Healthy worker effect in a longitudinal study of one-second forced expiratory volume (FEV1) and chronic exposure to granite dust.
Eisen-EA; Wegman-DH; Louis-TA; Smith-TJ; Peters-JM
Int J Epidemiol 1995 Dec; 24(6):1154-1162
The chronic effects of long term, low level exposure to granite dust and the shorter term effects of current exposure on pulmonary function were studied in a cohort of Vermont granite workers. Additionally, the potential bias due to healthy worker selection was assessed by comparing the dose response associations between survivors who remained in the study for the full 5 year observation period and dropouts. The association between granite dust and forced expiratory in 1 second (FEV1) was estimated in a cohort of 618 men working in the granite sheds. The cohort consisted of 353 survivors and 265 dropouts. The men had started work after 1940, had no previous occupational history in another dusty trade, were 25 to 65 year old in 1970, and performed an acceptable FEV1 in the initial survey in 1970. The survivors had an FEV1 of 96% of predicted at baseline and were losing FEV1 at an average rate of 44 milliliters/year (ml/yr). No association was found between the rate of FEV1 decline and lifetime dust exposure. The dropouts had a lower FEV1 at baseline (94%) and were losing FEV1 at an average rate of 69ml/yr. The association between dust exposure and decline in FEV1 was statistically significant in the dropout group. The authors conclude that the findings illustrate bias due to the healthy worker effect and an example of the failure to detect a true work related healthy effect in a study based only on a survivor population.
NIOSH-Publication; NIOSH-Grant; Training; Epidemiology; Dust-exposure; Mineral-dusts; Statistical-analysis; Quarry-workers; Occupational-exposure; Lung-disease; Pulmonary-function; Respiratory-system-disorders
Physiology Harvard School of Public Hlth 665 Huntington Avenue Boston, Mass 02115
International Journal of Epidemiology
Harvard University, Boston, Massachusetts