. Analysis of covariance and hierarchical linear regression analyses were used to evaluate group differences at each timepoint controlling for baseline. Attendance at Virtual PACE-Life groups was 58% and Fitbit adherence was above 70% in both conditions. Intent-to-treat results indicated greater competence and autonomy satisfaction for Virtual PACE-Life but not in relatedness satisfaction or autonomous motivation. There were no group differences in proximal or primary outcomes during the intervention period. Completer analyses showed improvements in steps/day and autonomous motivation favoring Virtual PACE-Life. Future research is needed to maximize the exercise and CRF benefits of virtual group-based exercise for persons with schizophrenia.

Accommodating a Latent XM Interaction in Statistical Mediation Analysis

Statistical mediation analysis is used in the social sciences and public health to uncover potential mechanisms, known as mediators, by which a treatment led to a change in an outcome. Recently, the estimation of the treatment-by-mediator interaction (i.e., the XM interaction) has been shown to play a pivotal role in understanding the equivalence between the traditional mediation effects in linear models and the causal mediation effects in the potential outcomes framework. However, there is limited guidance on how to estimate the XM interaction when the mediator is latent. In this article, we discuss eight methods to accommodate latent XM interactions in statistical mediation analysis, which fall in two categories: using structural models (e.g., latent moderated structural equations, Bayesian mediation, unconstrained product indicator method, multiple-group models) or scoring the mediator prior to estimating the XM interaction (e.g., summed scores and factor scores, with and without attenuation correction). Simulation results suggest that finite-sample bias is low, type 1 error rates and coverage of percentile bootstrap confidence intervals and Bayesian credible intervals are close to the nominal values, and statistical power is similar across approaches. The methods are demonstrated with an applied example, syntax is provided for their implementation, and general considerations are discussed.

Loss of starch synthase IIIa changes starch molecular structure and granule morphology in grains of hexaploid bread wheat

Starch synthase III plays a key role in starch biosynthesis and is highly expressed in developing wheat grains. To understand the contribution of SSIII to starch and grain properties, we developed wheat ssIIIa mutants in the elite cultivar Cadenza using in silico TILLING in a mutagenized population. SSIIIa protein was undetectable by immunoblot analysis in triple ssIIIa mutants carrying mutations in each homoeologous copy of ssIIIa (A, B and D). Loss of SSIIIa in triple mutants led to significant changes in starch phenotype including smaller A-type granules and altered granule morphology. Starch chain-length distributions of double and triple mutants indicated greater levels of amylose than sibling controls (33.8% of starch in triple mutants, and 29.3% in double mutants vs. 25.5% in sibling controls) and fewer long amylopectin chains. Wholemeal flour of triple mutants had more resistant starch (6.0% vs. 2.9% in sibling controls) and greater levels of non-starch polysaccharides; the grains appeared shrunken and weighed ~ 11% less than the sibling control which was partially explained by loss in starch content. Interestingly, our study revealed gene dosage effects which could be useful for fine-tuning starch properties in wheat breeding applications while minimizing impact on grain weight and quality.

The Effect of Noninvariance on the Estimation of the Mediated Effect in the Two-Wave Mediation Model

The two-wave mediation model is the most suitable model for examining mediation effects in a randomized intervention and includes measures taken at pretest and posttest. When using self-report measures, the meaning of responses may change for the treatment group over the course of the intervention and result in noninvariance across groups at posttest, a phenomenon referred to as response shift. We investigate how the mediated effect would be impacted by noninvariance when using sum scores (i.e., assuming invariance). In a Monte Carlo simulation study, the magnitude and proportion of items that had noninvariant intercepts, the direction of noninvariance, number of items, effect size of the mediated effect and sample size were varied. Results showed increased Type I and Type II errors due to a biased estimate of the intervention effect on the mediator resulting from noninvariance. Thus, measurement noninvariance could lead to erroneous conclusions about the process underlying the intervention.

Structure and Magnetism of Iron- and Chromium-Intercalated Niobium and Tantalum Disulfides

Transition metal dichalcogenides (TMDs) intercalated with spin-bearing transition metal centers are a diverse class of magnetic materials where the spin density and ordering behavior can be varied by the choice of host lattice, intercalant identity, level of intercalation, and intercalant disorder. Each of these degrees of freedom alters the interplay between several key magnetic interactions to produce disparate collective electronic and magnetic phases. The array of magnetic and electronic behavior typified by these systems renders them distinctive platforms for realizing tunable magnetism in solid-state materials and promising candidates for spin-based electronic devices. This Perspective provides an overview of the rich magnetism displayed by transition metal-intercalated TMDs by considering Fe- and Cr-intercalated NbS₂ and TaS₂. These four exemplars of this large family of materials exhibit a wide range of magnetic properties, including sharp switching of magnetic states, current-driven magnetic switching, and chiral spin textures. An understanding of the fundamental origins of the resultant magnetic/electronic phases in these materials is discussed in the context of composition, bonding, electronic structure, and magnetic anisotropy in each case study.

Robotic and laparoscopic Roux-en-Y gastric bypass after learning curve: 30-day and 12-month outcomes

This study compares laparoscopic RYGB (L-RYGB) and robotic RYGB (R-RYGB) performed by the same team after the learning curve in both approaches. A retrospective cohort study was done, and the surgical outcome was analyzed in 30 days and 12 months for patients with similar characteristics and an equal number of cases in each group (233 cases). Four hundred and sixty-six patients were included in this study. Mean age was 46.8 ± 8.3 years and 2/3 were women. R-RYGB presented a longer operative time (150.7 versus 135.4 min; p < 0.001) with no differences in the length of hospital stay. The main 30-day complications were G-J stricture, leakage, and intraluminal bleeding. The reoperation rate was 1.6% by leakage (G-J anastomosis) and was higher in R-RYGB (2.1 versus 0.4; p = 0.108). The multivariate analysis identified that L-RYGB was the factor independently associated with a LOS longer than 2 days (odds ratio: 4.7, 95% CI: 2.6-8.2, p value < 0.001). At the FU time (12 months), no differences between the groups were found. The outcomes between the groups after the learning curve did not present differences in terms of 30 days and 12 months of FU when same preoperative characteristics and an equal number of cases in each group are considered. L-RYGB was the unique independent factor associated with long LOS.

Psychometric and Machine Learning Approaches to Reduce the Length of Scales

Brief measures are important in psychology research because they reduce participant burden. Researchers can select items from longer measures either to build a short-form or to administer items conditional on a participant's previous responses. Researchers who carry out these item selection strategies either focus on estimating a precise score on the measure (typically carried out in a psychometric approach) or on predicting the score on the measure (possibly taking a machine learning approach). However, it is unclear how scores from the psychometric and machine learning approaches compare to each other. In this paper, the following four statistical approaches to select items are reviewed and illustrated: item response theory to build static short-forms, computerized adaptive testing, the genetic algorithm, and regression trees. Theoretical strengths and weaknesses between these four statistical approaches are discussed, and the overlap between the areas of psychometrics and machine learning is considered.

Laparoscopic Versus Robot-Assisted Roux-en-Y Gastric Bypass: A Center of Excellence for the EAC-BC Experience

Background: After the first laparoscopic Roux-en-Y gastric bypass (RYGB) in 1994 by Wittgrove, the introduction of robot-assisted procedures was the next step in the surgical race to reduce invasiveness. This breakthrough allowed us to perform bariatric surgery with less surgical trauma in obese patients with metabolic disorders, producing an exponential increase in procedures performed. Methods: This is a retrospective cohort study of a prospective database for patients who underwent RYGB during a 7-year period through two different approaches, laparoscopic and robotic. The robotic cases were performed by two generations of the da Vinci platform (S and Xi), and three groups were identified and compared (L-RYGB, RYGB-S, and RYGB-Xi). Results: A total of 495 patients underwent RYGB, of which 224 by laparoscopy (45.2%) and 271 by robotic approach (54.7%): 134 RYGB-S and 137 RYGB-Xi. The majority of the patients (71.1%) were females, with a mean age of 46.2 years and a mean body mass index of 44 kg/m2. The mean intraoperative time and intraoperative complication rate were higher in the robotic groups, especially in the RYGB-S group. Postoperative complications were higher in the same group, with a rate of 11.9%, where the main leakage occurred on the upper part of the gastric pouch and not in the hand-sewed robotic anastomosis (7.5%). General mortality was 0.6%. We found no significant differences at 1-year percentage of total weight loss (%TWL); at 2 years, the RYGB-Xi group had the lowest %TWL (25.24 ± 14.54, P ≤ .001). Conclusions: The present study reflects our experience during the robotic bariatric introduction and performance since 2011. Features of the da Vinci S platform along our learning curve may explain a higher complication rate. The patients who have been operated by the RYGB-Xi system had lower complications than the laparoscopic group. The robotic approach did not differ with laparoscopy in terms of weight loss and chronic complications after 24 months of follow-up.

A Comparison of Clinical Outcomes Between Two Different Models of Surgical Robots in Roux-en-Y Gastric Bypass

Introduction: For the past 20 years, robotic surgical systems have been used for the Roux-en-Y gastric bypass (RYGB). The da Vinci Surgical System (Intuitive Surgical, Inc.) has been one of the most used robotic platforms. This study aims to retrospectively compare the performance of two models of surgical robots. Materials and Methods: A retrospective comparative study was conducted from a prospective database including all patients who underwent robotic RYGB (RRYGB) from 2011 to 2020. Results: Of a total of 277 patients included, 134 were in the RRYGB using the da Vinci S™ (RRYGB-S™) group and 143 were in the RRYGB using the da Vinci Xi™ (RRYGB-Xi™) group. The mean operative time in the RRYGB-S and RRYGB-Xi groups was 154 ± 28 and 151 ± 32 minutes, respectively (P = .510). The was no statistically significant difference in terms of intraoperative complications between the groups with regard to positive blue test, bleeding, and failure of stapler line. The readmission rate was higher in the RRGB-S group (14.1%) than in the RRYGB-Xi group (3.4%) (P = .004), and it was mainly due to major complications (P = .003) including pouch and gastrojejunostomy anastomotic leaks (P = .001). The nonsurgical complications were statistically significantly higher in the RRYGB-S group (7.4%) than in the RRYGB-Xi group (2.1%) (P < .05), as well as the surgical complications were higher in the RRYGB-S group (7.5%) than in the RRYGB-Xi group (0%) (P < .001). The mean percentage of the total weight loss at 1 and 2 years of follow-up did not show any statistically significant difference (P = .547). Conclusions: The higher complication rate in the S surgical system might be correlated with the initial learning curve and stressed the need for proper robotic surgical training and accurate strategies when introducing emerging technologies into the surgical practice.

The Panoramic View of Revisional Bariatric Surgery

Introduction: Obesity remains a major public chronic disease, and the multifactorial components of its relapse in many patients remain inevitable. Methods: This article provides a panoramic view of the most commonly performed revisional bariatric surgery (RBS). RBS is a complex procedure; thus, primary procedures should be well chosen and performed to avoid the increasing number of RBS cases. Results: Bariatric surgery is the only successful long-term treatment for obesity. However, a proportion of primary bariatric surgeries has failed during the follow-up period. In recent decades, the solution for these complications is by performing RBS. It is mandatory to understand obesity as a chronic disease to appropriately treat patients. Treatment strategies are needed to determine the indications for revision. RBS requires a meticulous evaluation to facilitate good long-term results. Conclusions: Treatment strategies will be a fundamental pillar to wisely determine the indications for revision and identify the factors influencing failure by prudently and rationally evaluating the revisional procedure that the patient will benefit from and acquiring a high level of surgical skills.

Clarifying the Implicit Assumptions of Two-Wave Mediation Models via the Latent Change Score Specification: An Evaluation of Model Fit Indices

Statistical mediation analysis is used to investigate mechanisms through which a randomized intervention causally affects an outcome variable. Mediation analysis is often carried out in a pretest-posttest control group design because it is a common choice for evaluating experimental manipulations in the behavioral and social sciences. There are four different two-wave (i.e., pretest-posttest) mediation models that can be estimated using either linear regression or a Latent Change Score (LCS) specification in Structural Equation Modeling: Analysis of Covariance, difference and residualized change scores, and a cross-sectional model. Linear regression modeling and the LCS specification of the two-wave mediation models provide identical mediated effect estimates but the two modeling approaches differ in their assumptions of model fit. Linear regression modeling assumes each of the four two-wave mediation models fit the data perfectly whereas the LCS specification allows researchers to evaluate the model constraints implied by the difference score, residualized change score, and cross-sectional models via model fit indices. Therefore, the purpose of this paper is to provide a conceptual and statistical comparison of two-wave mediation models. Models were compared on the assumptions they make about time-lags and cross-lagged effects as well as statistically using both standard measures of model fit (χ2, RMSEA, and CFI) and newly proposed T-size measures of model fit for the two-wave mediation models. Overall, the LCS specification makes clear the assumptions that are often implicitly made when fitting two-wave mediation models with regression. In a Monte Carlo simulation, the standard model fit indices and newly proposed T-size measures of model fit generally correctly identified the best fitting two-wave mediation model.

Estimating classification consistency of screening measures and quantifying the impact of measurement bias

Screening measures are used in psychology and medicine to identify respondents who are high or low on a construct. Based on the screening, the evaluator assigns respondents to classes corresponding to different courses of action: Make a diagnosis versus reject a diagnosis; provide services versus withhold services; or conduct further assessment versus conclude the assessment process. When measures are used to classify individuals, it is important that the decisions be consistent and equitable across groups. Ideally, if respondents completed the screening measure repeatedly in quick succession, they would be consistently assigned into the same class each time. In addition, the consistency of the classification should be unrelated to the respondents' background characteristics, such as sex, race, or ethnicity (i.e., the measure is free of measurement bias). Reporting estimates of classification consistency is a common practice in educational testing, but there has been limited application of these estimates to screening in psychology and medicine. In this article, we present two procedures based on item response theory that are used (a) to estimate the classification consistency of a screening measure and (b) to evaluate how classification consistency is impacted by measurement bias across respondent groups. We provide R functions to conduct the procedures, illustrate the procedures with real data, and use Monte Carlo simulations to guide their appropriate use. Finally, we discuss how estimates of classification consistency can help assessment specialists make more informed decisions on the use of a screening measure with protected groups (e.g., groups defined by gender, race, or ethnicity). (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Robotic Revisional Experience. Single Centre Prospective Cohort Study and Review of the Literature

Background: Robotic bariatric surgery (RBS) has increased in recent years. Many doubts continue to exist regarding its utility in terms of postoperative complications, costs and technical aspects. RBS has increased its number and shows a more technical challenge associated with more post-operative complications compared to primary bariatric surgery. We herein present a single institution experience and review to describe its utility in revisional surgery. Methods: A retrospective review of our experience and a review of the literature has been conducted to evaluate the impact of robotic revisional surgery in the bariatric field. Results: A total of 17 patients (5 female and 12 male) were operated on. Most frequent surgery was conversion of sleeve gastrectomy to gastric bypass (n=9). No leaks were found nor severe complications. A systematic review showed similar results including a decreased number for complications when performing robotic revisional surgery. Conclusions: Revisional robotic surgery shows better results compared to standard laparoscopic revisional bariatric surgery in terms of efficacy, safety and hospital stay. No differences were seen in rates of mortality, morbidity and reintervention between both approaches. We encourage surgeons to learn to perform the robotic technique as part of the process of democratization and standardization of bariatric surgery.

Development of the Elective Outpatient Percutaneous Coronary Intervention Episode-Based Cost Measure

BACKGROUND

The Merit-Based Incentive Payment System adjusts clinician payments based on a performance score that includes cost measures. With the Centers for Medicare & Medicaid Services, we developed a novel cost measure that compared interventional cardiologists on a targeted set of costs related to elective percutaneous coronary intervention (PCI). We describe the measure and compare it to a hypothetical version including all expenditures post-PCI.

METHODS

Measure development was guided by 39 clinician experts. They identified services within 30 days of PCI that could be potentially affected by the interventional cardiologist. Expenditures for these PCI-related services were included as measure costs in a process termed service assignment. We used 1 year of Medicare claims to calculate clinician scores using the final measure that included only PCI-related costs (with service assignment) and a hypothetical version that included all costs post-PCI (without service assignment). We calculated reliability for both measures. This marker of precision breaks measure variance into signal (difference between clinicians) versus noise (difference between PCI episodes for a clinician). We also determined the change in clinician performance quintile between measures.

RESULTS

We identified 100 992 elective outpatient PCI episodes from May 2, 2016, to May 1, 2017. Total Medicare expenditures within 30 days of PCI averaged $13 234. After excluding costs unrelated to PCI, average cost was $10 966. For individual clinicians, mean reliability for the hypothetical measure without service assignment was 0.36. After service assignment, final measure reliability increased to 0.53. When evaluated as clinician groups, reliability increased from 0.43 to 0.73 following service assignment. Approximately 66% (2340 of 3527) of clinicians were reclassified into a different performance quintile after excluding unrelated costs.

CONCLUSIONS

The elective outpatient PCI cost measure had increased precision and reclassified clinician performance relative to a hypothetical version that included total expenditures.

Targeting Physical Health in Schizophrenia: Results from the Physical Activity Can Enhance Life (PACE-Life) 24-Week Open Trial

Poor health and low cardiorespiratory fitness (CRF) contribute substantially to the shortened lifespan of individuals with schizophrenia spectrum disorders (SSDs). Increasing physical activity has demonstrated value; however, there are limited interventions that are accessible and adequately address motivational challenges. This paper reports on an open trial of Physical Activity Can Enhance Life (PACE-Life), a motivational theory-based manualized multicomponent walking intervention. The primary aim was to examine the feasibility of implementing PACE-Life through meeting the recruitment target (n=14), attendance and adherence rates, and participant feedback. The secondary aim was to assess the impact of PACE-Life on intermediate targets (autonomous motivation and satisfaction of autonomy, relatedness, and competence needs), proximal outcomes (Fitbit steps/day and minutes spent walking), the primary outcome (CRF), and secondary outcomes (loneliness, symptoms, resting heart rate, blood pressure, weight, body mass index, and hip and waist circumference). Seventeen participants with SSDs enrolled in a 24-week open trial. Assessments occurred at baseline, midpoint, post-test, and one-month follow-up. The recruitment target was exceeded, the group attendance rate was 34%, Fitbit adherence rate was 54%, and participant feedback indicated satisfaction with the intervention as well as a positive group environment. There was a large improvement in the primary outcome of CRF with 77% of participants achieving clinically significant improvement at post-test. Small and medium effect size increases were observed in autonomous motivation and satisfaction of autonomy, relatedness, and competence needs. Fitbit data and secondary outcomes generally remained unchanged or worsened during the intervention. Results from this open trial indicate that PACE-Life leads to meaningful changes in CRF among people with SSDs.

The measurement of the mediator and its influence on statistical mediation conclusions

In psychology, the causal process between 2 variables can be studied with statistical mediation analysis. To make a causal interpretation about the relation between variables, researchers who use the statistical mediation model make many assumptions about the variables in the model, among which are measurement assumptions about the mediator. For example, researchers often assume that the measure of the mediator yields scores that are reliable and that have a valid interpretation. In this article, we address how several measurement challenges affect the conclusions of statistical mediation analysis, and how researchers can use different psychometric models to study theoretically different causal processes. We use simulated data sets to illustrate how 10 well-fitting and theoretically sound statistical mediation models could significantly detect the indirect effect or miss it entirely depending on how the mediator is represented in the model. In the example, power to detect the indirect effect varied by the amount of true mediator variance that the psychometric model of the mediator was able to isolate. Different strategies to incorporate psychometric methods into mediation research are discussed and future directions are considered. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Extrinsic Convergent Validity Evidence to Prevent Jingle and Jangle Fallacies

In psychology, there have been vast creative efforts in proposing new constructs and developing measures to assess them. Less effort has been spent in investigating construct overlap to prevent bifurcated literatures, wasted research efforts, and jingle-jangle fallacies. For example, researchers could gather validity evidence to evaluate if two measures with the same label actually assess different constructs (jingle fallacy), or if two measures with different labels actually assess the same construct (jangle fallacy). In this paper, we discuss the concept of extrinsic convergent validity, a source of validity evidence demonstrated when two measures of the same construct, or two measures of seemingly different constructs, have comparable correlations with external criteria. We introduce a formal approach to obtain extrinsic convergent validity evidence using tests of dependent correlations and evaluate the tests using Monte Carlo simulations. Also, we illustrate the methods by examining the overlap between the self-control and grit constructs, and the overlap among seven seemingly different measures of the connectedness to nature construct. Finally, we discuss how extrinsic convergent validity evidence supplements other sources of evidence that support validity arguments of construct overlap.

Reversal to Normal Anatomy (With Sleeve Gastrectomy) for Severe Hypoglycemia

Background. Laparoscopic Roux-en-Y gastric bypass (GBP) is an essential bariatric surgical procedure which is globally performed because of the associated effective weight loss and resolution of metabolic comorbidities, such as diabetes and dyslipidemia. Although some complications may occur, hypoglycemia is a rare complication, which can lead to lethal consequences. We aimed to describe the technical aspects and surgical results after reversal to normal anatomy (RNA). Methods. We conducted a retrospective data analysis including 16 patients who underwent laparoscopic RNA from 2011 to 2018. All data were archived in a prospective database. Previous bariatric surgery and postoperative outcomes were analyzed. Results. Sixteen patients underwent RNA, most of them after GBP, and 15 patients required sleeve gastrectomy. Among them, 80% were women; 5 patients presented with postoperative complications, such as colitis with intra-abdominal collection (n = 1), gastric leak (n = 2) treated with an endoprosthesis, mesenteric venous thrombosis (n = 1), and intra-abdominal bleeding (n = 1). Mean length of hospital stay was 5.93 (3-30). All patients recovered from their initial condition although 3 patients presented with mild hypoglycemia during follow-up. Seven patients regained weight (43.75%), and another 4 developed gastroesophageal reflux disease (25%). Conclusions. These laparoscopic RNA results are acceptable, indicating a clinical improvement in the hypoglycemic syndrome in all patients.

Effects of COVID-19 lockdown on a bariatric surgery waiting list cohort and its influence in surgical risk perception

Purpose

The COVID-19 outbreak has forced a 2-month lockdown (LD) in Spain. We aimed to assess how that had affected our cohort of bariatric patients waiting for surgery.

Methods

A review of electronic records and a structured phone interview with each patient were conducted. Changes in severity of obesity were analyzed using the Obesity Surgery Score (OSS) and changes in health-related quality of life (HRQoL) using the validated EQ-5D questionnaire. Other miscellaneous questions about behavior modifications and surgical risk perception were also analyzed.

Results

All 51 patients fully answered the questionnaires. Mean age was 47 years and mean time on waiting list 91 days. Mean BMI increased during LD (42.7 vs 43.2; p < 0.001). Both OSS (2.84 vs 3; p = 0.011) and EQ-5D (69 vs 64; p < 0.001) mildly worsened during LD, mainly due to psychosocial issues. Twenty-seven patients (53%) thought that perioperative risks were higher under the current circumstances but they were as willing to undergo surgery as those who believed that the risks had not increased (74% vs 87%, p = 0.2).

Conclusions

COVID-19 LD had a significant but mild effect on our cohort of bariatric surgery waiting list patients. Although perioperative risk perception had increased, patients were still willing to undergo their planned surgeries.

The Correspondence Between Causal and Traditional Mediation Analysis: the Link Is the Mediator by Treatment Interaction

Mediation analysis is a methodology used to understand how and why behavioral phenomena occur. New mediation methods based on the potential outcomes framework are a seminal advancement for mediation analysis because they focus on the causal basis of mediation. Despite the importance of the potential outcomes framework in other fields, the methods are not well known in prevention and other disciplines. The interaction of a treatment (X) and a mediator (M) on an outcome variable (Y) is central to the potential outcomes framework for causal mediation analysis and provides a way to link traditional and modern causal mediation methods. As described in the paper, for a continuous mediator and outcome, if the XM interaction is zero, then potential outcomes estimators of the mediated effect are equal to the traditional model estimators. If the XM interaction is nonzero, the potential outcomes estimators correspond to simple direct and simple mediated contrasts for the treatment and the control groups in traditional mediation analysis. Links between traditional and causal mediation estimators clarify the meaning of potential outcomes framework mediation quantities. A simulation study demonstrates that testing for a XM interaction that is zero in the population can reduce power to detect mediated effects, and ignoring a nonzero XM interaction in the population can also reduce power to detect mediated effects in some situations. We recommend that prevention scientists incorporate evaluation of the XM interaction in their research.

PETCO2 gradient: a novel prognostic parameter in cardiopulmonary exercise testing

Background

Previous parameters such as peak VO2, VE/VCO2 slope and OUES have been described to be prognostic in heart failure (HF). The aim of this study was to identify further prognostic factors of cardiopulmonary exercise testing (CPET) in HF patients.

Methods

A retrospective analysis of HF patients who underwent CPET from January to November 2019 in a single centre was performed. PETCO2 gradient was defined by the difference between final PETCO2 and baseline PETCO2. HF events were defined as decompensated HF requiring hospital admission or IV diuretics, or decompensated HF resulting in death.

Results

A total of 64 HF patients were assessed by CPET, HF events occurred in 8 (12.5%) patients. Baseline characteristics are shown in table 1. Patients having HF events had a negative PETCO2 gradient while patients not having events showed a positive PETCO2 gradient (−1.5 [IQR −4.8, 2.3] vs 3 [IQR 1, 5] mmHg; p=0.004). A multivariate Cox proportional-hazards regression analysis revealed that PETCO2 gradient was an independent predictor of HF events (HR 0.74, 95% CI [0.61–0.89]; p=0.002). Kaplan-Meier curves showed a significantly higher incidence of HF events in patients having negative gradients, p=0.002 (figure 1).

Conclusion

PETCO2 gradient was demonstrated to be a prognostic parameter of CPET in HF patients in our study. Patients having negative gradients had worse outcomes by having more HF events.

Time to first event, decompensated heart

Funding Acknowledgement

Type of funding source: None

Allelic diversity and patterns of selection at the major histocompatibility complex class I and II loci in a threatened shorebird, the Snowy Plover (Charadrius nivosus)

Background

Understanding the structure and variability of adaptive loci such as the major histocompatibility complex (MHC) genes is a primary research goal for evolutionary and conservation genetics. Typically, classical MHC genes show high polymorphism and are under strong balancing selection, as their products trigger the adaptive immune response in vertebrates. Here, we assess the allelic diversity and patterns of selection for MHC class I and class II loci in a threatened shorebird with highly flexible mating and parental care behaviour, the Snowy Plover (Charadrius nivosus) across its broad geographic range.

Results

We determined the allelic and nucleotide diversity for MHC class I and class II genes using samples of 250 individuals from eight breeding population of Snowy Plovers. We found 40 alleles at MHC class I and six alleles at MHC class II, with individuals carrying two to seven different alleles (mean 3.70) at MHC class I and up to two alleles (mean 1.45) at MHC class II. Diversity was higher in the peptide-binding region, which suggests balancing selection. The MHC class I locus showed stronger signatures of both positive and negative selection than the MHC class II locus. Most alleles were present in more than one population. If present, private alleles generally occurred at very low frequencies in each population, except for the private alleles of MHC class I in one island population (Puerto Rico, lineage tenuirostris).

Conclusion

Snowy Plovers exhibited an intermediate level of diversity at the MHC, similar to that reported in other Charadriiformes. The differences found in the patterns of selection between the class I and II loci are consistent with the hypothesis that different mechanisms shape the sequence evolution of MHC class I and class II genes. The rarity of private alleles across populations is consistent with high natal and breeding dispersal and the low genetic structure previously observed at neutral genetic markers in this species.

Psychometric and machine learning approaches for diagnostic assessment and tests of individual classification

Assessments are commonly used to make a decision about an individual, such as grade placement, treatment assignment, job selection, or to inform a diagnosis. A psychometric approach to classify respondents based on the assessment would aggregate items into a score, and then each respondent's score is compared to a cut score. In contrast, a machine learning approach to classify respondents would build a model to predict the probability of belonging to a specific class from assessment items, and then respondents are classified based on their predicted probability of belonging to that class. It remains unclear whether psychometric and machine learning methods have comparable classification accuracy or if 1 method is preferable in all or some situations. In the context of diagnostic assessment, this study used Monte Carlo simulation methods to compare the classification accuracy of psychometric and machine learning methods as a function of the diagnosis-test correlation, prevalence, sample size, and the structure of the diagnostic assessment. Results suggest that machine learning models using logistic regression or random forest could have comparable classification accuracy to the psychometric methods using estimated item response theory scores. Therefore, machine learning models could provide a viable alternative for classification when psychometric methods are not feasible. Methods are illustrated with an empirical example predicting an oppositional defiant disorder diagnosis from a behavior disorders scale in children of age seven. Strengths and limitations for each of the methods are examined, and the overlap between the field of machine learning and psychometrics is discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

When Does Differential Item Functioning Matter for Screening? A Method for Empirical Evaluation

When items in a screening measure exhibit differential item functioning (DIF) across groups (e.g., males vs. females), DIF might affect which individuals are "caught" in the screening. This phenomenon is common, but DIF detection procedures do not typically provide guidance on whether the presence of DIF will meaningfully affect screening accuracy. Millsap and Kwok proposed a method to quantify the impact of DIF on screening accuracy, but their approach had limitations that prevent its use in scenarios where items are discrete. We extend the Millsap and Kwok procedure to accommodate discrete items and provide R functions to apply the procedure to the user's own data. We illustrate our approach using published screening information and evaluate the proposed methodology with a small simulation study. Overall, we encourage researchers to use empirical methods to evaluate the extent to which the presence of DIF in a screening measure materially affects screening performance.

Correlation Database of 60 Cross-Disciplinary Surveys and Cognitive Tasks Assessing Self-Regulation

Self-regulation is studied across various disciplines, including personality, social, cognitive, health, developmental, and clinical psychology; psychiatry; neuroscience; medicine; pharmacology; and economics. Widespread interest in self-regulation has led to confusion regarding both the constructs within the nomological network of self-regulation and the measures used to assess these constructs. To facilitate the integration of cross-disciplinary measures of self-regulation, we estimated product-moment and distance correlations among 60 cross-disciplinary measures of self-regulation (23 self-report surveys, 37 cognitive tasks) and measures of health and substance use based on 522 participants. The correlations showed substantial variability, though the surveys demonstrated greater convergent validity than did the cognitive tasks. Variables derived from the surveys only weakly correlated with variables derived from the cognitive tasks (M = .049, range = .000 to .271 for the absolute value of the product-moment correlation; M = .085, range = .028 to .241 for the distance correlation), thus challenging the notion that these surveys and cognitive tasks measure the same construct. We conclude by outlining several potential uses for this publicly available database of correlations.

Population differentiation and historical demography of the threatened snowy plover Charadrius nivosus (Cassin, 1858)

Delineating conservation units is a complex and often controversial process that is particularly challenging for highly vagile species. Here, we reassess population genetic structure and identify those populations of highest conservation value in the threatened snowy plover (Charadrius nivosus, Cassin, 1858), a partial migrant shorebird endemic to the Americas. We use four categories of genetic data—mitochondrial DNA (mtDNA), microsatellites, Z-linked and autosomal single nucleotide polymorphisms (SNPs)—to: (1) assess subspecies delineation and examine population structure (2) compare the sensitivity of the different types of genetic data to detect spatial genetic patterns, and (3) reconstruct demographic history of the populations analysed. Delineation of two traditionally recognised subspecies was broadly supported by all data. In addition, microsatellite and SNPs but not mtDNA supported the recognition of Caribbean snowy plovers (C. n. tenuirostris) and Floridian populations (eastern C. n. nivosus) as distinct genetic lineage and deme, respectively. Low migration rates estimated from autosomal SNPs (m < 0.03) reflect a general paucity of exchange between genetic lineages. In contrast, we detected strong unidirectional migration (m = 0.26) from the western into the eastern nivosus deme. Within western nivosus, we found no genetic differentiation between coastal Pacific and inland populations. The correlation between geographic and genetic distances was weak but significant for all genetic data sets. All demes showed signatures of bottlenecks occurring during the past 1000 years. We conclude that at least four snowy plover conservation units are warranted: in addition to subspecies nivosus and occidentalis, a third unit comprises the Caribbean tenuirostris lineage and a fourth unit the distinct eastern nivosus deme.

Retinal Microperimetry: A Useful Tool for Detecting Insulin Resistance-Related Cognitive Impairment in Morbid Obesity

Background: There is clear association between type 2 diabetes (T2D) and cognitive decline. Retinal microperimetry is a useful tool for detecting cognitive impairment in T2D. Morbid obesity (MO) has been associated with cognitive impairment. Insulin resistance (IR) seems a major determinant, but the data are unclear. The aim of this study was to evaluate the cognitive impairment in MO as well as the utility of retinal microperimetry in identifying these alterations. Methods: In total, 50 consecutive patients with MO were matched by age and gender with 30 healthy controls. All patients underwent cognitive evaluation (Montreal Cognitive Assessment Test-MoCA) and retinal microperimetry, using MAIA microperimeter 3rd generation. Retinal sensitivity and gaze fixation parameters were used for the evaluation of the analysis. Results: MO patients showed a significantly lower neurocognitive performance than the controls: MoCA score 24.94 ± 2.74 vs. 28.95 ± 1.05, p < 0.001. Cognitive function inversely correlated with the HOMA-IR (r = −0.402, p = 0.007). The AUROC for cognitive impairment using microperimetry was 0.807, CI 95% (0.592–0.947), p = 0.017. Conclusions: (1) Systemic insulin resistance is a major underlying mechanism accounting for the higher prevalence of cognitive impairment detected in young MO subjects. (2) Retinal microperimetry is a useful tool for identifying MO patients with cognitive impairment.

Epitaxial stabilization versus interdiffusion: synthetic routes to metastable cubic HfO2 and HfV2O7 from the core-shell arrangement of precursors

Metastable materials that represent excursions from thermodynamic minima are characterized by distinctive structural motifs and electronic structure, which frequently underpins new function. The binary oxides of hafnium present a rich diversity of crystal structures and are of considerable technological importance given their high dielectric constants, refractory characteristics, radiation hardness, and anion conductivity; however, high-symmetry tetragonal and cubic polymorphs of HfO₂ are accessible only at substantially elevated temperatures (1720 and 2600 °C, respectively). Here, we demonstrate that the core-shell arrangement of VO₂ and amorphous HfO₂ promotes outwards oxygen diffusion along an electropositivity gradient and yields an epitaxially matched V₂O₃/HfO₂ interface that allows for the unprecedented stabilization of the metastable cubic polymorph of HfO₂ under ambient conditions. Free-standing cubic HfO₂, otherwise accessible only above 2600 °C, is stabilized by acid etching of the vanadium oxide core. In contrast, interdiffusion under oxidative conditions yields the negative thermal expansion material HfV₂O₇. Variable temperature powder X-ray diffraction demonstrate that the prepared HfV₂O₇ exhibits pronounced negative thermal expansion in the temperature range between 150 and 700 °C. The results demonstrate the potential of using epitaxial crystallographic relationships to facilitate preferential nucleation of otherwise inaccessible metastable compounds.

Item Response Theory Analysis of the Five Facet Mindfulness Questionnaire and its Short Forms

Objectives

The Five Facet Mindfulness Questionnaire (FFMQ) is a self-report measure of mindfulness with forms of several different lengths, including the FFMQ-39, FFMQ-24, and FFMQ-15. We use item response theory analysis to directly compare the functioning of these three forms.

Methods

Data were drawn from a non-clinical Amazon Mechanical Turk study (N = 522) and studies of aftercare treatment of individuals with substance use disorders (combined N = 454). The item and test functioning of the three FFMQ forms were studied and compared.

Results

All 39 items were strongly related to the facet latent variables, and the items discriminated over a similar range of the latent mindfulness constructs. Items provided more information in the low to medium range of latent mindfulness than in the high range. Scores in three of the five FFMQ-39 facets were unreliable when measuring individuals in the high range of latent mindfulness, resulting from ceiling effects in item responses. Reliability in the high range of mindfulness was further reduced in the FFMQ-24 and FFMQ-15, such that short forms may be ill-suited for applications that require reliable measurement in the high range.

Conclusions

Results suggest the existing FFMQ item pool cannot be reduced without negatively affecting either overall reliability or the span of mindfulness over which reliability is assessed. Conditional test reliability curves and item functioning parameters can aid investigators in tailoring their choice of FFMQ form to the reliability they hope to achieve and to the range of latent mindfulness over which they must reliably measure.

P6471Pronostic impact of significant valvular disease in long-term survivors of out-of-hospital-cardiac arrest

Background

There is scarce evidence about the prevalence and clinical relevance of moderate to severe valvular heart disease (VHD) in survivors of out of hospital cardiac arrest (OHCA).

Purpose

To determine whether VHD influence prognosis of OHCA survivors.

Methods

All consecutive patients admitted to the Acute Cardiac Care Unit after OHCA and surviving until hospital discharge were included. All patients received targeted-temperature management according to our local protocol. Univariate and multivariate Cox-proportional hazard models were employed.

Results

A total of 201 patients were included in the analysis. Mean age was 57.6±14.2 years and 168 (83.6%) were male. Eighteen patients (9.0%) had moderate or severe VHD during index admission (Table 1). Patients with VHD were less frequently of male sex, [11 (61.1%) vs 157 (85.8%), p=0.014], experienced less acute coronary syndrome-related arrhytmias [2 (11.1%) vs 85 (46.5%), p=0.005], and had a lower pH at hospital admission (6.9±1.6 vs 7.2±0.15, p=0.008). During a median follow-up of 40.3 (18.9–69.1) months, patients with VHD showed higher mortality [7 (38.9%) vs 28 (15.3%), p=0.004] and more heart failure-related admissions [7 (38.9%) vs 15 (8.2%), p<0.001]. Only five patients received surgical or percutaneous treatment for VHD during follow-up, with no deaths in this subgroup. Moderate or severe VHD proved to be an independent predictor of global cardiovascular events and specifically heart failure episodes (Figure 1).

Table1 Variable With valvular disease Without valvular disease p value Age, mean±DS, years 63.5±13.2 57.0±14.1 0.066 Hypertension, n (%) 12 (66.7) 95 (51.9) 0.231 Diabetes, n (%) 5 (27.8) 24 (13.1) 0.149 Dyslipidaemia, n (%) 7 (38.9) 79 (43.2) 0.726 Smokin habit, n (%) 4 (22.2) 90 (49.2) 0.045 Witnessed cardiac arrest, n (%) 18 (100) 175 (95.6) 1.000 Time from CA to ROSC, mean±DS, minute 19.1±7.5 21.2±13.1 0.506 Shockable rhythm, n (%) 13 (72.2) 163 (89.1) 0.055 LVEF at hospital discharge (%) 42.8±12.1 46.9±14.6 0.254

Figure 1

Conclusion

The presence of significant VHD in survivors after OHCA is a predictor of poor outcomes. Specific management of VHD may be specially relevant in this high-risk patients and guideline-oriented therapy, including surgery and percutaneous intervention should be encouraged when indicated.

P5349Platelet/lymphocyte ratio as an inflammatory marker and predictor of short-term neurological outcomes in survivors after cardiac arrest

Background

Platelet/lymphocyte ratio (PLR), an inflammatory marker associated with poor outcomes in different clinical situations, may play a role in the proinflammatory state triggered during hypoxic-ischemic brain injury secondary to cardiac arrest.

Purpose

To study PLR dynamics and its relationship with neurologic outcomes in survivors after CA treated with target-temperature-management (TTM).

Methods

Observational retrospective study from a prospective database of survivors of in-hospital and out-of-hospital CA admitted to our Acute Cardiac Care Unit between August 2006 to December 2018. All patients received TTM according to our local protocol.

Results

A total of 466 patients were included. Mean age was 62.7±14.4 years and 102 (21.9%) were women. Baseline characteristics are shown in Table 1. 430 (92.2%) of CA were witnessed, 312 (67.0%) had ventricular fibrillation as initial cardiac rhythm. Among them, 236 (51.1%) survived until hospital discharge and 208 (45.1%) presented favorable neurological outcomes (a score 1 or 2 on cerebral performance category (CPC)). The mean value of PLR at admission and during targeted temperature was 100.4±5.2 and 224.5±7.3 respectively (mean difference 123.1±7.1, p<0.0001). This increase in PLR was significantly higher among patients with worse neurological outcomes (CPC 3–5, mean DPLR 138.2±5.5) at 3 months compared with survivors with CPC 1–2 (mean DPLR 108.2±6.3, p=0.0348 for paired comparison between both groups).

Table 1 Hypertension, n (%) 235 (54.9) Diabetes, n (%) 113 (26.4) Dyslipidaemia, n (%) 171 (40.0) Smocking habit, n (%) 208 (48.5) Time to ROSC mean ± SD, min 26.6±18.6 Mean arterial pressure at HA mean±DS, mmHg 81.3±22.1 pH at HA mean ± SD 7.18±0.16 Lactic at HA mean ± SD 6.37±4.42 ROSC: return of spontaneus circulation; HA: hospital admission.

Conclusion

Our findings reflect the impact of inflammation in neurological outcomes after OHCA treated with TTM. Major increases of PLR constitute a novel marker of poor prognosis during early assessment of OHCA patients.

A Psychometric Evaluation of the Short Grit Scale: A Closer Look at its Factor Structure and Scale Functioning

Grit, the passion and perseverance for long-term goals, has received attention from personality psychologists because it predicts success and academic achievement. Grit has also been criticized as simply another measure of self-control or conscientiousness. A precise psychometric representation of grit is needed to understand how the construct is unique and how it overlaps with other constructs. Previous research suggests that the Short Grit Scale (Grit-S) has several psychometric limitations, such as uncertain factor structure within and across populations, uncertainty about reporting total or subscale scores, and different assessment precision at low and high levels on the construct. We conducted modern psychometric techniques including parallel analysis, measurement invariance, extrinsic convergent validity, and Item Response Theory models on two American samples. Our results suggest that the Grit-S is essentially unidimensional and that there is construct overlap with the self-control construct. Subscale factors were the result of an item doublet, where two items had high correlated uniquenesses, showed similar item information, and were more likely to exhibit measurement bias. Findings replicated across samples. Finally, we discuss recommendations for the use of the Grit-S based on the theoretical interpretation of the unidimensional factor and our empirical findings.

Adrenergic cardiomyopathy and cardiogenic shock as initial presentation of pheochromocytoma. A case report and review of the literature

INTRODUCTION

Pheochromocytomas are infrequent tumors arised from the chromaphine cells of the adrenal sympathetic system. The excess of circulating catecholamines may lead to different cardiovascular disorders from silent alterations of the myocardial conduction to different forms of cardiomyopathy. The onset as cardiogenic shock is exceptional.

PRESENTATION OF CASE

A 35-year-old male, with a known history of acute myopericarditis of unknown origin which debuted as acute pulmonary edema, was admitted with dyspnea in the context of a new heart failure episode with pulmonary edema. An initial ECG showed segmentary repolarization changes, reversed in subsequent ECGs. The echocardiogram showed severe left ventricular dysfunction and lateral and apical hypokinesia. Subsequent echocardiograms showed partial recovery of alterations and preserved systolic function. A cardiac MRI showed a subepicardial minimum catchment focus and myocardial edema suggestive of adrenergic myocarditis. A solid nodular lesion was found in the left adrenal gland, suggesting a pheochromocytoma. Laparoscopic left adrenalectomy confirmed a 30 mm adrenal tumor without signs of locoregional invasion. The patient had normal catecholamine excretion and heart function a few weeks after surgery. Histopathology confirmed the diagnosis of pheochromocytoma.

DISCUSSION AND CONCLUSIONS

Adrenergic cardiomyopathy is a rare entity with a variable clinical presentation. The onset as cardiogenic shock is exceptional. The differential diagnosis of a patient with cardiogenic shock of unknown origin should consider the presence of an underlying pheocromocytoma as well as other states of adrenergic hyperstimulation. The reversibility of the myocardial affection in pheocromocytoma-associated myocardiopathy is common after the tumor resection.

Bias, Type I Error Rates, and Statistical Power of a Latent Mediation Model in the Presence of Violations of Invariance

When testing a statistical mediation model, it is assumed that factorial measurement invariance holds for the mediating construct across levels of the independent variable X. The consequences of failing to address the violations of measurement invariance in mediation models are largely unknown. The purpose of the present study was to systematically examine the impact of mediator noninvariance on the Type I error rates, statistical power, and relative bias in parameter estimates of the mediated effect in the single mediator model. The results of a large simulation study indicated that, in general, the mediated effect was robust to violations of invariance in loadings. In contrast, most conditions with violations of intercept invariance exhibited severely positively biased mediated effects, Type I error rates above acceptable levels, and statistical power larger than in the invariant conditions. The implications of these results are discussed and recommendations are offered.