Sepsis cost the Centers for Medicare & Medicaid Services $6 billion in fiscal 2015, making it the most expensive condition or procedure among inpatient discharges, according to new data.

Information published by CMS last week found sepsis costs narrowly beat out the $5.6 billion the Medicare program paid for major joint replacement procedures in FY 2015. Infectious and parasitic diseases “with surgery/procedure,” heart failure with major complications, and spinal fusion rounded out the top diagnosis-related groups in terms of cost for that year.

The drop in joint replacement costs — down from the $6.6 billion paid in 2013 — came even as the number of inpatient discharges for the procedures increased (by 5,671 from 2014 to 2015).

That trend is likely due to improvements in surgical care, as well as CMS’ care coordination initiatives, said Francois de Brantes, vice president and director of the Center for Payment Innovation at the Altarum Institute, to Modern Healthcare.

“We have improvements in the procedures that [are] likely creating fewer readmissions and redos,” de Brantes said.

The increase in sepsis discharges — up 82,761 between 2014 and 2015 — from could be due to “massive overcoding,” or non-sepsis stays being coded as the illness, de Brantes noted.