Misspecification of longitudinal measurement invariance within the latent transition analysis framework

Assessing the impact of violations to longitudinal measurement invariance (LMI) within a mixture modeling context is not well-covered territory in current methodological research, and is notably unexplored in latent transition analyses (LTA). At a minimum, it can be assumed that any substantial departure from LMI within the LTA framework would thwart unambiguous interpretations of the latent classes as well as the probabilities of transitioning in and out of each latent class over time. The intent of this dissertation is to initiate the conversation by providing some thoughts and examples of how LMI can manifest in LTA models, followed by a statistical assessment of the most straightforward violation to LMI in LTA: configural non-invariance, or unequal numbers of latent classes emerging at each time point in the population. Monte Carlo simulation methods were used to generate data exhibiting varying degrees of departure from configural LMI, then class enumeration decisions and parameter recovery were explored under LTA models that assume configural invariance. The conditions manipulated in this simulation include the pattern of non-invariance (i.e., classes merging or splitting over time), class homogeneity and separation, class prevalence splits in the non-invariant class, overall sample size, and the transition matrix design (i.e., ordered or unordered movement). By imposing a configurally invariant LTA model on data that are non-invariant in nature, the researcher is risking a complete misestimation of the number and type of latent classes that exist at a particular time point, particularly in terms of both under- and overestimated values of within-class agreement. For this reason, it is recommended that researchers make class enumeration decisions at each measurement occasion, based on time-specific latent class analyses (LCA), before fitting the overall LTA model to the data. Any non-invariance discovered at the LCA level can be substantively explored and modeled with a non-symmetrical LTA. However, if the best-fitting class solution must be made at the LTA level, results from this study suggest that the AIC and ABIC indices are preferable for their overfitting tendencies. It seems reasonable to prefer an overfitted lens for analyzing non-invariant data, due to the added flexibility of the additional parameters estimated, but the parsimony of an underfitted model may be preferable in certain situations. As per usual, larger sample sizes (in this study, N = 1,000) are protective against parameter bias and convergence issues.Educational Psycholog

Addressing Barriers to Breast Cancer Screening: Where to Intervene to Increase Mammogram Completion Rates

Methods: Study sought to determine if an intervention would aid in increasing mammogram screening rates in the Jefferson Family Medicine Associates practice.https://jdc.jefferson.edu/patientsafetyposters/1061/thumbnail.jp

The State of the Region: Hampton Roads 2010

This is Old Dominion University\u27s 11th annual State of the Region Report. While it represents the work of many people connected in various ways to the university, the report does not constitute an official viewpoint of Old Dominion or it\u27s president, John R. Broderick. The report maintains the goal of stimulating thought and discussion that ultimately will make Hampton Roads an even better place to live. We are proud of our region\u27s many successes, but realize that it is possible to improve our performance. In order to do so, we must have accurate information about where we are and a sound understanding of the policy options open to us.https://digitalcommons.odu.edu/economics_books/1008/thumbnail.jp

Exploring the genetics of irritable bowel syndrome: A GWA study in the general population and replication in multinational case-control cohorts

OBJECTIVE: IBS shows genetic predisposition, but adequately powered gene-hunting efforts have been scarce so far. We sought to identify true IBS genetic risk factors by means of genome-wide association (GWA) and independent replication studies. DESIGN: We conducted a GWA study (GWAS) of IBS in a general population sample of 11\u2005326 Swedish twins. IBS cases (N=534) and asymptomatic controls (N=4932) were identified based on questionnaire data. Suggestive association signals were followed-up in 3511 individuals from six case-control cohorts. We sought genotype-gene expression correlations through single nucleotide polymorphism (SNP)-expression quantitative trait loci interactions testing, and performed in silico prediction of gene function. We compared candidate gene expression by real-time qPCR in rectal mucosal biopsies of patients with IBS and controls. RESULTS: One locus at 7p22.1, which includes the genes KDELR2 (KDEL endoplasmic reticulum protein retention receptor 2) and GRID2IP (glutamate receptor, ionotropic, delta 2 (Grid2) interacting protein), showed consistent IBS risk effects in the index GWAS and all replication cohorts and reached p=9.31 710(-6) in a meta-analysis of all datasets. Several SNPs in this region are associated with cis effects on KDELR2 expression, and a trend for increased mucosal KDLER2 mRNA expression was observed in IBS cases compared with controls. CONCLUSIONS: Our results demonstrate that general population-based studies combined with analyses of patient cohorts provide good opportunities for gene discovery in IBS. The 7p22.1 and other risk signals detected in this study constitute a good starting platform for hypothesis testing in future functional investigations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions

Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2δ1) has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia) similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR) neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cavα2δ1 transgenic mice. Our data indicated that overexpression of Cavα2δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal horn neurons to innocuous stimuli. This spinal sensitization mechanism may mediate at least partially the neuropathic pain states derived from increased pre-synaptic Cavα2δ1 expression

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

The impact of nonnormal and heteroscedastic level one residuals in partially clustered data

textThe multilevel model (MLM) is easily parameterized to handle partially clustered data (see, for example, Baldwin, Bauer, Stice, & Rohde, 2011). The current study evaluated the performance of this model under various departures from underlying assumptions, including assumptions of normally distributed and homoscedastic Level 1 residuals. Two estimating models – one assuming homoscedasticity, the other allowing for the estimation of unique Level 1 variance components – were compared. Results from a Monte Carlo simulation suggest that the MLM for partially clustered data yields consistently unbiased parameter estimates, except for an underestimation of the Level 2 variance component under heteroscedastic generating conditions. However, this negative parameter bias desisted when the MLM allowed for Level 1 heteroscedasticity. Standard errors for variance component estimates at both levels were underestimated in the presence of nonnormally distributed Level 1 residuals. A discussion of results, as well as suggestions for future research, is provided.Educational Psycholog

Aspirin Use for Prevention of Cardiovascular Disease and Colorectal Cancer

Learning Objectives: Identify specific risk factors for cardiovascular disease Summarize the USPSTF recommendations for aspirin use for primary prevention of cardiovascular disease and colorectal cancer Judge bleeding risk in your own patients Recognize the evidence and need for further studies on aspirin use for primary prevention Apply the USPSTF recommendations to your own patients Counsel patients on the use of aspirin for primary prevention Presentation: 44:4