Minor injury turns into major problem in severe acute kidney injury: a propensity matched analysis.

OBJECTIVE: Severe acute kidney injury (sAKI) has been associated with a higher mortality in trauma patients, and severity of trauma often correlates with risk of sAKI. Whether minor to moderate trauma is associated with sAKI is less clear. The purpose of the study was to examine the outcomes of minor to moderate trauma patients who developed sAKI.

METHODS: The National Trauma Database participant use files of 2017 and 2018 were accessed for the study. All patients aged 18 years old and above who sustained an Injury Severity Score (ISS) of <16 and who were brought to a level I or level II trauma center were included in the study. sAKI was defined as an abrupt decrease in kidney function either three times increase in serum creatinine (SCr) level from the baseline or increase in SCr to ≥4.0 mg/dL (≥353.6 µmol/L), initiation of renal replacement therapy, or anuria for ≥12 hours. Propensity matching analysis was performed between the groups who developed sAKI and without sAKI. Outcome of interest was in-hospital mortality.

RESULTS: A total of 655 872 patients fulfilled the inclusion criteria with complete information, of which 1896 patients were found to have sAKI. There were significant differences between the two groups on baseline characteristics. The propensity score matching eliminated all the differences and created 1896 pairs of patients. The median hospital length of stay was longer in patients with sAKI when compared with patients who did not develop sAKI (14 (13 to 15) vs. 5 (5 to 5), days p<0.001). The overall in-hospital mortality was 20.6% in patients with sAKI compared with 2.1% without sAKI (p<0.001).

CONCLUSION: The occurrence of sAKI in minor to moderate trauma patients was less than 0.5%. There was a three times longer hospital stay in patients with sAKI and 10-fold increase in mortality when compared with patients who did not develop sAKI.

LEVEL OF EVIDENCE: IV.

STUDY TYPE: Observational cohort study.