The keys to control a COVID-19 outbreak in a haemodialysis unit

Abstract

Background: The high rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreading represents a challenge to haemodialysis (HD) units. While fast isolation of suspected cases plays an essential role to avoid disease outbreaks, significant rates of asymptomatic cases have recently been described. After detecting an outbreak in one of our HD clinics, wide SARS-CoV-2 screening and segregation of confirmed cases were performed.

Methods: The entire clinic population, 192 patients, underwent testing for SARS-CoV-2 detection by real-time reverse-transcriptase polymerase chain reaction . We used univariate and multivariate logistic regression to define variables involved in SARS-CoV-2 infection in our dialysis unit. Later, we analysed differences between symptomatic and asymptomatic SARS-CoV-2-positive patients.

Results: In total, 22 symptomatic and 14 of the 170 asymptomatic patients had a SARS-CoV-2-positive result. Living in a nursing home/homeless [odds ratio (OR) 3.54; P = 0.026], having been admitted to the reference hospital within the previous 2 weeks (OR 5.19; P = 0.002) and sharing health-care transportation with future symptomatic (OR 3.33; P = 0.013) and asymptomatic (OR 4.73; P = 0.002) positive patients were independent risk factors for a positive test. Nine positive patients (25.7%) remained asymptomatic after a 3-week follow-up. We found no significant differences between symptomatic and asymptomatic SARS-CoV-2-positive patients.

Conclusions: Detection of asymptomatic SARS-CoV-2-positive patients is probably one of the key points to controlling an outbreak in an HD unit. Sharing health-care transportation to the dialysis unit, living in a nursing home and having been admitted to the reference hospital within the previous 2 weeks, are major risk factors for SARS-CoV-2 infection.

Keywords: COVID-19; asymptomatic carriers; dialysis; haemodialysis; outbreak; outcomes; risk factors.

FIGURE 1:

(A) Between 20 and 28 March 2020, a total of 192 nasopharyngeal samples from HD patients were collected and screened for SARS-CoV-2 detection by RT-PCR. A first group of symptomatic patients (n = 22) were initially tested and confirmed as positive for COVID-19 disease. After this finding, the rest of the patients from the clinic, asymptomatic at that moment, were also screened. Fourteen out of 170 asymptomatic patients had a SARS-CoV-2-positive result. One patient was considered as lost to follow-up. Since early April, four patients COVID-positive who remained asymptomatic communicated the appearance of COVID-19 symptoms. However, a group of nine patients remained totally asymptomatic after a follow-up of 21 days. ⁺, positive population; ⁻, negative population; FUp, follow-up. (B) Cumulative incidence of the number of COVID-19-positive cases along the study.