Risk Factors for Outbreaks of COVID-19 in Care Homes Following Hospital Discharge: A National Cohort Analysis

Abstract

Background: Adult residential and nursing care homes are settings in which older and often vulnerable people live in close proximity. This population experiences a higher proportion of respiratory and gastrointestinal illnesses than the general population and has been shown to have a high morbidity and mortality in relation to COVID-19.Methods: We examined 3,115 hospital discharges to 1,068 Welsh adult care homes and the subsequent outbreaks of COVID-19 occurring over an 18 week period between 22 February and 27 June 2020. A Cox proportional hazards regression model was used to assess the impact of time-dependent exposure to hospital discharge on the incidence of the first known outbreak, over a window of 7-21 days after discharge, and adjusted for care home characteristics, including size, type of provision and health board.Results: A total of 330 homes experienced an outbreak of COVID-19, and 544 homes received a discharge from hospital over the study period. The exposure to discharge from hospital was not associated with a significant increase in the risk of a new outbreak (hazard ratio 1·15, 95% CI 0·89, 1·47, p = 0.29) after adjusting for care home characteristics. Care home size was by far the most significant predictor. Hazard ratios (95% CI) in comparison to homes of Conclusion: Our analyses showed that large homes were at considerably greater risk of outbreaks throughout the epidemic, and after adjusting for care home size, a discharge from hospital was not associated with a significant increase in risk.Funding Statement: No specific funding was sought or provided for this work.Declaration of Interests: None declared.Ethics Approval Statement: This analysis was carried out as part of the ongoing response to the Covid-19 epidemic in Wales, under the governance of the Public Health Wales Incident Management Team, so ethical approval was not required.