During a recent weekend shift in the Emergency Department, four patients presented with the same chief complaint: “I just want to know if I have the flu.”
Flu Case Presentations:
Patient #1: 63yo African-American female with upper-respiratory infection (URI) and flu-like symptoms for 2 days. She had subjective fevers, has an undetectable HIV viral load, and is compliant with her medical therapies for HIV. She also has a history of COPD and states that she has had an intermittent cough which is only occasionally productive with a little post-nasal drainage sensation.
Patient #2: 47yo Caucasian female with URI/flu symptoms for 3-4 days. She has a history of CAD including CABG with stent placement. She has a fever and chills and states that know the body aches have moved to her chest and it hurts when she breathes. She looks uncomfortable and something just doesn’t pass “the eyeball test” from the door or clinical gestalt.
Patient #3: 3yo Hispanic male. URI/flu symptoms for 3-4 days. Temperature at triage was 103.3F. Siblings have tested positive for influenza last week. Child has a history of asthma/wheezing but has not been hospitalized for this in the past.
Patient #4: 26yo Caucasian female, “not feeling well” for about a week. She doesn’t seem to be getting any better. She is having some mild URI symptoms but otherwise she just wants to know if she has the flu.
Flu Season
In case you missed it, flu season is here! According to the CDC, we are entering the most active period of the flu season. Already, 7.3 million people have been diagnosed with the flu since October with an estimated 69,000-84,000 requiring hospitalization (USA Today, 13 January 2019). As a ER clinician, I would typify my practice style as an “appropriate minimalist”. So how can we address these patient’s complaints in a fashion that is appropriate but efficiently using resources such as time, testing, and costs…and yet, still have a happy and satisfied customer/patient experience?
At this time of the year (October-late May), any patient presenting to you with URI symptoms and a fever should have flu in the diagnosis. Given the wide range of symptoms, infectious pathogens, and complications of the patient’s specific history the possible differential diagnosis are too numerous to list. For the purposes of discussion, typical URI/flu symptoms include: fever, cough, sore throat, nasal congestion, myalgias and body aches. In children, I would also add in vomiting and diarrhea. However, one definition to keep handy is “influenza-like illness.” The CDC defines influenza-like illness as a temperature of >100F, with either a cough or sore throat, without a known cause other than flu.
Some Basic Flu Statistics
Before we answer the question, ”to swab or not to swab” or “Treat or don’t treat with anitvirals”, let’s do a quick review of basic statistics. The rapid influenza diagnostic test (or what we usually just call the flu swab), has a sensitivity of 40-70% and a specificity of 90-95%. But what does that mean and how does it help us clinically? In discussion with patients, I let them know that the test we use is pretty good at telling us that you really have the flu (90-95%); however, if the test is negative there is still around a 40% chance that you might actually have the flu as this test has a high “false negative” rate. The false negative rate is actually higher during flu season because the prevalence of the disease is higher. (https://www.cdc.gov/flu/pdf/professionals/diagnosis/clinician_guidance_ridt.pdf). Most patients will understand the basics of this.
The last decision point we need to look at is the patient history. Is my patient at a high risk for complications of the flu or having a more severe disease course? These conditions would include
Patient History
- Age > 65
- Age < 2
- COPD (or asthma or chronic obstructive lung disease)
- Hematologic disease (like sickle cell)
- Metabolic disorders (like diabetes)
- Immunosuppression (whether from disease like HIV or from medications)
- Pregnancy and up to 2 weeks post-partum
(Influenza: Diagnosis and Management in the Emergency Department, December 2018, p 13. www.ebmedicine.net).
Flu Treatment and Recommendations
Armed with knowledge of the local flu prevalence, a knowledge of the symptoms, and a knowledge of the patient history, we are ready to make our treatment and testing recommendations to the patients. First, does the patient have symptoms suggestive of influenza? If yes, is there a local prevalence? If there is a high prevalence, is your patient in the “high risk” group? If they are, are they showing signs of severe disease like pneumonia, respiratory distress…basically do they require hospitalization. If so, administer the flu swab. However, due to the high risk/severe disease, the CDC still recommends treating with an antiviral even outside of the typically accepted 48hr window. Typically, a large majority of these patients end up getting admitted anyway and if they are admitted a flu test should be performed. The flu testing helps the inpatient management as well as guides further levels of viral testing.
What about your high risk patient that is only showing mild or moderate symptoms of the flu? In this case, do NOT swab. Routine testing is not indicated. However, current recommendations are to start them on empiric antiviral therapy.
If the patient has flu-symptoms and the prevalence is high but my patient is low-risk, not testing is indicated. Additionally, no empiric therapies should be initiated. The most important discussion to have with your patient is the rationale for not testing or treating as well as a thorough discussion of supportive therapies and any red-flag symptoms to warrant return to your office.
During off-flu season when the disease prevalence is lower, the guidelines are even easier. If the patient has symptoms of flu, are they a high-risk patient or low-risk patient? If they are low-risk, no testing and no treating. These patients receive supportive therapy only. For the high-risk patients, administer the flu-swab and treat the result. If the test is positive, administer antiviral therapy.
A quick search of the internet will introduce you to new antiviral therapies as well as the traditional ones that we are more familiar with. Trade names of some of these medications are: Oseltamivir, Zanamivir, and Peramivir. The CDC also has a good listing of online resources both for the clinician and the patient. The main page to begin for the information: https://www.cdc.gov/flu/index.htm. From this page, you are able to branch out to many useful sites.
Conclusions of Case Presentations
Patient #1: She was obviously in the high risk category due to both her COPD and the HIV. As her vital were normal and lungs sounded great, I placed her in the mild-moderate category. Clinically, she was in no distress and looked pretty good. She was tested for the flu which was negative and her chest x-ray was clear of infiltrates. I discussed the case with her infectious disease provider and we thought it best to start her on both the antiviral therapy as well as antibiotics that guideline recommend you would do for high risk COPD exacerbation. She was seen the next day by her infectious disease team in a routine follow-up.
Patient #2: Remember that she has a cardiac history, didn’t pass the eyeball test, looked miserable and states that she was now having some pleuritic chest pain. She did receive flu testing which was positive. Additionally, she received a cardiac work-up. Of note, her chest x-ray showed no acute pulmonary disease or infiltrate. The EKG was non-ischemic appearing with non-specific ST changes. Her troponin was 1500 (500 is our local cut-off for calling NSTEMI and STEMI) and her D-dimer was just over the upper end of normal at 0.66 with a upper normal of 0.4. The admitting staff requested a CT-angiogram to rule out a pulmonary embolus due to the vitals signs, patient presentation, and the elevated d-dimer. The CT-A was negative for PE. Due to increasing pain out of proportion and the elevated troponin, the patient was taking to the cardiac catheterization lab where she was found to have a thrombus/occluded stent. The rest of the hospitalization stay was unremarkable and the cardiologist jokingly thanked the ER for the diagnosis of influenza so that he could practice isolation precautions.
Patient #3: Using our treatment/testing algorithm, the disease prevalence was high and the patient had signs and symptoms of influenza. Additionally, he had recent exposure to sick contacts with influenza. Based on age, the patient would not have been a high risk patient; however, the mother related a history that sounded a lot like asthma or reactive airway disease with frequent use of the nebulizer. He was febrile and there was mild wheezing on initial presentation. This patient received a chest x-ray which was positive for pneumonia (left lower lobe) and a breathing treatment. He was treated empirically on antiviral as well as receiving antibiotic for the pneumonia (although the likelihood was that it was a viral pneumonia). This highlights the take home point that two common complications of the flu are ear infections and pneumonia. The most common secondary bacterial infections associated with influenza are Staphylococcus aureus, Streptococcus pneumonia, and Haemophilus influenza. Knowing this, I hedged my bets with the antibiotic decision.
Patient #4: There was a high prevalence of the disease. The patient manifest some symptoms of URI/flu. Although on physical exam, most of the findings were normal. She was about 5 days into her disease process. She had no significant past medical history. She was placed in mild disease/low-risk patient status. No testing or chest x-ray was performed. I had a lengthy discussion with her about CDC recommendation for testing and treatment as well as supportive therapies. She was diagnosed with influenza-like illness vs URI.
This is such a great guide as we are in peak flu season!