Rapid, Panel Viral Testing May Be Cost Effective in Hospitals, Less So in Outpatient Settings

Panel-based diagnostics for respiratory viral (RV) infections may be cost-effective in hospital settings, according to several abstracts presented at the Clinical Virology Symposium (May 19-22; Daytona Beach, Fla.). Population-specific implementation can yield improved patient outcomes and cost savings in the hospital’s emergency department and intensive care unit (ICU), but such comprehensive panels may not be cost effective in outpatient settings.

Researchers from Geisinger Health System (Danville, Penn.) assessed the impact of rapid results of non-batched respiratory virus assays on downstream patient outcomes in the ICU. Geisinger performs multiplex RV testing prior to all admissions. From Nov. 1, 2010 to Mar 19, 2012, batch molecular RV testing (pre-intervention; n=278) was performed once per day for all inpatients (Luminex Corporation). From Mar. 19, 2012 to Apr. 30, 2014, this testing switched to a first-in first-out (FIFO), random access basis (post-implementation; n=462) with priority for ICU and emergency department orders (BioFire Diagnostics).

Post-implementation there were significant improvements in 28-day mortality, length of stay (LOS), ICU days, ventilator days, antimicrobial (including viral and bacterial) utilization, laboratory test utilization, and total cost. The mean collect to report time (CTR) dropped by 30.5 hours for the post-implementation period. This reduction in CTR was associated with significantly improved mortality when results were reported in less than seven hours. For patients with negative respiratory virus results, mean ICU stay, mean overall LOS, and mean total cost decreased by 3.3 days, 1.9 days, and $8,082.60, respectively.

“Although random access molecular methods tend to be more costly than batch molecular assays, improved outcomes in certain populations, such as ICU, may warrant their use,” writes Raquel Martinez, Ph.D. “Additionally, this study demonstrated that 28 day mortality significantly increased when results were reported in more than seven hours. ... Attention to CTR appears to be an important quality indicator. ... Although a FIFO workflow may not be feasible for some laboratories, it may be possible to implement batch testing to achieve similar CTR.”

Another study, from University Medical Center Groningen in the Netherlands, found that implementing rapid diagnostic testing for respiratory viral infections in the emergency department showed value not just in positive cases, but also in patients that tested negative. The BioFire respiratory panel (bioMerieux) was used for rapid testing and diagnostic services were extended from five days per week between eight to 17 hours to seven days per week between eight to 22 hours during the 2014-2015 respiratory season (Dec. 11, 2014 to April 5, 2015) as part of a new adequate and LEAN diagnostic policy at University Medical Center Groningen.

The researchers found that over the study period 641 tests were ordered in the emergency department and of those, 492 contained all needed data for analysis. The median turnaround time was 110 minutes at the medical microbiology department (from sample to answer), yielding a total median time to result of 165 minutes (from patient registration at the emergency department to final result and medical decision). While only 15 percent of samples (n=51) tested positive for influenza, 24 percent (n=79) tested positive for coronavirus, rhinovirus, human metapneumovirus, RSV, PIV or influenza B. In the vast majority of positive cases (93 percent), results were available before admission for 330 patients, which, the researchers say, improved the bed management and in-hospital patient flow. Furthermore, timely negative results prevented 186 patients from going in isolation.

Yet, in the outpatient settings, more targeted testing approaches may be more cost-effective, according to Yale researchers presenting at the conference.

Researchers evaluated measures associated with testing positive for influenza and non-influenza RV among outpatients at the West Haven Veterans Administration Hospital (Connecticut). The FilmArray Respiratory Panel (Biofire) was used from Dec. 15, 2014 to April 15, 2015 in 408 outpatients seen in the emergency department, off-site urgent care, and outpatient clinics. Differences in antibiotic and oseltamivir prescription rates were analyzed through medical records.

Among the 295 patients managed as outpatients, 105 tested positive for influenza, 109 tested positive for a non-influenza pathogen, and 81 tested negative. Those that tested positive for influenza viruses received fewer antibiotic prescriptions and more oseltamivir prescriptions than those who tested positive for another pathogen or those who tested negative.

“While there is a specific therapeutic intervention available for outpatients who test positive for influenza viruses (oseltamivir), the implications of testing positive for a non-influenza virus are unclear,” writes co-author David Peaper, M.D., Ph.D., Yale- New Haven Hospital in New Haven, Conn. “There was no difference in antibiotic prescription rates among those who tested positive for a non-influenza pathogen compared to those who tested negative, suggesting that testing for influenza viruses alone may be sufficient and more cost-effective than multiplex pathogen testing for outpatients with respiratory tract infections.”

Takeaway: Comprehensive panels for RVs may be more cost effective to use in certain hospital populations, like the emergency department and ICUs, compared to outpatient settings.