Retrospective Analysis of Outcomes in Acute Myeloid Leukemia (AML) Patients Exposed to Intravenous Contrast Prior to Stem Cell Transplantation
Authors: Ravi Gayathri , Abou-Ismail Yazan , Rothgery Margaret , Shekar Anjali , Golec Sophie , de Lima Marcos , Tomlinson Ben 
Published: October 2019

Abstract
Background:
Patients with AML are inherently at increased risk of Acute Kidney Injury (AKI) due to multiple reasons including chemotherapy, antibiotics and risk of tumor lysis syndrome (TLS). Prolonged hospital admissions and persistent neutropenia with increased risk of infections necessitate diagnostic testing including computed tomography (CT) scans with contrast. Contrast induced nephropathy (CIN) is a well-known risk of contrast exposure and is a leading cause of hospital acquired AKI. Acute kidney injury is increasingly being recognized as an independent risk factor for survival in patients with hematologic malignancies. To our knowledge, the incidence of CIN in AML patients and its impact on subsequent cancer management has not been studied.
Methods:
Retrospective chart review of all newly diagnosed AML patients who received inpatient chemotherapy at Seidman Cancer Center from 2004-2017 were included.
Out of the 432 patients screened, 223 were excluded as they did not receive any CT imaging. Serum creatinine (S.cr) was documented prior to receiving chemotherapy for induction, consolidation and/or re-induction for relapsed disease. We recorded the highest S.cr during the 2-7 days after undergoing CT with and without contrast, as per the definition of CIN. Outcomes evaluated include hospital length of stay (LOS), transfer to intensive care unit (ICU), need for renal replacement therapy (RRT) and need for changing subsequent management of AML. We also compared the yield of CT without contrast to CT with contrast. Continuous outcomes were evaluated with univariate generalized linear regression models and binary outcomes were evaluated with univariate logistic regression models.
Results:
Out of the 209 patients included in the study, 255 cycles of chemotherapy were identified where the patient had a diagnostic CT. This includes 191 inductions, 20 consolidations and 39 relapse inductions. Out of the 255 encounters,136 were CT with contrast and 119 without contrast. LOS, transfer to medical ICU, RRT and need for change in AML management was compared in both groups for induction, consolidation and relapse.
Baseline characteristics of patients are summarized in Table 1. The co-morbidities contributing to renal dysfunction and concomitant use of nephrotoxic medications were equally prevalent in both groups.
Patients with higher creatinine at presentation predominantly had non-contrast CT done (p <0.001). Average length of stay was 36.6 days in non-contrast group compared to 37.0 days in contrast group (p 0.878). There was a slightly increased need for ICU transfer among the patients who received contrast when compared to non contrast group (22 vs 17 days respectively) however this was not statistically significant (p 0.699). There was no significant change in creatinine post contrast exposure compared to the non-contrast group. Interestingly, need for permanent RRT was noticed to be increased in patients who had non-contrast CT compared to the contrast group (4.2% vs 0.7%, respectively). Subsequent treatment change was needed in 9 patients (6.6%) who received contrast and 7 patients (5.9%) in non-contrast group (p 0.822).
CT scan was able to yield positive results half the time (50%) in both contrast and non-contrast group. Of note, patients who had non-contrast CT had a slightly higher need for repeat imaging with IV contrast.
Conclusion:
CT imaging remains the standard of care for diagnosing many of the complications associated with hematologic malignancies such as pulmonary embolus, atypical pulmonary infection and neutropenic enteritis. Patients with AML are prone to develop AKI for numerous reasons. It is important to note that even if it was only a small number of patients who had a need for permanent RRT in our study it was higher in the setting of no contrast exposure, emphasizing the vulnerability of this subgroup of patients to AKI. Even though no permanent unfavorable outcome was associated with IV contrast exposure in our study, any intervention that could potentially increase the risk of AKI still warrants caution and it may be reasonable to start with a non-contrast CT as an initial diagnostic tool.

Disclosures
No relevant conflicts of interest to declare.