Point-of-care influenza testing in emergency departments reduces chest x-rays and blood tests but not antibiotic use, according to a systematic review.

"Antibiotic prescribing was the most common outcome the included studies looked at and what everyone was hoping point-of-care tests (POCTs) would improve," Dr. Joseph J. Lee of the University of Oxford, U.K., told Reuters Health by email. "We need to take care of antibiotics, but we can't expect these tests to do it for us."

Blue antibiotics. Source

POCTs are highly specific (>98%), but their sensitivity ranges widely, from 53%-54% for rapid antigen-detection tests (RIDTs) to 92%-95% for nucleic acid amplification tests (NAATs). These tests offer rapid, accurate diagnoses, but they may not automatically lead to beneficial clinical outcomes.

Dr. Lee's team examined the impact of influenza POCTs on hospital admissions, antibiotic and antiviral prescribing, and the use of other diagnostic tests in their systematic review and meta-analysis of 13 studies (seven of which were randomized).

POCTs reduced the use of routine blood tests by 20%, the use of blood cultures by 18% and the use of chest radiography by 19%, but had no effect on the rates of urinalysis or lumbar puncture, the team reports in Clinical Infectious Diseases, online October 4.

POCT use was associated with increased antiviral prescribing in randomized studies but not in nonrandomized studies. Antibiotic prescribing did not drop with the use of POCTs.

POCT use did not reduce hospital admissions, returns for follow-up, or time spent in emergency departments.

"In the U.K. we use these tests relatively infrequently, but they are being introduced more widely, so there is an opportunity to take stock and make sure we understand the likely benefit before rolling them out," Dr. Lee said. "I understand influenza POCTs are used more routinely in the U.S. and some other countries, and there may be a case to be made that this could be rationalized, particularly in situations where further blood tests, antivirals, or x-rays wouldn't be planned anyway."

"Most of the included studies used older tests, which are not as sensitive for picking up influenza as newer tests," he noted. "Our results are likely to be conservative compared to what would be found with newer tests."

"The main message I would hope physicians take away from this report would be: test for influenza early and look at the result before requesting x-rays and further tests, but we need to look to other means to conserve antibiotics," Dr. Lee said.

Dr. Elissa Schechter-Perkins from Boston University School of Medicine, who recently evaluated a combined influenza and respiratory syncytial virus (RSV) POCT, told Reuters Health by email that the authors' "main findings, that point-of-care influenza testing can influence certain (but not all) outcomes, really mirrors my experience in emergency department settings."

"We should understand, based on these findings, that POCTs are not a panacea that can fix all problems related to the high burden of influenza-like illnesses coming to the emergency department during influenza season," she said. "Point-of-care testing will likely never decrease important patient-oriented outcomes, such as morbidity and mortality from influenza-like illnesses. However, this study shows that in spite of these limitations, POC tests still have an important role to play in decreasing unnecessary adjunctive testing and increasing the use of important antiviral medications."

"There is a strong role for POC influenza testing in emergency department settings, especially among pediatric patients, especially during influenza season," Dr. Schechter-Perkins concluded.

SOURCE: https://bit.ly/2zs1hsl

Clin Infect Dis 2018.