Acute Kidney Injury After PICU: Jumping on Giants’ Shoulders*
In this issue of Pediatric Critical Care Medicine, Hessey et al (1) report the results of a simple and good hypothesis: let us see what happens to the renal function of critically ill children who survive an acute kidney injury (AKI) episode after the PICU discharge but before ultimate hospital dismissal. If AKI in PICU is the giant topic that promoted one of the most remarkable and exciting bursts to critical care literature of the last decade (fortunately, both in the adult and pediatric settings) (2), we currently need to jump onto AKI’s shoulders to look at AKI recovery. Interestingly, even if this issue has been identified as one of the most important priorities of AKI research agenda (3), it has never before attempted to “dwarf” the follow-up soon after PICU discharge. If the findings of this article are interesting, we are left with open questions that are equally surprising. According to the results by Hessey et al (1), among patients who survived PICU and who had at least one serum creatinine (SCr) measurement thereafter, the proportion of children who definitely left the hospital with recovered renal function depended on definition: 92.5% when recovery was defined as SCr less than 1.5 times baseline versus 75.9% when defined as less than 1.15 times baseline. Of 7.5% patients without a complete renal recovery, 2% were children not diagnosed with AKI in the PICU. The independent variables associated with lack of recovery were, at multivariate analyses, oncologic diagnosis and Kidney Disease: Improving Global Outcomes (KDIGO) stage 3 AKI (4). With this information in mind, regardless of the astonishing message that between seven and 15 children (or maybe more) of 100 go home with non-normal renal function, we appraise that these results are relative to only 40% of post-PICU patients—those patients who had at least one SCr level measured in the ward. After stratification for AKI diagnosis, about two-thirds of patients with a previous PICU-AKI episode—and less than half the patients without—were sampled with SCr after PICU discharge. Clearly, severity of AKI (according to KDIGO SCr criteria) was proportionally associated with the odds of controlling renal function before hospital discharge; still, incredibly, 10% of patients with stage 3 AKI (those with the highest risk of lacking renal recovery) were not controlled before going home.
Other details of the multiple associations performed by the authors deserve attention.