Outcomes After Post-Traumatic AKI Requiring RRT in United States Military Service Members

Abstract

Background and objectives: Mortality and CKD risk have not been described in military casualties with post-traumatic AKI requiring RRT suffered in the Iraq and Afghanistan wars.

Design, setting, participants, & measurements: This is a retrospective case series of post-traumatic AKI requiring RRT in 51 military health care beneficiaries (October 7, 2001-December 1, 2013), evacuated to the National Capital Region, documenting in-hospital mortality and subsequent CKD. Participants were identified using electronic medical and procedure records.

Results: Age at injury was 26±6 years; of the participants, 50 were men, 16% were black, 67% were white, and 88% of injuries were caused by blast or projectiles. Presumed AKI cause was acute tubular necrosis in 98%, with rhabdomyolysis in 72%. Sixty-day all-cause mortality was 22% (95% confidence interval [95% CI], 12% to 35%), significantly less than the 50% predicted historical mortality (P<0.001). The VA/NIH Acute Renal Failure Trial Network AKI integer score predicted 60-day mortality risk was 33% (range, 6%-96%) (n=49). Of these, nine died (mortality, 18%; 95% CI, 10% to 32%), with predicted risks significantly miscalibrated (P<0.001). The area under the receiver operator characteristic curve for the AKI integer score was 0.72 (95% CI, 0.56 to 0.88), not significantly different than the AKI integer score model cohort (P=0.27). Of the 40 survivors, one had ESRD caused by cortical necrosis. Of the remaining 39, median time to last follow-up serum creatinine was 1158 days (range, 99-3316 days), serum creatinine was 0.85±0.24 mg/dl, and eGFR was 118±23 ml/min per 1.73 m(2). No eGFR was <60 ml/min per 1.73 m(2), but it may be overestimated because of large/medium amputations in 54%. Twenty-five percent (n=36) had proteinuria; one was diagnosed with CKD stage 2.

Conclusions: Despite severe injuries, participants had better in-hospital survival than predicted historically and by AKI integer score. No patient who recovered renal function had an eGFR<60 ml/min per 1.73 m(2) at last follow-up, but 23% had proteinuria, suggesting CKD burden.

Keywords: acute renal failure; chronic kidney disease; dialysis; military casualties; mortality risk.

Figure 1.

Observed versus predicted 60-day mortality in 49 participants in whom AKI integer score mortality risk could be determined. (Hosmer–Lemeshow goodness of fit test with five subgroups [3 df]: H-statistic 19.3; P<0.001). Vertical bars indicate 95% confidence interval.

Figure 2.

Receiver operator characteristic analysis of 49 participants in whom AKI integer score mortality risk could be determined versus reference AKI integer score cohort (18). The area under the curve (C-statistic) was 0.72 (95% confidence interval, 0.56 to 0.88) for the National Capital Region cohort. The 95% confidence bands are shown for both curves, and they were not significantly different (P=0.27). Model cohort, reference AKI integer score cohort; NCR cohort, participants in whom AKI integer score mortality risk could be determined.