Limitations of this interesting study include the small sample size, apparent lack of follow-up with the control patients, and the diagnosis of recurrent wheezing episodes being characterized by the parents.
Influenza Pneumonia in Pediatric Patients
Lahti E, Peltola V, Virkki R, et al. Influenza pneumonia. Pediatr Infect Dis J. 2006 Feb;25(2):160-164.
Influenza and pneumonia are common in children. The objective of this study was to describe the frequency and characteristics of laboratory-documented and radiographically proven influenza-associated pneumonia in children.
This retrospective, single site study was conducted at Turku University Hospital (Finland). Chart reviews of both inpatient and outpatient visits of children younger than 16 were performed for a 24-year period between 1980 through 2003. Children with influenza A or B antigen detected nasopharyngeal aspirates were identified. Also children with chest radiographs obtained during their influenza infection were identified. Clinical findings upon initial presentation were summarized, in addition to laboratory values for white blood cell count (WBC) and C-reactive protein (CRP).
A total of 936 patients with virologically confirmed influenza were identified. Of this total, 79% had influenza A and the remaining had influenza B. Chest radiographs were reported on 400 (43%) of these patients. Of the 400 films, 228 were initially read as having infiltrates. However, during over-reading of the films 70 chest radiographs did not have an infiltrate and an additional 24 films could not be found. In summary, 134 children had both confirmed influenza and radiographically proven pneumonia. Thus 14% of the children with influenza who also had a chest radiograph had pneumonia.
Clinical findings of the 134 patients with influenza and pneumonia were similar among those with influenza A or B. The most common symptoms were fever (98%), cough (84%), and rhinorrhea (65%). The classical findings of headaches and myalgias were difficult to uncover due to the young age of the patients (median age 2.2 years). Of the 134 identified patients with influenza and pneumonia only 27% presented with dyspnea and 22% with tachypnea. Crackles were heard in 22%, rhonchi in 43%, and decreased breath sounds in 10%. No abnormal auscultation findings were found in 32% of the children. Sixty-eight percent of the study population was admitted to the hospital. The rate of hospitalization was greater for the younger patients. One-third of the patients had received antibiotics prior to enrollment, and 80% of the children received antibiotics during the hospitalization or at time of discharge. Four children required ventilator therapy. One patient with muscular dystrophy died of severe pneumonia.
Laboratory assessment found that 89% of the children had WBC less than 15 x 109/liter. CRP values were normal or only slightly increased in 55% of the children. Three children (2%) had laboratory-documented concomitant bacterial infections. Of these three cases two were due to bacteremia and one to a positive tracheal aspirate. Five children (7%) had double viral infections.
In this hospital-based study 14% of the patients with influenza had radiographically proven pneumonia. The authors found that in contrast with what we know about adults with influenza pneumonia, data shows influenza pneumonia in children is generally a benign disease. The greater burden of disease tends to be in the children younger than three years of age. Respiratory clinical findings may be absent in light of radiographically proven pneumonia. Laboratory findings show that most children with influenza pneumonia have normal WBC counts and normal to only slightly elevated CRP levels.