African American race, obesity, and blood product transfusion are risk factors for acute kidney injury in critically ill trauma patients

Abstract

Purpose: Acute kidney injury (AKI) is a common source of morbidity after trauma. We sought to determine novel risk factors for AKI, by Acute Kidney Injury Network (AKIN) criteria, in critically ill trauma patients.

Materials and methods: A prospective cohort of 400 patients admitted to the intensive care unit of a level 1 trauma center was followed for the development of AKI over 5 days.

Results: Acute kidney injury developed in 147 (36.8%) of 400 patients. In multivariable regression analysis, independent risk factors for AKI included African American race (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.08-3.18; P = .024), body mass index of 30 kg/m(2) or greater (OR, 4.72 versus normal body mass index; 95% CI, 2.59-8.61; P < .001), diabetes mellitus (OR, 3.26; 95% CI, 1.30-8.20; P = .012), abdominal Abbreviated Injury Scale score of 4 or more (OR, 3.78; 95% CI, 1.79-7.96; P < .001), and unmatched packed red blood cells administered during resuscitation (OR, 1.13 per unit; 95% CI, 1.04-1.23; P = .004). Acute Kidney Injury Network stages 1, 2, and 3 were associated with hospital mortality rates of 9.8%, 13.7%, and 30.4%, respectively, compared with 3.8% for those without AKI (P < .001).

Conclusions: Acute kidney injury in critically ill trauma patients is associated with substantial mortality. The findings of African American race, obesity, and blood product administration as independent risk factors for AKI deserve further study to elucidate underlying mechanisms.

Fig. 1. Screening and enrollment

^aSome subjects excluded for more than one reason.

Fig. 2. Risk of death by day of AKI diagnosis

Numbers at the top of each bar represent the total number of subjects who developed AKI on each day (or, for “No AKI,” the number who never developed AKI). ^aNon-parametric test of trend for those with AKI.

Fig. 3. Acute Kidney Injury Network (AKIN) stage association with hospital mortality

Numbers at the top of each bar represent the total number of subjects for each stage. Stage 0 represents no AKI. ^aOdds ratio for death is adjusted for age and non-renal APACHE III score.