Study: Skip prehydration before contrast CT of kidneys

2017 03 24 11 45 14 696 Dutch Flag 400

Prehydrating patients who have chronic kidney disease before they undergo a contrast-enhanced CT exam has been the standard of care for years. But new research suggests that the practice results in unnecessary costs with few patient benefits. The findings were published online on 17 February in JAMA Internal Medicine.

International guidelines for evaluating patients with kidney disease recommend intravenous prehydration, or volume expansion with saline or sodium bicarbonate, before administering iodine-based contrast media for CT scans. The guideline was established as a preventive measure against possible postcontrast acute kidney injury based on limited clinical evidence.

"Although hydration protocols to prevent postcontrast acute kidney injury have been implemented in daily clinical practice for more than a decade, there is a lack of evidence for the effectiveness of these costly measures," wrote the authors, led by Dr. Menno Huisman, PhD, from Leiden University Medical Center in the Netherlands.

Given the low risk of postcontrast acute kidney injury, Huisman and colleagues launched a multicenter randomized trial to determine whether prehydration was a necessary step in the evaluation of kidney disease on contrast-enhanced CT.

They examined the outcomes of 523 patients with stage III chronic kidney disease who underwent a contrast-enhanced CT exam either with or without prehydration. The prehydration protocol involved infusing 250 mL of 1.4% sodium bicarbonate an hour before contrast administration at an average cost of 119 euros per person. Roughly 64% of the patients were men, and none of the patients required dialysis or developed acute heart failure.

After completing the trial, the researchers found no statistically significant difference in postcontrast acute kidney injury rates between the patients who did and did not receive the prehydration protocol.

The researchers also tracked the patients' mean relative increase in serum creatinine -- a marker of kidney disease -- at two to five days and at seven to 14 days after contrast administration. They found that the changes in serum creatinine levels were roughly the same in both patient cohorts.

Prehydration vs. no prehydration before CT for chronic kidney disease
  Prehydration No prehydration
Postcontrast acute kidney injury rate 1.5% 2.7%
Increase in serum creatinine 2 to 5 days after contrast administration 3.5% 3%
Increase in serum creatinine 7 to 14 days after contrast administration 3.5% 3.5%
Average total hospital costs 1,315 euros 1,243 euros

Finally, the mortality rates for the two patient cohorts were both slightly under 10%, with no direct associations made between the causes of death and kidney injury.

The results show that withholding short sodium bicarbonate prehydration before contrast-enhanced CT does not compromise renal safety in patients with stage III chronic kidney disease and "support the option of not giving prehydration as a safe and cost-efficient measure," the authors wrote.

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