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Transmission of SARS-CoV-2 Considering Shared Chairs in Outpatient Dialysis: A Real-World Case-Control Study

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

Posted: February 23, 2021
Server: medRxiv
DOI: 10.1101/2021.02.20.21251855

Background

SARS-CoV-2 is primarily transmitted through aerosolized droplets; however, the virus can remain transiently viable on surfaces.

Objective

We examined transmission within hemodialysis facilities, with a specific focus on the possibility of indirect patient-to-patient transmission through shared dialysis chairs.

Design

We used real-world data from hemodialysis patients treated between February 1^stand June 8^th, 2020 to perform a case-control study matching each SARS-CoV-2 positive patient (case) to a non-SARS-CoV-2 patient (control) in the same dialysis shift and traced back 14 days to capture possible exposure from chairs sat in by SARS-CoV-2 patients. Cases and controls were matched on age, sex, race, facility, shift date, and treatment count.

Setting

2,600 hemodialysis facilities in the United States.

Patients

Adult (age ≥18 years) hemodialysis patients.

Measurements

Conditional logistic regression models tested whether chair exposure after a positive patient conferred a higher risk of SARS-CoV-2 infection to the immediate subsequent patient.

Results

Among 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.

Limitation

Analysis used real-world data that could contain errors and only considered vertical transmission associated with shared use of dialysis chairs by symptomatic patients.

Conclusions

The risk of indirect patient-to-patient transmission of SARS-CoV-2 infection from dialysis chairs appears to be low.

Primary Funding Source

Fresenius Medical Care North America; National Institute of Diabetes and Digestive and Kidney Diseases (R01DK130067)

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