Why rapid viral testing for kids with URIs may not help in the ER

Originally published in MedPage Today

by Todd Neale, MedPage Today Staff Writer

Rapid viral diagnostic testing did not reduce the burden of treating children with respiratory symptoms and fever in the emergency department, according to a Cochrane Review meta-analysis.

Pooling the results of four trials, researchers found a significant reduction in the use of chest radiography (RR 0.77, 95% CI 0.65 to 0.91), but the reduction was short of the 25% deemed clinically meaningful, according to Quynh Doan, MDCM, of British Columbia Children’s Hospital in Vancouver, and colleagues.

There was no effect on the primary outcome — antibiotic use — or on other secondary outcomes such as blood and urine testing, length of ED stay, or postdischarge visits to a primary care physician or ED.

However, there were trends toward a benefit from rapid viral testing for most outcomes, and the researchers said the results might not have reached statistical significance because of a lack of power.

“Current evidence is insufficient, although promising, to support routine rapid viral testing as a means to reduce antibiotic use in pediatric EDs,” they said. “A large trial addressing these outcome measures is needed.”

Children arriving at the ED with respiratory symptoms and fever undergo numerous tests, including chest x-rays and blood and urine tests to rule out a bacterial infection.

But many receive antibiotics as a precaution, even though most acute febrile respiratory illnesses are caused by viruses, Doan and colleagues said, which puts a burden on health systems in terms of staff and hospital resources.

Rapid viral testing in the ED was one proposal for addressing this issue and cutting the inappropriate use of antibiotics.

The authors noted that “advances in virology testing now allow for viral detection within 30 to 120 minutes by direct immunofluorescent antibody detection. These have been reported to have high sensitivity (up to 90%) and specificity (up to 99%).”

To assess the technique’s effectiveness, Doan and colleagues reviewed data from four trials — three randomized controlled trials and one quasi-randomized controlled trial. They included a total of 759 youngsters in the rapid-testing group and 829 in the control group.

Three of the trials used rapid influenza testing and one used a rapid respiratory virus panel employing direct immunofluorescence assay.

Although one trial showed a significant reduction in antibiotic use in the ED, pooled results failed to show a significant difference (RR 0.89, 95% CI 0.71 to 1.12).

That same trial also demonstrated a shorter mean length of stay in the ED, but pooled results again failed to show significance (mean difference -10.6 min, 95% CI -22.5 to +1.25).

The meta-analysis revealed nonsignificant trends toward lower use of blood tests (RR 0.79, 95% CI 0.62 to 1.0) and urine analysis (RR 0.97, 95% CI 0.79 to 1.19).

There was no effect on return visits to a physician or ED (RR 1.00, 95% CI 0.77 to 1.29).

The authors said “the small number of trials included in this review may have contributed to the lack of significance on these statistical tests.”

They called for a large controlled trial to explore the possible benefits of rapid viral testing in the ED and also further study of the safety of rapid viral testing, as well as cost comparisons between the rapid diagnostic tests and the tests typically performed on children presenting with acute febrile respiratory illness.

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