Transmission of SARS-CoV-2 considering shared chairs in outpatient dialysis: a real-world case-control study

Ravi Thadhani,Kathleen Belmonte,Peter Kotanko,Robert Kossmann,Catherine Wang,Franklin Maddux,Yuedong Wang,John Larkin,Hanjie Zhang,Joanna Willetts,Len Usvyat,Jeffrey Hymes,Lemuel Rivera Fuentes

doi:10.1186/s12882-021-02518-4

Abstract

BackgroundSARS-CoV-2 can remain transiently viable on surfaces. We examined if use of shared chairs in outpatient hemodialysis associates with a risk for indirect patient-to-patient transmission of SARS-CoV-2.MethodsWe used data from adults treated at 2,600 hemodialysis facilities in United States between February 1st and June 8th, 2020. We performed a retrospective case-control study matching each SARS-CoV-2 positive patient (case) to a non-SARS-CoV-2 patient (control) treated in the same dialysis shift. Cases and controls were matched on age, sex, race, facility, shift date, and treatment count. For each case-control pair, we traced backward 14 days to assess possible prior exposure from a ‘shedding’ SARS-CoV-2 positive patient who sat in the same chair immediately before the case or control. Conditional logistic regression models tested whether chair exposure after a shedding SARS-CoV-2 positive patient conferred a higher risk of SARS-CoV-2 infection to the immediate subsequent patient.ResultsAmong 170,234 hemodialysis patients, 4,782 (2.8 %) tested positive for SARS-CoV-2 (mean age 64 years, 44 % female). Most facilities (68.5 %) had 0 to 1 positive SARS-CoV-2 patient. We matched 2,379 SARS-CoV-2 positive cases to 2,379 non-SARS-CoV-2 controls; 1.30 % (95 %CI 0.90 %, 1.87 %) of cases and 1.39 % (95 %CI 0.97 %, 1.97 %) of controls were exposed to a chair previously sat in by a shedding SARS-CoV-2 patient. Transmission risk among cases was not significantly different from controls (OR = 0.94; 95 %CI 0.57 to 1.54; p = 0.80). Results remained consistent in adjusted and sensitivity analyses.ConclusionsThe risk of indirect patient-to-patient transmission of SARS-CoV-2 infection from dialysis chairs appears to be low.

Highlights

SARS-CoV-2 can remain transiently viable on surfaces
For each SARS-CoV-2 positive patient, we identified their most recent dialysis treatment during their exposure period, identified non-SARS-CoV-2 patients who were treated in that same facility on that day, and selected a control as the patient who has the best match with the case based on shift time, number of treatments during exposure period, gender, age, and race, in that hierarchical order (Fig. 1)
We considered data from 170,234 adult hemodialysis patients treated at 2,600 outpatient facilities for matching and identification of case-control pairs (Fig. 2)

Summary

Introduction

SARS-CoV-2 can remain transiently viable on surfaces. We examined if use of shared chairs in outpatient hemodialysis associates with a risk for indirect patient-to-patient transmission of SARS-CoV-2. Most ESKD patients are treated in an outpatient setting and require thrice weekly maintenance hemodialysis. The pandemic has highlighted several population-specific vulnerabilities to increased mortality risk, including older age, non-white race, and presence of underlying conditions such as diabetes, obesity, cardiovascular disease, and ESKD requiring maintenance hemodialysis [4,5,6,7]. Outpatient dialysis facilities worldwide implemented enhanced infection control measures to limit transmission of SARS-CoV-2 [13,14,15]. While the primary mode of person-to-person transmission of the SARS-CoV-2 virus is through aerosolized droplets, [17, 18] the virus can deposit and remain transiently viable on surfaces, and surface-to-individual transmission represents yet another opportunity for infection [19,20,21]

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Discussion

Conclusion