Individual-level Factors Associated With Acute Hospitalization After Medically Attended Acute Gastroenteritis and Norovirus Gastroenteritis in the United States, 2022-2024.

Background: Norovirus is a leading cause of acute gastroenteritis (AGE) in the United States and is associated with substantial healthcare utilization, including risk of hospitalization. The extent to which underlying medical conditions contribute to this risk is not well understood. Methods: This retrospective cohort study analyzed adults with incident medically attended all-cause AGE or cause-specified norovirus AGE episodes identified via Results: Of 1 705 514 all-cause AGE and 5805 norovirus AGE cases, 11.3% and 44.6%, respectively, were hospitalized within 3 days of their episode. Hospitalization risk was higher for patients with cardiovascular disease (CVD) (all-cause AGE aRR: 1.67 [95% CI, 1.64-1.69]; norovirus AGE aRR: 1.37 [1.22-1.54]), blood disorders, chronic respiratory disease, and chronic kidney disease. Relative to individuals without underlying conditions, hospitalization risk was higher for those with ≥2 conditions (all-cause AGE aRR: 2.02 [95% CI, 1.98-2.07]; norovirus AGE aRR: 1.79 [1.50-2.14]), exceeding the risk among those with 1 condition. Relative risk of acute hospitalization associated with presence of underlying conditions was higher among adults aged 18-64 years than among those ≥65 years. Conclusions: Underlying conditions, notably CVD and ≥2 underlying conditions, significantly increased the risk of acute hospitalization, which was elevated among adults aged 18-64 years.