Stanley N. Rokaw

The UCLA population studies of CORD: X. A cohort study of changes in respiratory function associated with chronic exposure to SOx, NOx, and hydrocarbons

Two never-smoking cohorts in Southern California, one in Lancaster (N = 2340) exposed only to moderate levels of oxidants and the other in Long Beach (N = 1326) exposed to high levels of SOx, NO2, hydrocarbons and particulates completed spirometry and the single-breath nitrogen test five to six years apart. Forty-seven percent and 45 percent of the participants were retested. Mean results at baseline for those tested and not retested were similar. Loss to follow-up was primarily due to moving (39 percent and 47 percent). Every difference of consequence indicated greater deterioration in lung function in Long Beach. The level of significance of the difference was greatest, even in the youngest age groups, for delta N2(750-1250), suggesting that the earliest site of impairment may occur in the small airways. Greater deterioration in spirometric parameters was observed in every age group in Long Beach females above seven years of age at baseline and in Long Beach males above 15 years of age, suggesting that chronic exposure to the pollutant mix occurring in Long Beach ultimately adversely affects the large airways as well as small airways.

The UCLA population studies of chronic obstructive respiratory disease. II. Determination of reliability and estimation of sensitivity and specificity.

Abstract A probability sample of 218 adults tested at a mobile lung function (field) laboratory was retested at a UCLA reference laboratory. Results in the two laboratories were compared for (i) numerical correlation, (ii) variability, and (iii) agreement in disease classification. FEV 1 and FVC showed good agreement between laboratories. Plethysmography showed good agreement and moderate correlation. SBNT showed poor correlation, high variability, but good agreement. Test subjects were classified by two respiratory specialists as having or not having chronic obstructive respiratory disease. Individuals thus diagnosed were considered to be true positives and the results of each of the tests, groups of tests, and all tests in each laboratory were evaluated, using these criteria, for their estimated sensitivity and specificity: (i) FEV 1 , FVC , and plethysmography were estimated to be specific but relatively insensitive; (ii) FEF 25–75% was less specific but more sensitive; (iii) the flow-volume curve had the highest sensitivity and reasonable specificity; (iv) closing volume showed reasonable sensitivity and specificity but was not reliable. Determination of specificity may have been confounded by the presence of disease too early to diagnose clinically. The disparity in classification between the two laboratories was no greater than that between the two physicians. Field screening using spirometry, SBNT, and body plethysmography is apparently comparable to comprehensive diagnostic procedures in a clinic setting.

The UCLA Population Studies of Chronic Obstructive Respiratory Disease. VIII. Effects of Smoking Cessation on Lung Function: A Prospective Study of a Free-Living Population

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.