Incidence and risk factors for norovirus‐related diarrhea in Japanese geriatric intermediate care facilities: A prospective cohort study

Abstract

AimThe risk of developing infectious diarrhea among elderly residents at Japanese geriatric intermediate care facilities is unclear. We investigated the incidence rate and risk factors of norovirus‐related diarrhea at such facilities.MethodsThis prospective cohort study followed 1727 residents from November 2018 to April 2020 at 10 geriatric intermediate care facilities in Osaka, Japan regarding the occurrence of diarrhea. Resident data were collected from their medical records using structured forms at two to three of the following three time points: at recruitment, if they developed diarrhea, and when they left the facility. Residents who developed diarrhea were tested using rapid diagnostic tests for norovirus. Cox proportional hazard model was employed to hazard ratios (HRs) with 95% confidence intervals (CIs) to estimate the risk factors for norovirus‐related diarrhea.ResultsDuring the study period, 74 residents developed diarrhea, 13 of whom were norovirus positive. The incidence rate of norovirus‐related diarrhea was 10.11 per 1000 person‐years (95% CI: 4.61–15.61). In terms of risk factors, people with care‐needs level 3 were at a higher risk for developing norovirus‐related diarrhea (adjusted HR [aHR] = 7.35, 95% CI: 1.45–37.30). Residents with hypertension (aHR = 3.41, 95% CI: 1.05–11.04) or stroke (aHR = 8.84, 95% CI: 2.46–31.83), and those who walked with canes (aHR = 16.68, 95% CI: 1.35–206.52) also had a significantly higher risk for norovirus‐related diarrhea.ConclusionsThroughout the study period, the incidence of development of diarrhea was low. Care‐needs level 3, stroke, hypertension and use of a cane were identified as risk factors for norovirus‐related diarrhea in Japanese geriatric intermediate care facilities. Geriatr Gerontol Int 2023; 23: 179–187.