Occupational asthma - Occupational asthma DR. AMIT RAODEO...

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Occupational asthma DR. AMIT RAODEO DM SEMINAR
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Introduction ± Occupational asthma is the most prevalent form of occupational lung disease in industrialized nations ± Occupational asthma caused by more than 250 chemicals ± With the introduction of new organic and inorganic chemicals, the list continues to grow ± About 15% of adult-onset asthma attributed to occupational exposure to irritants. ± Finds mention even in Hippocratic era ± Poorly recognized entity
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Definition ± Variable airflow limitation, bronchial hyperresponsiveness, or both, due to exposures in a particular workplace separate from those outside the work environment ± Controversial issues - whether to include work aggravated asthma - how many objective tests should be positive
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Subgroups of occupational asthma RADS Work related asthma Work aggravated asthma
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Subgroups of occupational asthma OA Asthma with latency Asthma without latency IgE dependent IgE independent Chan-Yeung et al. N Engl J Med 1995; 333:107–112
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Subgroups of occupational asthma Work related asthma (WRA) Work aggravated asthma (WAA) Work related new onset asthma (NOA) Sensitizer induced asthma Irritant induced asthma RADS S K Goe et al . Occup. Environ. Med. 2004;61;512-517
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SENSITIZER INDUCED OA Definite OA Possible OA Probable OA At least one positive work related test Work related changes in PEFR Three fold improvement in PC 20 away from work Positive skin test to relevant sensitizer Absence of conflicting findings Positive work related test result negative response to other tests e.g. PC 20 Negative result of one objective work related test Other work related tests not performed. Marlene SS et al. CHEST 2007; 131:1768–1775
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RADS ± Controversial – subgroup of irritant induced asthma or a separate entity ± Initial description was persistent asthma syndrome after high level irritant exposures. Brookes SM et al. Chest 1985;88:376–384 . ± Essential criteria-strong temporal association between inhalation exposure and the rapid onset of asthmatic symptoms ± Few authors believe, it should never be diagnosed in patients with preexisting asthma ± Others disagree ± Vandenplas et al suggested that, although widely used, the term “RADS” should be replaced “acute irritant induced asthma” or “sudden-onset irritant-induced asthma” to avoid confusion Eur Respir J 2003;21:706–712
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Epidemiology ± Data largely based on surveys in individual workplaces ± Few population based studies ± Limitations - survivor bias effect- most important drawback - large discrepancy in reporting - information bias - lack of uniform definition - controversy regarding work aggravated asthma - most epidemiological studies of occupational asthma cross-sectional in type - no validated tool for OA Gautrin D et al. Eur Respir J 2003; 22: 551–559
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Epidemiology ± Study by Brisman et al tackled most of these issues ± Retrospective cohort design among bakers in 1959–1989 (n=2,923) ± Two different reference groups, one comprising persons who
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Occupational asthma - Occupational asthma DR. AMIT RAODEO...

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