Community-acquired pneumonia in infants: Not simply an acute event with complete recovery

Background: Pneumonia in infancy has been linked to long-term consequences for the rapidly developing lung. We examined the impact of hospitalized community-acquired pneumonia (CAP) on subsequent respiratory health.

Methods: We conducted a retrospective matched-cohort study using the Optum® de-identified Electronic Health Record Dataset (2009-2018). Study population comprised healthy infants hospitalized for CAP ("CAP patients"), and matched comparators without pneumonia ("comparison patients"), before age 2 years. Study outcomes included any chronic respiratory disorder, reactive airway disease (asthma, hyperactive airway disease, recurrent wheezing), and CAP hospitalization occurring between age 2-5 years, and were evaluated overall as well as by age and etiology at first CAP hospitalization.

Results: Study population totaled 1,343 CAP patients and 6,715 comparison patients. Rates per 100 patient-years and relative rates (RR) of study outcomes from age 2-5 years for CAP patients versus comparison patients were: any chronic respiratory disorder, 11.6 vs. 4.9 (RR = 2.4 [95% CI: 2.1-2.6]); reactive airway disease, 6.1 vs 1.9 (RR = 3.2 [2.6-3.8]); and CAP hospitalization, 1.0 vs 0.2 (RR = 6.3 [3.6-10.9]). Rates of study outcomes were highest among CAP patients who had their initial hospitalization in the second year of life.

Conclusions: Infant CAP foreshadows an increased risk of subsequent chronic respiratory disorders, which may be elevated when CAP occurs closer to pre-school age (i.e., age 2-5 years). These findings are most consistent with the hypothesis that inflammation persists beyond the acute stage of pneumonia and plays a role in the development of chronic respiratory sequelae.