Norovirus doubles death risk for older veterans, study finds
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Key takeaways:
- A positive norovirus test was associated with an increased risk of hospitalization for older veterans with comorbidities.
- Patients also had an increased risk of mortality within 3 days of receiving a norovirus test.
Older veterans were slightly more likely to be hospitalized and more than twice as likely to die in the 3 days after testing positive for norovirus compared with those who tested negative, according to study results.
“Norovirus causes diarrhea and vomiting. For most people, this will usually resolve within 1 to 3 days, however, for older adults, particularly those with underlying health conditions, norovirus can sometimes have severe complications that may require hospitalization, and in some rare instances can cause death,” Jordan Cates, PhD, an epidemiologist in CDC’s Division of Viral Diseases, told Healio.
“This study helps to understand the impact of norovirus infection on the risk of hospitalization and mortality, particularly death within three days of being diagnosed with norovirus infection, using a large database with laboratory-confirmed norovirus infection,” Cates said.
Cates and colleagues analyzed electronic health record data from a cohort study of adults who were tested for norovirus within the Veterans Affairs health care system between Jan. 1, 2010, and Dec. 31, 2018. The researchers then determined adjusted risk ratios for hospitalization and mortality using log-binomial regression models, adjusting for age, Clostridioides difficile, underlying medical conditions and nursing home residence status.
In total, 25,668 stool samples were collected from more than 23,000 veterans, with 2,156 (8.4%) testing positive for norovirus. The average age at time of testing was 65 years, though the study showed that a larger proportion of patients who tested positive for norovirus were aged 85 years or older (12.3%) vs. patients who tested negative (6.6%).
A larger proportion of these patients also had documentation of a nursing home residence (24.9%) compared with those who tested negative for norovirus (15.8%). Additionally, approximately one in every four patients who tested positive had a Charlson Comorbidity Index severity score of 5 or greater.
The researchers also reported that testing positive was associated with a slight increased risk of hospitalization (aRR = 1.13; 95% CI, 1.06-1.21) and a significant increased risk of mortality within 3 days after receiving a norovirus test (aRR = 2.14; 95% CI, 1.1-4.14), though they added that the mortality aRR within 1 week and 1 month reduced to 1.4 (95% CI, 0.84-2.34) and 0.97 (95% CI, 0.7-1.35), respectively.
“Clinicians treating older patients for acute gastroenteritis should be aware of these elevated risks and be sure to include norovirus as a potentially serious diagnosis, particularly in vulnerable patients with other diseases, and those living in congregate settings such as nursing homes,” Cates said. “Infection control measures, such as thorough hand washing, cleaning and disinfecting surfaces with bleach and patient isolation and contact precautions in congregate or health care settings are the best ways to prevent norovirus and keep it from spreading to others.”