Risk of intravenous contrast material-mediated acute kidney injury: a propensity score-matched study stratified by baseline-estimated glomerular filtration rate

Incidence and Risk Factors for Postcontrast Acute Kidney Injury in Survivors of Sudden Cardiac Arrest

STUDY OBJECTIVE

Survivors of sudden cardiac arrest may be exposed to iodinated contrast from invasive coronary angiography or contrast-enhanced computed tomography, although the effects on incident acute kidney injury are unknown. The study objective was to determine whether contrast administration within the first 24 hours was associated with acute kidney injury in survivors of sudden cardiac arrest.

METHODS

This cohort study, derived from a prospective clinical trial, included patients with sudden cardiac arrest who survived for 48 hours, had no history of end-stage renal disease, and had at least 2 serum creatinine measurements during hospitalization. The contrast group included patients with exposure to iodinated contrast within 24 hours of sudden cardiac arrest. Incident acute kidney injury and first-time dialysis were compared between contrast and no contrast groups and then controlled for known acute kidney injury risk factors.

RESULTS

Of the 199 survivors of sudden cardiac arrest, 94 received iodinated contrast. Mean baseline serum creatinine level was 1.3 mg/dL (95% confidence interval [CI] 1.4 to 1.5 mg/dL) for the contrast group and 1.6 mg/dL (95% CI 1.4 to 1.7 mg/dL) for the no contrast group. Incident acute kidney injury was lower in the contrast group (12.8%) than the no contrast group (17.1%; difference 4.4%; 95% CI -9.2% to 17.5%). Contrast administration was not associated with significant increases in incident acute kidney injury within quartiles of baseline serum creatinine level or after controlling for age, sex, race, congestive heart failure, diabetes, and admission serum creatinine level by regression analysis. Older age was independently associated with acute kidney injury.

CONCLUSION

Despite elevated baseline serum creatinine level in most survivors of sudden cardiac arrest, iodinated contrast administration was not associated with incident acute kidney injury even when other acute kidney injury risk factors were controlled for. Thus, although acute kidney injury is not uncommon among survivors of sudden cardiac arrest, early (<24 hours) contrast administration from imaging procedures did not confer an increased risk for acute kidney injury.

Risk of Acute Kidney Injury, Dialysis, and Mortality in Patients With Chronic Kidney Disease After Intravenous Contrast Material Exposure

OBJECTIVE

To examine the effect of intravenous iodinated contrast material administration on the subsequent development of acute kidney injury (AKI), emergent dialysis, and short-term mortality using a propensity score-adjusted analysis of computed tomographic scan recipients with chronic kidney disease (CKD).

PATIENTS AND METHODS

In this institutional review board-approved retrospective study, all patients with CKD who received a contrast-enhanced (contrast group) or unenhanced (noncontrast group) computed tomographic scan from January 1, 2000, to August 1, 2013 were identified. Patients were subdivided into CKD stage III (baseline estimated glomerular filtration rate, 30-59 mL/min per 1.73 m(2)) and CKD stage IV-V (baseline estimated glomerular filtration rate, <30 mL/min per 1.73 m(2)) subgroups and separately underwent propensity score generation, stratification, and 1:1 matching. Rates of AKI, 30-day emergent dialysis, and mortality were compared between contrast and noncontrast groups. Sensitivity analyses examining only patients with stable prescan serum creatinine levels and incorporating intravenous fluid administration at the time of the CT scan into the model were also performed.

RESULTS

A total of 6902 patients (4496 CKD stage III, matched: 1220 contrast and 1220 noncontrast; 2086 CKD stage IV-V, matched: 491 contrast and 491 noncontrast) were included in the study. After propensity score adjustment, rates of AKI, emergent dialysis, and mortality were not significantly higher in the contrast group than in the noncontrast group in either CKD subgroup (CKD stage III: OR, 0.65-1.00; P<.001-.99 and CKD stage IV-V: OR, 0.93-2.33; P=.22-.99). Both sensitivity analyses revealed similar results.

CONCLUSION

Intravenous contrast material administration was not associated with an increased risk of AKI, emergent dialysis, and short-term mortality in a cohort of patients with diminished renal function.

Incidence of CT Contrast Agent-Induced Nephropathy: Toward a More Accurate Estimation

OBJECTIVE

Acute kidney injury is common among hospitalized patients and likely leads to inflated reports of the incidence of CT contrast agent-induced nephropathy as a cause of acute kidney injury. For a more accurate estimation, we compared the incidence of acute kidney injury immediately after contrast agent administration and a few days afterward in the same population. We also controlled for a creatinine level increase starting before and continuing after CT, which may be incorrectly associated with the scan itself.

MATERIALS AND METHODS

After excluding patients undergoing dialysis, we included all adults who underwent CT from January 2006 through May 2013 in our health region. The incidence of acute kidney injury (Acute Kidney Injury Network stages) and dialysis after acute kidney injury were assessed in the immediate period (24-48 hours) and in a delayed period (72-96 hours) after the scan. New acute kidney injury in either period occurred if the creatinine level had increased at a greater rate than that in a preceding 24-hour interval. The incidence of acute kidney injury and dialysis after acute kidney injury attributable to CT were calculated by subtracting the delayed incidence from the immediate incidence.

RESULTS

Incidences of acute kidney injury and dialysis after acute kidney injury attributable to contrast-enhanced CT were statistically insignificant across glomerular filtration rate (GFR) subgroups. Acute kidney injury incidences (Acute Kidney Injury Network stage I or worse) were 0.5% (95% CI, -0.4% to 1.4%) for GFR greater than 60 mL/min/1.73 m(2), 2.4% (95% CI, -0.7% to 5.6%) for GFR 30-59 mL/min/1.73 m(2), -4.3% (95% CI, -19.8% to 11.3%) for GFR 15-29 mL/min/1.73 m(2), and 0% (95% CI, -24.5% to 24.5%) for GFR less than 15 mL/min/1.73 m(2).

CONCLUSION

There appears to be a minimal risk of CT contrast agent-induced nephropathy at mild to moderate levels of renal dysfunction.

Contrast-associated AKI in the critically ill: relevant or irrelevant?

PURPOSE OF REVIEW

Iodinated contrast media are frequently administered in ICU patients. Recent studies challenge the relevance of contrast media toxicity in ICU patients and relate occurrence of acute kidney injury to baseline characteristics and severity of illness.

RECENT FINDINGS

Various findings in studies with kidney biomarkers indicate the causal relationship between contrast media exposure and kidney damage. Contrast media exposure not only causes direct tubular damage and renal hypoperfusion but also initiates the formation of reactive oxygen species in its turn causing tissue damage. The route of administration determines the incidence of contrast-induced acute kidney injury with a higher incidence when contrast media are administered by intra-arterial route versus intravenous route. The impact of contrast-associated acute kidney injury on hospital length of stay, the need for renal replacement therapy and survival remains a matter of debate because of discrepancies between observational versus case-matched studies and limitations of the individual studies.

SUMMARY

There are diverse pathophysiologic mechanisms explaining the causal relationship between the administration of contrast media and the development of acute kidney injury. Some studies challenge the relevance of contrast media toxicity in ICU patients. However, limitations of the available studies in ICU patients preclude firm conclusions. A precautionary approach in the administration of contrast media is justified.

No increase in Kidney Injury Molecule-1 and Neutrophil Gelatinase-Associated Lipocalin excretion following intravenous contrast enhanced-CT

Objectives

To analyze kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (N-GAL) excretion post-intravenous contrast enhanced-CT (CE-CT) in patients with chronic kidney disease (CKD).

Methods

Patients were enrolled in a trial on hydration regimes to prevent contrast-induced acute kidney injury (CI-AKI). Blood and urine samples were taken at baseline, 4 – 6, and 48 – 96 h post CE-CT. Urinary KIM-1 and N-GAL values were normalized for urinary creatinine levels, presented as medians with 2.5 – 97.5 percentiles.

Results

Of the enrolled 511 patients, 10 (2 %) were lost to follow-up. CI-AKI occurred in 3.9 % of patients (20/501). Median KIM-1 values were 1.2 (0.1 – 7.7) at baseline, 1.3 (0.1 – 8.6) at 4 – 6 h, and 1.3 ng/mg (0.1 – 8.1) at 48 – 96 h post CE-CT (P = 0.39). Median N-GAL values were 41.0 (4.4 – 3,174.4), 48.9 (5.7 – 3,406.1), and 37.8 μg/mg (3.5 – 3,200.4), respectively (P = 0.07). The amount of KIM-1 and N-GAL excretion in follow-up was similar for patients with and without CI-AKI (P-value KIM-1 0.08, P-value N-GAL 0.73). Neither patient characteristics at baseline including severe CKD, medication use, nor contrast dose were associated with increased excretion of KIM-1 or N-GAL during follow-up.

Conclusion

KIM-1 and N-GAL excretion were unaffected by CE-CT both in patients with and without CI-AKI, suggesting that CI-AKI was not accompanied by tubular injury.

Key Points

• KIM-1 and N-GAL excretion were unaffected by intravenous contrast-enhanced CT (CE-CT).

• Patient or procedure characteristics were not associated with increased KIM-1 or N-GAL excretion.

• Performance of CE-CT in CKD patients is likely to be safe.

Contrast media controversies in 2015: imaging patients with renal impairment or risk of contrast reaction

OBJECTIVE

The incidence and significance of complications related to intravascular contrast material administration have become increasingly controversial. This review will highlight current thinking regarding the imaging of patients with renal impairment and those at risk for an allergiclike contrast reaction.

CONCLUSION

The risk of contrast-induced acute kidney injury remains uncertain for patients with an estimated glomerular filtration rate (GFR) less than 45 mL/min/1.73 m(2), but if there is a risk, it is greatest in those with estimated GFR less than 30 mL/min/1.73 m(2). In this population, low-risk gadolinium-based contrast agents appear to have a large safety margin. Corticosteroid prophylaxis remains the standard of care in the United States for patients identified to be at high risk of a contrast reaction, but it has an incomplete mitigating effect on contrast reaction rates and the number needed to treat is large.

Randomised trial of no hydration vs. sodium bicarbonate hydration in patients with chronic kidney disease undergoing acute computed tomography-pulmonary angiography

BACKGROUND

Hydration to prevent contrast-induced acute kidney injury (CI-AKI) induces a diagnostic delay when performing computed tomography-pulmonary angiography (CTPA) in patients suspected of having acute pulmonary embolism.

AIM

To analyze whether withholding hydration is non-inferior to sodium bicarbonate hydration before CTPA in patients with chronic kidney disease (CKD).

METHODS

We performed an open-label multicenter randomized trial between 2009 and 2013. One hundred thirty-nine CKD patients were randomized, of whom 138 were included in the intention-to-treat population: 67 were randomized to withholding hydration and 71 were randomized to 1-h 250 mL 1.4% sodium bicarbonate hydration before CTPA. Primary outcome was the increase in serum creatinine 48-96 h after CTPA. Secondary outcomes were the incidence of CI-AKI (creatinine increase > 25%/> 0.5 mg dL(-1) ), recovery of renal function, and the need for dialysis within 2 months after CTPA. Withholding hydration was considered non-inferior if the mean relative creatinine increase was ≤ 15% compared with sodium bicarbonate.

RESULTS

Mean relative creatinine increase was -0.14% (interquartile range -15.1% to 12.0%) for withholding hydration and -0.32% (interquartile range -9.7% to 10.1%) for sodium bicarbonate (mean difference 0.19%, 95% confidence interval -5.88% to 6.25%, P-value non-inferiority < 0.001). CI-AKI occurred in 11 patients (8.1%): 6 (9.2%) were randomized to withholding hydration and 5 (7.1%) to sodium bicarbonate (relative risk 1.29, 95% confidence interval 0.41-4.03). Renal function recovered in 80.0% of CI-AKI patients within each group (relative risk 1.00, 95% confidence interval 0.54-1.86). None of the CI-AKI patients developed a need for dialysis.

CONCLUSION

Our results suggest that preventive hydration could be safely withheld in CKD patients undergoing CTPA for suspected acute pulmonary embolism. This will facilitate management of these patients and prevents delay in diagnosis as well as unnecessary start of anticoagulant treatment while receiving volume expansion.

Imaging for appendicitis: should radiation-induced cancer risks affect modality selection?

PURPOSE

To compare life expectancy (LE) losses attributable to three imaging strategies for appendicitis in adults-computed tomography (CT), ultrasonography (US) followed by CT for negative or indeterminate US results, and magnetic resonance (MR) imaging-by using a decision-analytic model.

MATERIALS AND METHODS

In this model, for each imaging strategy, LE losses for 20-, 40-, and 65-year-old men and women were computed as a function of five key variables: baseline cohort LE, test performance, surgical mortality, risk of death from delayed diagnosis (missed appendicitis), and LE loss attributable to radiation-induced cancer death. Appendicitis prevalence, test performance, mortality rates from surgery and missed appendicitis, and radiation doses from CT were elicited from the published literature and institutional data. LE loss attributable to radiation exposure was projected by using a separate organ-specific model that accounted for anatomic coverage during a typical abdominopelvic CT examination. One- and two-way sensitivity analyses were performed to evaluate effects of model input variability on results.

RESULTS

Outcomes across imaging strategies differed minimally-for example, for 20-year-old men, corresponding LE losses were 5.8 days (MR imaging), 6.8 days (combined US and CT), and 8.2 days (CT). This order was sensitive to differences in test performance but was insensitive to variation in radiation-induced cancer deaths. For example, in the same cohort, MR imaging sensitivity had to be 91% at minimum (if specificity were 100%), and MR imaging specificity had to be 62% at minimum (if sensitivity were 100%) to incur the least LE loss. Conversely, LE loss attributable to radiation exposure would need to decrease by 74-fold for combined US and CT, instead of MR imaging, to incur the least LE loss.

CONCLUSION

The specific imaging strategy used to diagnose appendicitis minimally affects outcomes. Paradigm shifts to MR imaging owing to concerns over radiation should be considered only if MR imaging test performance is very high.

Incidence of nonconfounded post-computed tomography acute kidney injury in hospitalized patients with stable renal function receiving intravenous iodinated contrast material

OBJECTIVE

The purpose of our investigation was to determine the frequency of proximate acute and chronic confounding risk factors for acute kidney injury (AKI) in a cohort of adult hospitalized patients with stable renal function who developed AKI following an intravenous (IV) contrast-enhanced computed tomography (CT) examination.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective, Health Insurance Portability and Accountability Act-compliant investigation. Overall, 100 adult inpatients (50 males [mean age = 61 years, range: 24-94 years] and 50 females [mean age = 60 years, range: 20-95 years]) with stable pre-CT renal function who developed post-CT AKI using the Acute Kidney Injury Network (AKIN) laboratory criteria following an IV contrast-enhanced CT examination comprised the study population. Electronic International Classification of Disease-9 analysis followed by a comprehensive manual electronic medical record review was systematically performed by 5 radiologists to identify known acute (n = 24, within 5 days before or 3 days after CT) and chronic (n = 21) risk factors for AKI other than contrast material administration that might confound a diagnosis of contrast-induced nephrotoxicity. Descriptive statistics were performed.

RESULTS

Of 100 inpatients with post-CT AKI, 99 (99%) had 1 or more acute risk factor(s) for AKI other than contrast material administration (median = 3 risk factors, range: 0-8) and 86 (86%) had one or more chronic risk factor(s) for AKI (median = 2 risk factors, range: 0-7). The median number of risk factors (acute or chronic) per patient was 5 (range: 1-13). Only 1 inpatient (1%) developed post-CT AKI without a confounding acute risk factor (estimated glomerular filtration rate = 62-71 mL/min/1.73 m(2), 4 chronic risk factors, and CT 7 days after pancreaticoduodenectomy). The most common acute risk factors were nephrotoxic medications (83%) and parenteral blood product administration (30%). The most common chronic risk factors were hypertension (59%) and chronic kidney disease (56%).

CONCLUSION

Nonconfounded post-CT AKI is rare in hospitalized adults with stable renal function who have been exposed to IV low- or iso-osmolality iodinated contrast material.