Nephrology researchers at the University of Cincinnati (UC) College of Medicine found that hospitalizations associated with acute kidney injury (AKI) in the pre-dialysis period adversely impacted dialysis outcomes. The study, conducted in collaboration with researchers from the University of Alabama-Birmingham (UAB) and Wright State University, was recently published in the American Journal of Nephrology.

Each year in the United States, over a half million patients receive dialysis and approximately 100,000 new patients start dialysis. Dialysis patients experience high morbidity and an average mortality of 20% at 1 year. In addition, dialysis care is expensive—Medicare spends an average of $80,000 per patient per year for total care of a dialysis patient.

"Given that patients with advanced kidney disease, a precursor to end-stage renal disease (ESRD), can experience higher risk for hospitalizations, our study focused on acute care utilization prior to dialysis,” says Charuhas Thakar, MD, professor and director, Division of Nephrology, Kidney CARE Program at UC, and senior author of the study.

The study found that hospitalizations due to AKI is associated with a 1.4-fold increase in 1-year mortality after dialysis initiation.

"Compared to the 25% 1-year mortality rate in those without AKI, the 1-year mortality rate was almost 40% in those with AKI,” says Thakar. "This impact is much more pronounced in octogenarians, with only one in two of those who experience AKI prior to dialysis surviving to 1 year.”

The study examines a national dataset derived from United States Renal Data System (USRDS), with linked data from Medicare Parts A and B, and shows that 54% of patients had at least one pre-dialysis AKI event. The authors identified 47,341 patients initiated on in-center hemodialysis and examined whether AKI events in the 2 years prior to ESRD diagnosis impacted patient outcomes.

"Pre-dialysis health status impacts long-term outcomes in dialysis patients. This study design uniquely allows us to temporally correlate pre-dialysis AKI events and post-dialysis outcomes,” says Silvi Shah, MD, assistant professor in the Division of Nephrology, Kidney CARE Program and a co-lead author of the study. Shah cautions that the linked USRDS data limit the observation to only those patients who have Medicare Parts A and B for 2 years prior to dialysis initiation as the insurance payer, which restricts the study largely to older adults.

She also notes that the average age at dialysis initiation in the United States is now 67, and elderly people represent one of the fastest growing population of ESRD patients.

The study also examined the impact of pre-dialysis AKI on the method of dialysis, and successful initiation of hemodialysis with an arteriovenous access compared to dialysis catheters.

"There is a national expectation that use of catheters for permanent dialysis should be the least preferred choice,” says Timothy Lee, MD, associate professor of medicine at UAB and co-lead author of the study. "The present data show that patients experiencing AKI prior to ESRD started in-center hemodialysis more frequently than home methods, and also were only half as likely to do so with an arteriovenous access.”

As a result, Lee says, "AKI episodes may hasten the progression of chronic kidney disease and may not allow sufficient time to prepare for appropriate dialysis method or type of access.”

There are policy implications to this observation, according to Thakar, who notes that quality of dialysis care is tightly scrutinized by payors including Medicare, and reimbursement models are tied to quality. Thus, factors such as AKI during pre-dialysis care may need to be considered when accounting for severity of care, he says.

"More importantly, the study points out that there may be an opportunity to improve care,” says Thakar. "We need imminent strategies to prevent or treat AKI, as well as improve processes of care in the post-AKI period, including after dialysis initiation. Dialysis initiation is a life-changing event, and the study suggests that this transition of care may need to be customized based on pre-dialysis acute care events.”