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BackgroundDevelopment of adult respiratory disease is influenced by events in childhood. The impact of childhood pneumonia on chronic obstructive pulmonary disease (COPD) is not well defined. We hypothesize that childhood pneumonia is a risk factor for reduced lung function and COPD in adult smokers.MethodsCOPD cases and control smokers between 45–80 years old from the United States COPDGene Study were included. Childhood pneumonia was defined by self-report of pneumonia at <16 years. Subjects with lung disease other than COPD or asthma were excluded. Smokers with and without childhood pneumonia were compared on measures of respiratory disease, lung function, and quantitative analysis of chest CT scans.ResultsOf 10,192 adult smokers, 854 (8.4 %) reported pneumonia in childhood. Childhood pneumonia was associated with COPD (OR 1.40; 95 % CI 1.17-1.66), chronic bronchitis, increased COPD exacerbations, and lower lung function: post-bronchodilator FEV1 (69.1 vs. 77.1 % predicted), FVC (82.7 vs. 87.4 % predicted), FEV1/FVC ratio (0.63 vs. 0.67; p < 0.001 for all comparisons). Childhood pneumonia was associated with increased airway wall thickness on CT, without significant difference in emphysema. Having both pneumonia and asthma in childhood further increased the risk of developing COPD (OR 1.85; 95 % CI 1.10-3.18).ConclusionsChildren with pneumonia are at increased risk for future smoking-related lung disease including COPD and decreased lung function. This association is supported by airway changes on chest CT scans. Childhood pneumonia may be an important factor in the early origins of COPD, and the combination of pneumonia and asthma in childhood may pose the greatest risk.Clinical trials registrationClinicalTrials.gov, NCT00608764 (Active since January 28, 2008).Electronic supplementary materialThe online version of this article (doi:10.1186/s12931-015-0273-8) contains supplementary material, which is available to authorized users.

Scientific Knowledge on the Subject: COPD progresses over decades so little is known about longitudinal changes in individual patients, and whether there are different patterns of disease progression in different patient subgroups.What this Study Adds to the Field: Computational modelling of CT biomarkers suggests there are two patterns of disease progression in COPD. These disease progression patterns or 'subtypes' can be used to stratify individuals into two groups with distinct clinical characteristics, and to stage individuals along their disease time-course. Early stages of both subtypes are identifiable in a proportion of 'healthy smokers' providing a biomarker of early COPD.