Nathanael R. Fillmore
Topics / Real World Evidence
Topic

Real World Evidence

Fillmore utilizes large-scale electronic health records and longitudinal data to evaluate clinical outcomes and develop predictive models in diverse patient populations. His work focuses on bridging the gap between clinical trials and bedside practice, specifically through the development of machine learning tools to predict cancer-associated complications and the analysis of how frailty and socioeconomic factors influence survival. By implementing learning health system infrastructures, he has demonstrated that real-world evidence can refine risk stratification and optimize therapeutic selection for patients with complex comorbidities.

U.S. Veterans and VA Data 37 Retrospective Cohort Study 26 Patient Outcomes 19 Electronic Health Records 18 Overall Survival 13 Survival Analysis 13 Cancer Patients 13 Model Validation 9 Frailty 9 Observational Study 8 External Validation 8 Predictive Modeling 8

Publications (39)

2026

Sentinel lymph node biopsy utilization and positivity in veterans with cutaneous melanoma: A comparative analysis of the VA Cancer Registry and the SEER Program.

Daniel Y. Kim, Susan M. Swetter, Linden Huhmann, Jacqueline M. Ferguson, Kimberly Breglio, Allyson C. Spence, Lee Wheless, Mary T. Brophy, Nhan V. Do, Nathanael Fillmore‡, Rebecca I. Hartman‡‡ Equal senior authorship

Journal of the American Academy of Dermatology
U.S. Veterans and VA Data Cutaneous Melanoma VA Cancer Registry SEER Database Sentinel Lymph Node Biopsy
2026

Development and validation of venous thromboembolism-bidirectional encoder representations from transformers (VTE-BERT) natural language processing model.

Omid Jafari, Shengling Ma, Barbara D. Lam, Jun Y. Jiang, Emily Zhou, Mrinal Ranjan, Justine Ryu, Raka Bandyo, Arash Maghsoudi, Bo Peng, Christopher I. Amos, Abiodun Oluyomi, Nathanael R. Fillmore, Jennifer La‡, Ang Li‡‡ Equal senior authorship

Journal of Thrombosis and Haemostasis24(7), 2522-2531
Natural Language Processing External Validation Clinical Notes Radiology and Pathology Reports Cancer Patients
2026

Development and External Validation of a Machine Learning-Based Risk Classification Score for Prostate Cancer-Specific Cardiovascular Risk.

Nickolas Stabellini, Tarek Nahle, Viraj Shah, Sai S. Kollapaneni, Omar M. Makram, Jennifer Cullen, Neal L. Weintraub, Harikrishnan H. Kunhiraman, Umang Swami, Morteza Mahmoudi, Nathanael Fillmore, Isla P. Garraway, Darryl Leong, Jehonathan Pinthus, John Shanahan, Alberto J. Montero, Neeraj Agarwal, Avirup Guha

JCO Oncology PracticeOP2600131
Prostate Cancer Cardiovascular Disease Cardio-Oncology Machine Learning Predictive Modeling
2026

A deep learning model to dynamically predict cancer-associated thromboembolism in large-scale healthcare systems.

Tianshe He†, Chunlei Zheng†, Jennifer La, Dang Pham, Omid Jafari, Jamie Strampe, Karlynn Dulberger, Jaime Ramos-Cejudo, J. Michael Gaziano, Nhan V. Do, Vipul Chitalia, Katya Ravid, Ang Li‡, Nathanael R. Fillmore‡† Equal first authorship · ‡ Equal senior authorship

npj Digital Medicine
U.S. Veterans and VA Data Electronic Health Records Cancer-Associated Thrombosis Predictive Modeling External Validation
2025

Potentially Inappropriate Medications, Frailty, and Outcomes in Patients With Cancer Managed in a National Health Care System.

Jennifer La, Tammy Hshieh, Anahid Hamparsumian, Robert Zwolinski, Jameson Wood, Mayuri Dharne, J. Michael Gaziano, Mary T. Brophy, Nhan V. Do, Nikhil C. Munshi, Jane A. Driver, Gregory A. Abel, Nathanael R. Fillmore‡, Clark DuMontier‡‡ Equal senior authorship

Journal of the National Comprehensive Cancer Network23(9), 363-370
U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records Frailty Overall Survival
2025

Leveraging near-real-time patient and population data to incorporate fluctuating risk of severe COVID-19: development and prospective validation of a personalised risk prediction tool.

Kaitlin Swinnerton†, Nathanael R. Fillmore†, Austin Vo, Jennifer La, Danne Elbers, Mary Brophy, Nhan V. Do, Paul A. Monach‡, Westyn Branch-Elliman‡† Equal first authorship · ‡ Equal senior authorship

eClinicalMedicine81, 103114
U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Severe COVID-19 Predictive Modeling
2025

External validation of a novel cancer-associated venous thromboembolism risk assessment score in a safety-net hospital.

Karlynn N. Dulberger†, Jennifer La†, Ang Li†, Saran Lotfollahzadeh, Asha Jose, Nhan V. Do, Mary T. Brophy, J. Michael Gaziano, Katya Ravid, Vipul C. Chitalia, Nathanael R. Fillmore† Equal first authorship

Research and Practice in Thrombosis and Haemostasis9(1), 102650
Cancer-Associated Thrombosis External Validation Electronic Health Records Retrospective Cohort Study Cancer Patients
2024

Real-world effectiveness of immune checkpoint inhibitors and BRAF/MEK inhibitors among veteran patients with cutaneous melanoma.

Daniel Y. Kim, Susan M. Swetter, Linden Huhmann, Matthew P. Dizon, Jacqueline M. Ferguson, Thomas F. Osborne, Allyson C. Spence, Amina Ziad, Nathanael Fillmore‡, Rebecca I. Hartman‡‡ Equal senior authorship

Journal of the American Academy of Dermatology90(3), 620-623
U.S. Veterans and VA Data Retrospective Cohort Study Cutaneous Melanoma Immune Checkpoint Inhibitors BRAF/MEK Inhibitors
2023

Maintaining the Utility of Coronavirus Disease 2019 Pandemic Severity Surveillance: Evaluation of Trends in Attributable Deaths and Development and Validation of a Measurement Tool.

Caitlin Trottier†, Jennifer La†, Lucy L. Li†, Majd Alsoubani, Austin D. Vo, Nathanael R. Fillmore, Westyn Branch-Elliman, Shira Doron‡, Paul A. Monach‡† Equal first authorship · ‡ Equal senior authorship

Clinical Infectious Diseases77(9), 1247-1256
COVID-19 U.S. Veterans and VA Data Logistic Regression Model Validation Pandemic Surveillance
2023

More intensive therapy as more effective treatment for frail patients with multiple myeloma [corrected].

Clark DuMontier†, Jennifer La†, John Bihn, June Corrigan, Cenk Yildirim, Mayuri Dharne, Hamza Hassan, Sarvari Yellapragada, Gregory A. Abel, J. Michael Gaziano, Nhan V. Do, Mary Brophy, Dae H. Kim, Nikhil C. Munshi, Nathanael R. Fillmore‡, Jane A. Driver‡† Equal first authorship · ‡ Equal senior authorship

Blood Advances7(20), 6275-6284
U.S. Veterans and VA Data Retrospective Cohort Study Multiple Myeloma Frailty Overall Survival
2023

Derivation and Validation of a Clinical Risk Assessment Model for Cancer-Associated Thrombosis in Two Unique US Health Care Systems.

Ang Li†, Jennifer La†, Sarah B. May, Danielle Guffey, Costa Wilson L. da, Christopher I. Amos, Raka Bandyo, Emily M. Milner, Karen M. Kurian, Daniel C. R. Chen, Nhan V. Do, Carolina Granada, Nimrah Riaz, Mary T. Brophy, Vipul Chitalia, J. Michael Gaziano, David A. Garcia, Marc Carrier, Christopher R. Flowers, Neil A. Zakai‡, Nathanael R. Fillmore‡† Equal first authorship · ‡ Equal senior authorship

Journal of Clinical Oncology41(16), 2926-2938
Cancer-Associated Thrombosis Predictive Modeling Retrospective Cohort Study External Validation U.S. Veterans and VA Data
2023

Epidemiology of Cancer-Associated Venous Thromboembolism in Patients With Solid and Hematologic Neoplasms in the Veterans Affairs Health Care System.

Kylee L. Martens†, Ang Li†, Jennifer La, Sarah B. May, Kaitlin N. Swinnerton, Hannah Tosi, Danne C. Elbers, Nhan V. Do, Mary T. Brophy, J. Michael Gaziano, Saran Lotfollahzadeh, Vipul Chitalia, Katya Ravid, Nathanael R. Fillmore† Equal first authorship

JAMA Network Open6(6), e2317945
U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records Cancer-Associated Thrombosis Health Disparities
2023

Coronavirus disease 2019 (COVID-19) hospitalization metrics that do not account for disease severity underestimate protection provided by severe acute respiratory coronavirus virus 2 (SARS-CoV-2) vaccination and boosting: A retrospective cohort study.

June K. Corrigan†, Jennifer La†, Nathanael R. Fillmore, Nhan V. Do, Mary Brophy, Shira Doron, Paul A. Monach‡, Westyn Branch-Elliman‡† Equal first authorship · ‡ Equal senior authorship

Infection Control and Hospital Epidemiology44(1), 149-151
U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records COVID-19 Vaccine Effectiveness
2022

The COVID-19 hospitalization metric in the pre- and postvaccination eras as a measure of pandemic severity: A retrospective, nationwide cohort study.

Nathanael R. Fillmore†, Jennifer La†, Chunlei Zheng, Shira Doron, Nhan V. Do, Paul A. Monach‡, Westyn Branch-Elliman‡† Equal first authorship · ‡ Equal senior authorship

Infection Control and Hospital Epidemiology43(12), 1767-1772
U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Vaccine Effectiveness Hospitalization Metrics
2022

Association of COVID-19 Vaccination With SARS-CoV-2 Infection in Patients With Cancer: A US Nationwide Veterans Affairs Study.

Julie Tsu-Yu Wu†, Jennifer La†, Westyn Branch-Elliman, Linden B. Huhmann, Summer S. Han, Giovanni Parmigiani, David P. Tuck, Mary T. Brophy, Nhan V. Do, Albert Y. Lin‡, Nikhil C. Munshi‡, Nathanael R. Fillmore‡† Equal first authorship · ‡ Equal senior authorship

JAMA Oncology8(2), 281-286
U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Vaccine Effectiveness Cancer Patients
2021

Contemporary Analysis of Electronic Frailty Measurement in Older Adults with Multiple Myeloma Treated in the National US Veterans Affairs Healthcare System.

Clark DuMontier†, Nathanael R. Fillmore†, Cenk Yildirim, David Cheng, Jennifer La, Ariela R. Orkaby, Brian Charest, Diana Cirstea, Sarvari Yellapragada, John Michael Gaziano, Nhan Do, Mary T. Brophy, Dae H. Kim, Nikhil C. Munshi, Jane A. Driver† Equal first authorship

Cancers13(12)
U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records Multiple Myeloma Frailty
2021

Updating and Validating the U.S. Veterans Affairs Frailty Index: Transitioning From ICD-9 to ICD-10.

David Cheng†, Clark DuMontier†, Cenk Yildirim, Brian Charest, Chelsea E. Hawley, Min Zhuo, Julie M. Paik, Enzo Yaksic, J. Michael Gaziano, Nhan Do, Mary Brophy, Kelly Cho, Dae H. Kim, Jane A. Driver, Nathanael R. Fillmore‡, Ariela R. Orkaby‡† Equal first authorship · ‡ Equal senior authorship

Journals of Gerontology: Series A76(7), 1318-1325
U.S. Veterans and VA Data Electronic Health Records Frailty Electronic Frailty Index ICD-10 Coding
2019

Machine Learning Methods to Predict Lung Cancer Survival Using the Veterans Affairs Research Precision Oncology Data Commons.

Nhan V. Do, Jaime C. Ramos, Nathanael R. Fillmore, Robert L. Grossman, Michael Fitzsimons, Danne C. Elbers, Frank Meng, Brett R. Johnson, Samuel Ajjarapu, Corri L. DeDomenico, Karen E. Pierce-Murray, Robert B. Hall, Andrew F. Do, Kelly Gaynor, Peter L. Elkin, Mary T. Brophy

Studies in Health Technology and Informatics264, 1453
U.S. Veterans and VA Data Lung Cancer Machine Learning Predictive Modeling Overall Survival