How did your lab do with POCT?

By: Patrick Murray   
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The end of flu season is in view:

At this point in the year, most healthcare providers are seeing a steady wave of patients with flu-like symptoms. They may be struggling to pinpoint underlying causes and identify the appropriate treatment in a timely manner. Flu and respiratory syncytial virus (RSV) have overlapping peak infection seasons, making it difficult to distinguish the two clinically. Group A streptococcus is also common now.

We’ve likely seen the peak of flu season,1 and RSV may be starting its wind-down as well,2 so this is a good time to begin reflecting on how point-of-care testing (POCT) in your institution affected performance in managing winter respiratory tract infections. Upon reflection, how might your POCT strategy be improved for the next flu season? Here are some considerations for lab managers, which may help with planning for 2017-2018.

Effect on overuse of antibiotics

An incorrect diagnosis or inaccurate test result may point providers to the wrong treatment, exacerbating the overuse of antibiotics. More than 25 percent of antibiotics are prescribed for conditions that don’t warrant them.3 Out of 97 million annual office visits among adults in the United States between 2007 and 2009 that resulted in an antibiotic prescription, 41 percent were for a respiratory condition, the most common out of seven categories.3

A fast and correct influenza diagnosis can help reduce the incorrect use of antibiotics by providing critical information that healthcare providers need to treat patients’ illnesses and symptoms effectively. Point-of-care tests in general, and rapid influenza virus detection tests (RIDTs) in particular, can help staff quickly detect influenza A and B and determine the most appropriate treatment. These rapid immunoassays are simple to perform and are commonly used in office labs, retail clinics, emergency departments, and as rapid initial diagnostic tests in core hospital labs.

Avoidable expenses

Clinical labs must consider the impact that flu and RSV have on ancillary testing due to lack of a clear diagnosis. Rapid, accurate diagnosis plays a role here, too. In a 2014 study of influenza testing in emergency departments, 45 percent of patients diagnosed with influenza, including use of an RIDT, received an antibiotic, versus 53 percent for influenza patients diagnosed without use of an RIDT.4

Sensitivity of POCT

Rapid streptococcal carbohydrate visually read antigen tests are the most commonly used diagnostic tool for detecting group A streptococcus, due to their fast turnaround time and the appeal of getting test results during a patient’s visit. These tests have variable sensitivity (70 percent to 95 percent) that is shown to be higher when the test is performed by laboratorians than when performed by non-laboratory personnel.5

Likewise, some visually read influenza rapid tests perform with only 10 percent to 80 percent sensitivity when compared to reverse transcription-polymerase chain reaction (PCR) testing, the reference standard for confirmation of infection.6 The low-quality results can be attributed, in part, to the subjective nature of visually read rapid tests.7 Current visually read rapid tests require the user to form a results conclusion by reading an output of colored lines; given the variety in color shades and the inherent subjectivity of interpretation, this can lead to inaccurate results as well as repeat tests. The ambiguous nature of the conclusions drawn from such tests may prompt physicians to repeat testing for confirmation or to discount test results entirely and diagnose the patient based on symptoms alone.

The newer generation of rapid testing systems, known as digital immunoassays (DIAs), provides an objective, digital result while maintaining sensitivity. A poster presented at ID Week 2016 showed that novel DIAs have higher sensitivity for influenza A and B compared to traditional RIDTs, with equal specificity when compared to a high-sensitivity reference test.8

POCT and workflow

During busy winter months when flu, strep, and RSV seasons overlap, healthcare practices are best served by diagnosing and identifying treatments in one consultation, reducing the need for follow-up visits or communication. DIAs, which can produce results in under 15 minutes, can streamline the POC diagnostic workflow and enable providers to quickly review patient results to assist in determining the appropriate treatment in a single consultation.6 Systems that integrate with electronic medical records (EMR) or laboratory information systems (LIS) can improve workflow by avoiding potential errors associated with manual documentation and provide physicians with easier access to test results. Connecting to EMRs and LISs is also important for pooling information for data analytics and medical billing.

Quick, accurate diagnosis is critical to managing respiratory infections. DIAs can help healthcare providers quickly identify infections, determine the cause, and assign an appropriate treatment, while helping to minimize the overuse of antibiotics and ancillary testing. Wireless digital immunoassays help providers manage their workflow and treat patients quickly. Many lab managers are considering the addition of a digital rapid diagnostic test to aid their institutions in managing the annual influx of respiratory infections.

How did your lab fare with regard to the points discussed above? Do you plan to implement any changes in time for the 2017-2018 season?

REFERENCES

  1. Centers for Disease Control and Prevention. The flu season. http://www.cdc.gov/flu/about/season/flu-season.htm.
  2. Centers for Disease Control and Prevention. Respiratory Syncytial Virus (RSV).
    http://www.cdc.gov/rsv/research/us-surveillance.html.
  3. Shapiro JS, Hicks LA, Pavia AT, Hersh AL. Antibiotic prescribing for adults in ambulatory care in the USA, 2007–09. J. Antimicrob. 2013;69(1):234-240.
  4. Blaschke AJ, Shapiro DJ, Pavia AT, et al. A national study of the impact of rapid influenza testing on clinical care in the emergency department. J Pediatric Infect Dis Soc. 2014;3(2):112-118.
  5. Gerber MA, Shulman ST. Rapid diagnosis of pharyngitis caused by Group A streptococci. Clin Microbiol Rev. 2004;17(3):571-580.
  6. Centers for Disease Control and Prevention. Rapid influenza diagnostic tests.
    http://www.cdc.gov/flu/professionals/diagnosis/clinician_guidance_ridt.htm.
  7. Yamaguchi I, Aoyama T, Yamamoto M, et al. Evaluation of the sensitivity of a densitometry system, in judging the result of influenza virus antigen-detection kit using immunochromatography]. J Japan Soc for Clin Microbiol. 2014;24(2):69-70.
  8. Merckx J, Wali R, Schiller I, et al. Diagnostic accuracy of novel and traditional rapid tests for influenza infection compared to RT-PCR: a systematic review and meta-analysis. Poster presented at: ID Week; October 2016; New Orleans, LA.

 


 

Patrick Murray, PhD, serves as senior director, Worldwide Scientific Affairs, for BD, manufacturer of the BD Veritor Plus™System. He has been professor of pathology and medicine at the Washington University School of Medicine, director of the clinical microbiology laboratories at the University of Maryland Medical Center, and chief of microbiology and senior scientist at the NIH Clinical Center. In July 2011, he accepted his current position at BD Life Sciences.

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