Statistical comparison of aerosol-induced and spontaneous sputum specimens in the Tyler Asbestos Workers Program

More than 10,000 sputum specimens, including both aerosol-induced and three-day pooled spontaneous specimens, were processed within a five-year period from a surveillance program of a cohort of 858 former asbestos workers and 188 controls. During the first two years, slides were prepared by the "pick and smear" method; thereafter, the Saccomanno technique was used. Each specimen was examined for both the degree of cellular atypia and the number of ferruginous bodies. Data analysis revealed that the number of ferruginous bodies in the spontaneous specimens showed a higher correlation with chest X rays and pulmonary function tests than did those in aerosol-induced specimens. Consequently, a study was undertaken to compare the results of all aerosol-induced and spontaneous cough specimens prepared by the pick and smear and Saccomanno methods. Matched pairs of specimens from the same individuals were also compared. More specimens with atypias were obtained from the spontaneous sputa using the Saccomanno technique. More ferruginous bodies were found in the aerosol-induced specimens using the pick and smear method. The pick and smear method was more effective for detecting ferruginous bodies in both induced and spontaneous specimens.