Cumulative iodinated contrast exposure for computed tomography during acute kidney injury and major adverse kidney events

Iodinated Contrast and Nephropathy: Does It Exist and What Is the Actual Evidence?

Iodinated contrast material (ICM) is a critical component for many radiologic examinations and procedures. However, ICM has often been withheld in the past out of concern for its potential nephrotoxicity and increased risk of morbidity and mortality, often at the expense of diagnostic accuracy and timely diagnosis. Evidence from controlled studies now suggest that most cases of acute kidney injury (AKI) caused by ICM were instead due to contrast-independent causes of AKI or normal variation in renal function. This study will discuss current knowledge of contrast-induced AKI, including the incidence, sequelae, risk factors, and prevention strategies of this potential complication.

Association Between IV Contrast Media Exposure and Acute Kidney Injury in Patients Requiring Emergency Admission: A Nationwide Observational Study in Japan

OBJECTIVE

This study aimed to elucidate the association between IV contrast media CT and acute kidney injury (AKI) and in-hospital mortality among patients requiring emergency admission.

DESIGN

In this retrospective observational study, we examined AKI within 48 hours after CT, renal replacement therapy (RRT) dependence at discharge, and in-hospital mortality in patients undergoing contrast-enhanced CT or nonenhanced CT. We performed 1:1 propensity score matching to adjust for confounders in the association between IV contrast media use and outcomes. Subgroup analyses were performed according to age, sex, diagnosis at admission, ICU admission, and preexisting chronic kidney disease (CKD).

SETTING AND PATIENTS

This study used the Medical Data Vision database between 2008 and 2019. This database is Japan's largest commercially available hospital-based claims database, covering about 45% of acute-care hospitals in Japan, and it also records laboratory results.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The study included 144,149 patients with (49,057) and without (95,092) contrast media exposure, from which 43,367 propensity score-matched pairs were generated. Between the propensity score-matched groups of overall patients, exposure to contrast media showed no significant risk of AKI (4.6% vs. 5.1%; odds ratio [OR], 0.899; 95% CI, 0.845-0.958) or significant risk of RRT dependence (0.6% vs. 0.4%; OR, 1.297; 95% CI, 1.070-1.574) and significant benefit for in-hospital mortality (5.4% vs. 6.5%; OR, 0.821; 95% CI, 0.775-0.869). In subgroup analyses regarding preexisting CKD, exposure to contrast media was a significant risk for AKI in patients with CKD but not in those without CKD.

CONCLUSIONS

In this large-scale observational study, IV contrast media was not associated with an increased risk of AKI but concurrently showed beneficial effects on in-hospital mortality among patients requiring emergency admission.

Heterogeneity in the definition of major adverse kidney events: a scoping review

Acute kidney injury (AKI) is associated with persistent renal dysfunction, the receipt of dialysis, dialysis dependence, and mortality. Accordingly, the concept of major adverse kidney events (MAKE) has been adopted as an endpoint for assessing the impact of AKI. However, applied criteria or observation periods for operationalizing MAKE appear to vary across studies. To evaluate this heterogeneity for MAKE evaluation, we performed a systematic scoping review of studies that employed MAKE as an AKI endpoint. Four major academic databases were searched, and we identified 122 studies with increasing numbers over time. We found marked heterogeneity in applied criteria and observation periods for MAKE across these studies, with some even lacking a description of criteria. Moreover, 13 different observation periods were employed, with 30 days and 90 days as the most common. Persistent renal dysfunction was evaluated by estimated glomerular filtration rate (34%) or serum creatinine concentration (48%); however, 37 different definitions for this component were employed in terms of parameters, cut-off criteria, and assessment periods. The definition for the dialysis component also showed significant heterogeneity regarding assessment periods and duration of dialysis requirement (chronic vs temporary). Finally, MAKE rates could vary by 7% [interquartile range: 1.7-16.7%] with different observation periods or by 36.4% with different dialysis component definitions. Our findings revealed marked heterogeneity in MAKE definitions, particularly regarding component assessment and observation periods. Dedicated discussion is needed to establish uniform and acceptable standards to operationalize MAKE in terms of selection and applied criteria of components, observation period, and reporting criteria for future trials on AKI and related conditions.

Risk of Acute Kidney Injury Following IV Iodinated Contrast Media Exposure: 2023 Update, From the AJR Special Series on Contrast Media

Iodinated contrast material (ICM) has revolutionized the field of diagnostic radiology through improvements in diagnostic performance and the expansion of clinical indications for radiographic and CT examinations. Historically, nephrotoxicity was a feared complication of ICM use, thought to be associated with a significant risk of morbidity and mortality. Such fears often precluded the use of ICM in imaging evaluations, commonly at the expense of diagnostic performance and timely diagnosis. Over the past 20 years, the nephrotoxic risk of ICM has become a topic of debate, as more recent evidence from higher-quality studies now suggests that many cases of what was considered contrast-induced acute kidney injury (CI-AKI) likely were cases of mistaken causal attribution; most of these cases represented either acute kidney injury (AKI) caused by any of myriad other known factors that can adversely affect renal function and were coincidentally present at the time of contrast media exposure (termed "contrast-associated AKI" [CA-AKI]) or a manifestation of the normal variation in renal function that increases with worsening renal function. This Special Series Review discusses the current state of knowledge regarding CI-AKI and CA-AKI, including the incidence, risk factors, outcomes, and prophylactic strategies in the identification and management of these clinical conditions.

The Image Quality and Diagnostic Performance of CT with Low-Concentration Iodine Contrast (240 mg Iodine/mL) for the Abdominal Organs

Purpose: To evaluate the difference between CT examinations using 240 mgI/mL contrast material (CM) and 320 mgI/mL CM in the contrast enhancement of the abdominal organs and the diagnostic performance for focal hepatic lesions. Materials and methods: This retrospective study included 422 CT examinations, using 240 mgI/mL iohexol (Group A, 206 examinations) and 320 mgI/mL ioversol (Group B, 216 examinations), performed between April 2019 and May 2020. Two CT scanners (single-source CT (machine A) and dual-source CT (machine B)) were used to obtain CT images. Two radiologists independently drew regions of interest (ROIs) in the liver, pancreas, spleen, kidney, aorta, portal vein, and paraspinal muscle. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for each organ. They evaluated the degree of subjective enhancement of the organs and detected/differentiated focal hepatic lesions. Results: The SNR, CNR, and subjective enhancement of most organs were significantly higher in Group B than in Group A (p < 0.05). The sensitivity and specificity for cysts and malignancy were higher than 85.0% in both groups. The sensitivity for hemangioma was lower in Group B (<75%) than in Group A. In Group A, the SNR and CNR were significantly higher in most organs with machine B than with machine A. Conclusion: Although the SNR and CNR of the abdominal organs were lower with 240 mgI/mL CM than with 320 mgI/mL CM, 240 mgI/mL CM was feasible for evaluating the liver. A CT scanner with more advanced specifications may be beneficial for examinations with 240 mgI/mL CM by using lower tube voltage.

Is intravenous iodinated contrast medium administration really harmful in hospitalized acute kidney injury patients: a propensity score-matched study

OBJECTIVES

To evaluate the effects of intravenous iodinated contrast medium (ICM) administration on the deterioration of renal function (DRF), new renal replacement therapy (RRT) induction and mortality of hospitalized acute kidney injury (AKI) patients.

METHODS

Adult hospitalized patients undergoing a contrast-enhanced or unenhanced CT scan within 7 days after AKI diagnosis from January 2015 to December 2019 were identified in this retrospective study. Propensity score matching was performed. Outcomes in 7 and 30 days after CT scan were compared between the contrast and non-contrast groups. Additional analyses were also performed in patients stratified by SCr levels at AKI diagnosis, times and time of CT scan, and in patients without chronic kidney disease or RRT requirement prior to CT scan.

RESULTS

In total, 1172 pairs were generated after 1:1 propensity score matching from 1336 cases exposed to ICM and 2724 unexposed. No significant differences were found in the outcomes between the two groups: DRF, 7.8% vs 9.0% (odds ratio (OR) 0.83, 95% confidence interval (CI) 0.62-1.11) in 7 days, 5.1% vs 5.4% (OR 0.93, 95%CI 0.64-1.34) in 30 days; new RRT induction, 2.3% vs 3.3% (OR 0.72,95%CI 0.43-1.18) in 7 days, 4.2% vs 4.5% (OR 0.95,95%CI 0.64-1.41) in 30 days; and mortality, 3.9% vs 4.8% (OR 0.83,95%CI 0.56-1.22) in 7 days, 9.0% vs 10.2% (OR 0.88,95%CI 0.68-1.15) in 30 days. Subset analyses showed similar results.

CONCLUSION

Intravenous ICM administration during AKI duration did not increase the risks of DRF, new RRT induction, and mortality in 7 and 30 days after CT scan.

KEY POINTS

• Intravenous ICM administration in hospitalized AKI patients does not increase the risks of deterioration of renal function, RRT induction, and mortality in 7 and 30 days after CT scan. • The effects of intravenous ICM on adverse outcomes are minimal even in AKI patients with high level of SCr values or multiple CT scans.