North East Italian Prospective Hospital Renal Outcome Survey on Acute Kidney Injury (NEiPHROS-AKI)

Abstract

Acute kidney injury (AKI) in the intensive care unit (ICU) is associated with an enhanced mortality. The Acute Dialysis Quality Initiative group has proposed the RIFLE (Risk-Injury-Failure-Loss-ESRD) classification to standardize the approach to AKI. This study was performed to estimate the AKI incidence in ICU patients in northeastern Italy and describe clinical characteristics and outcomes of patients with AKI on the basis of their RIFLE class. A prospective multicenter observational study was performed of patients who fulfilled AKI criteria in 19 ICU in northeastern Italy. Data were analyzed using multivariate logistic regression and survival curve analysis. Of 2164 ICU patients who were admitted during the study period, 234 (10.8%; 95% confidence interval 9.5 to 12.1%) developed AKI; 19% were classified as risk (R), 35% as injury (I), and 46% as failure (F). Preexisting kidney disease was present in 36.8%. The most common causes of AKI were prerenal causes (38.9%) and sepsis (25.6%). At diagnosis of AKI, median serum creatinine and urine output were 2.0 mg/dl and 1100 ml/d, respectively. ICU mortality was 49.5% in class F, 29.3% in I, and 20% in R. Independent risk factors for mortality included RIFLE class, sepsis, and need for renal replacement therapy, whereas a postsurgical cause of AKI, exposure to nephrotoxins, higher serum creatinine, and urine output were associated with lower mortality risk. In this study, AKI incidence in the ICU was between 9 and 12%, with 3.3% of ICU patients requiring renal replacement therapy. Sepsis was a significant contributing factor. Overall mortality was between 30 and 42%, and was highest among those in RIFLE class F.

Are Surrogate Assumptions and Use of Diuretics Associated with Diagnosis and Staging of Acute Kidney Injury after Cardiac Surgery?

“…Those staged with SCr criteria have poorer outcomes compared with UO criteria (3,6,17,22), but there remains a lack of studies calibrating UO against SCr criteria (23). Using hourly observations of UO and exact AKIN criteria, we found that the UO criterion was a specific but not sensitive diagnostic test for AKI compared with SCr.…”

“…Although utilized in previous studies (3)(4)(5)(6)(7), only recently has the clinical validity of this assumption been questioned (8) and shown to result in significant bi-directional misclassification (6).…”

Back-Calculating Baseline Creatinine with MDRD Misclassifies Acute Kidney Injury in the Intensive Care Unit

“…Consequently, they recommended that an estimated baseline creatinine be calculated using the Modification of Diet in Renal Disease (MDRD) formula (11) with an assumed GFR for all patients between 75 and 100 ml/min. As a tool for post hoc analysis in research studies, this back-calculation method has become widespread, with most studies adopting 75 ml/min (5,8,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). A few epidemiologic studies have used an estimated baseline for all of their patients (e.g., those using the Australian and New Zealand Intensive Care Society database (5,(12)(13)(14)), whereas in other studies the proportion of patients for whom a baseline is estimated by back-calculation is as low as 7% (19).…”

Acute Kidney Injury; Frequency in Hospitalized Patients

“…Our results match with those of Coca et al 18 (26.6%) in American and Medve and Gondos 19 (24.4%) in Hungarian population. A much lower frequency of 10.8% has been reported by Cruz et al 20 among American population. While Lin et al 11 reported extremely high frequency of 78% among same population.…”