Survey of Influenza and Other Respiratory Viruses Diagnostic Testing in US Hospitals, 2012–2013

Su Su; Alicia M. Fry; Pam Daily Kirley; Deborah Aragon; Kimberly Yousey-Hindes; James Meek; Kyle Openo; Oluwakemi Oni; Ruta Sharangpani; Craig Morin; Gary Hollick; Krista Lung; Matt Laidler; Mary Lou Lindegren; William Schaffner; Annette Atkinson; Sandra S. Chaves

Disclosures

Influenza Resp Viruses. 2016;30(2):86-90. 

In This Article

Results

Characteristics of Hospitals

Most (267/316, 84%) participating hospitals in the FluSurv-NET catchment area responded to the survey; 206 (78%) were located in urban areas (i.e. population density ≥ 2000 people per square mile), whereas the remainder were located in suburban or rural areas. Approximately half (n = 129) of all hospitals had fewer than 200 beds. The hospitals represented a variety of practices including 210 general hospitals, 16 children's hospitals, 12 Veteran's Affairs hospitals and 7 other specialty hospitals. Fifty-three (20%) of the hospitals were affiliated with academic institutions and 220 (83%) were equipped with a general ED.

The majority of the hospitals (80%) did not have a policy in place to systematically test patients with acute respiratory infections (ARI) presenting to the ED during influenza seasons for influenza. All hospitals that had a policy in place for testing patients with ARI were located in urban/suburban areas. Having a testing policy was not associated with hospital size or academic affiliation. Most of these hospitals applied the testing policy to both adults and children (42/52).

Sixty (22%) hospitals performed RIDTs during influenza season directly in the ED or clinic (i.e. 'point-of-care testing'): 55/60 in the ED, 20 of 60 in outpatient clinics, and 31 of 60 in inpatient wards. Most of these hospitals were urban (45/60), non-academic affiliated (49/60) and with less than 200 beds (40/60). There were no difference in the availability of POC testing and a hospital policy to test patients for influenza during influenza season (20% versus 20%, P = 0·79).

Laboratory Capacity for Influenza Diagnostic Testing

Two hundred and twenty-nine hospital laboratories and 11 independent laboratories (e.g. reference, commercial, physician's office, satellite clinic) responded to the survey. All laboratories had at least one influenza diagnostic assay available. RIDTs were the most frequently used (87%), followed by molecular assays (26%), viral culture (13%), direct or indirect fluorescent antibody assay (DFA/IFA) (10%), and serology (1%). RIDT was the only diagnostic test available for influenza in 67% of the laboratories. Compared to results from the survey conducted in 2006–2007, the proportion of laboratories reporting the use of molecular assays increased significantly during the 2012–2013 season (4% versus 26% respectively, P < 0·001), while the use of viral culture and DFA/IFA slightly decreased (Figure 1). Among 63 laboratories with reverse transcription polymerase chain reaction (RT-PCR) capacity, 8% developed their own influenza RT-PCR assay in house and 60% were able to subtype influenza A viruses. Most of these laboratories (57/63) were capable of providing RT-PCR test results within 1 day, among which 60% (34/57) ran tests immediately or as needed. The other six laboratories performed testing at various frequencies within a week.

Figure 1.

Comparison of types of influenza diagnostic tests performed in clinical laboratories serving hospitals during the 2006–2007 and 2012–2013 influenza season.

Influenza Testing Algorithms

Among 228 local hospital laboratories with available data, 30 (13%) used molecular testing as the only technique for inpatient influenza testing (Figure 2). Among 198 laboratories that performed RIDT as their first choice for an influenza diagnostic, ~50% reported both positive and negative results back to the physician as final, without proceeding with a confirmatory test. Laboratories were more likely to send positive RIDT results for confirmation than negative RIDT results (44% versus 31%); this reflects participation in FluSurv-NET surveillance for influenza A virus subtypes. Most of the confirmatory testing was sent to and performed at the corresponding state public health reference laboratory.

Figure 2.

Description of influenza testing practices in hospital laboratories, 2012–2013. Note: Hospitals with missing data are excluded. Confirmatory testing could be performed at the hospital laboratory or at public health laboratories. Participating hospital laboratories were asked to send influenza A specimens to state public health laboratories for subtyping. Some network sites asked laboratories to send RIDT-negative specimens to public health laboratories.

Testing Capacity for Respiratory Viruses Other Than Influenza

Overall, 172 of 240 (72%) of the laboratories were able to perform some kind of testing for other respiratory viruses (Table 1); 55 of 172 (32%) offered a molecular multiviral panel which often included influenza virus, respiratory syncytial virus (RSV), parainfluenza viruses, human metapneumovirus (hMPV), human rhinoviruses, and adenoviruses. Among the 172 laboratories performing tests for respiratory viruses other than influenza, all were able to test for RSV, 30% for adenovirus, 29% for parainfluenza viruses, 18% for hMPV, 13% for rhinovirus, and 3% for coronavirus. Rapid RSV diagnostic test was more frequently used (62%) for RSV testing than molecular assay (20%). For other respiratory viruses, the most common test available was a molecular assay (including Luminex, FilmArray, nucleic acid test (NAT), and RT-PCR assays).

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