Acute Kidney Injury After Repeated Contrast Studies: Identifying a High-Risk Geriatric Trauma Population

Background While contrast-associated acute kidney injury (CA-AKI) is a recognized entity, data regarding CA-AKI risk after repeated intravascular (IV) contrast exposures in older adults remain limited. We hypothesized that repeated IV contrast exposures were not associated with AKI in geriatric trauma patients. Methods We retrospectively studied patients aged ≥65 years at a level 1 trauma center from January to December 2023. Patients who underwent at least one computed tomography scan or arteriogram within 48 hours were included. Exclusion criteria were death within 48 hours or pre-admission renal replacement therapy. CA-AKI was defined using Kidney Disease: Improving Global Outcomes criteria. Adjusted risks of AKI and CA-AKI were estimated using logistic regression. Results Of 1486 patients, 455 (30.6%), 881 (59.2%), and 150 (10.1%) received none, one and ≥2 contrast exposures respectively. AKI occurred in 126 (8.5%). CA-AKI occurred in 64 (6.2%) of 1031 patients who received IV contrast. Multivariate analyses showed that AKI was associated with receiving ≥2 exposures (odds ratio [95% confidence interval] 2.58 (1.42-4.59), but not with only one exposure (0.78 [0.50-1.24]). In patients who received contrast, ≥2 contrast exposures was an independent risk factor for CA-AKI (3.43 [1.89-6.09]). Admission estimated glomerular filtration rate, Charlson comorbidity index and diabetes mellitus were also independent risk factors for AKI and CA-AKI. Discussion In geriatric trauma patients, receiving ≥2 contrast exposures was associated with AKI. Concomitant reduced renal function, diabetes mellitus and high comorbidity burden could identify a subgroup in whom greater attention to imaging strategy and contrast stewardship may be warranted.