Di Xiong

Ms. Di Xiong


Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 March 2021 in PLOS Computational Biology
Verified
Journal Article
Open access
PDF file
GWGregory L Watson
Gregory L Watson
DXDi Xiong
Di Xiong
LZLu Zhang
Lu Zhang
JZJoseph Zoller
Joseph Zoller
JSJohn Shamshoian
John Shamshoian
Christina M. RamirezChristina M. Ramirez
Christina M. Ramirez
Predictions of COVID-19 case growth and mortality are critical to the decisions of political leaders, businesses, and individuals grappling with the pandemic. This predictive task is challenging due to the novelty of the virus, limited data, and dynamic political and societal responses. We embed a Bayesian time series model and a random forest algorithm within an epidemiological compartmental model for empirically grounded COVID-19 predictions. The Bayesian case model fits a location-specific curve to the velocity (first derivative) of the log transformed cumulative case count, borrowing strength across geographic locations and incorporating prior information to obtain a posterior distribution for case trajectories. The compartmental model uses this distribution and predicts deaths using a random forest algorithm trained on COVID-19 data and population-level characteristics, yielding daily projections and interval estimates for cases and deaths in U.S. states. We evaluated the model by training it on progressively longer periods of the pandemic and computing its predictive accuracy over 21-day forecasts. The substantial variation in predicted trajectories and associated uncertainty between states is illustrated by comparing three unique locations: New York, Colorado, and West Virginia. The sophistication and accuracy of this COVID-19 model offer reliable predictions and uncertainty estimates for the current trajectory of the pandemic in the U.S. and provide a platform for future predictions as shifting political and societal responses alter its course.

1 December 2021 in Dentistry Journal
Verified
Journal Article
Open access
PDF file
FRFrancisco Ramos-Gomez
Francisco Ramos-Gomez
MMMarvin Marcus
Marvin Marcus
CMCarl A. Maida
Carl A. Maida
YWYan Wang
Yan Wang
JKJanni Kinsler
Janni Kinsler
HLHonghu Liu
Honghu Liu
Background: Dental caries is the most common chronic childhood infectious disease and is a serious public health problem affecting both developing and industrialized countries, yet it is preventable in most cases. This study evaluated the potential of screening for dental caries among children using a machine learning algorithm applied to parent perceptions of their child’s oral health assessed by survey. Methods: The sample consisted of 182 parents/caregivers and their children 2–7 years of age living in Los Angeles County. Random forest (a machine learning algorithm) was used to identify survey items that were predictors of active caries and caries experience. We applied a three-fold cross-validation method. A threshold was determined by maximizing the sum of sensitivity and specificity conditional on the sensitivity of at least 70%. The importance of survey items to classifying active caries and caries experience was measured using mean decreased Gini (MDG) and mean decreased accuracy (MDA) coefficients. Results: Survey items that were strong predictors of active caries included parent’s age (MDG = 0.84; MDA = 1.97), unmet needs (MDG = 0.71; MDA = 2.06) and the child being African American (MDG = 0.38; MDA = 1.92). Survey items that were strong predictors of caries experience included parent’s age (MDG = 2.97; MDA = 4.74), child had an oral health problem in the past 12 months (MDG = 2.20; MDA = 4.04) and child had a tooth that hurt (MDG = 1.65; MDA = 3.84). Conclusion: Our findings demonstrate the potential of screening for active caries and caries experience among children using surveys answered by their parents.

11 November 2019 in JDR Clinical & Translational Research
Verified
Journal Article
Closed access
PDF file
YWYan Wang
Yan Wang
RHRon D. Hays
Ron D. Hays
MMM. Marcus
M. Marcus
CMC.A. Maida
C.A. Maida
JSJ. Shen
J. Shen
HLH. Liu
H. Liu
Objectives: Evaluating children’s oral health status and treatment needs is challenging. We aim to build oral health assessment toolkits to predict Children’s Oral Health Status Index (COHSI) score and referral for treatment needs (RFTN) of oral health. Parent and Child toolkits consist of short-form survey items (12 for children and 8 for parents) with and without children’s demographic information (7 questions) to predict the child’s oral health status and need for treatment. Methods: Data were collected from 12 dental practices in Los Angeles County from 2015 to 2016. We predicted COHSI score and RFTN using random Bootstrap samples with manually introduced Gaussian noise together with machine learning algorithms, such as Extreme Gradient Boosting and Naive Bayesian algorithms (using R). The toolkits predicted the probability of treatment needs and the COHSI score with percentile (ranking). The performance of the toolkits was evaluated internally and externally by residual mean square error (RMSE), correlation, sensitivity and specificity. Results: The toolkits were developed based on survey responses from 545 families with children aged 2 to 17 y. The sensitivity and specificity for predicting RFTN were 93% and 49% respectively with the external data. The correlation(s) between predicted and clinically determined COHSI was 0.88 (and 0.91 for its percentile). The RMSEs of the COHSI toolkit were 4.2 for COHSI (and 1.3 for its percentile). Conclusions: Survey responses from children and their parents/guardians are predictive for clinical outcomes. The toolkits can be used by oral health programs at baseline among school populations. The toolkits can also be used to quantify differences between pre- and post-dental care program implementation. The toolkits’ predicted oral health scores can be used to stratify samples in oral health research. Knowledge Transfer Statement: This study creates the oral health toolkits that combine self- and proxy- reported short forms with children’s demographic characteristics to predict children’s oral health and treatment needs using Machine Learning algorithms. The toolkits can be used by oral health programs at baseline among school populations to quantify differences between pre and post dental care program implementation. The toolkits can also be used to stratify samples according to the treatment needs and oral health status.

19 September 2019 in Clinical and Translational Science
Verified
Journal Article
Open access
PDF file
EDEric S. Daar
Eric S. Daar
MRMarc I. Rosen
Marc I. Rosen
YWYan Wang
Yan Wang
LSLisa Siqueiros
Lisa Siqueiros
JSJie Shen
Jie Shen
HLHonghu Liu
Honghu Liu
Adherence with antiretroviral therapy is important for preventing disease progression and HIV transmission. The co‐encapsulated pill sensor system sends a signal through a cutaneous patch and allows real‐time monitoring of pill ingestion. A 16‐week pilot study used a sensor system in 15 HIV‐infected individuals with real‐time monitoring of pill‐taking with a personalized short message system text. System acceptability was assessed by survey at weeks 4, 8, 12, and 16. Follow‐up occurred in 80% of subjects through 8 weeks. The system effectively collected measures of pill ingestion, which triggered text message reminders. Only 2 of 14 participants stated that co‐encapsulated pills were “unable to take” or “poorly tolerated.” At least 75% of respondents stated at each visit that the patch was very or somewhat comfortable. With regard to text message reminders, only 10–15% of the participants at any visit did not find the messages to be helpful. Larger studies will define the utility of this system to assess antiretroviral adherence relative to standard measures.

1 December 2020 in Epidemics
Verified
Journal Article
Open access
DXDi Xiong
Di Xiong
LZLu Zhang
Lu Zhang
GWGregory L Watson
Gregory L Watson
PSPhillip Sundin
Phillip Sundin
TBTeresa Bufford
Teresa Bufford
Christina M. RamirezChristina M. Ramirez
Christina M. Ramirez
In emerging epidemics, early estimates of key epidemiological characteristics of the disease are critical for guiding public policy. In particular, identifying high-risk population subgroups aids policymakers and health officials in combating the epidemic. This has been challenging during the coronavirus disease 2019 (COVID-19) pandemic because governmental agencies typically release aggregate COVID-19 data as summary statistics of patient demographics. These data may identify disparities in COVID-19 outcomes between broad population subgroups, but do not provide comparisons between more granular population subgroups defined by combinations of multiple demographics. We introduce a method that helps to overcome the limitations of aggregated summary statistics and yields estimates of COVID-19 infection and case fatality rates - key quantities for guiding public policy related to the control and prevention of COVID-19 - for population subgroups across combinations of demographic characteristics. Our approach uses pseudo-likelihood based logistic regression to combine aggregate COVID-19 case and fatality data with population-level demographic survey data to estimate infection and case fatality rates for population subgroups across combinations of demographic characteristics. We illustrate our method on California COVID-19 data to estimate test-based infection and case fatality rates for population subgroups defined by gender, age, and race/ethnicity. Our analysis indicates that in California, males have higher test-based infection rates and test-based case fatality rates across age and race/ethnicity groups, with the gender gap widening with increasing age. Although elderly infected with COVID-19 are at an elevated risk of mortality, the test-based infection rates do not increase monotonically with age. The workforce population, especially, has a higher test-based infection rate than children, adolescents, and other elderly people in their 60-80. LatinX and African Americans have higher test-based infection rates than other race/ethnicity groups. The subgroups with the highest 5 test-based case fatality rates are all-male groups with race as African American, Asian, Multi-race, LatinX, and White, followed by African American females, indicating that African Americans are an especially vulnerable California subpopulation.

5 March 2018 in Quality of Life Research
Verified
Journal Article
Closed access
PDF file
HLHonghu Liu
Honghu Liu
RHRon Hays
Ron Hays
YWYan Wang
Yan Wang
MMMarvin Marcus
Marvin Marcus
CMCarl Maida
Carl Maida
JCJames Crall
James Crall