A matter of life and breath: childhood socioeconomic status is related to young adult pulmonary function in the CARDIA study

Background Socioeconomic status (SES) may contribute to the trajectory of pulmonary function over the life course. Studies suggest that people with lower (versus higher) SES during childhood subsequently have lower levels of adult pulmonary function. But prospective studies are sparse across young adulthood, an important phase in pulmonary development. Methods Participants were from the Coronary Artery (Disease) Risk Development in (Young) Adults (CARDIA) study: 5113 young adults ages 18-30 at baseline, approximately balanced within centres across gender, self-identified race/ethnicity (Black, White), and current SES. Childhood SES was ascertained from baseline self-reports of parents' highest completed education. Pulmonary function in young adulthood was measured using FEV1 (forced expiratory volume in one second) and FVC (forced vital capacity), assessed on three occasions over a period of 5 years. Results Longitudinal analyses suggested that rates of change in both FEV1 and FVC differed in a gradient fashion by childhood SES. As shown by significant childhood SES by time interaction terms, these associations with FEV1 were robust for men (b = 1.59E-3, SE = 5.21E-4, P < 0.001) and women (b = 1.93E-3, SE = 4.80E-4, P < 0.001), and adjusted for multiple potential confounders including smoking. Results were similar for FVC. Subsequent examination of the interaction terms suggested that FEV1 and FVC declined for participants in the lowest childhood SES group, showed continued plateau or growth for those in the highest group, and were intermediate for the middle group. Conclusions Childhood SES may influence men's and women's young adult pulmonary function in two ways. First, individuals with lower childhood SES may not attain as high levels of pulmonary function in early adulthood relative to individuals with higher childhood SES. Second, pulmonary function may decline earlier and faster for individuals with lower childhood SES.