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result(s) for
"Patel, Chirag J."
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A standard database for drug repositioning
2017
Drug repositioning, the process of discovering, validating, and marketing previously approved drugs for new indications, is of growing interest to academia and industry due to reduced time and costs associated with repositioned drugs. Computational methods for repositioning are appealing because they putatively nominate the most promising candidate drugs for a given indication. Comparing the wide array of computational repositioning methods, however, is a challenge due to inconsistencies in method validation in the field. Furthermore, a common simplifying assumption, that all novel predictions are false, is intellectually unsatisfying and hinders reproducibility. We address this assumption by providing a gold standard database, repoDB, that consists of both true positives (approved drugs), and true negatives (failed drugs). We have made the full database and all code used to prepare it publicly available, and have developed a web application that allows users to browse subsets of the data (
http://apps.chiragjpgroup.org/repoDB/
).
Design Type(s)
data integration objective • database creation objective
Measurement Type(s)
Concomitant Medication Use Indication
Technology Type(s)
digital curation
Factor Type(s)
Machine-accessible metadata file describing the reported data
(ISA-Tab format)
Journal Article
An Environment-Wide Association Study (EWAS) on Type 2 Diabetes Mellitus
by
Bhattacharya, Jayanta
,
Patel, Chirag J.
,
Butte, Atul J.
in
Analysis
,
Blood glucose
,
Blood levels
2010
Type 2 Diabetes (T2D) and other chronic diseases are caused by a complex combination of many genetic and environmental factors. Few methods are available to comprehensively associate specific physical environmental factors with disease. We conducted a pilot Environmental-Wide Association Study (EWAS), in which epidemiological data are comprehensively and systematically interpreted in a manner analogous to a Genome Wide Association Study (GWAS).
We performed multiple cross-sectional analyses associating 266 unique environmental factors with clinical status for T2D defined by fasting blood sugar (FBG) concentration > or =126 mg/dL. We utilized available Centers for Disease Control (CDC) National Health and Nutrition Examination Survey (NHANES) cohorts from years 1999 to 2006. Within cohort sample numbers ranged from 503 to 3,318. Logistic regression models were adjusted for age, sex, body mass index (BMI), ethnicity, and an estimate of socioeconomic status (SES). As in GWAS, multiple comparisons were controlled and significant findings were validated with other cohorts. We discovered significant associations for the pesticide-derivative heptachlor epoxide (adjusted OR in three combined cohorts of 1.7 for a 1 SD change in exposure amount; p<0.001), and the vitamin gamma-tocopherol (adjusted OR 1.5; p<0.001). Higher concentrations of polychlorinated biphenyls (PCBs) such as PCB170 (adjusted OR 2.2; p<0.001) were also found. Protective factors associated with T2D included beta-carotenes (adjusted OR 0.6; p<0.001).
Despite difficulty in ascertaining causality, the potential for novel factors of large effect associated with T2D justify the use of EWAS to create hypotheses regarding the broad contribution of the environment to disease. Even in this study based on prior collected epidemiological measures, environmental factors can be found with effect sizes comparable to the best loci yet found by GWAS.
Journal Article
Assessment of vibration of effects due to model specification can demonstrate the instability of observational associations
by
Ioannidis, John P.A.
,
Patel, Chirag J.
,
Burford, Belinda
in
Adjustment
,
Biomarkers
,
Biostatistics
2015
Model specification—what adjusting variables are analytically modeled—may influence results of observational associations. We present a standardized approach to quantify the variability of results obtained with choices of adjustments called the “vibration of effects” (VoE).
We estimated the VoE for 417 clinical, environmental, and physiological variables in association with all-cause mortality using National Health and Nutrition Examination Survey data. We selected 13 variables as adjustment covariates and computed 8,192 Cox models for each of 417 variables' associations with all-cause mortality.
We present the VoE by assessing the variance of the effect size and in the −log10(P-value) obtained by different combinations of adjustments. We present whether there are multimodality patterns in effect sizes and P-values and the trajectory of results with increasing adjustments. For 31% of the 417 variables, we observed a Janus effect, with the effect being in opposite direction in the 99th versus the 1st percentile of analyses. For example, the vitamin E variant α-tocopherol had a VoE that indicated higher and lower risk for mortality.
Estimating VoE offers empirical estimates of associations are under different model specifications. When VoE is large, claims for observational associations should be very cautious.
Journal Article
Systematically assessing microbiome–disease associations identifies drivers of inconsistency in metagenomic research
by
Yang, Zhen
,
Tierney, Braden T.
,
Shui, Bing
in
Algorithms
,
Bacteria - classification
,
Bacteria - genetics
2022
Evaluating the relationship between the human gut microbiome and disease requires computing reliable statistical associations. Here, using millions of different association modeling strategies, we evaluated the consistency—or robustness—of microbiome-based disease indicators for 6 prevalent and well-studied phenotypes (across 15 public cohorts and 2,343 individuals). We were able to discriminate between analytically robust versus nonrobust results. In many cases, different models yielded contradictory associations for the same taxon–disease pairing, some showing positive correlations and others negative. When querying a subset of 581 microbe–disease associations that have been previously reported in the literature, 1 out of 3 taxa demonstrated substantial inconsistency in association sign. Notably, >90% of published findings for type 1 diabetes (T1D) and type 2 diabetes (T2D) were particularly nonrobust in this regard. We additionally quantified how potential confounders—sequencing depth, glucose levels, cholesterol, and body mass index, for example—influenced associations, analyzing how these variables affect the ostensible correlation between Faecalibacterium prausnitzii abundance and a healthy gut. Overall, we propose our approach as a method to maximize confidence when prioritizing findings that emerge from microbiome association studies.
Journal Article
Gene-level metagenomic architectures across diseases yield high-resolution microbiome diagnostic indicators
by
Tierney, Braden T.
,
Patel, Chirag J.
,
Kostic, Aleksandar D.
in
631/114
,
631/326/2565/2134
,
692/53/2421
2021
We propose microbiome disease “architectures”: linking >1 million microbial features (species, pathways, and genes) to 7 host phenotypes from 13 cohorts using a pipeline designed to identify associations that are robust to analytical model choice. Here, we quantify conservation and heterogeneity in microbiome-disease associations, using gene-level analysis to identify strain-specific, cross-disease, positive and negative associations. We find coronary artery disease, inflammatory bowel diseases, and liver cirrhosis to share gene-level signatures ascribed to the
Streptococcus
genus. Type 2 diabetes, by comparison, has a distinct metagenomic signature not linked to any one specific species or genus. We additionally find that at the species-level, the prior-reported connection between
Solobacterium moorei
and colorectal cancer is not consistently identified across models—however, our gene-level analysis unveils a group of robust, strain-specific gene associations. Finally, we validate our findings regarding colorectal cancer and inflammatory bowel diseases in independent cohorts and identify that features inversely associated with disease tend to be less reproducible than features enriched in disease. Overall, our work is not only a step towards gene-based, cross-disease microbiome diagnostic indicators, but it also illuminates the nuances of the genetic architecture of the human microbiome, including tension between gene- and species-level associations.
Here, combing the massive gene-universe of the gut microbiome to identify strain-specific, cross-disease, associations across seven human diseases, the authors introduce the concept of microbiome architecture, defined as the complete set of positive and negative associations between microbial genes and human host disease, highlighting microbiome architectures as potential diagnostic indicators.
Journal Article
Repurposing large health insurance claims data to estimate genetic and environmental contributions in 560 phenotypes
2019
We analysed a large health insurance dataset to assess the genetic and environmental contributions of 560 disease-related phenotypes in 56,396 twin pairs and 724,513 sibling pairs out of 44,859,462 individuals that live in the United States. We estimated the contribution of environmental risk factors (socioeconomic status (SES), air pollution and climate) in each phenotype. Mean heritability (
h
2
= 0.311) and shared environmental variance (
c
2
= 0.088) were higher than variance attributed to specific environmental factors such as zip-code-level SES (var
SES
= 0.002), daily air quality (var
AQI
= 0.0004), and average temperature (var
temp
= 0.001) overall, as well as for individual phenotypes. We found significant heritability and shared environment for a number of comorbidities (
h
2
= 0.433,
c
2
= 0.241) and average monthly cost (
h
2
= 0.290,
c
2
= 0.302). All results are available using our Claims Analysis of Twin Correlation and Heritability (CaTCH) web application.
Analysis of a health insurance dataset comprising more than 44 million individuals allows for the estimation of genetic and environmental contributions in 560 phenotypes by using twins and sibling pairs.
Journal Article
Specification curve analysis of the TEDDY study reveals large variation in microbiome-based T1D predictive performance
by
Zimmerman, Samuel
,
Tierney, Braden T.
,
Patel, Chirag J.
in
631/114/2399
,
631/326/2565/2134
,
631/326/2565/2142
2025
The microbiome may play a role in predicting future Type 1 Diabetes (T1D) risk. Associations between the microbiome and T1D onset are well documented but observational microbiome studies are difficult to interpret and reproduce due to differences in study designs. To evaluate if the microbiome is a robust predictor of T1D or T1D associated autoantibodies, we performed a “specification curve analysis” from a longitudinal cohort of 783 individuals at high risk of T1D, that attempts to parameterize and systematically test all possible study design specifications. We predicted T1D and autoantibodies using 11,189 different specifications. We show a large amount of variation in the predictive ability of the microbiome across specifications. 72.5% of models that only use microbial features had an area under the curve (AUC) of 0.5 and the “best” model had an AUC of 0.78. Results for every specification can also be found in an interactive app at:
http://apps.chiragjpgroup.org/teddy
.
In this study, the authors systematically tested how seemingly small changes in a computational analysis can lead to significant variations in results, and show that regardless of all such choices, the microbiome poorly predicts Type 1 Diabetes risk.
Journal Article
Using deep learning to predict abdominal age from liver and pancreas magnetic resonance images
2022
With age, the prevalence of diseases such as fatty liver disease, cirrhosis, and type two diabetes increases. Approaches to both predict abdominal age and identify risk factors for accelerated abdominal age may ultimately lead to advances that will delay the onset of these diseases. We build an abdominal age predictor by training convolutional neural networks to predict abdominal age (or “AbdAge”) from 45,552 liver magnetic resonance images [MRIs] and 36,784 pancreas MRIs (R-Squared = 73.3 ± 0.6; mean absolute error = 2.94 ± 0.03 years). Attention maps show that the prediction is driven by both liver and pancreas anatomical features, and surrounding organs and tissue. Abdominal aging is a complex trait, partially heritable (h_g
2
= 26.3 ± 1.9%), and associated with 16 genetic loci (e.g. in
PLEKHA1
and
EFEMP1
), biomarkers (e.g body impedance), clinical phenotypes (e.g, chest pain), diseases (e.g. hypertension), environmental (e.g smoking), and socioeconomic (e.g education, income) factors.
Approaches to both determine abdominal age and identify risk factors for accelerated abdominal age will help delay the onset of several diseases. Here, the authors build an abdominal age predictor by training convolutional neural networks to predict abdominal age from liver and pancreas MRIs.
Journal Article
Pediatric and Young Adult Household Transmission of the Initial Waves of SARS-CoV-2 in the United States: Administrative Claims Study
2024
The correlates responsible for the temporal changes of intrahousehold SARS-CoV-2 transmission in the United States have been understudied mainly due to a lack of available surveillance data. Specifically, early analyses of SARS-CoV-2 household secondary attack rates (SARs) were small in sample size and conducted cross-sectionally at single time points. From these limited data, it has been difficult to assess the role that different risk factors have had on intrahousehold disease transmission in different stages of the ongoing COVID-19 pandemic, particularly in children and youth.
This study aimed to estimate the transmission dynamic and infectivity of SARS-CoV-2 among pediatric and young adult index cases (age 0 to 25 years) in the United States through the initial waves of the pandemic.
Using administrative claims, we analyzed 19 million SARS-CoV-2 test records between January 2020 and February 2021. We identified 36,241 households with pediatric index cases and calculated household SARs utilizing complete case information. Using a retrospective cohort design, we estimated the household SARS-CoV-2 transmission between 4 index age groups (0 to 4 years, 5 to 11 years, 12 to 17 years, and 18 to 25 years) while adjusting for sex, family size, quarter of first SARS-CoV-2 positive record, and residential regions of the index cases.
After filtering all household records for greater than one member in a household and missing information, only 36,241 (0.85%) of 4,270,130 households with a pediatric case remained in the analysis. Index cases aged between 0 and 17 years were a minority of the total index cases (n=11,484, 11%). The overall SAR of SARS-CoV-2 was 23.04% (95% CI 21.88-24.19). As a comparison, the SAR for all ages (0 to 65+ years) was 32.4% (95% CI 32.1-32.8), higher than the SAR for the population between 0 and 25 years of age. The highest SAR of 38.3% was observed in April 2020 (95% CI 31.6-45), while the lowest SAR of 15.6% was observed in September 2020 (95% CI 13.9-17.3). It consistently decreased from 32% to 21.1% as the age of index groups increased. In a multiple logistic regression analysis, we found that the youngest pediatric age group (0 to 4 years) had 1.69 times (95% CI 1.42-2.00) the odds of SARS-CoV-2 transmission to any family members when compared with the oldest group (18 to 25 years). Family size was significantly associated with household viral transmission (odds ratio 2.66, 95% CI 2.58-2.74).
Using retrospective claims data, the pediatric index transmission of SARS-CoV-2 during the initial waves of the COVID-19 pandemic in the United States was associated with location and family characteristics. Pediatric SAR (0 to 25 years) was less than the SAR for all age other groups. Less than 1% (n=36,241) of all household data were retained in the retrospective study for complete case analysis, perhaps biasing our findings. We have provided measures of baseline household pediatric transmission for tracking and comparing the infectivity of later SARS-CoV-2 variants.
Journal Article
Prediction and stratification of longitudinal risk for chronic obstructive pulmonary disease across smoking behaviors
by
Martin, Alicia R.
,
Silverman, Edwin K.
,
Diao, James A.
in
631/114/2413
,
631/208/1516
,
631/208/205/2138
2023
Smoking is the leading risk factor for chronic obstructive pulmonary disease (COPD) worldwide, yet many people who never smoke develop COPD. We perform a longitudinal analysis of COPD in the UK Biobank to derive and validate the Socioeconomic and Environmental Risk Score which captures additive and cumulative environmental, behavioral, and socioeconomic exposure risks beyond tobacco smoking. The Socioeconomic and Environmental Risk Score is more predictive of COPD than smoking status and pack-years. Individuals in the highest decile of the risk score have a greater risk for incident COPD compared to the remaining population. Never smokers in the highest decile of exposure risk are more likely to develop COPD than previous and current smokers in the lowest decile. In general, the prediction accuracy of the Social and Environmental Risk Score is lower in non-European populations. While smoking status is often considered in screening COPD, our finding highlights the importance of other non-smoking environmental and socioeconomic variables.
Many people who never smoke develop COPD. Here, the authors derive and validate the Socioeconomic and Environmental Risk Score (SERS) which captures cumulative exposure risks beyond tobacco smoking to predict and stratify risk of COPD.
Journal Article