The Spectrum of Irritant-Induced Asthma

23 Mar

The Spectrum of Irritant-Induced AsthmaBrooks and colleagues, in 1985, described the clinical and pathological features of the reactive airways dysfunction syndrome (RADS), ie, the sudden onset of asthma following a high-level irritant gas, vapor, or fume exposure. The diagnosis of RADS required that asthma begins within 24 h of an exposure that was characteristically single, high level, and brief. Several subsequent publications modified the original diagnostic criteria of RADS to include asthma after exposures lasting >24 h. Exposures were sometimes repetitive and occurred over >1 day. A restrictive pattern on pulmonary function testing was noted in some cases, and exposures were occasionally “low level.” The disparate clinical issues regarding RADS were elucidated by designing a retrospective analysis of occupationally and environmentally induced cases of asthma to accomplish several objectives: to better define the clinical features of irritant-induced bronchial asthma, and to evaluate the contributing role of such host factors as allergic/atopy in its pathogenesis.
Materials and Methods
Study Population
The patient population consisted of subjects with diagnosis of occupationally or environmentally induced asthma who had been evaluated at the University of South Florida (USF) Occupational and Environmental Medical Clinic during the 3V2-year period between June 1989 and December 1992.
The initial study population consisted of 136 subjects who were believed to suffer from asthma. After examination, 50 cases were deemed ineligible for consideration. Of the 50 excluded cases, 9 subjects had asthma associated with significant past asbestos exposure, often with evidence of asbestos-related disease. There were 17 subjects who lacked the diagnostic criteria for asthma and were considered not to suffer from asthma. The remaining 24 subjects were excluded because their information was incomplete or lacked the specific predefined information requirements necessary for data analysis in this investigation. When the information base of the three excluded groups (ie, asthma/ asbestos; not asthma; and insufficient information) was compared to the study population, there were no statistically significant differences in age, gender, or other demographic characteristics. There were 86 subjects in the final study population.