Chest radiograph yields excellent negative predictive value in pneumonia diagnosis in kids
A negative chest radiograph (CXR) rules out pneumonia in children presenting with signs and symptoms of acute lower respiratory tract infection, a study has found.
“We recognize that the diagnosis of pneumonia often relies on a combination of clinical and radiographic features,” the authors said. “However, our findings reveal that the majority of children with suspected pneumonia and negative CXRs, especially those in whom the clinical suspicion of pneumonia is low, can be safely managed without antibiotic therapy.”
The study included 683 children (median age 3.1 years) undergoing CXRs for suspected pneumonia in a tertiary-care paediatric emergency department (ED), none of whom were currently receiving antibiotics and had underlying chronic medical conditions. CXR results were negative in 497 children (72.8 percent), positive in 113 (16.5 percent) and equivocal in 73 (10.7 percent).
Clinical diagnosis of pneumonia was given in 108 children (96 percent) with positive CXR, in 48 (66 percent) with equivocal CXR and in 44 (8.9 percent) with negative radiographic findings. An additional 42 children with negative CXR received a different diagnosis, the most common being otitis media, and were treated with antibiotics. [Pediatrics 2018;doi:10.1542/peds.2018-0236]
Of the 411 children with negative CXRs and who were managed without antibiotics, five were subsequently diagnosed with pneumonia within 2 weeks. This shows that a negative radiographic finding had an excellent negative predictive value (NPV) for an infection in the lung (98.8 percent; 95 percent CI, 97.0–99.6).
“To our knowledge, this is the first prospective study in which researchers manage a large cohort of children with suspected pneumonia and negative CXR results and allow for the evaluation of chest radiography to exclude the diagnosis of pneumonia,” the authors noted.
Despite the presence of several limitations, the current investigation provides “important new insights into the paradigm of CXR performance for the evaluation of pneumonia in children,” they added.
Most clinicians managing children in the outpatient setting rely on clinical signs and symptoms to determine whether to prescribe an antibiotic for pneumonia, they said. However, reliance on physical examination alone may lead to an overdiagnosis of the infection, in light of recent literature citing poor reliability and validity of physical examination findings. [JAMA 2017;318:462-471; JAMA Pediatr 2016;170:803-805]
“Thus, clinicians must balance the risk of antibiotic overuse against the risks and costs of chest radiography,” they said.
In an accompanying editorial, Drs Matthew Garber from the University of Florida College of Medicine–Jacksonville and Ricardo Quinonez from the Baylor College of Medicine and Texas Children’s Hospital pointed out that while clinicians should take comfort in the fact that CXR for community-acquired pneumonia (CAP) has a high NPV, it is possible that some or most of the children in the current study who were diagnosed with the infection in the ED did not have bacterial pneumonia. [Pediatrics 2018;doi:10.1542/peds.2018-2025]
“Although both viruses and bacteria can cause CAP, physicians are generally trying to rule out a bacterial infection with a CXR, because the main clinical decision is whether to prescribe antibiotics,” they said, while raising the question of the benefit of performing a CXR in children with suspected bacterial CAP.
Previous studies suggest the possibility that only a small fraction of paediatric patients with CAP benefit from antibiotic therapy and, by extension, radiography. A single-centre study in the inpatient setting revealed a high rate of discontinuation of antibiotics in children diagnosed with CAP in the ED and admitted to the hospital (62 percent), without any noticeable effect seen in outcomes, such as readmissions or transfer to higher level of care. [Hosp Pediatr 2015;5:111-118]
Given the results of the current and previous studies, Garber and Quinonez postulated that children with low clinical suspicion for pneumonia can safely be observed without CXRs. “This path would decrease radiation, cost, inconvenience and unnecessary antibiotic prescriptions.”