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

  1. Ravi Thadhani
  2. Joanna Willetts
  3. Catherine Wang
  4. John Larkin
  5. Hanjie Zhang
  6. Lemuel Rivera Fuentes
  7. Len Usvyat
  8. Kathleen Belmonte
  9. Yuedong Wang
  10. Robert Kossmann
  11. Jeffrey Hymes
  12. Peter Kotanko
  13. Franklin Maddux

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Abstract

Background

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.

Methods

We 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.

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.

Conclusions

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

Article activity feed

  1. Version published to 10.1186/s12882-021-02518-4
  2. PREreview

    This Zenodo record is a permanently preserved version of a PREreview. You can view the complete PREreview at https://prereview.org/reviews/4589904.

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

     

    By Margarita Orlova Student Reviewer, Rapid Reviews: COVID-19

     

    Main Claim & Relevance: Evaluated the rate of SARS-CoV-2 transmission among 170,234 hemodialysis patients focusing on patient-to-patient transmission through shared chairs. Data between February 1st and June 8th, 2020 was used to match 2,379 SARS-CoV-2 positive cases to 2,379 non-SARS-CoV-2 controls through a 14 day traceback. The study concluded that transmission risk was low and not significantly different between the cases and controls.

    Are the findings strong, reliable, potentially informative, not informative, or misleading? Why? The findings seem reliable, as it was mentioned that the results were consistent in both adjusted and sensitivity analysis. The manuscript also went over potential limitations such as the errors that come with the use of real-world data and that only vertical transmission was considered in the study.

     

    How might these ideas presented by the main claims further knowledge of the COVID-19 pandemic?

    The ideas and claims presented help assess the chance of indirect patient-to-patient transmission through surfaces. While this study specifically analyzes the transmission risks involved in hemodialysis, its data can be extrapolated into other medical services and settings.

     

     

    https://rapidreviewscovid19.mitpress.mit.edu/

  3. ScreenIT

    SciScore for 10.1101/2021.02.20.21251855: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: Patient data were de-identified for analysis, which was performed under a regulatory protocol reviewed by New England Institutional Review Board (Needham Heights, MA, United States; NEIRB WO#: 17-1349084-1); the analysis was approved under Exempt Category (45 CFR 46.104-d4ii) and consent was not required.
    Consent: Patient data were de-identified for analysis, which was performed under a regulatory protocol reviewed by New England Institutional Review Board (Needham Heights, MA, United States; NEIRB WO#: 17-1349084-1); the analysis was approved under Exempt Category (45 CFR 46.104-d4ii) and consent was not required.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Our study has some limitations. We had no data to assess potential transmission in shared vehicle transport to facility. Since most facilities had at only 0 or 1 infected patient, and since patients scheduled in similar shifts are usually transported together in shared personal or medical/public transport vehicles, infection during transport is not anticipated to have affected our results. Second, our analysis considers only symptomatic patients. Therefore, we cannot exclude the possibility of transmission from asymptomatic carriers who never developed symptoms that warranted RT-PCR testing. While asymptomatic spread is possible, individuals who remain asymptomatic throughout their entire course of SARS-CoV-2 infection are typically >30 years younger than the average dialysis patient, who is usually in the mid-sixties, and the secondary attack rate among asymptomatic carriers is generally lower than symptomatic carriers.(32-34) Finally, while we believe the fidelity of linking a specific dialysis machine to a specific chair was maintained, and thus we could examine vertical transmission, we could not examine the potential for horizontal transmission during a single shift because the proximity of one station to another could not be ascertained by the available data. That said, stations are spaced apart, ideally 6 feet, and patients were required to wear masks, making the likelihood of such transmission low. We also acknowledge that in these challenging times, occasional errone...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  4. Version published to 10.1101/2021.02.20.21251855v1 on medRxiv