In the three decades before the pandemic, the number of Americans with end-stage renal disease had more than quadrupled, from about 180,000 in 1990 to about 810,000 in 2019, according to the United States Renal Data System, a national data registry. About 70% of these patients relied on dialysis in 2019; the other 30% received kidney transplants.

The Midwest stood out as the region with the highest rate of patients with the disease, and Illinois had the nation’s third highest prevalence after Washington, D.C., and South Dakota, according to the Centers for Disease Control and Prevention.

A rare bright spot was the downturn in the death rate. Although diagnoses have been going up, death rates for patients who are on dialysis have declined since the early 2000s.

Then COVID-19 struck. Nearly 18,000 more dialysis patients died in 2020 than would have been expected based on previous years. That staggering toll represents an increase of nearly 20% from 2019, when more than 96,000 patients on dialysis died, according to federal data released this month.

The loss led to an unprecedented outcome: The nation’s dialysis population shrank, the first decline since the U.S. began keeping detailed numbers nearly a half century ago.