What influenza testing do you choose? — Influenza in the ED Conclusion
December 12, 2018
Posted by Andy Jagoda, MD in: What's Your Diagnosis , trackback
Your patient is a 32-year-old man with the following chief complaints: cough and fever. His maximum temperature over the past 5 days was 40˚C (103.9°F). He has been taking over-the-counter cold remedies without relief, and today he is markedly short of breath. The patient has no regular primary care provider and has no significant past medical history. His initial vital signs are: temperature 39.2˚C (102.5°F); heart rate, 118 beats/min; respiratory rate, 28 breaths/min; blood pressure, 134/78 mm Hg; and oxygen saturation, 88% on room air. On examination, he appears uncomfortable, with notable tachypnea. The oropharynx is clear and the neck supple. Crackles are noted in the right lower lung field, without any wheezing. The abdomen is soft and nontender. The patient is given oxygen via face mask, with an improvement in saturation to 100%. Chest x-ray reveals a right lower lobar pneumonia with a small pleural effusion. You start IV antibiotics and request an inpatient bed, as he is hypoxic with his pneumonia.
You wonder whether influenza testing is indicated, and if so, what type of test to do?
Delving further into the CDC website, you find that the false-negative rate with rapid antigen testing for influenza can be significant, especially when disease prevalence is high, as it is in your region. Based on this information, you decide to start your more seriously ill 32-year-old patient on oseltamivir 75 mg twice a day for 5 days despite the initially negative result reported by the hospital laboratory.