Commentary

Upper respiratory infections: Viral testing in primary care


 

It’s upper respiratory infection (URI) season. The following is a clinical scenario drawn from my own practice. I’ll tell you what I plan to do, but I’m most interested in crowdsourcing a response from all of you to collectively determine best practice. So please answer the polling questions and contribute your thoughts in the comments, whether you agree or disagree with me.

The patient

The patient is a 69-year-old woman with a 3-day history of cough, nasal congestion, malaise, tactile fever, and poor appetite. She has no sick contacts. She denies dyspnea, presyncope, and chest pain. She has tried guaifenesin and ibuprofen for her symptoms, which helped a little.

She is up to date on immunizations, including four doses of COVID-19 vaccine and the influenza vaccine, which she received 2 months ago.

The patient has a history of heart failure with reduced ejection fraction, coronary artery disease, hypertension, chronic kidney disease stage 3aA2, obesity, and osteoarthritis. Current medications include atorvastatin, losartan, metoprolol, and aspirin.

Her weight is stable at 212 lb, and her vital signs today are:

  • Temperature: 37.5° C
  • Pulse: 60 beats/min
  • Blood pressure: 150/88 mm Hg
  • Respiration rate: 14 breaths/min
  • SpO2: 93% on room air

What information is most critical before deciding on management?

Your peers chose:

  • The patient’s history of viral URIs

14%

  • Whether her cough is productive and the color of the sputum

38%

  • How well this season’s flu vaccine matches circulating influenza viruses

8%

  • Local epidemiology of major viral pathogens (e.g., SARS-CoV-2, influenza, RSV)

40%

Dr. Vega’s take

To provide the best care for our patients when they are threatened with multiple viral upper respiratory pathogens, it is imperative that clinicians have some idea regarding the epidemiology of viral infections, with as much local data as possible. This knowledge will help direct appropriate testing and treatment.

Modern viral molecular testing platforms are highly accurate, but they are not infallible. Small flaws in specificity and sensitivity of testing are magnified when community viral circulation is low. In a U.K. study conducted during a period of low COVID-19 prevalence, the positive predictive value of reverse-transcriptase polymerase chain reaction (RT-PCR) testing was just 16%. Although the negative predictive value was much higher, the false-positive rate of testing was still 0.5%. The authors of the study describe important potential consequences of false-positive results, such as being temporarily removed from an organ transplant list and unnecessary contact tracing.

Testing and treatment

Your county public health department maintains a website describing local activity of SARS-CoV-2 and influenza. Both viruses are in heavy circulation now.

What is the next best step in this patient’s management?

Your peers chose:

  • Treat empirically with ritonavir-boosted nirmatrelvir

7%

  • Treat empirically with oseltamivir or baloxavir

14%

  • Perform lab-based multiplex RT-PCR testing and wait to treat on the basis of results

34%

  • Perform rapid nucleic acid amplification testing (NAAT) and treat on the basis of results

45%

Every practice has different resources and should use the best means available to treat patients. Ideally, this patient would undergo rapid NAAT with results available within 30 minutes. Test results will help guide not only treatment decisions but also infection-control measures.

The Infectious Diseases Society of America has provided updates for testing for URIs since the onset of the COVID-19 pandemic. Both laboratory-based and point-of-care rapid NAATs are recommended for testing. Rapid NAATs have been demonstrated to have a sensitivity of 96% and specificity of 100% in the detection of SARS-CoV-2. Obviously, they also offer a highly efficient means to make treatment and isolation decisions.

There are multiple platforms for molecular testing available. Laboratory-based platforms can test for dozens of potential pathogens, including bacteria. Rapid NAATs often have the ability to test for SARS-CoV-2, influenza, and respiratory syncytial virus (RSV). This functionality is important, because these infections generally are difficult to discriminate on the basis of clinical information alone.

The IDSA clearly recognizes the challenges of trying to manage cases of URI. For example, they state that testing of the anterior nares (AN) or oropharynx (OP) is acceptable, even though testing from the nasopharynx offers increased sensitivity. However, testing at the AN/OP allows for patient self-collection of samples, which is also recommended as an option by the IDSA. In an analysis of six cohort studies, the pooled sensitivity of patient-collected nasopharyngeal samples from the AN/OP was 88%, whereas the respective value for samples taken by health care providers was 95%.

The U.S. Centers for Disease Control and Prevention also provides recommendations for the management of patients with acute upper respiratory illness. Patients who are sick enough to be hospitalized should be tested at least for SARS-CoV-2 and influenza using molecular assays. Outpatients should be tested for SARS-CoV-2 with either molecular or antigen testing, and influenza testing should be offered if the findings will change decisions regarding treatment or isolation. Practically speaking, the recommendations for influenza testing mean that most individuals should be tested, including patients at high risk for complications of influenza and those who might have exposure to individuals at high risk.

Treatment of COVID-19 should only be provided in cases of a positive test within 5 days of symptom onset. However, clinicians may treat patients with anti-influenza medications presumptively if test results are not immediately available and the patient has worsening symptoms or is in a group at high risk for complications.

What are some of the challenges that you have faced during the COVID-19 pandemic regarding the management of patients with acute URIs? What have you found in terms of solutions, and where do gaps in quality of care persist? Please add your comments. I will review and circle back with a response. Thank you!

A version of this article first appeared on Medscape.com.

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