Respiratory Distress is the Best Predictor of Pneumonia on Chest X-ray in Febrile Infants

Febrile infants aged 60 days and younger present unique challenges for emergency physicians, with serious bacterial infections (SBI) posing a significant risk. Among the various potential infections, pneumonia is a critical concern, with prevalence ranging from 0.1% to 8% in these young infants. Current diagnostic practices, primarily relying on clinical evaluation, struggle to identify pneumonia accurately. A recent secondary analysis of our data sheds light on the demographic, clinical, and biomarker factors associated with radiographic pneumonias in this vulnerable population [1].

This research is a step forward in our understanding of pneumonia in febrile infants and refining clinical practices to optimize outcomes.

Dr. Todd A. Florin, first author of publication

Study question

Which febrile infants in the ED have pneumonia? What demographic, clinical, or lab factors are associated with radiographic pneumonias in febrile infants? 

Study design

This study involved a secondary analysis of data from a larger study conducted between June 2016 and April 2019, focusing on febrile infants under 60 days old across 18 PECARN emergency departments (2). The main study aimed to explore different diagnostic strategies, including analyzing the activity of genes within these infants’ bodies (transcriptomic analysis), for detecting serious bacterial infections (SBIs). Various clinical and laboratory factors were assessed, including vital signs, laboratory results, and imaging findings, to categorize pneumonia cases and analyze associated patient factors using multivariable logistic regression models.

Results

  • Study Population Overview:
    • 2,612 infants were enrolled in the parent study.
    • 568 infants (21.7%) underwent chest x-rays (CXRs) and were included in this analysis.
    • Median age of infants: 38 days (IQR 24, 48)
  • Pneumonia Classification:
    • Definite pneumonia: 3.3% (n=19)
    • Possible pneumonia: 6.0% (n=34)
    • No significant differences in age, sex, race, or ethnicity among different pneumonia groups
  • Clinical Characteristics:
    • VITAL SIGNS:
      • No differences in temperature or heart rate observed between infants with and without radiographic pneumonia.
      • Infants with possible or definite pneumonias showed slightly higher respiratory rates and slightly lower oxygen saturation.
      • Increased work of breathing is more common in infants with possible or definite pneumonias compared to those without.
    • LABS:
      • Median white blood cell (WBC) count and absolute neutrophil count (ANC) were slightly higher in infants with possible or definite pneumonias.
      • Median procalcitonin (PCT) concentrations were significantly elevated in children with possible or definite pneumonias.
      • Higher proportions of infants with possible or definite pneumonias had influenza or RSV detected in their nasopharynx compared to those without.
      • Bacteremia was rare in the entire cohort and not observed in patients with pneumonias.
    • DISPO:
      • Higher hospitalization rates observed in infants with possible or definite pneumonias compared to those without.
  • Multivariable Logistic Regression Analyses:
    • Infants with evidence of respiratory distress on physical examination had 2 times the odds of having possible or definite pneumonia.

Caution

Pneumonia is a relatively rare event in febrile infants and most in our study had viruses. It is possible that many cases of pneumonia were caused by viruses since many with radiographic pneumonia and a known virus had low biomarkers (ANC, PCT).  Further research is warranted to understand if the viral detection was secondary to colonization, co-infection with a bacterium, or an isolated viral pneumonia.

Take home messages

    Emergency physicians and pediatricians should be attentive to signs of respiratory distress when evaluating febrile infants aged 60 days and younger. As we strive for precision in diagnosis and care, this research is a significant step forward in enhancing our understanding of pneumonia in febrile infants and refining clinical practices to ensure optimal outcomes.

  1. Avoid obtaining a CXR for every febrile infant with a respiratory complaint, because pneumonias are rare and the majority are from viral causes.
  2. Consider a CXR if a febrile infant exhibits an increased work of breathing or respiratory distress.
  3. Elevated biomarkers (ANC/procalcitonin) may support the diagnosis of pneumonia.

Why is this important for patients and caregivers

A baby with a fever can be very scary for families and caregivers. Researchers with the HRSA-supported Pediatric Emergency Care Applied Research Network (PECARN) did a study to identify how babies with pneumonia presented in emergency departments across the country. They found that pneumonia is not common in babies who come to the emergency department with fever. But respiratory distress was the best indicator of pneumonia and viruses were very common. This research could help to decrease stress among families, caregivers and clinician burden by reducing costly chest x-rays and unnecessary hospitalizations. Parents, caregivers, and clinicians should be attentive to signs of respiratory distress when evaluating infants with a fever aged 60 days and younger. As we strive for precision in diagnosis and care, this research is a significant step forward in enhancing our understanding of pneumonia in infants and refining clinical practices to ensure optimal outcomes.

References

  1. Florin TA, Ramilo O, Banks RK, Schnadower D, Quayle KS, Powell EC, Pickett ML, Nigrovic LE, Mistry R, Leetch AN, Hickey RW, Glissmeyer EW, Dayan PS, Cruz AT, Cohen DM, Bogie A, Balamuth F, Atabaki SM, VanBuren JM, Mahajan P, Kuppermann N; Febrile Infant Working Group of the Pediatric Emergency Care Applied Research Network (PECARN). Radiographic pneumonia in young febrile infants presenting to the emergency department: secondary analysis of a prospective cohort study. Emerg Med J. 2023 Dec 22;41(1):13-19. doi: 10.1136/emermed-2023-213089. PMID: 37770118; PMCID: PMC10841819.
  2. Kuppermann N, Dayan PS, Levine DA, Vitale M, Tzimenatos L, Tunik MG, Saunders M, Ruddy RM, Roosevelt G, Rogers AJ, Powell EC, Nigrovic LE, Muenzer J, Linakis JG, Grisanti K, Jaffe DM, Hoyle JD Jr, Greenberg R, Gattu R, Cruz AT, Crain EF, Cohen DM, Brayer A, Borgialli D, Bonsu B, Browne L, Blumberg S, Bennett JE, Atabaki SM, Anders J, Alpern ER, Miller B, Casper TC, Dean JM, Ramilo O, Mahajan P; Febrile Infant Working Group of the Pediatric Emergency Care Applied Research Network (PECARN). A Clinical Prediction Rule to Identify Febrile Infants 60 Days and Younger at Low Risk for Serious Bacterial Infections. JAMA Pediatr. 2019 Apr 1;173(4):342-351. doi: 10.1001/jamapediatrics.2018.5501. PMID: 30776077; PMCID: PMC6450281.

Julia Magana, MD

Associate Professor of Emergency Medicine University of California Davis

This website is supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS) as part of the Emergency Medical Services for Children Data Center award totaling $3,200,000 with 0% financed with non-governmental sources. The contents are those of the author(s) and do not necessarily represent the official views of, nor an endorsement, by HRSA, HHS, or the U.S. Government. For more information, please visit HRSA.gov.