Longitudinal Change in Forced Expiratory Volume in Healthy, Non-Smoking Men and Women: The Baltimore Longitudinal Study of Aging

Studies of age-associated changes in forced expiratory volume at one second (FEV₁) have varied in the degree of screening for health and smoking, and have not examined age differences in variability in FEV₁. Longitudinal rates of change and variability in FEV₁ among healthy lifetime-non-smoking White men and women in the Baltimore Longitudinal Study of Aging (BLSA) are reported. Longitudinal FEV₁ data collected at 2-year in-tervals for up to 28 yr in 91 men (417 observations) and 14 yr in 82 women (248 observations) were modelled using mixed-effects regression models. Longitudinal percentile distributions of FEV₁ were calculated which reflect age differences in between-subjects variability. The results show that longitudinal rate of decline in FEV₁ is more rapid in men than women (340 ml/decade in men compared to 240-330 ml/decade in women), but similar on a percentage basis (10%) and the difference is not statistically significant; FEV₁ decline begins in early adulthood and progresses at a relatively constant rate over the adult lifespan; longitudinal decline in FEV₁ in BLSA participants is not statistically different from cross-sectional estimates from the BLSA and Crapo et al. (1981); and between-subjects variability is greater in men than women and increases with age. The results document a relatively steady progressive longitudinal decline in FEV₁ in healthy non-smoking White adults, as well as age and gender differences in variability in FEV₁. The percentile distribution curves reported here are apparently the first reference values for FEV₁ to be derived using longitudinal methods that reflect age-specific differences in variability.