Acute kidney injury is common in children and young adults admitted to ICUs, and cannot always be identified by plasma creatinine level alone, according to the authors of a study presented at the meeting sponsored by the American Society of Nephrology.
The Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology (AWARE) study was a prospective, international, observational study in 4,683 patients aged 3 months to 25 years, recruited from 32 pediatric ICUs over the course of 3 months.
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Ahmad Kaddourah, MD, from the Center for Acute Care Nephrology at the Cincinnati Children’s Hospital Medical Center, and his coauthors found that 27% of the participants developed acute kidney injury and 12% developed severe acute kidney injury – defined as stage 2 or 3 acute kidney injury – within the first 7 days after admission.
The risk of death within 28 days was 77% higher among individuals with severe acute kidney injury, even after accounting for their original diagnosis when they were admitted to the ICU. Mortality among these individuals was 11%, compared with 2.5% among patients without severe acute kidney injury. These patients also had an increased use of renal replacement therapy and mechanical ventilation, and were more likely to have longer stays in hospital.
Researchers also saw a stepwise increase in 28-day mortality associated with maximum stage of acute kidney injury.
“The common and early occurrence of acute kidney injury reinforces the need for systematic surveillance for acute kidney injury at the time of admission to the ICU,” Dr. Kaddourah and his associates wrote. “Early identification of modifiable risk factors for acute kidney injury (e.g., nephrotoxic medications) or adverse sequelae (e.g., fluid overload) has the potential to decrease morbidity and mortality.”
Of particular note was the observation that 67% of the patients who met the urine-output criteria for acute kidney injury would not have been diagnosed using the plasma creatinine criteria alone. Furthermore, “mortality was higher among patients diagnosed with stage 3 acute kidney injury according to urine output than among those diagnosed according to plasma creatinine levels,” the authors reported.
There was a steady increase in the daily prevalence of acute kidney disease, from 15% on day 1 after admission to 20% by day 7. Patients with stage 1 acute kidney injury on day 1 also were more likely to progress to stage 2 or 3 by day 7, compared with patients who did not have acute kidney injury on admission.
However, around three-quarters of this increase in stage occurred within the first 4 days after admission, which the authors suggested would support a 4-day time frame for future studies on acute kidney injury in children. They also stressed that as their assessments for acute kidney injury stopped at day 7 after admission, there may have been incidents that were missed.
Dr. Kaddourah and his associates noted that although the rates of severe and acute kidney injury seen in the study were slightly lower than those observed in studies in adults, the associations with morbidity and mortality were similar.
“The presence of chronic systemic diseases contributes to residual confounding in studies of acute kidney injury in adults,” they wrote. “Children have a low prevalence of such chronic diseases; thus, although the incremental association between acute kidney injury and risk of death mirrors that seen in adults, our study suggests that acute kidney injury itself may be key to the associated morbidity and mortality.”
The study was supported by the Pediatric Nephrology Center for Excellence at Cincinnati Children’s Hospital Medical Center. The authors declared grants, consultancies, speaking engagements, and other support from private industry, some related to and some outside of the submitted work.