Nathanael Fillmore

Dr. Nathanael Fillmore

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

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

Representative Publications

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9 March 2021 in The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences
Verified
Journal Article
Open access
PDF file
DCDavid Cheng
David Cheng
CDClark DuMontier
Clark DuMontier
CYCenk Yildirim
Cenk Yildirim
BCBrian Charest
Brian Charest
CHChelsea E Hawley
Chelsea E Hawley
AOAriela R Orkaby
Ariela R Orkaby
The Veterans Affairs Frailty Index (VA-FI) is an electronic frailty index developed to measure frailty using administrative claims and electronic health records data in Veterans. An update to ICD-10 coding is needed to enable contemporary measurement of frailty. International Classification of Diseases, ninth revision (ICD-9) codes from the original VA-FI were mapped to ICD-10 first using the Centers for Medicaid and Medicare Services (CMS) General Equivalence Mappings. The resulting ICD-10 codes were reviewed by 2 geriatricians. Using a national cohort of Veterans aged 65 years and older, the prevalence of deficits contributing to the VA-FI and associations between the VA-FI and mortality over years 2012–2018 were examined. The updated VA-FI-10 includes 6422 codes representing 31 health deficits. Annual cohorts defined on October 1 of each year included 2 266 191 to 2 428 115 Veterans, for which the mean age was 76 years, 97%–98% were male, 78%–79% were White, and the mean VA-FI was 0.20–0.22. The VA-FI-10 deficits showed stability before and after the transition to ICD-10 in 2015, and maintained strong associations with mortality. Patients classified as frail (VA-FI > 0.2) consistently had a hazard of death more than 2 times higher than nonfrail patients (VA-FI ≤ 0.1). Distributions of frailty and associations with mortality varied with and without linkage to CMS data and with different assessment periods for capturing deficits. The updated VA-FI-10 maintains content validity, stability, and predictive validity for mortality in a contemporary cohort of Veterans aged 65 years and older, and may be applied to ICD-9 and ICD-10 claims data to measure frailty.

13 June 2019 in Blood
Verified
Journal Article
Open access
PDF file
NFNathanael Fillmore
Nathanael Fillmore
SYSarvari V. Yellapragada
Sarvari V. Yellapragada
CIChizoba Ifeorah
Chizoba Ifeorah
AMAnsh Mehta
Ansh Mehta
DCDiana Cirstea
Diana Cirstea
NMNikhil C. Munshi
Nikhil C. Munshi

8 October 2020 in JNCI: Journal of the National Cancer Institute
Verified
Journal Article
Closed access
NFNathanael Fillmore
Nathanael Fillmore
JLJennifer La
Jennifer La
RSRaphael E Szalat
Raphael E Szalat
DTDavid P Tuck
David P Tuck
VNVinh Nguyen
Vinh Nguyen
NMNikhil C Munshi
Nikhil C Munshi
Background: Emerging data suggest variability in susceptibility and outcome to coronavirus disease 2019 (COVID-19) infection. Identifying risk factors associated with infection and outcomes in cancer patients is necessary to develop healthcare recommendations. Methods: We analyzed electronic health records of the US Veterans Affairs Healthcare System and assessed the prevalence of COVID-19 infection in cancer patients. We evaluated the proportion of cancer patients tested for COVID-19 who were positive, as well as outcome attributable to COVID-19, and stratified by clinical characteristics including demographics, comorbidities, cancer treatment, and cancer type. All statistical tests are 2-sided. Results: Of 22 914 cancer patients tested for COVID-19, 1794 (7.8%) were positive. The prevalence of COVID-19 was similar across age. Higher prevalence was observed in African American (15.0%) compared with White (5.5%; P < .001) and in patients with hematologic malignancy compared with those with solid tumors (10.9% vs 7.8%; P < .001). Conversely, prevalence was lower in current smokers and patients who recently received cancer therapy (<6 months). The COVID-19–attributable mortality was 10.9%. Higher attributable mortality rates were observed in older patients, those with higher Charlson comorbidity score, and in certain cancer types. Recent (<6 months) or past treatment did not influence attributable mortality. Importantly, African American patients had 3.5-fold higher COVID-19–attributable hospitalization; however, they had similar attributable mortality as White patients. Conclusion: Preexistence of cancer affects both susceptibility to COVID-19 infection and eventual outcome. The overall COVID-19–attributable mortality in cancer patients is affected by age, comorbidity, and specific cancer types; however, race or recent treatment including immunotherapy do not impact outcome.

1 June 2023 in Journal of Clinical Oncology
Verified
Journal Article
Open access
ALAng Li
Ang Li
JLJennifer La
Jennifer La
SMSarah B. May
Sarah B. May
DGDanielle Guffey
Danielle Guffey
WCWilson L. da Costa
Wilson L. da Costa
NFNathanael Fillmore
Nathanael Fillmore
PURPOSE: Venous thromboembolism (VTE), especially pulmonary embolism (PE) and lower extremity deep vein thrombosis (LE-DVT), is a serious and potentially preventable complication for patients with cancer undergoing systemic therapy.METHODS: Using retrospective data from patients diagnosed with incident cancer from 2011-2020, we derived a parsimonious risk assessment model (RAM) using least absolute shrinkage and selection operator regression from the Harris Health System (HHS, n = 9,769) and externally validated it using the Veterans Affairs (VA) health care system (n = 79,517). Bootstrapped c statistics and calibration curves were used to assess external model discrimination and fit. Dichotomized risk strata using integer scores were created and compared against the Khorana score (KS).RESULTS: Incident VTE and PE/LE-DVT at 6 months occurred in 590 (6.2%) and 437 (4.6%) patients in HHS and 4,027 (5.1%) and 3,331 (4.2%) patients in the VA health care system. Assessed at the time of systemic therapy initiation, the new RAM included components of the KS with the modified cancer subtype, cancer staging, systemic therapy class, history of VTE, history of paralysis/immobility, recent hospitalization, and Asian/Pacific Islander race. The c statistic was 0.71 in HHS and 0.68 in the VA health care system (compared with 0.65 and 0.60, respectively, for KS). Furthermore, the new RAM appropriately reclassified 28% of patients and increased the proportion of VTEs in the high-risk group from 37% to 68% in the validation data set.CONCLUSION: The novel RAM stratified patients with cancer into a high-risk group with 8%-10% cumulative incidence of VTE and 7% PE/LE-DVT at 6 months ( v 3% and 2%, respectively, in the low-risk group). The model had improved performance over the original KS and doubled the number of VTE events in the high-risk stratum. We encourage additional external validation from prospective studies. [Media: see text]

2 December 2021 in JAMA Oncology
Verified
Journal Article
Open access
PDF file
JWJulie Tsu-Yu Wu
Julie Tsu-Yu Wu
JLJennifer La
Jennifer La
WBWestyn Branch-Elliman
Westyn Branch-Elliman
LHLinden B. Huhmann
Linden B. Huhmann
SHSummer S. Han
Summer S. Han
NFNathanael Fillmore
Nathanael Fillmore
Although patients with cancer have poor COVID-19–related outcomes,1-4 the effectiveness of SARS-CoV-2 vaccination in this population is unclear because they were excluded from vaccination trials.5,6 Recent studies suggest that patients with cancer mount less robust antibody responses to vaccination than immunocompetent controls.7-10 The objective of this retrospective cohort study in the national Veterans Affairs (VA) health care system was to estimate the SARS-CoV-2 vaccination effectiveness in patients with cancer in a real-world setting during the 140-day period following initial vaccine availability.

28 October 2021 in PLOS ONE
Verified
Journal Article
Open access
PDF file
NFNathanael Fillmore
Nathanael Fillmore
SBSteven Bell
Steven Bell
CSCiyue Shen
Ciyue Shen
VNVinh Nguyen
Vinh Nguyen
JLJennifer La
Jennifer La
CSChris Sander
Chris Sander
Effective, low-cost therapeutics are needed to prevent and treat COVID-19. Severe COVID-19 disease is linked to excessive inflammation. Disulfiram is an approved oral drug used to treat alcohol use disorder that is a potent anti-inflammatory agent and an inhibitor of the viral proteases. We investigated the potential effects of disulfiram on SARS-CoV-2 infection and disease severity in an observational study using a large database of clinical records from the national US Veterans Affairs healthcare system. A multivariable Cox regression adjusted for demographic information and diagnosis of alcohol use disorder revealed a reduced risk of SARS-CoV-2 infection with disulfiram use at a hazard ratio of 0.66 (34% lower risk, 95% confidence interval 24–43%). There were no COVID-19 related deaths among the 188 SARS-CoV-2 positive patients treated with disulfiram, in contrast to 5–6 statistically expected deaths based on the untreated population (P = 0.03). Our epidemiological results suggest that disulfiram may contribute to the reduced incidence and severity of COVID-19. These results support carefully planned clinical trials to assess the potential therapeutic effects of disulfiram in COVID-19.