Evaluation of resampling-based inference for topological features of neuroimages.

Many recent studies have demonstrated the inflated type 1 error rate of the original Gaussian random field (GRF) methods for inference of neuroimages and identified resampling (permutation and bootstrapping) methods that have better performance. There has been no evaluation of resampling procedures when using robust (sandwich) statistical images with different topological features (TF) used for neuroimaging inference. Here, we consider estimation of distributions TFs of a statistical image and evaluate resampling procedures that can be used when exchangeability is violated. We compare the methods using realistic simulations and study sex differences in life-span age-related changes in gray matter volume in the Nathan Kline Institute Rockland sample. We find that our proposed wild bootstrap and the commonly used permutation procedure perform well in sample sizes above 50 under realistic simulations with heteroskedasticity. The Rademacher wild bootstrap has fewer assumptions than the permutation and performs similarly in samples of 100 or more, so is valid in a broader range of conditions. We also evaluate the GRF-based pTFCE method and show that it has inflated error rates in samples less than 200. Our R package, pbj , is available on Github and allows the user to reproducibly implement various resampling-based group level neuroimage analyses.

Functional analysis of RYR1 variants in patients with confirmed susceptibility to malignant hyperthermia.

BACKGROUND: A major bottleneck to the introduction of noninvasive presymptomatic diagnostic tests for the pharmacogenetic disorder malignant hyperthermia is the lack of functional data for associated variants. METHODS: We screened 50 genes having a potential role in skeletal muscle calcium homeostasis using the HaloPlex™ (Agilent Technologies, Santa Clara, CA, USA) target enrichment system and next-generation sequencing. Twenty-one patients with a history of a clinical malignant hyperthermia reaction together with a positive in vitro contracture test were included. Eight variants in RYR1 were subsequently introduced into the cDNA for the human ryanodine receptor gene and tested in cultured human embryonic kidney (HEK293) cells for their effect on calcium release from intracellular stores in response to the ryanodine receptor-1 agonist 4-chloro-m-cresol using fura-2 as calcium indicator. Each variant was subjected to in silico curation using the European Malignant Hyperthermia Group scoring matrix and ClinGen RYR1 variant curation expert panel guidelines. RESULTS: Potentially causative RYR1 variants were identified in 15 patients. Of these, two families carried two RYR1 variants, five variants had been previously reported as 'pathogenic', two variants had been previously reported as 'likely benign', and eight were of 'uncertain significance'. Of these eight variants, four showed hypersensitivity to 4-chloro-m-cresol. Three variants were reclassified as either 'pathogenic' or 'likely pathogenic'. Two were classified as 'benign', whilst three remained of 'uncertain significance'. CONCLUSIONS: Three (p.Tyr1711Cys, p.Val2280Ile, and p.Arg4737Gln) additional variants can be added to the list of RYR1 disease-associated variants managed by the European Malignant Hyperthermia Group. These can therefore be used diagnostically in the future. Three variants (p.Glu2348Gly, p.Asn2634Lys, and p.Arg3629Trp) that remained classified as of uncertain significance require further family studies or a different functional test to determine clinical relevance in malignant hyperthermia.

The IeDEA harmonist data toolkit: A data quality and data sharing solution for a global HIV research consortium.

We describe the design, implementation, and impact of a data harmonization, data quality checking, and dynamic report generation application in an international observational HIV research network. The IeDEA Harmonist Data Toolkit is a web-based application written in the open source programming language R, employs the R/Shiny and RMarkdown packages, and leverages the REDCap data collection platform for data model definition and user authentication. The Toolkit performs data quality checks on uploaded datasets, checks for conformance with the network's common data model, displays the results both interactively and in downloadable reports, and stores approved datasets in secure cloud storage for retrieval by the requesting investigator. Including stakeholders and users in the design process was key to the successful adoption of the application. A survey of regional data managers as well as initial usage metrics indicate that the Toolkit saves time and results in improved data quality, with a 61% mean reduction in the number of error records in a dataset. The generalized application design allows the Toolkit to be easily adapted to other research networks.

Psychologists update their beliefs about effect sizes after replication studies.

Self-correction-a key feature distinguishing science from pseudoscience-requires that scientists update their beliefs in light of new evidence. However, people are often reluctant to change their beliefs. We examined belief updating in action by tracking research psychologists' beliefs in psychological effects before and after the completion of four large-scale replication projects. We found that psychologists did update their beliefs; they updated as much as they predicted they would, but not as much as our Bayesian model suggests they should if they trust the results. We found no evidence that psychologists became more critical of replications when it would have preserved their pre-existing beliefs. We also found no evidence that personal investment or lack of expertise discouraged belief updating, but people higher on intellectual humility updated their beliefs slightly more. Overall, our results suggest that replication studies can contribute to self-correction within psychology, but psychologists may underweight their evidentiary value.

Improving the replicability of neuroimaging findings by thresholding effect sizes instead of p-values.

The classical approach for testing statistical images using spatial extent inference (SEI) thresholds the statistical image based on the p-value. This approach has an unfortunate consequence on the replicability of neuroimaging findings because the targeted brain regions are affected by the sample size-larger studies have more power to detect smaller effects. Here, we use simulations based on the preprocessed Autism Brain Imaging Data Exchange (ABIDE) to show that thresholding statistical images by effect sizes has more consistent estimates of activated regions across studies than thresholding by p-values. Using a constant effect size threshold means that the p-value threshold naturally scales with the sample size to ensure that the target set is similar across repetitions of the study that use different sample sizes. As a consequence of thresholding by the effect size, the type 1 and type 2 error rates go to zero as the sample size gets larger. We use a newly proposed robust effect size index that is defined for an arbitrary statistical image so that effect size thresholding can be used regardless of the test statistic or model.

Functional analysis of RYR1 variants linked to malignant hyperthermia.

Malignant hyperthermia manifests as a rapid and sustained rise in temperature in response to pharmacological triggering agents, e.g. inhalational anesthetics and the muscle relaxant suxamethonium. Other clinical signs include an increase in end-tidal CO2, increased O2 consumption, as well as tachycardia, and if untreated a malignant hyperthermia episode can result in death. The metabolic changes are caused by dysregulation of skeletal muscle Ca2+ homeostasis, resulting from a defective ryanodine receptor Ca2+ channel, which resides in the sarcoplasmic reticulum and controls the flux of Ca2+ ions from intracellular stores to the cytoplasm. Most genetic variants associated with susceptibility to malignant hyperthermia occur in the RYR1 gene encoding the ryanodine receptor type 1. While malignant hyperthermia susceptibility can be diagnosed by in vitro contracture testing of skeletal muscle biopsy tissue, it is advantageous to use DNA testing. Currently only 35 of over 400 potential variants in RYR1 have been classed as functionally causative of malignant hyperthermia and thus can be used for DNA diagnostic tests. Here we describe functional analysis of 2 RYR1 variants (c. 7042_7044delCAG, p.ΔGlu2348 and c.641C>T, p.Thr214Met) that occur in the same malignant hyperthermia susceptible family. The p.Glu2348 deletion, causes hypersensitivity to ryanodine receptor agonists using in vitro analysis of cloned human RYR1 cDNA expressed in HEK293T cells, while the Thr214Met substitution, does not appear to significantly alter sensitivity to agonist in the same system. We suggest that the c. 7042_7044delCAG, p.ΔGlu2348 RYR1 variant could be added to the list of diagnostic mutations for susceptibility to malignant hyperthermia.

Development of a nomogram for identification of asthma among adults in epidemiologic studies.

BACKGROUND: The criteria used to identify persons with asthma in epidemiologic studies are varying and, depending on the method used, can be challenging and resource consuming. OBJECTIVE: To develop a nomogram (scoring system) to identify adult patients with asthma using a combination of variables collected via a validated questionnaire. METHODS: We studied the first 268 women aged 40 to 69 years in the Shanghai Women's Asthma and Allergy Study who reported signs and symptoms of asthma and underwent either methacholine challenge testing or test of reversibility during the asthma screening survey between 2003 and 2007. These women were defined as having definite asthma (n=106) or not (n=162). Multivariable logistic regression analysis was performed to develop a predictive model for identifying asthma using survey information alone. RESULTS: Clinically relevant questions were used for the predictive multivariable logistic regression model and included the following: ever wheezing or whistling in the chest, current medication use for asthma, self-reported ever asthma, self-reported ever allergic rhinitis, family history of allergy, and age. The area under the receiver operating characteristic curve of the prediction model was 0.75 (95% confidence interval, 0.69-0.81). A nomogram was developed to assess the individual probability of asthma based on individually weighted variables in the predictive model. CONCLUSIONS: In clinical or epidemiologic studies, this asthma nomogram could be used as a tool to assess the probability of asthma for an individual patient by incorporating asthma-related predictor variables obtained through a field questionnaire.