COVID-19 and functional dependence: cohort study of an outbreak in a nursing home for elderly

Background: Older people have been severely affected by the COVID-19 pandemic. The aim of this study was to describe the main epidemiological findings of a COVID-19 outbreak occurred in March 2020 at a nursing home for elderly in Granada. Risk factors associated with the spread of the virus in the center were investigated. Methods: A retrospective cohort study was conducted, collecting the most relevant clinical and epidemiological findings, occurred during the outbreak follow-up period (from 03/13/2020 to 06/20/2020). The association between the residents' health conditions (underlying diseases, level of physical dependence, level of cognitive impairment) and the risk of infection was estimated using multivariate Cox regression. Results: 52 PCR-confirmed COVID-19 cases were identified among the residents and 50 cases among the employees of the nursing home. The epidemic curve was characteristic of a person to person transmission. Among residents with a higher level of physical dependence, according to the Barthel index score, a higher incidence of infection was detected, adjusting for age, sex and health conditions. At 55 days of exposure, moderately (RR 2.82), severely (RR 4.71) and completely (RR 3.49) dependent residents had between 2-4 times greater risk of infection than the minimally dependent residents (p<0.05). Conclusions: The epidemic curve supports the hypothesis of a cross-transmission of infections between residents and staff members of the nursing home. In the context of sustained transmission of the virus, physical dependence of the residents increases the risk of exposure to the virus, facilitating its spreading.