Abstract

We have investigated the relationship between annual decline in forced expiratory volume in one second (delta FEV1) and bronchial responsiveness (BR) in aluminium potroom workers. BR was measured in a cross-sectional study of 337 aluminium potroom workers half-way through a 6 yr follow-up study of lung function. A skin-prick test (SPT) was also performed. During follow-up the mean number of measurements of lung function (FEV1) in each subject was 6.8. Mean delta FEV1 was 21.3 ml.yr-1 (within subject SD = 30.5 ml.yr-1). Mean delta FEV1 was 57.0, 44.5 and 16.6 ml.yr-1 in subjects who had provocative concentration producing a 20% fall in FEV1 (PC20) < or = 8.0, 8.1-32.0 and > 32.0 mg.ml-1, respectively. After adjustment for gender, atopy, smoking habit, FEV1, age and familial asthma the association between BR and delta FEV1 was weakened, and was not statistically significant. A significantly accelerated decline in FEV1 with age was found. The difference in delta FEV1 between smokers and nonsmokers was 39.3 ml.yr-1, and between subjects who had a positive skin-prick test compared to subjects with a negative skin-prick test 39.6 ml.yr-1. In subjects reporting work-related asthmatic symptoms the decline in FEV1 was 43.2 ml.yr-1 greater than in asymptomatic subjects. In asymptomatic subjects, positive skin-prick test was also associated with increased delta FEV1. These data indicate that a single measurement of BR is not a predictor of delta FEV1 in aluminium potroom workers. Smoking, work-related asthmatic symptoms, and positive reaction to skin-prick test in asymptomatic workers were risk factors of increased delta FEV1

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