CLINICAL PREDICTORS OF MORTALITY FROM ASBESTOSIS IN THE NORTH-AMERICAN INSULATOR COHORT, 1981 TO 1991

Recorded mortality from asbestosis has increased markedly in the Unite d States in recent decades, from 0.49 to 3.06 per million persons betw een 1970 and 1990. Although asbestosis is generally considered to be a slowly progressive disorder, little is known about how clinical and e xposure parameters among individuals with asbestosis quantitatively pr edict subsequent risk of death from asbestosis. We followed 2,609 insu lators from the North American insulator cohort 10 yr to determine cau se of death and to relate clinical findings to risk of death. This gro up had undergone clinical and radiologic examination between 1981 and 1983 in 19 cities in the United States. Seventy-four (11.0%) of 674 de aths during the subsequent 10 yr were due to asbestosis, according to the best clinical and radiologic evidence available at the time of dea th. The 10 yr risk of death (expressed as a percentage) due to asbesto sis rose sharply with increasing interstitial fibrosis as identified o n the baseline chest X-ray, from 0.9% to 2.4%, 10.8%, and 35.4% for In ternational Labor Office (ILO) profusion categories 0, 1, 2, and 3, re spectively. Dyspnea, a low FVC, and/or physical examination findings t ypical of interstitial fibrosis (rales, clubbing, or cyanosis) raised the risk of subsequent death from asbestosis by 2- to 6-fold. The effe ct of cigarette smoking on risk of death from asbestosis was small and disappeared after adjustment for ILO profusion score.