Cross-Sectional Analysis of Risk Factors for Outbreak of COVID-19 in Nursing Homes for Older Adults in the Community of Madrid

Abstract

<b><i>Introduction:</i></b> Nursing homes for older adults have been hot spots for SARS-CoV-2 infections and mortality. Factors that facilitate COVID-19 outbreaks in these settings need to be assessed. <b><i>Methods:</i></b> A retrospective cross-sectional study of a cohort of residents and workers in nursing homes taking occasion of a point seroprevalence survey was done in the Community of Madrid. Factors related to outbreaks in these facilities were analyzed. <b><i>Results:</i></b> A total of 369 nursing homes for older adults, making a population of 23,756 residents and 20,795 staff members, were followed from July to December 2020. There were 54.2% SARS-CoV-2 IgG+ results in residents and in 32.2% of workers. Sixty-two nursing homes (16.8%) had an outbreak during the follow-up. Nursing homes with outbreaks had more residents than those without (median number of 81 [IQR, 74] vs. 50 [IQR, 56], <i>p</i> < 0.001). Seropositivity for SARS-CoV-2 was lower in facilities with versus without outbreaks, for residents (42.2% [IQR, 55.7] vs. 58.7% [IQR, 43.4], <i>p</i> = 0.002) and for workers (23.9% [IQR, 26.4] vs. 32.8% [IQR, 26.3], <i>p</i> = 0.01). For both residents and staff, the number of infections in outbreaks was larger in centers with lower, as compared with intermediate or high seroprevalence. The size of the facility did not correlate with the number of cases in the outbreak. Taking the incidence of cases in the community as a time-dependent variable (<i>p</i> = 0.03), a Cox analysis (HR [95% CI], <i>p</i>) showed that intermediate or high seroprevalence among residents in the facility was related to a reduction of 55% (0.45 [0.25–0.80], <i>p</i> = 0.007) and 78% (0.22 [0.10–0.48], <i>p</i> < 0.001) in the risk of outbreaks, respectively, as compared with low sero­prevalence. Also, as compared with smaller, medium (1.91 [1.00–3.65], <i>p</i> = 0.05) or large centers (4.57 [2.38–8.75], <i>p</i> < 0.001) had more respective risk of outbreaks. <b><i>Conclusions:</i></b> The size of the facility and the seroprevalence among residents in nursing homes, and the incidence of infections in the community, are associated with the risk of outbreaks of COVID-19. Facilities with greater proportion of seropositives had smaller number of cases. Monitoring of immunity in nursing homes may help detect those at a greater risk of future cases.

Expert Consensus: Main Risk Factors for Poor Prognosis in COVID-19 and the Implications for Targeted Measures against SARS-CoV-2

“…The strength of this association increases with the number of comorbidities affecting the patient, with the association being highest for three or more pathological processes, both in unvaccinated and vaccinated subjects, including pediatric patients [ 9 , 40 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 ]. In nursing homes for older adults (NHOA), the factors associated with poorer clinical outcomes are age, health status and frailty [ 31 , 88 , 90 , 92 , 95 , 107 , 108 , 109 , 110 , 111 , 112 , 113 ]. There are different scales for determining frailty (CFS, Rockwood, FRAIL, ISAR, Green) [ 114 ], although in all of them the worst prognosis is defined by a score of 4 or higher.…”

Factors Associated with SARS-CoV-2 Infection in Fully Vaccinated Nursing Home Residents and Workers

“…Additionally, our sample size was limited to two nursing homes, each with specific characteristics, such as the number of beds, internal seroprevalence, and incidence of cases in the surrounding community [ 4 ], influencing the generalizability of findings. Clinical information during the Omicron outbreak was limited to case diagnoses and deaths, lacking detailed characteristics, such as severity, hospitalization, or cause of death, which would have been valuable for assessment.…”

“…After this initial wave, nursing homes faced heightened infection risks, with 62 in the Community of Madrid reporting outbreaks between July and December 2020. These outbreaks were linked to facility size and resident seroprevalence [ 4 ]. Subsequently, from August 2020 to February 2021, 30 outbreaks were reported among 39 centers in Madrid, showing an incidence rate of 11%, a 55% hospitalization rate, and a 22% mortality rate [ 5 ].…”

Drivers of COVID-19 Outcomes in Long-Term Care Facilities Using Multi-Level Analysis: A Systematic Review

“…The environmental factors frequently emerged and supported by a substantial body of evidence linked to outbreaks include a higher number of beds, occupancy rate [21,25,26,30,31,34,47,54,56,60,61,63,65,67,72,73,[82][83][84]91,94,97,106], presence of outbreaks in surrounding counties/communities [6,26,[29][30][31]37,38,60,69,79,80,84,91,93,99,104], high-density communities [21,29,56,67,73,106] socioeconomic status of the community, [24,64,77,84,…”