Comparison of methacholine protocols in three occupational studies.
Agalliu-I; Eisen-EA; Hauser-R; Redlich-C; Cullen-MR; Kennedy-SM
Am J Respir Crit Care Med 2001 Apr; 163(5)(2)(Suppl):A810
Rationale: Methacholine challenge testing has become a common tool for detecting nonspecific bronchial hyper-responsiveness. We examined the impact of differences in field and analysis protocols on the degree of measured airway responsiveness in our three recent studies of working populations exposed to respiratory hazards; apprentices exposed to metalworking fluids, boilermaker construction workers exposed to combustion particulate, and auto body shop workers exposed to hexarnethylene diisocyanate. Methods: All three protocols used the tidal breathing method. Slopes were based on concentration rather than cumulative dose of methacholine and anchored by the saline FEV I. The protocols differed in the number of dose levels, the maximum concentration administered (64, 25, and 10 mg/ml) and in the maximum time elapsed before the FEV I measurement after each dose (up to 3, 2, and 1 minutes). Slopes were recalculated after standardizing the protocol across studies by truncating the data at a similar final concentration and waiting the same length of time before measuring FEV I. Results: There were no significant differences in methacholine slopes or the prevalence of responsiveness (pC20 < 8 mg/ml) between auto body shop workers exposed to isocyanates and apprentice machinists exposed to metalworking fluids, -14.2 and -19.0, respectively. The boilermakers exposed to combustion particulate were more responsive. When the protocol in the autobody shop study was truncated at 10 mg/ml (the highest dose in the boilermakers' protocol) the mean response slope did not change significantly. Conclusions: Low dose protocols may be adequate for assessing airway responsiveness in working populations. The findings have practical implications for the cost of conducting field studies of occupational and environmental respiratory hazards.
Lung-function; Lung-disease; Respiratory-system-disorders; Metalworking-fluids; Construction-workers; Construction-industry; Automobile-repair-shops; Automotive-industry; Breathing; Occupational-hazards; Occupational-health
American Journal of Respiratory and Critical Care Medicine. Abstracts of the American Thoracic Society 2001 International Conference, May 18-23, 2001, San Francisco, California
Harvard University, Boston, MA