SGEM#287: Difficult to Breathe – It Could Be Pneumonia

Date: March 18th, 2020 Reference: Ebell et al. Accuracy of Biomarkers for the Diagnosis of Adult Community-Acquired Pneumonia: A Meta-analysis. AEM March 2020 Guest Skeptic: Dr. Chris Bond is an emergency medicine physician and assistant Professor at the University of Calgary. He is also an avid FOAM supporter/producer through various online outlets including TheSGEM. Disclaimer: This is Not an Episode on COVID19 Things are changing quickly with the COVID19 pandemic.  Here are five basic things you can do to help flatten the curve as of this blogpost: Wash your hands well and often (at least 20 seconds with soap and water) Try not to touch your face Physically isolate yourself from large gatherings but stay socially connected electronically Cough into your elbow or use a tissue, throw the tissue out and go to #1 Disinfect objects or surfaces with a regular household cleaning wipe or spray If you are unsure of what to do or for more information, here are five websites to get up-to-date information about COVID19: COVID19 Centre for Disease Control and Prevention Health Canada Public Health Ontario World Health Organization Food and Drug Administration   Case: A 47-year-old healthy, non-smoker, presents to the emergency department (ED) with a productive cough, fever and says it has been difficult to breathe for the past four days. He appears well, with a temperature of 38.7 Celsius, heart rate of 90 beats per minute, respiratory rate of 20 breaths per minute and room air oxygen saturation of 91%. On auscultation you hear some fine crackles at the bases. You wonder if there is value in ordering any bloodwork, particularly a biomarker such as C-reactive protein (CRP), procalcitonin (PCT) or a complete blood count for white blood cell count (WBC) in addition to doing a chest x-ray (CXR). Background: Community-acquired pneumonia (CAP) is a significant source of morbidity and mortality in adults (1,2).  We have covered this issue a couple of times on the SGEM. One episode looked at β-Lactam monotherapy vs. β-Lactam plus macrolide combination therapy in adult patients admitted to hospital with moderately severe CAP (SGEM#120). This study supported the combination therapy in these patients. More recently, we looked at the question of whether steroids improve morbidity and mortality in patients admitted to hospital with CAP (SGEM#216). The bottom line was that corticosteroids appear to improve mortality and/or morbidity in patients admitted to hospital with CAP. There is evidence that an accurate diagnosis of CAP may lead to earlier treatment while avoiding unnecessary antibiotics for patients who do not have CAP. Pervious research has demonstrated that individual signs and symptoms have limited accuracy in the diagnosis of CAP. The diagnosis of CAP is usually based on an abnormal chest x-ray in a patient with signs and symptoms of a lower respiratory tract infection (3,4). White blood cell count (WBC), C-reactive protein (CRP), and procalcitonin are biomarkers associated with an increased likelihood of CAP. There are also clinical prediction rules that include CRP for the diagnosis of CAP (5,6). Procalcitonin is another potential biomarker that may help in the diagnosis of bacterial pneumonia (7).  Guidelines such as the National Institute for Health and Care Excellence (NICE) recommend the use of CRP at the point of care to reduce inappropriate antibiotic when diagnosing CAP (8) These various biomarkers are readily available in the ED setting in the US, as well as in the primary care setting in other countries in Europe. The study we are reviewing on this SGEM episode performs an updated systematic review and meta-analysis (SRMA) of the diagnostic accuracy of biomarkers for CAP. Clinical Question: What is the accuracy of biomarkers for the diagnosis of community acquired pneumonia? Reference: Ebell et al.