What are the sensitivity and the specificity of changes in non-specific reactivity at work and away from work in the diagnosis of validated cases of occupational asthma?

The following references have been associated with this question by users of this website. They do not form part of the BOHRF occupational asthma guidelines.

burgeps Tarlo 1989 not all cases validated, but 4 fold change in methacholine Pc20 seen in 2/3 with probable low dose irritant oa and 16/49 with sensitizer oa
burgeps Pralong 2016 This study reports a a very high sensitivity for non-specific reactivity in predicting a positive specific challenge test to an occupational agent. Most of those with negative NSBR were away from exposure at the time of the test, something generally found by others. The high sensitivity is partly explained by using a higher cut-off for normality (16mg/ml) than the usual 8mg/ml, but this is still unlikely to explain the very high sensitivity found. We need assurance that NSBR was not used to decide who should have a specific challenge (this is recommended in some guidelines). Another possible explanation is the high prevalence of the eosinophilic phenotype, something associated with NSBR. Others have found much lower sensitivities for NSBR in predicting the response to specific challenges, particular in those without sputum eosinophilia. The specificities quoted depend on the controls selected (or in this case those with negative specific challenges) as NSBR cannot separate occupational from non-occupational asthma.

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