Abstract

We investigated the relationship between annual change in pulmonary function and changes in respiratory symptoms among male grain elevator workers who participated in a health surveillance program mandated by Labour Canada. The surveillance was conducted every 3 yr starting from the period 1978 to 1981. The 1,211 workers who participated in the second (1981 to 1984) and fifth (1990 to 1993) surveillance were included in the analysis and the mean duration of the follow-up was 8.6 yr. In the analysis we also included the pulmonary function measurements that were available for some subjects at the third and fourth surveillance. The subjects who reported persistent wheeze had the largest mean annual rate change in FEV1 (-44.4 ml/yr) and FVC (-55.3 ml/yr). When adjusted for age, height, weight change, smoking, baseline lung function, location of grain elevators, and duration of employment, the subjects with persistent wheeze had an annual rate change of -28.3 ml/yr (SE 10.5; p = 0.007) in FEV1 and -37.3 ml/yr (SE = 12.3; p = 0.003) in FVC in comparison to subjects without any respiratory symptoms. The subjects who reported new onset of wheeze had significantly greater annual rate changes only in FEV1 (-13.7 ml/yr; SE 6.0; p = 0.02) in comparison to asymptomatic subjects' symptoms. Persistent wheeze is an important predictor of decline in lung function among grain elevator workers and should not be ignored in surveillance programs or clinical evaluations

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