Exposure to novel coronavirus in patients on renal replacement therapy during the exponential phase of COVID-19 pandemic: survey of the Italian Society of Nephrology.

Background: Between February and April 2020, Italy experienced an overwhelming growth of the COVID-19 pandemic. Little is known, at the country level, where and how patients on renal replacement therapy (RRT) have been mostly affected.

Methods: Survey of the network of Nephrology centers using a simplified 17 items electronic questionnaire designed by Italian Society of Nephrology COVID-19 Research Group. We used spatial epidemiology and geographical information systems to map SARS-CoV-2 spread among RRT patients in Italy.

Results: On April 9th 2020, all nephrology centers (n = 454) listed in the DialMap database were invited to complete the electronic questionnaire. Within 11 days on average, 365 centers responded (80.4% response rate; 2.3% margin of error) totaling 60,441 RRT patients. The surveyed RRT population included 30,821 hemodialysis (HD), 4139 peritoneal dialysis (PD), and 25,481 transplanted (Tx) patients respectively. The proportion of SARS-CoV-2 positive RRT patients in Italy was 2.26% (95% CI 2.14-2.39) with significant differences according to treatment modality (p < 0.001). The proportion of patients positive for SARS-CoV-2 was significantly higher in HD (3.55% [95% CI 3.34-3.76]) than PD (1.38% [95% CI 1.04-1.78] and Tx (0.86% [95% CI 0.75-0.98]) (p < 0.001), with substantial heterogeneity across regions and along the latitude gradient (p < 0.001). In RRT patients the highest rate was in the north-west (4.39% [95% CI 4.11-4.68], followed by the north-east (IR 2.06% [1.79-2.36]), the center (0.91% [0.75-1.09]), the main islands (0.67% [0.47-0.93]), and the south (0.59% [0.45-0.75]. During the COVID-19 pandemic, among SARS-Cov-2 positive RRT patients the fatality rate was 32.8%, as compared to 13.3% observed in the Italian population as of April 23rd.

Conclusions: A substantial proportion of the 60,441 surveyed RRT patients in Italy were SARS-Cov-2 positive and subsequently died during the exponential phase of COVID-19 pandemic. Infection risk and rates seems to differ substantially across regions, along geographical latitude, and by treatment modality.