Study suggests meds to prevent contrast reaction do more harm than good

Patients who have had an allergic reaction to iodinated CT contrast in the past don’t fare better by taking preventive corticosteroid pills the next time around.

In fact, Matthew Davenport, MD, of the University of Michigan, and colleagues found that 1,424 inpatients who received oral 13-hour inpatient corticosteroid prophylaxis showed only modest benefit—and suffered three indirect harms potentially worse than the direct harm the pre-treatment aimed to prevent.

Moreover, this added up to significantly escalated costs over the dollars spent on a control cohort.

Davenport et al. report the results of their retrospective study ahead of print in Radiology.

The subjects in the experiment group were pre-treated against contrast reaction according to a 13-hour regimen advocated by the American College of Radiology.

This calls for a 150-mg dose of oral prednisone administered in 50-mg doses 13 hours, seven hours, and one hour before the contrast CT study, along with 50 mg of oral diphenhydramine administered in a single 50-mg dose one hour before the scan.  

Compared with the control subjects, the premedicated patients had:

  • significantly longer median length of stay (+25 hours; 158 vs 133 hours, P < .001);
  • significantly longer median time to CT (+25 hours, 42 vs 17 hours, P < .001); and
  • significantly greater risk of hospital-acquired infection (HAI) (5.1 percent [72 of 1424] vs 3.1 percent [44 of 1424], P = .008).

The authors computed that, on the basis of these data and existing references, the prolonged length of stay would translate to an additional hospitalization cost of $159,131 for each prevented reaction of any severity.

In their study discussion, the authors warn against extrapolating from their findings a scenario that might be expected in an outpatient population, especially one for which premedication is administered in a low-cost, low-risk environment.

As for the inpatient setting, however, they assert that their results “question the utility of continuing standard premedication practices.”

The authors conclude that future study with a prospective cohort, perhaps one “focused on patients with a previous mild allergic-like reaction to contrast material with attentive postinjection care after randomization on the basis of prophylaxis (vs none), may shed further light on the population risks and benefits of inpatient premedication.”