Research
My research focuses on integrationg data from diverse sources for cardiovascular health studies with a particular emphasis on health disparities in underserved populations defined by race/ethnicity, sexual orientation, and socioeconomic factors. Numerous issues and challenges could arise when integrating data from multiple sources. Different sources often generate data in different formats-- some provide individual-level data, while others ofer only aggregate or summary statistics. Study designs, data types, model assumptions, and analytical results can differ significantly across studies, even when addressing the same research question. Additionally, the measurements for the set of variables may also vary considerably between studies. I am leading an initiative to tackle these issues, aiming to enhance the accuracy of conclusions and improve decision-making in the cardiovascular study.
Biography
Dr. Liu is a Staff in biostatistics and data science in the Department of Quantitative Health Sciences at the Cleveland Clinic Research of Cleveland Clinic Foundation (CCF), and a Professor in the Department of Medicine in the Case Western Reserve University School of Medicine. He leads a Lerner biostatistics support core to provide scientific method guidance and consulting services for Lerner principal investigators in basic and translational sciences to facilitate their grant preparation and submission. The guidance areas provided includes the optimal experimental design, power analysis, statistics analysis plan, sample size justification, data curation and integration, design-related statistical techniques and approaches, and result interpretations.
Dr. Liu has a long-standing history of advancing statistical methods in their application to public health, clinical, and biological sciences. The methods he has developed and used in his research programs (either independent or collaborative) include, but are not limited to, repeated measures/longitudinal models, latent class/trait models, mixed effects models, missing data models, hierarchical/multilevel models, GWAS, high-dimensional high throughout methods, and data reduction methods (PCA, FA, SEM). He has led or co-led multiple NIH-funded projects and carried out methodology development research on the longitudinal study of substance use, mental disorders, cardiovascular risk, and hypertension control. The main goal of his research program is to develop innovative analytical approaches and data science technology to improve the precision and accuracy of scientific findings in health sciences.
Before joining CCF, Dr. Liu held professorship in the University of Michigan Ann Arbor, where he conducted research in innovative statistical methods and provided support for other PI’s grants, taught analytical courses for medical, nursing and public health programs, and mentored graduate students for dissertations and research publications.
Dr. Liu has published over 200 papers in statistical and health science journals and presented numerous invited talks in national and international conferences. After work, he enjoys staying active with jogging, hiking, and playing basketball, as well as unwinding with some music.
Education & Professional Highlights
Appointed
2021
Education
MS in Statistics, University of Florida, Gainesville, FL, 2002
PhD in Statistics, University of Florida, Gainesville, FL, 2006
Professional Society Affiliation
American Statistical Association
American Public Health Association
International Chinese Statistical Association
Institute of Mathematical Statistics
Research
My research encompasses three primary areas of inquiry. The first focuses on advancing statistical methodology, developing and applying innovative statistical techniques to tackle emerging challenges and issues in health-related fields. I am particularly interested in addressing issues related to integrating data from diverse sources. My methodological expertise includes Bayesian statistics, repeated measures or longitudinal models, missing data methods, high-dimensional statistics, and latent class or trait models. The second area centers on cardiovascular health, with an emphasis on hypertension and associated risk factors—clinical, behavioral, dietary, and environmental—that contribute to health disparities in uncontrolled hypertension and other cardiovascular diseases. I have led or co-led several cardiovascular projects, including assignments within NIH- or HRSA-funded centers/programs, focusing on racial disparities, pharmacotherapy, and tele-home care. The third area involves consulting and collaborating with investigators across disciplines in basic, translational, and clinical sciences, such as substance use, mental health, obesity, genetic epidemiology, and cancer, to enhance scientific outcomes in these fields. These research interests align seamlessly with my primary role of leading Lerner biostatistics support at the Cleveland Clinic Research of Cleveland Clinic Foundation, providing methodological guidance and assisting Lerner investigators with grant preparation and submission, manuscript development and revision, and data reporting and interpretations.
Our Team
Selected Publications
Sumi MP, Tupta B, Song K, Mavrakis L, Comhair S, Erzurum SC, Liu XF, Stuehr DJ, Ghosh A. Expression of soluble guanylate cyclase (sGC) and its ability to form a functional heterodimer are crucial for reviving the NO-sGC signaling in PAH. Free Radical Biology and Medicine 2024; 25: 846-855.
Vollset SE, Ababneh HS, ···Liu XF···, Smith A, Murrary CJL. GBD 2021 Forecasting Collaborators. Burden of disease scenarios for 204 countries and territories, 2022–2050: a forecasting analysis for the Global Burden of Disease Study 2021. Lancet 2024; 403: 2204-2256.
GBD 2021 Risk Factors Collaborators. Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021. Lancet 2024; 403: 2162-2203.
GBD 2021 Causes of Death Collaborators. Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021. Lancet 2024; 403: 2100-2132.
Ferrari AJ, Santomauro DF, Aali A, ···Liu XF···, Zyoud SH, Vos T, Murray CJL. GBD 2021 Diseases and Injuries Collaborators. Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021. Lancet 2024; 403: 2133-2161.
Ong KL, Stafford LK, McLaughlin SA, Boyko EJ, ···Liu XF···, Magliano DJ, Murray CJL, Hay SI, Vos T. GBD 2021 Diabetes Collaborators. Global, regional, and national burden of diabetes from 1990 to 2021, with projections of prevalence to 2050: a systematic analysis for the Global Burden of Disease Study 2021. Lancet 2023; 402: 203-234.
Ghosh G, Myers R, O’Connor C, Williams S, Liu XF, Hossain M, Nemeth M, Najm IM. Cortical dysplasia in rats provokes neurovascular alterations, GLUT1 dysfunction, and metabolic disturbances that are sustained post-seizure induction. Molecular Neurobiology 2022; 59: 2389-2406.
Feigin VL, Vos T,··· Liu XF, Lo WD, ···Adelson JD, Murray CJL. Burden of Neurological Disorders Across the US From 1990-2017 A Global Burden of Disease Study. JAMA Neurology 2021; 78:165-176.
Lozano R, Fullman N,··· Liu XF et al. GBD 2019 Universal Health Coverage Collaborators. Measuring universal health coverage using the UHC effective coverage index in 204 countries and territories, 1990–2019: a systematic analysis from the Global Burden of Disease Study 2019. The Lancet 2020; 396: 1250-1284.
Liu XF, Baylin A, Levy PD. Vitamin D deficiency and insufficiency among US adults: prevalence, predictors, and clinical implications. British Journal of Nutrition 2018; 119:928-936.
Liu XF, Byrd JB, Rodriguez CJ. Use of physician-recommended non-pharmacological strategies for hypertension control among hypertensive patients. Journal of Clinical Hypertension 2018; 20:518-527.
Liu XF, Zhu TH, Manojlovich M, Cohen HW, Tsilimingras D. Racial/ethnic disparity in the associations of smoking status with uncontrolled hypertension subtypes among hypertensive subjects. Plos One 2017; 12(8): e0182807
Liu XF, Wang K. Generalized latent trait models for multiple correlated health endpoints. Proceedings of American Statistical Association 2016; pp. 1121-1129.
Liu XF, Rodriguez CJ, Wang KS. Prevalence and trends of isolated systolic hypertension among untreated adults in the United States. Journal of the American Society of Hypertension 2015; 9(3):197-205.
Liu XF, Tsilimingras D, Paul TR. Prevalence and changes of isolated systolic hypertension among US Non-Hispanic black adults in 1999-2010. Hypertension Research 2014; 37(7):685-691.
Liu XF, Song P. Is the association of diabetes with uncontrolled blood pressure stronger in Mexican Americans and blacks than in whites among diagnosed hypertensive patients? American Journal of Hypertension 2013; 26 (11):1328-1334.
Zheng S, Gupta AK, Liu XF. A matrix variate generalization of the skew pearson type VII and skew T distribution. Mathematical Sciences Research Journal 2012; 16(6):136-156.
Wang KS, Liu XF, Zhang QY, Aragam N, Pan Y. Parent-of-origin effects of FAS and PDLIM1 in attention-deficit hyperactivity disorder. Journal of Psychiatry and Neuroscience 2012; 37(1):46-52.
Liu XF, Liu M, Tsilimingras D, Schiffrin EL. Racial disparities in cardiovascular risk factors among diagnosed hypertensive subjects. Journal of the American Society of Hypertension 2011; 5(4):239-248.
Liu XF, Wang KS, Lee K. The Association of standardized estimated glomerular filtration rate with the prevalence of hypertension in adults in the United States. Journal of Human Hypertension 2011; 25(8):469-475.
Baker MK, Hillhouse JJ, Liu XF. The Effect of initial indoor tanning with mother on current tanning patterns. Archives of Dermatology 2010; 146(12):1427-1428.
Liu XF, Daniels MJ, Marcus B. Joint models for the association of longitudinal binary and continuous processes with application to a smoking cessation trial. Journal of the American Statistical Association 2009; 104:429-438.
Liu XF, Roth J. Development and validation of an infant morbidity index using latent variable models. Statistics in Medicine 2008; 27(7):971-989.
Liu XF, Daniels MJ. A new efficient algorithm for sampling a correlation matrix based on parameter expansion and re-parameterization. Journal of Computational and Graphical Statistics 2006; 15(4):897-914.