Relation of early childhood growth and wheezing phenotypes to adult lung function

Abstract

Rationale: Several studies have reported associations between indicators of birth size and postnatal growth rates with levels of pulmonary function achieved as adults. The objective of this study was to determine if levels and/or rates of weight gain, measured in early life (birth-6 years), are associated with FVC or FEV1 levels achieved in young adulthood and if these associations differ by early childhood wheezing phenotypes.

Methods: We used data from participants in the Tucson Children's Respiratory Study (CRS), a prospective birth cohort study. Weight was measured quarterly up to age 3 years and again at age 6 years. Pulmonary function was assessed at ages 16 and 22. Mean weight and slope of weight growth between 3 and 6 years were estimated using standardized residuals. Longitudinal models were used to determine predictors of FVC and FEV1 at ages 16 and 22 years.

Results: There were 127 non-Hispanic white subjects that had at least four weight measures and one or more pulmonary function measures as young adults. After adjusting for sex, height, and age, the standardized slope of weight growth (between 3 and 6 years) was positively associated with higher levels of FVC at age 16 and 22 years (P = 0.0001) among subjects who did not have preschool wheezing. However, this association was completely absent among subjects who had wheezing lower respiratory tract illnesses in the first 3 years of life. Similar trends were found for FEV1.

Conclusion: The rate of weight gain between 3 and 6 years is significantly positively related to adult FVC and FEV1 and this association is modified by early wheezy phenotypes.

Figure 1

Figure 1 illustrates the predicted FVC values, resulting from fitting the LMM to the longitudial FVC observations (Table 3), plotted versus rate of weight gain between 3-6 years of age. Subjects that never wheeze (Black line) have a strong positive linear relationship that was completely absent among subjects experiencing any childhood wheeze (Colored lines). There were no signifcant diffences in the predicted FVC vlaues between wheezing phenotypes (tested using linear contrast in the LMM).