The UCLA population studies of chronic obstructive respiratory disease. VI. Relationship of physiologic factors to rate of change in forced expiratory volume in one second and forced vital capacity.

The mean annualized changes in height (delta height), in forced expiratory volume in one second (delta FEV1), and in forced vital capacity (delta FVC), measured at a 5-yr interval, were determined by year of age for 1,458 residents 7 to 59 yr of age in 2 communities in Los Angeles. The rate of change in delta height, delta FEV1, and delta FVC increased each year until early puberty and then decreased thereafter. The age at which the delta FEV1 and delta FVC reversed from an increasing to a decreasing rate was older in males (13 yr) than in females (11 yr) and lagged about 1 yr behind the age at which rate of delta height reversed. The rate of delta FEV1 and delta FVC sharply declined thereafter until the early 20s, at which age the rate of change leveled off to a constant value. The age at which the delta FEV1 and delta FVC reversed from positive to negative ranged from 21 to 23+ yr, but was probably of less importance physiologically than the age at which the rate of change in delta FEV1 and delta FVC leveled off. The results suggest that growth factors are the major determinants for changes in delta FEV1 and delta FVC until the late teens. From the until the mid-20s, both growth factors and physiologic deterioration may affect delta FEV1 and delta FVC. Thereafter, the primary determinant of delta FEV1 and delta FVC appears to be a gradual but steady decline in physiologic status.