Cardiac, vascular surgeries fuel increase in acute dialysis
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Nausheen F. Siddiqui, MD, of the University of Toronto in Ontario, and colleagues used data from the university’s healthcare database on all consecutive patients 18 years and older in Ontario who underwent elective surgery at 118 hospitals between 1995 and 2009. They linked data from discharge records, physician claims on insurance records and a registry that included vital statistics on of all permanent residents in Ontario for the study.
Their goal was to identify trends over time to help find potential opportunities for mitigating these events.
The surgeries were categorized as abdominal, cardiac, retroperitoneal, thoracic and vascular. They excluded emergent and urgent surgeries and limited surgical procedures to during the same stay to the first surgery. Their primary outcome was acute dialysis. The secondary outcomes were death within 90 days of surgery and chronic dialysis for those who received acute dialysis and survived beyond 90 days.
The final study group consisted of 552,672 patients. They noted that both the age and comorbidities of these patients increased during the 15-year study period. The annual number of vascular surgeries decreased slightly during that time while cardiac and thoracic surgeries increased.
Siddiqui and colleagues found that 0.4 percent of patients received acute dialysis within 14 days of surgery. The incidence ticked up from 0.2 percent in 1995 to 0.6 percent in 2009, with increases occurring primarily among patients who underwent cardiac and vascular surgeries. First treatment started at a median of two days after surgery in 2009 compared with five days in 1995. Forty-two percent of patients who received acute dialysis died within 90 days and among survivors, 27.2 percent needed chronic dialysis.
“In recent years, as many as one in 80 patients had their cardiac surgery complicated by acute dialysis, compared with one in 390 in 1995,” they wrote. “Similarly, in recent years, as many as one in 85 patients had their vascular surgery complicated by acute dialysis, compared with one in 230 in 1995.”
They observed a three-fold increase in the use if dialysis in their sample of surgeries, primarily due to vascular and cardiac surgeries. The authors attributed some of their findings to changes in the patient population. They wrote that there likely was a higher risk for acute kidney injury among older and sicker patients, and that the increasing use of less invasive procedures made these patients candidates for surgeries.
“For example, patients who undergo cardiac surgery today may primarily be those with diffuse coronary lesions not amenable to angioplasty, or those who need concomitant valve repair; such patients might be expected to have higher rates of acute kidney injury than their predecessors,” Siddiqui et al suggested.
They also observed that the proportion of patients with perioperative chronic kidney disease increased during the study period, and they are at high risk of acute kidney injury. “This group, with reduced renal reserve, may be contributing to trends in starting dialysis earlier,” they wrote, as well as efforts to consult nephrologists earlier and greater access to dialysis. But despite these trends, they wrote, survival remained poor.
They pointed out limitations in their study, including lack of patient characteristics at the initiation of dialysis and lack of laboratory results. But their study provided findings on trends and outcomes that could be useful for future research, according to the authors.
“Our results should prompt renewed efforts to develop and test interventions to prevent severe acute kidney injury and to attenuate the high burden of death and end-stage renal disease after such injury has occurred,” they concluded.