In 2007, the Acute Kidney Injury Network (AKIN) developed a modified standard for diagnosing and classifying acute kidney injury (AKI). This classification system is a modification of the previously described risk, injury, failure, loss, and end-stage (RIFLE) criteria. Among other modifications, the AKIN staging requires an absolute serum creatinine change of 0.3 mg/dl in a 48-hour period to establish the diagnosis of AKI. The purpose of this study was to apply these new criteria in the severely burned population and to compare the prevalence, stage, and mortality impact of these criteria to the RIFLE criteria. The authors performed a retrospective analysis of consecutive patients with burns admitted to their burn center for at least 24 hours from June 2003 through December 2008. Each patient was classified by both the AKIN and RIFLE criteria by three referees. Both univariate and multivariate analyses were performed to determine the impact of the various AKI stages on mortality. A total of 1973 patients met inclusion and exclusion criteria and were included in the analysis. The average age, %TBSA, injury severity score, and percent with smoke inhalation injury were 36 ± 16, 16 ± 18, 10 ± 12, and 13%, respectively. Overall, the prevalence of AKI was 33% using the AKIN criteria and 24% using the RIFLE criteria with an associated mortality of 21 and 25%, respectively. Of those meeting criteria for AKIN stage 1 (N = 434), 41% (N = 180) would have been categorized as not having AKI on the basis of the RIFLE criteria. In this cohort of patients, mortality increased by almost 8-fold when compared with those without AKI (odds ratio 7.8 [95% confidence interval (CI) 3.7-16.2], P < .0001). The area under the receiver operator characteristic curve for in-hospital mortality was significantly higher for the AKIN criteria at 0.877 (95% CI 0.848-0.906) when compared to the RIFLE criteria at 0.838 (95% CI 0.801-0.874; P = .0007). Burn patients identified as having AKI by the AKIN criteria missed by RIFLE appear to be an important cohort. On the basis of our study, AKIN criteria may be more precise and are more predictive of death than the RIFLE criteria in this population. Prospective validation is needed.

The contribution of rhabdomyolysis to acute kidney injury (AKI) in the context of burn injury is poorly studied. We sought to determine the impact of rhabdomyolysis on AKI (defined by the AKI Network classification), renal replacement therapy (RRT), and death. Patients admitted to the burn unit at our institution were examined. Information on sex, age, presence of inhalation injury, electrical burn, percentage TBSA burned, percentage of full-thickness burns, Injury Severity Score, and peak creatine kinase (CK) were recorded. These variables were examined via multivariate logistic regression analysis against AKI Network stage, RRT, and death. Of 1973 consecutive admissions meeting the inclusion criteria, 525 met our eligibility criteria. Log peak CK was found to be correlated with any stage of AKI (odds ratio [OR], 1.71; 95% confidence interval [CI], 1.36-2.16; P < .0001), moderate to severe AKI (OR, 2.09; 95% CI, 1.40-3.11; P = .0003), need for RRT (OR, 1.67; 95% CI, 1.16-2.40; P = .0057), and mortality (OR, 1.49; 95% CI, 1.01-2.20; P = .0441), after adjustment. Each 10-fold increase in peak CK was associated with a 70% increase in the odds of AKI, more than a 100% increase in the odds of moderate to severe AKI, a nearly 70% increase in the odds of RRT, and an almost 50% increase in the odds of mortality in patients with burn injury.

SummaryBackground and objectives Although associated with increased morbidity and mortality, AKI has not been systematically examined in military personnel injured from combat operations in Iraq and Afghanistan.Design, settings, participants, & measurements Patients evacuated from Iraq and Afghanistan to a burn unit were examined. AKI was classified by the Acute Kidney Injury Network (AKIN) and Risk-Injury-Failure-Loss-End Stage (RIFLE) schemas. Age, sex, percentage of total body surface area burned (TBSA), percentage of fullthickness burn, inhalation injury, and injury severity score were recorded. Additional data that could be associated with poor outcomes were recorded for patients with TBSA $20%. Multivariate logistic regression analyses were performed to determine factors associated with morbidity and mortality.Results AKI prevalence rates by the RIFLE and AKIN criteria were 23.8% and 29.9%, respectively. After logistic regression, RIFLE categories of risk (odds ratio [OR], 15.34; 95% confidence interval [CI], 1.75-134; P=0.01), injury (OR, 46.28; 95% CI, 5.02-427; P,0.001), and failure (OR, 126; 95% CI, 13.39-.999; P,0.001); AKIN-2 (OR, 23.70; 95% CI, 2.32-242; P=0.008); and AKIN-3 (OR, 130; 95% CI, 13.38-.999; P,0.001) were significantly associated with death. AKIN-3, injury, and failure remained significant in the subset of patients with $20% TBSA. There was also a strong interaction between TBSA and the stage of AKI with respect to ventilator and intensive care unit days.Conclusions AKI is prevalent in military casualties with burn injury and is independently associated with morbidity and mortality after adjustment for factors associated with injury severity.

Background/Aims: Dysnatremias have been evaluated in many populations and have been found to be significantly associated with mortality. However, this relationship has not been well described in the burn population. Methods: Admissions to the burn center at our institution from January 2003 to December 2008 were examined. Independent variables included gender, age, percentage total body surface area burned (%TBSA), percentage of third-degree burn, inhalation injury, injury severity score (ISS), Acute Kidney Injury Network (AKIN) stage, hypernatremia, and hyponatremia. They were examined via Cox proportional hazard regression models against death. Moderate to severe hypo- and hypernatremia were defined as serum sodium <130 and >150 mmol/l, respectively. Results: In 1,969 subjects with a mean age of 36.3 ± 16.4 years, a median %TBSA of 9 (interquartile range 4–20) and a median ISS of 5 (interquartile range 1–16) hypernatremia occurred in 9.9% (n = 194), while hyponatremia occurred in 6.8% (n = 134) with mortality rates of 33.5 and 13.8%, respectively. Patients without a dysnatremia had a mortality rate of 4.3%. On Cox proportional hazard regression age, %TBSA, ISS, and AKIN stage were found to be significant predictors of mortality. Hypernatremia (HR 2.00, 95% CI 1.212–3.31; p = 0.0066), but not hyponatremia (HR 1.72, 95% CI 0.89–3.34; p = 0.1068) was associated with mortality. Conclusions: In the burn population, hypernatremia, but not hyponatremia, is an independent predictor of mortality.