659. Increased Incidence of Norovirus-Associated Medically-Attended Acute Gastroenteritis among Older Adults with Underlying Chronic Disease
Session: Poster Abstract Session: Oh, Those Pesky Viruses!
Thursday, October 27, 2016
Room: Poster Hall
Background: Norovirus is known to exert a significant burden of disease among elderly individuals and is the major cause of acute gastroenteritis outbreaks in long-term care facilities. However, little is known about whether norovirus-associated gastroenteritis is associated with underlying chronic disease among sporadic cases occurring in the community. The goal of our work was to compare rates of norovirus-associated, medically-attended acute gastroenteritis (MAAGE) among elderly members of Kaiser Permanente Northwest (KPNW) with and without a previously-diagnosed, chronic condition.Methods:  We identified MAAGE episodes based on ICD-9 and chief complaint codes recorded during health care encounters among KPNW members aged ≥60 years occurring from 4/1/2014-3/31/2015. We recruited a sample of individuals with a MAAGE episode to provide a stool specimen for norovirus laboratory testing. We defined the presence of a chronic condition as having at least one ICD-9 code associated with disease in one of eleven categories (i.e. diabetes, heart disease, kidney disease, cancer, etc.).

Results: We observed 6,238 MAAGE episodes occurring among 117,185 KPNW members aged ≥60 years (53.2 episodes per 1,000 individuals). Of these, 4,881 episodes (78%) occurred among those with at least one chronic condition. Among those sampled, the proportion of individuals testing positive for norovirus was not different between those with (23/367, [6.3%]) and without (10/142, [7.0%]) a chronic condition (p=0.74). Despite similar norovirus positivity rates between the two groups, the incidence of norovirus-associated MAAGE was higher among those with at least one underlying condition (2.6 per 1,000; 95% confidence interval [CI] 1.6-3.9) than those without (0.8; CI 0.4-1.4).

Conclusion: Our findings suggest an increased incidence of norovirus-associated MAAGE among those with a chronic condition, compared to those without. Additional research is necessary to compare norovirus-associated MAAGE among patients with different types of conditions, to determine whether having a chronic condition alters the clinical course and severity of acute norovirus-associated disease, and whether norovirus infection affects chronic disease outcomes.

Mark Schmidt, PhD, MPH1, Kayoko Shioda, DVM, MPH2, Allison Naleway, PhD1, Christianne Biggs, MS3 and Aron J. Hall, DVM, MSPH2, (1)Kaiser Permanente Center for Health Research, Portland, OR, (2)Centers for Disease Control and Prevention, Atlanta, GA, (3)Oregon State Public Health Laboratory, Portland, OR


M. Schmidt, None

K. Shioda, None

A. Naleway, None

C. Biggs, None

A. J. Hall, None

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