Abstract
IMPORTANCE: Norovirus is the leading cause of acute gastroenteritis among all ages in the US. Older adults, including veterans, are a potential target group for future vaccination and therapeutics, and more data are needed on the economic burden of norovirus among this population. OBJECTIVE: To quantify the outpatient, emergency department (ED), and inpatient health care costs associated with laboratory-confirmed norovirus episodes among veterans seeking care in the Veterans Health Administration (VHA). DESIGN, SETTING, AND PARTICIPANTS: This economic evaluation used VHA electronic health record and health care cost data between January 1, 2010, and December 31, 2024, with costs adjusted to 2024 dollars. Participants were veterans (aged ≥18 years) with norovirus who sought care from VHA clinics and hospitals nationwide. Norovirus episodes were categorized as outpatient, ED, or inpatient. EXPOSURE: Norovirus episodes laboratory-confirmed by polymerase chain reaction assays. MAIN OUTCOMES AND MEASURES: Outpatient, ED, and inpatient costs for encounters or admissions within 2 days of the norovirus-positive test result. Costs were extrapolated to the expected number of annual norovirus episodes with and without laboratory confirmation in the VHA using published incidence rates. RESULTS: A total of 7768 norovirus episodes from 7520 patients (median [IQR] age, 62 [45-74] years; 6862 males [88%]; median [IQR] Charlson Comorbidity Index [CCI], 1 [0-4]) were included in the analysis. There were 3520 outpatient, 2018 ED, and 2230 inpatient norovirus episodes, with respective median (IQR) costs of $640 ($207-$1291), $2203 ($1596-$2989), and $14 083 ($8045-$26 672). Median (IQR) inpatient costs were higher among older age groups ($12 777 [$7297-$23 737], $16 075 [$9291-$29 311], and $18 566 [$10 676-$33 582] for those aged 45-64 years, 65-84 years, and ≥85 years, respectively) than younger adults ($7751 [$4768-$14 984] and $9394 [$5474-$15 830] for those aged 18-24 years and 25-44 years, respectively; P < .001). Median (IQR) inpatient costs were also higher across CCI categories, with the highest for CCI of 5 or higher ($18 508 [$10 445-$35 900]). The overall extrapolated annual cost to the VHA was $28 438 556. CONCLUSIONS AND RELEVANCE: This study found norovirus to be a substantial economic burden in the VHA. Developing targeted interventions, such as vaccines and antivirals, for this population may result in cost savings.