Long-term implications of severe acute kidney problems

Hospitalized patients who experience acute kidney problems that require dialysis are at increased risk of receiving chronic dialysis once discharged, but do not have an increased risk of death, according to a study in the September 16 issue of JAMA.

"Acute kidney injury, which leads to a sudden decline in kidney function, is a common and serious complication of hospitalization in the adult population. Many patients with severe acute kidney injury require initiation of hemodialysis or hemofiltration [dialysis], and their in-hospital mortality rate ranges from 45 percent to 70 percent. Among those who survive, as many as 15 percent require dialysis at the time of discharge," according to background information in the article. The authors note that little is known about the long-term outcomes of patients with an acute kidney injury that requires in-hospital dialysis, especially once they leave the hospital and recover enough kidney function to be free of dialysis in the short term.

Ron Wald, M.D.C.M., M.P.H., F.R.C.P.C., of St Michael's Hospital, Toronto, and the University of Toronto, and colleagues evaluated the long-term risk of chronic dialysis and death among hospitalized patients in Ontario, Canada, who sustained an acute kidney injury while hospitalized, required dialysis and survived free of dialysis for at least 30 days after discharge. These individuals (n = 3,769) were matched with patients without acute kidney injury or dialysis during their hospitalization (n = 13,598). Patients were followed up until March 2007. The average age of the enrolled participants was 62 years, and approximately 40 percent were women.

After a median (midpoint) follow-up of 3 years, the researchers "found that survivors of a hospitalization complicated by acute kidney injury requiring dialysis were approximately 3 times more likely to require chronic dialysis compared with those without acute kidney injury. However, no difference was observed between these groups for long-term mortality."

"Our findings expand on prior knowledge to provide clinicians with new information about the long-term effect of acute kidney injury that arises during a hospitalization. First, if affected patients survive to hospital discharge, then they remain at high risk of needing dialysis over the next 3 to 5 years. Patients who survive a hospitalization complicated by acute kidney injury requiring dialysis may benefit from specialized care to address complications of chronic kidney disease, and also from concerted efforts to prevent progression to chronic dialysis. At the same time, their high mortality rate is similar to hospitalized patients without acute kidney injury or need for dialysis. Hence, an episode of acute kidney injury requiring in-hospital dialysis may not be an independent contributing factor to long-term survival," the authors conclude.

"Based on the available evidence from administrative and laboratory-based databases, severe acute kidney injury seems to increase the risk of progressive chronic kidney disease and may increase the risk of death. Given the extraordinarily high rates of morbidity and mortality observed in chronic kidney disease patients and acute kidney injury patients, the complex interconnection between them, and increasing incidence of both, kidney disease prevention and treatment should be a major public health priority."