The interplay between infection risk factors of SARS-CoV-2 and mortality: a cross-sectional study from a cohort of long-term care nursing home residents

Abstract

Background: Covid-19 pandemic has particularly affected older people living in Long-term Care settings in terms of infection and mortality.

Methods: We carried out a cross-sectional analysis within a cohort of Long-term care nursing home residents between March first and June thirty, 2020, who were ≥ 65 years old and on whom at least one PCR test was performed. Socio-demographic, comorbidities, and clinical data were recorded. Facility size and community incidence of SARS-CoV-2 were also considered. The outcomes of interest were infection (PCR positive) and death.

Results: A total of 8021 residents were included from 168 facilities. Mean age was 86.4 years (SD = 7.4). Women represented 74.1%. SARS-CoV-2 infection was detected in 27.7% of participants, and the overall case fatality rate was 11.3% (24.9% among those with a positive PCR test). Epidemiological factors related to risk of infection were larger facility size (pooled aOR 1.73; P < .001), higher community incidence (pooled aOR 1.67, P = .04), leading to a higher risk than the clinical factor of low level of functional dependence (aOR 1.22, P = .03). Epidemiological risk factors associated with mortality were male gender (aOR 1.75; P < .001), age (pooled aOR 1.16; P < .001), and higher community incidence (pooled aOR 1.19, P = < 0.001) whereas clinical factors were low level of functional dependence (aOR 2.42, P < .001), Complex Chronic Condition (aOR 1.29, P < .001) and dementia (aOR 1.33, P <0.001). There was evidence of clustering for facility and health area when considering the risk of infection and mortality (P < .001).

Conclusions: Our results suggest a complex interplay between structural and individual factors regarding Covid-19 infection and its impact on mortality in nursing-home residents.

Keywords: Covid-19; Epidemiology; Long-term care nursing homes; Mortality; SARS-CoV-2.

Fig. 1

Flow-chart of study population and participants with PCR test available

Fig. 2

Cumulative incidence of SARS-CoV-2 infection of LTCLTCF residents and corresponding catchment area. The testing coverage was similar between different catchment areas during the study period and was mainly focused on symptomatic cases and contacts of positive cases. The incidence shown here is therefore an underestimation of the true incidence but should be considered proportional to it and an acceptable proxy. The size of the pie charts are correlated to the number of LTCF residents registered in each catchment area, not to the size of the LTCF’s

Fig. 3

Forest plot of a OR and 95%CI of studied variables and infection (PCR positive) and death. §. Baseline strata. *Significative results (p ≤ 0,05)