Acute Lower Respiratory Illness in Childhood as a Predictor of Lung Function and Chronic Respiratory Symptoms

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Abstract
This study investigated the relationship of acute lower respiratory illness (LRI) to level and change in level of forced expiratory volumes in a cohort of 801 children, followed longitudinally for a maximum of 13 yr. The co-occurrence of respiratory illness before 2 yr of age and two or more LRI during a single surveillance year was associated with a 20.3% lower mean cross-sectional level of FEF25–75, and with reduced longitudinal change in level of FEF25–75. The effect of LRI on lung function was uniformly stronger for boys than for girls. Of the children with illness before 2 yr of age and two or more LRI, six of 14 were male asthmatics with mean levels of FEF25–75 that were lower than those of other asthmatic children. Pneumonia and/or hospitalization for respiratory illness prior to the onset of study were associated with lower cross-sectional levels of forced expiratory volumes at entry to the study, even when asthmatics/persistent wheezers were eliminated from the analysis (6.1% lower level of FEV1 for a nonasthmatic boy with previous hospitalization versus a nonasthmatic boy without hospitalization). In the longitudinal analysis, pneumonia and/or hospitalization were associated with slower increase in level of forced expiratory volumes, even after adjusting for “ever diagnosis of asthma/current any wheeze” (starting at the same level, after eight years a boy with hospitalization would develop a 5.0% lower FEV1 than a boy without hospitalization). Acute LRI also was evaluated as a predictor of chronic respiratory symptoms. A strong association was found between previous hospitalization and subsequent chronic cough (Odds Ratio[OR] = 3.8)/chronic phlegm (OR = 7.1) at entry to the study; eight years later, smoking was the only significant predictor of these symptoms, and no hospitalized child had taken up smoking. Future studies may enable us to explore interactions between severe respiratory illness in early childhood and the effect of cigarette smoke or indoor/outdoor air pollution.