Yizhe (Crystal) Xu

Yizhe (Crystal) Xu, MSc, PhD

Languages spoken: English

Academic Information

Departments Adjunct - Population Health Sciences , Primary - Internal Medicine

Divisions: Epidemiology

Academic Office Information

Crystal.Xu@hsc.utah.edu

Yizhe (Crystal) Xu is a research assistant professor in the Division of Epidemiology. She did her postdoc at the Center for Biomedical Informatics Research (BMIR) at Stanford University, advised by Dr. Nigam Shah. She graduated from the Division of Biostatistics, Department of Population Health Sciences at the University of Utah in 2020. Yizhe’s primary research interests are in causal inference and machine learning, and she is passionate about applying advanced methods in statistics to answer meaningful questions in biomedical research, using large-scale EHR or claims data as well as data from clinical trials. She is interested in estimating treatment effect heterogeneity, identifying the optimal individualized treatment rule, and evaluating the tradeoff between the effectiveness and cost or adverse effects of treatment. Her major clinical research areas are in cardiovascular disease, dementia, and cancer.

Research Statement

I am interested in causal inference, semiparametric models, and machine learning. I am passionate about applying advanced methods in statistics and machine learning to answer meaningful questions in biomedical research. My recent research has focused on deriving and evaluating risk stratification tools, estimating heterogeneous treatment effects, and identifying individualized treatment rules using data from randomized controlled trials or insurance claims and electronic health records

Education History

Undergraduate Liaoning Medical University
 BSc
Graduate Training University of Utah School of Medicine
 MSc
Doctoral Training University of Utah School of Medicine
 PhD
Postdoctoral Training Stanford University
 Postdoctoral Scholar

Selected Publications

Journal Article

  1. Xu Y, Greene TH, Bress AP, Sauer BC, Bellows BK, Zhang Y, Weintraub WS, Moran AE, Shen J (2022). Estimating the optimal individualized treatment rule from a cost-effectiveness perspective. Biometrics, 78(1), 337-351.
  2. Xu Y, Greene TH, Bress AP, Bellows BK, Zhang Y, Zhang Z, Kolm P, Weintraub WS, Moran AS, Shen J (2022). An efficient approach for optimizing the cost-effective individualized treatment rule using conditional random forest. Stat Methods Med Res, 31(11), 2122-2136.
  3. Pfohl SR, Zhang H, Xu Y, Foryciarz A, Ghassemi M, Shah NH (2022). A comparison of approaches to improve worst-case predictive model performance over patient subpopulations. Sci Rep, 12(1), 3254.
  4. Lu J, Sattler A, Wang S, Khaki AR, Callahan A, Fleming S, Fong R, Ehlert B, Li RC, Shieh L, Ramchandran K, Gensheimer MF, Chobot S, Pfohl S, Li S, Shum K, Parikh N, Desai P, Seevaratnam B, Hanson M, Smith M, Xu Y, Gokhale A, Lin S, Pfeffer MA, Teuteberg W, Shah NH (2022). Considerations in the reliability and fairness audits of predictive models for advance care planning. Front Digit Health, 4, 943768.
  5. Bress AP, Greene T, Derington CG, Shen J, Xu Y, Zhang Y, Ying J, Bellows BK, Cushman WC, Whelton PK, Pajewski NM, Reboussin D, Beddu S, Hess R, Herrick JS, Zhang Z, Kolm P, Yeh RW, Basu S, Weintraub WS, Moran AE, SPRINT Research Group (2021). Patient Selection for Intensive Blood Pressure Management Based on Benefit and Adverse Events. J Am Coll Cardiol, 77(16), 1977-1990.
  6. Corbett KL, Presson AP, Zhang C, Xu Y, Bratton SL, Dixon RR (2021). Does Non-Neurologic Multiorgan Dysfunction After Out-of-Hospital Cardiac Arrest among Children Admitted in Coma Predict Outcome 1 Year Later? J Pediatr Intensive Care, 10(3), 188-196.
  7. Sauer BC, Chen W, Xu Y, Shen J, Accortt NA, Collier DH, Cannon GW (2020). Empirical evidence of disease activity thresholds used to indicate need for major therapeutic change in US veterans with rheumatoid arthritis. Arthritis Res Ther, 22(1), 253.
  8. Bailey TL, Stephens AR, Adeyemi TF, Xu Y, Presson AP, Aoki SK, Maak TG (2019). Traction Time, Force and Postoperative Nerve Block Significantly Influence the Development and Duration of Neuropathy Following Hip Arthroscopy. Arthroscopy, 35(10), 2825-2831.
  9. Kazmers NH, Stephens AR, Presson AP, Xu Y, Feller RJ, Tyser AR (2019). Comparison of Direct Surgical Costs for Proximal Row Carpectomy and Four-Corner Arthrodesis. J Wrist Surg, 8(1), 66-71.
  10. Kazmers NH, Presson AP, Xu Y, Howenstein A, Tyser AR (2018). Cost Implications of Varying the Surgical Technique, Surgical Setting, and Anesthesia Type for Carpal Tunnel Release Surgery. J Hand Surg Am, 43(11), 971-977.e1.
  11. Kazmers NH, Judson CH, Presson AP, Xu Y, Tyser AR (2018). Evaluation of Factors Driving Cost Variation for Distal Radius Fracture Open Reduction Internal Fixation. J Hand Surg Am, 43(7), 606-614.e1.
  12. Kwok AC, Edwards K, Donato DP, Tatro E, Xu Y, Presson AP, Agarwal JP (2018). Operative Time and Flap Failure in Unilateral and Bilateral Free Flap Breast Reconstruction. J Reconstr Microsurg, 34(6), 428-435.
  13. Pirozzi CS, Mendoza DL, Xu Y, Zhang Y, Scholand MB, Baughman RP (2018). Short-Term Particulate Air Pollution Exposure is Associated with Increased Severity of Respiratory and Quality of Life Symptoms in Patients with Fibrotic Sarcoidosis. Int J Environ Res Public Health, 15(6).
  14. Workman JK, Wilkes J, Presson AP, Xu Y, Heflin JA, Smith JT (2018). Variation in Adolescent Idiopathic Scoliosis Surgery: Implications for Improving Healthcare Value. J Pediatr, 195, 213-219.e3.
  15. Keihani S, Xu Y, Presson AP, Hotaling JM, Nirula R, Piotrowski J, Dodgion CM, Black CM, Mukherjee K, Morris BJ, Majercik S, Smith BP, Schwartz I, Elliott SP, DeSoucy ES, Zakaluzny S, Thomsen PB, Erickson BA, Baradaran N, Breyer BN, Miller B, Santucci RA, Carrick MM, Hewitt T, Burks FN, Kocik JF, Askari R, Myers JB, Genito-Urinary Trauma Study Group (2018). Contemporary management of high-grade renal trauma: Results from the American Association for the Surgery of Trauma Genitourinary Trauma study. J Trauma Acute Care Surg, 84(3), 418-425.
  16. Awad AW, Karsy M, Sanai N, Spetzler R, Zhang Y, Xu Y, Mahan MA (2017). Impact of removed tumor volume and location on patient outcome in glioblastoma. J Neurooncol, 135(1), 161-171.
  17. Lucas J, Myers J, Keihani S, Moses R, Xu Y, Morris B, Majercik S, Hewitt T, Burks F, Schwartz I, Elliott S (2019). MP04-03 Treatment Complications Associated with Extraperitoneal Bladder Injuries: Results from the Multi-Institutional AAST Study of Bladder Trauma [Abstract]. Journal of Urology, 201(Supplement 4), e30-e31.
  18. Bailey T, Maak TG, Stephens A, Adeyemi T, Xu Y, Presson A (2018). The Association of Traction Time, Force and Postoperative Nerve Block on the Development and Duration of Neuropathy Following Hip Arthroscopy [Abstract]. Arthroscopy, 34(12), e18.
  19. Kazmers NH, Stephens A, Presson AP, Xu Y, Feller RJ, Tyser A (2018). Comparison of Direct Surgical Costs for Proximal Row Carpectomy and 4-Corner Arthrodesis: Level 3 Evidence [Abstract]. Journal of Hand Surgery, 43(9), S52.
  20. Keihani S, Moses R, Xu Y, Putbrese B, Rogers D, Luo-Owen X, Mukherjee K, Morris, B., Majercik, S., Piotrowski, J. and Dodgion, C (2018). MP25-18 Imaging Findings Associated with Renal Bleeding Interventions after High-grade Trauma: Results from the Amer- ican Association for Surgery of Trauma (AAST) Genito-urinary Trauma Study [Abstract]. Journal of Urology, 199(4S), e333-e334.
  21. Corbett K, Xu Y, Presson A, Bratton S, Dixon R (2018). Multiple Organ Dysfunction Prevalence Following Out-of-hospital Cardiac Arrest in Pediatrics [Abstract]. Critical Care Medicine, 46(1), 220.
  22. Elkeeb D, Xu Y, Presson A, Petersen M, Secrest A (2017). Nonmodifiable patient characteristics as predictors of patient satisfaction in dermatology [Abstract]. Journal of the American Academy of Dermatology, 76(6), AB181-AB181.
  23. Keihani S, Xu Y, Presson AP, Smith BP, Reilly PM, Luo-Owen X, Mukherjee K, Morris BJ, Majercik S, Thomsen PB, Erickson BA (2017). MP79-01 Nephrectomy after High-grade Renal Trauma: Results from the American Association for the Surgery of Trauma (AAST) Genitourinary Trauma Study [Abstract]. Journal of Urology, 197(4S), e1072-ae1073.
  24. Matsen CB, Fagerlin A, Xu Y, Presson A, Kaphingst KA (2017). An Intervention Aimed at Improving Decision Role Concordance in Newly Diagnosed Breast Cancer Patients [Abstract]. Journal of Women's Health, 26(9), 1032-1033.
  25. Cohen JB, Addo DK, Jacobs JA, Greene TH, Xu Y, Picone DS, Shimbo D, Bress A (2026). Impact of a Smartwatch Hypertension Notification Feature for Population Screening. JAMA, 335(11), 1001-1003.
  26. Winn M, Karra P, Benson R, Pauleck S, Chaiyakunapruk N, Khaing W, Veettil SK, McFarland MM, Casucci T, Xu Y, Hu-Lieskovan S, Litchman M, Playdon M, Hardikar (2026). Metabolic Syndrome and Obesity-related cancer Risk and Survival: An Umbrella Review of Systematic Reviews With Meta-analysis of Observational Studies. Obesity reviews, e70073.
  27. An J, Zhou H, Ni L, Juan R, Portugal C, Romero DI, Reynolds K, Brettler JW, Ong-Su AL, Derington CG, Xu Y, Bress AP, Cohen J (2025). Trends in Initial Combination Antihypertensive Therapy in a US Health System. American journal of hypertension,
  28. Winn M, Pauleck S, Richardson S, Viskochil R, Karra P, Colman H, Doherty JA, Xu Y, Hu-Lieskovan S, Litchman M, Playdon MC, Hardikar (2026). New-onset prediabetes/diabetes worsens overall survival in patients with cancer: A real-world retrospective cohort study. Diabetes, obesity & metabolism, 28(2), 1247-1257.
  29. Derington CG, Berchie RO, Greene T, Jacobs JA, Moran AE, Xu Y, Narita K, Zheutlin AR, Cohen JB, Shimbo D, Bress A (2025). Using PREVENT Equations to Compare Intensive vs Standard Systolic Blood Pressure Control for Primary Prevention in SPRINT. Journal of the American College of Cardiology, 86(17), 1437-1448.
  30. Derington CG, Berchie RO, Scharfstein DO, Andrews RM, Greene TH, Xu Y, King JB, Supiano MA, Sonnen JA, Williamson J, Pajewski NM, Pruzin JJ, Cohen JB, Bress A (2025). Effect of Initiation and Continuous Adherence to ARBs Versus ACEIs on Risk of Adjudicated Mild Cognitive Impairment or Dementia. The journals of gerontology. Series A, Biological sciences and medical sciences, 80(7),
  31. Xu Y, Derington CG, Addo DK, He T, Jacobs JA, Mohanty AF, An J, Cushman WC, Ho PM, Bellows BK, Cohen JB, Bress A (2024). Trends in Initial Antihypertensive Medication Prescribing Among >2.8¿Million Veterans Newly Diagnosed With Hypertension, 2000 to 2019. Journal of the American Heart Association, 13(20), e036557.
  32. Andrews RM, Addo DK, Marcum ZA, Greene TH, Xu Y, Derington CG, Berchie R, Pajewski NM, Cohen JB, Pruzin J, Supiano MA, Williamson JD, Bress A (2025). Initiation of ARB-vs ACEI-Based Antihypertensive Regimens and Rates of Cognitive Decline: An Analysis of SPRINT. Neurology open access,
  33. Steinberg E, Ignatiadis N, Yadlowsky S, Xu Y, Shah (2023). Using public clinical trial reports to probe non-experimental causal inference methods. BMC medical research methodology, 23(1), 204.
  34. Wornow M, Xu Y, Thapa R, Patel B, Steinberg E, Fleming S, Pfeffer MA, Fries J, Shah N (2023). The shaky foundations of large language models and foundation models for electronic health records. NPJ digital medicine, 6(1), 135.
  35. Xu Y, Bechler K, Callahan A, Shah (2023). Principled estimation and evaluation of treatment effect heterogeneity: A case study application to dabigatran for patients with atrial fibrillation. Journal of biomedical informatics, 143, 104420.
  36. Xu Y, Foryciarz A, Steinberg E, Shah N (2023). Clinical utility gains from incorporating comorbidity and geographic location information into risk estimation equations for atherosclerotic cardiovascular disease. Journal of the American Medical Informatics Association, 30(5), 878-887.

Book Chapter

  1. Xu Y, Ignatiadis N, Sverdrup E, Fleming S, Wager S, Shah N (2022). Chapter 21: Treatment Heterogeneity with Survival Outcomes. In Zubizaretta JR, Stuart EA, Small DS, Rosenbaum PR (Eds.), Handbook of Matching and Weighting Adjustments for Causal Inference. Chapman & Hall/CRC Press.

Conference Proceedings

  1. Xu Y, Yadlowsky S (2022). Calibration Error for Heterogeneous Treatment Effects. International Conference on Artificial Intelligence and Statistics (AISTAT), 9280-9303.
  2. Pfohl SR, Xu Y, Foryciarz A, Ignatiadis N, Genkins J, Shah NH (2022). Net benefit, calibration, threshold selection, and training objectives for algorithmic fairness in healthcare. Association for Computing Machinery Conference on Fairness, Accountability, and Transparency (ACM FAccT).
  3. Steinberg E, Fries J, Xu Y, Shah (2024). A Time-to-Event Foundation Model For Structured Medical Records.