THE UCLA POPULATION STUDIES OF CHRONIC OBSTRUCTIVE RESPIRATORY-DISEASE .6. RELATIONSHIP OF PHYSIOLOGIC FACTORS TO RATE OF CHANGE IN FORCED EXPIRATORY VOLUME IN ONE 2ND AND FORCED VITAL CAPACITY

Abstract

The mean annualized changes in height (.DELTA. height), in forced expiratory volume in 1 s (.DELTA.FEV1), and in forced vital capacity (.DELTA.FVC), measured at a 5-yr interval, were determined by year of age for 1458 residents 7-59 yr of age in 2 communities in Los Angeles [California, USA]. 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 .apprx. 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 21-23 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. Evidently, growth factors are the major determinants for changes in .DELTA.FEV1 and .DELTA.FVC until the late teens. From then until the mid-20s, both growth factors and physiologic deterioration may affect .DELTA.FEV1 and .DELTA.FVC. The primary determinant of .DELTA.FEV1 and .DELTA.FVC appears to be a gradual but steady decline in physiologic status.