IV Contrast May Have Lower Risk of Contrast-Induced Nephropathy than Previously Suspected


In a recent retrospective study from Mayo Clinic, researchers demonstrated that intravenous contrast material was not associated with acute kidney injury (i.e., increase in serum creatinine level of ≥0.5 mg/dL) during the 72 hours after computed tomography (CT) of the chest, abdomen, or pelvis (NEJM JW Gen Med Apr 10 2014). Now, the team has examined two “hard” outcomes — dialysis and death.

Using propensity-score matching, two groups of about 10,000 patients each were created from a large database; these groups were virtually identical in clinical characteristics, except that one group had undergone contrast-enhanced CT and the other had undergone unenhanced CT. The 30-day incidences of dialysis (≈0.2%) and mortality (≈8%) after CT scanning were nearly identical in the two groups. Receiving contrast was not associated with higher rates of dialysis or death among patients whose serum creatinine levels before CT scanning were >2.0 mg/dL or among patients with other high-risk conditions (e.g., diabetes, heart failure).

 

Comment:

Although this was a retrospective study which has its inherent limitations, it did involve a large number of patients with risk factors for contrast-induced nephropathy (creatinine >2 mg/dL, CHF, and diabetes).  The study did not show an increased risk of either death or need for dialysis with the receipt of IV contrast.

This warrants a true large RCT to verify these results.

IV contrast and contrast-induced nephropathy

Reference:

McDonald RJ et al. McDonald RJ et al. Intravenous contrast material exposure is not an independent risk factor for dialysis or mortality. Radiology 2014 Sep 9

Outcomes similar with different low-osmolar iodinated contrast agents.


Among patients undergoing coronary angiography or percutaneous coronary interventions with low-osmolar contrast media (LOCM), adverse outcomes are uncommon, with no advantage apparent between different agents.

That finding comes from a retrospective look at data on more than 100,000 patients, reported in theAmerican Journal of Cardiology online March 22 by Dr. James K. Min, with Cedars-Sinai Medical Center in Los Angeles, California, and colleagues.

“In contrast to previous studies that compared LOCM to iso-osmolar contrast media, our study directly compared alternate LOCM for differences in clinical outcomes,” the authors point out.

They note that previous reports have suggested that iohexol may be associated with increased rates of contrast-induced nephropathy (CIN) compared to an iso-osmolar contrast medium, whereas this has not been reported with other LOCM such as ioversol and iopamidol.

To determine if there is any difference between LOCMs, the team looked at outcomes in patients exposed to iohexol (n = 20,136), iopamidol (n = 21,539), or ioversol (n = 66,319) during invasive coronary procedures.

Propensity scoring generated 19,482 matched pairs of patients exposed to iohexol versus ioversol, and 10,204 pairs exposed to iohexol versus iopamidol.

The researchers found no significant difference between the iohexol-ioversol pairs in rates of new inpatient hemodialysis (relative risk 0.72; p = 0.05), inpatient mortality (RR 0.90; p = 0.42), or 30-day readmission for CIN (RR 0.81; p = 0.52).

Outcomes were also similar between the matched iohexol-iopamidol patients in terms of inpatient hemodialysis (RR 1.18; p = 0.45), inpatient mortality (RR 1.09; p = 0.60), or 30-day CIN readmission (RR 1.11; p = 0.82).

“Encouragingly, in this large dataset, even before matching, rates of in-hospital hemodialysis and mortality and 30-day readmission rates for CIN were low for all patients, irrespective of contrast medium used,” Dr. Min and colleagues comment.

“After matching,” they conclude, “we could not identify any significant differences in adverse events for patients who underwent ICA and/or PCI with different LOCM.”

 

Source: Am J Cardiol 

 

Hydration before contrast cuts CIN in high-risk patients.


Even patients with advanced kidney disease can steer clear of contrast-induced nephropathy (CIN) if given plenty of hydration, say researchers from the Netherlands. Results from the study of nearly 1,000 patients with stage 3 or 4 kidney disease were published in the June issue of Radiology.

The study found that fewer than 2.5% of the patients examined developed CIN when current guidelines emphasizing hydration were followed, according to the researchers from Radboud University Nijmegen Medical Centre in the Netherlands. The study also found that heart failure, low body mass index, and repeat contrast administration were associated with CIN.

CIN is the third most common cause of acute renal failure in hospitalized patients, and while most cases are limited to mild and transient impairment of renal function, serious morbidity and mortality, as well as longer hospital stays, can occur.

“In current practice, hydration is considered the preventive method of choice; however, evidence supporting its use is limited,” wrote Dr. Corinne Balemans and colleagues. Previous studies have relied on a variety of hydration protocols that were often used inconsistently (Radiology, June 2012, Vol. 263:3 pp. 706-713).

Balemans and colleagues aimed to determine risk factors associated with CIN by evaluating its incidence in patients with an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m2 who received iodinated contrast media intravenously and were treated using current guidelines.

Current CIN guidelines developed in Europe and the U.S. emphasize the identification of patients at high risk for CIN and the use of hydration as a preventive measure, either using normal saline or sodium bicarbonate as an alternative option, they wrote.

In the study, patients with renal insufficiency were evaluated at a special outpatient clinic where CIN was assessed and normal saline hydration was prescribed (Centraal Begeleidings Orgaan guidelines, 2007), with renal function assessed after the procedures.

The researchers stratified all patients with eGFR less than 60 mL/min/1.73 m2 for risk of CIN; those at high risk based on absolute GFR and risk factors were hydrated with 1,000 mL of isotonic saline before and after contrast injection. Serum creatinine was measured three to five days later, and CIN was defined as an increase of 25% or more from baseline. Finally, the authors recorded and compared risk factors between patients with CIN and those without using stepwise multiple logistic regression analysis.

The study included 747 patients (43% female; mean age, 71.3 years ± 10) who underwent 944 procedures. Patients were hydrated in 511 (54.1%) procedures. CIN developed after 23 procedures (2.4%).

Independent predictors of CIN were heart failure (odds ratio, 3.0), body mass index (BMI) (odds ratio, 0.9), and repeated contrast material administration (odds ratio, 2.8), Balemans and colleagues wrote. No patients needed dialysis.

The population was carefully prepared before iodinated contrast injection, and only 7.7% of patients at high risk for CIN did not receive hydration.

“Our study provides reliable estimates of CIN and shows that the incidence of CIN is low in a homogeneous population of patients with stage 3 or 4 chronic kidney disease who underwent treatment in accordance with existing guidelines and who received intravenous iodinated contrast material,” the authors wrote.

In the study, money was saved by restricting hydration to about half of the study population; patients at high risk for CIN were hydrated, whereas those at low risk were not. However, it’s possible the incidence could have been reduced further by a less restrictive policy.

Regarding heart failure, a well-known risk factor for CIN, such patients may have more severe atherosclerotic vascular disease and are more prone to hemodynamic changes during and after procedures. For them, hydration may not be helpful, the authors wrote.

The inverse association between BMI and CIN may not have been reported previously, they noted. Patients with low BMI usually have a lower percentage of muscle mass, and as a result the formulas used to calculate eGFR overestimate renal function, Balemans and colleagues wrote.

Another study reported the association between repeat contrast exposure and CIN. In that study (Trivedi and Foley), the increased risk was even notable in patients with preserved renal function.

As for study limitations, the population was large but the number of events was small. Absolute GFR was used to classify risk, and there is debate about whether GFR should be corrected for body surface area.

The incidence of CIN in patients with stage 3 or 4 chronic kidney disease is low when treated in accordance with current guidelines, the authors concluded.

“Our findings support the efficacy of hydration regimens,” they wrote. “The risk of CIN is increased in patients with heart failure, low BMI, and repeated contrast material administration. These risk factors need to be validated in future studies.”

Higher creatinine can occur after CT — even without contrast.


Contrast media is often blamed for what appears to be contrast-induced nephropathy (CIN) in patients getting CT scans. But Chinese researchers have found that elevated rates of serum creatinine — a marker for CIN — can occur after CT even in

There are lots of reasons why patients could have higher serum creatinine levels after CT exams, according to two studies presented by researchers from Peking University First Hospital in Beijing at the 2013 International Symposium on Multidetector-Row CT. Clarifying those reasons is critical, according to the group.

“There are many factors affecting creatinine levels, especially among inpatients,” said Dr. Xiaoying Wang in her presentation. “Many patients have severe diseases where, due to the disease, doctors find it is not appropriate for them to have contrast-enhanced CT.”

Nailing down renal impairment

The findings don’t necessarily fit with conventional wisdom on contrast-induced nephropathy; however, they do highlight the multifactorial nature of impaired renal function and remind clinicians that several factors must be present for a CIN diagnosis, Wang said.

“The definition of CIN is clear and simple, but in practice it’s not easy to define,” she said. CIN requires an absolute or relative increase in serum creatinine (SCr) compared to baseline values, a temporal relationship between the rise in SCr and exposure to a contrast agent, and the exclusion of alternative explanations for renal impairment — which means looking for these explanations.

“Generally, as radiologists it is easy for us to detect an increase in serum creatinine, but it is not very easy for us — sometimes not even easy for nephrologists — to exclude alternative reasons for renal impairment,” Wang said.

In an effort to identify at-risk patients, in Wang’s practice, patients making appointments for contrast-enhanced CT are asked about a range of factors suggestive of CIN risk. The literature shows higher levels of risk for patients with a history of diabetes mellitus, hypertension, renal impairment, liver disease, renal-toxic medications, and a few other circumstances, though the studies used to identify the risk factors involved intra-arterial injection of contrast agents, Wang said.

Study 1: Are at-risk patients really more at risk for CIN?

For patients undergoing contrast-enhanced CT between 2010 and 2012, her group analyzed the association between risk factors and the subsequent development of CIN. The researchers examined a total of 2,556 patients, of whom 1,243 formed an observation group. The patients were measured for SCr before contrast-enhanced CT as well as 48 to 72 hours after CT; if SCr levels rose by the second test, the patient was referred to a nephrologist, and SCr was measured again seven to 10 days later.

In all, 68 (5.5%) of the 1,243 patients were diagnosed with CIN, including 12 with acute renal failure. (Fifty-one patients recovered and five were lost to follow-up.) However, the study showed no statistically significant difference in the development of CIN between the patients with risk factors and those without.

Of the patients who were not at risk, 4.5% (17/375) developed CIN, while in the at-risk group, 5.9% (51/868) developed the condition (p = 0.21). Among patients with no history of chronic kidney disease, only female gender (p = 0.03) and the use of low-osmolar contrast media (p = 0.03) were associated with a significantly increased risk of CIN.

Logistic regression analysis of risk factors showed several that increased the odds of CIN, including a history of diabetes mellitus (odds ratio [OR] = 1.83), history of tumor (OR = 1.54), use of nephrotoxic drugs (OR = 1.69), frequent use of contrast media (OR = 1.13), and use of low-osmolarity contrast media (OR = 2.28). In addition, women had an odds ratio of 1.69, and those older than 75 had an odds ratio of 1.26. The difference was only statistically significant in women (p = 0.04), however.

“These [risk] factors are not very strong to [predict] the incidence of CIN,” Wang said.

Study 2: Is ‘CIN’ risk really higher after noncontrast CT?

To continue to refine risk-factor prediction, the group recently completed a prospective cohort study of 623 patients who underwent CT with and without contrast. Of the 623 patients, 171 formed an observation group that received multiple SCr tests to allow the nephrologist to confirm a temporal association between increased SCr and contrast administration.

Among these 171 patients, 99 underwent contrast-enhanced CT and 72 had CT without contrast. There was no statistically significant difference in demographics and CIN-related risk factors between the 171 patients and the remaining 452, Wang said.

In all, 17 (9.9%) of the 171 patients developed what appeared to be CIN. Dividing up the patients between those who received contrast and those who did not, seven (7.1%) of the 99 who got contrast developed CIN. Meanwhile, 10 (13.9%) of the 72 patients who did not receive contrast developed “CIN.” Again, the difference in CIN rates between those who did and did not receive contrast was not statistically significant (p = 1.414).

Many factors affect creatinine levels, especially among those like the inpatients in this study, who have a wide range of medical conditions and are prescribed a variety of medications, Wang concluded. Even factors ranging from higher muscle mass to recent ingestion of cooked meat can result in higher SCr levels.

“That’s how we explain the higher SCr levels among noncontrast CT patients,” she said. “The increase of serum creatinine level after CT examination may occur without iodine contrast administration.”

She cautioned, though, that the sample sizes were small in both studies.

Excluding alternative explanations for renal impairment is crucial for diagnosing CIN, Wang concluded, and large, prospective cohort studies are needed to determine the true incidence of CIN in contrast-enhanced CT.

Source: auntminnie.com

Prevention of acute renal failure post-contrast imaging in cardiology: a randomized study..


Abstract

BACKGROUND:

The contrast-induced nephropathy (CIN) is the third most common cause of acute renal failure (ARF) and the worsening in a pre-existing chronic renal failure (CRF), with a foreseeable increase of morbidity, mortality, length of the stay in hospital and, as a consequence, of the health costs. We studied the effectiveness of N-acetylcysteine (NAC) associated with sodium bicarbonate (Na2HCO3) infusion in order to prevent CIN in patients undergoing coronary angiography with administration of contrast medium.

MATERIALS AND METHODS:

296 patients with indication to perform coronary angiography were included in a randomized, observational study. All patients were randomly assigned to receive pre- and post-contrast hydration with 1500 ml of 0.9% saline solution infusion (Group A) or NAC (1200 mg × 2 days) + Na2HCO3 (Group B). The primary end-point was to examine CIN appearance, defined as a raise in serum values of Cr (Creatinine) ≥ 0.5 mg/dl or ≥ 25% within 24-72 hours after the exposure to the contrast medium.

RESULTS:

It has been observed a frequency of CIN of 9.4% in Gr. A compared to 7.2% in Gr. B. Nevertheless, when we put these results through a more accurate screening according to gender, degree of raise in creatinine levels and the extent of change in GFR (glomerular filtration rate), we observed a very different behaviour. In patients with normal Cr and CrCl (Clearance of Creatinine) the frequency of CIN was similar in both group A and B (approximately 5%). In patients with normal Cr but reduced ClCr the use of NAC was more effective than hydration in preventing CIN (0% vs 18% in prevalence respectively in B and A group). In patients with moderately reduced Cr and CrCl, hydration with saline solution was more effective than NAC + Na2HCO3 (8.6% vs 17.6%) while in patients with severe CRF the combined use of NAC + Na2HCO3 showed off to be very successful in preventing CIN compared to the merely hydration (0% vs 50%).

CONCLUSIONS:

In patients affected by severe CRF who are undergoing investigations with contrast medium administration, such as coronary angiography, the combined use of NAC + Na2HCO3 infusion significantly reduces the risk of developing CIN. In other circumstances the final result is related to the degree of previous GFR or creatinine values alteration or to gender. In such situations the combined use of both substances is more questionable and sometimes ineffective.

Source: Pubmed