Pneumonia accounts for a significant degree of morbidity in children, especially those less than five years of age. The annual incidence is approximately 30 to 45 cases per 1,000 children in this age group. Among older children, the incidence is approximately 16 to 22 cases per 1,000. A number of these children have repeated episodes of pneumonia, which usually raises a red flag to the physician that an underlying disease process may be predisposing the child to pneumonia. “Recurrent” pneumonia is defined in the literature as two episodes or more in one year or more than three episodes of pneumonia in a child at any time, with radiographic clearing between episodes. How to further evaluate these children has not been well addressed with primary studies in the pediatric literature. Owayed and colleagues performed a retrospective study to determine the frequency of underlying illnesses in children hospitalized with recurrent pneumonia and the percentage of those with known underlying illness before pneumonia recurrence.

The authors reviewed the charts for a 10-year period of all patients younger than 18 years who were admitted to a children's hospital with a diagnosis of pneumonia. From this group, children who had two or more episodes of pneumonia in one year or three or more episodes in their lifetime, plus children who had radiographic confirmation of pneumonia on admission, were included in the study. Using a standard data extraction form, information was abstracted from the charts regarding patient age, sex, percentile body weight and the age at which an underlying illness was diagnosed. Also reviewed were the results of the diagnostic evaluations that included computed tomography of the chest, sweat chloride testing, echocardiography, barium swallow, laryngoscopy and bronchoscopy, esophageal pH manometry, quantitative serum immunoglobulins and testing for human immunodeficiency virus (HIV) infection.

Of the 2,952 charts reviewed, 238 children met the definition for recurrent pneumonia. Approximately 60 percent were males, and the mean age at diagnosis was 3.7 years (range: 2.5 months to 15.6 years). An underlying illness was diagnosed in 220 of these children. Aspiration syndrome was diagnosed as the cause of pneumonia in 114 children, an immune disorder in 24 and congenital heart disease in 22. Additional diagnoses included bronchial asthma in 19 children, congenital or acquired anomalies of the airway or lung in 18, gastroesophageal reflux in 13 and sickle cell anemia in 10. A predisposing factor for recurrent pneumonia could not be determined in 18 of the children.

More than one half of the children with aspiration syndrome had cerebral palsy. Of those with an immune deficiency, 13 had a malignant neoplasm, five had a dysgammaglobulinemia, five had HIV infection and one had autoimmune pancytopenia. Of significance, 178 of the 238 children had been diagnosed with an underlying illness before the first episode of pneumonia, and 25 children were diagnosed during their first episode of pneumonia. Only 17 children were diagnosed with an underlying disease after having recurrent pneumonia. Of these 17 children, seven had asthma, and four had aspiration syndrome, three had gastroesophageal reflux and two had airway anomalies. Only one child had an underlying immune disorder.

The authors conclude from this data that most children with recurrent pneumonia are known to have an underlying illness. The most common predisposing factor is aspiration syndrome. In children without a known medical or anatomic condition who have recurrent pneumonia, bronchial asthma and gastroesophageal reflux should be ruled out as part of the evaluation. Underlying immune disorders that were not previously diagnosed are rare and, in about 10 percent of children, an underlying illness will not be found despite an extensive work-up.