Excess mortality following community-onset norovirus enteritis in the elderly.

Norovirus has been associated with excess deaths. A retrospective study of mortality following norovirus enteritis (NVE) was undertaken. All hospitalized adult patients with a stool sample positive for norovirus genogroup II on polymerase chain reaction, treated at Sahlgrenska University Hospital, Gothenburg, Sweden between August 2008 and June 2009, were included as cases (N = 598, aged 18-101 years). Matched controls without enteritis (N = 1196) were selected for comparison. Medical records were reviewed and deaths up to 90 days following positive sampling were noted, as well as comorbidities and length of hospital stay. Thirty- and 90-day survival rates were calculated. Total 30-day mortality was 7.6% and no deaths were recorded in cases aged 18-59 years. Thirty-day mortality was higher in cases with underlying medical conditions compared with those without these comorbidities (age 60-101 years: 89.5% vs 94.7% alive at Day 30, respectively; P < 0.05). In cases aged > 80 years, mortality was higher in those with community-onset NVE (N = 64) compared with hospital-onset NVE (N = 305) (81.2% vs 90.2% alive at Day 30, respectively; P < 0.05), and compared with controls (N = 128) (81.2% vs 91.4% alive at Day 30, respectively; P < 0.05). Median length of hospital stay was 20 [interquartile range (IQR) 12-29] days for cases with hospital-onset NVE, and seven (IQR 2-13) days for controls (P < 0.001). In conclusion, community-onset NVE requiring hospitalization was associated with higher mortality compared with hospital-onset NVE and matched controls in hospitalized elderly patients.