Epidemiology of COVID-19 in an Urban Dialysis Center

Abstract

Background: During the coronavirus disease 2019 (COVID-19) epidemic, many countries have instituted population-wide measures for social distancing. The requirement of patients on dialysis for regular treatment in settings typically not conducive to social distancing may increase their vulnerability to COVID-19.

Methods: Over a 6-week period, we recorded new COVID-19 infections and outcomes for all adult patients receiving dialysis in a large dialysis center. Rapidly introduced control measures included a two-stage routine screening process at dialysis entry (temperature and symptom check, with possible cases segregated within the unit and tested for SARS-CoV-2), isolated dialysis in a separate unit for patients with infection, and universal precautions that included masks for dialysis nursing staff.

Results: Of 1530 patients (median age 66 years; 58.2% men) receiving dialysis, 300 (19.6%) developed COVID-19 infection, creating a large demand for isolated outpatient dialysis and inpatient beds. An analysis that included 1219 patients attending satellite dialysis clinics found that older age was a risk factor for infection. COVID-19 infection was substantially more likely to occur among patients on in-center dialysis compared with those dialyzing at home. We observed clustering in specific units and on specific shifts, with possible implications for aspects of service design, and high rates of nursing staff illness. A predictive epidemic model estimated a reproduction number of 2.2; cumulative cases deviated favorably from the model from the fourth week, suggesting that the implemented measures controlled transmission.

Conclusions: The COVID-19 epidemic affected a large proportion of patients at this dialysis center, creating service pressures exacerbated by nursing staff illness. Details of the control strategy and characteristics of this epidemic may be useful for dialysis providers and other institutions providing patient care.

Keywords: COVID-19; clinical epidemiology; haemodialysis.

Figure 1.

Epidemic timeline by incident patient testing. Epidemic timeline in patients on dialysis showing counts of patients with symptoms suggestive of COVID-19 and testing for SARS-CoV-2 according to date of test. From March 10, all patients on in-center hemodialysis were screened before each dialysis session (symptom questions and temperature) to select those for SARS-CoV-2 testing and dialysis in a segregated area of the unit: patients with positive tests were treated in a dedicated isolation unit starting from their next session. Tests were performed as clinically indicated in patients on home dialysis and those presenting to hospital emergency departments.

Figure 2.

Cumulative counts of patients positive for SARS-CoV-2 according to clinical status and absent nursing staff during the epidemic between March 9 and April 20, 2020. (A) Clinical status of all patients on dialysis developing COVID-19. Patients on in-center hemodialysis who were not hospitalized were isolated for outpatient dialysis for at least 14 days. Prior to March 17, a hospital ward was used, after which three dedicated isolation units were created (arrows) by moving patients between units. (B) Absence from work due to illness (usually without SARS-CoV-2 testing) in dialysis nursing staff.

Figure 3.

Variation in infection proportion between satellite unit and shift. (A) Funnel plot showing unit infection by unit size (number of patients) for the seven nonisolation satellite units (indicated as A–G), with hospital dialysis (indicated as H) and home dialysis (indicated as I) included for comparison along with 90% (solid lines) and 99% (dashed lines) control limits. (B) Infection in specific shifts (n=39) of satellite units by proportion with infection in the whole unit, with linear regression line.

Figure 4.

Deviation from predictive model suggesting control of the epidemic. Cumulative number of COVID-19 cases between March 9 and April 20. Observed cumulative cases (log scale) starting from the tenth case alongside the modeled epidemic curve assuming an R₀ of 2.2 (solid line), showing deviation from predicted course after the third week. The total dialysis population is also shown (dashed line).