Protracted Bacterial Bronchitis in Children: Natural History and Risk Factors for Bronchiectasis.

BACKGROUND Protracted bacterial bronchitis (PBB) and bronchiectasis are distinct diagnostic entities that share common clinical and laboratory features. It is postulated, but remains unproved, that PBB precedes a diagnosis of bronchiectasis in a subgroup of children. In a cohort of children with PBB, our objectives were to (1) determine the medium-term risk of bronchiectasis and (2) identify risk factors for bronchiectasis and recurrent episodes of PBB. METHODS One hundred sixty-one children with PBB and 25 control subjects were prospectively recruited to this cohort study. A subset of 106 children was followed for 2 years. Flexible bronchoscopy, BAL, and basic immune function tests were performed. Chest CT was undertaken if clinical features were suggestive of bronchiectasis. RESULTS Of 161 children with PBB (66% boys), 13 were diagnosed with bronchiectasis over the study period (8.1%). Almost one-half with PBB (43.5%) had recurrent episodes (> 3/y). Major risk factors for bronchiectasis included lower airway infection with Haemophilus influenzae (recovered in BAL fluid) (P = .013) and recurrent episodes of PBB (P = .003). H influenzae infection conferred a more than seven times higher risk of bronchiectasis (hazard ratio, 7.55; 95% CI, 1.66-34.28; P = .009) compared with no H influenzae infection. The majority of isolates (82%) were nontypeable H influenzae. No risk factors for recurrent PBB were identified. CONCLUSIONS PBB is associated with a future diagnosis of bronchiectasis in a subgroup of children. Lower airway infection with H influenzae and recurrent PBB are significant predictors. Clinicians should be cognizant of the relationship between PBB and bronchiectasis, and appropriate follow-up measures should be taken in those with risk factors.