Reference

Baur X, Huber H, Degens PO, Allmers H, Ammon J, Relation Between Occupational Asthma Case History, Bronchial Methachlorine Challenge, And Specific Challenge Test In Patients With Suspected Occupational Asthma, Am J Ind Med, 1998;33:114-122,

BOHRF Original Authors' Main Conclusions

The original authors' main conclusions are taken from Abstract, Results and Discussion. They are decided upon by the authors of the BOHRF occupational asthma guidelines and form part of the guidelines.

Methacholine challenge (MC) was performed in 229 subjects with suspected occupational asthma. They were also subjected to specific challenge tests, questionnaire, and interviewed by an experienced physician. Study aimed to investigate whether MC and/or occupational asthma case history are reliable predictors of specific challenge test outcomes. MC results are only moderately associated with workplace-related asthma case histories whereas positive outcomes of challenges with occupational agents are well correlated with positive MC results plus occupational asthma case histories. Authors conclude that in most cases, occupational asthma is combined with bronchial hyper-responsiveness (BHR) and workplace-related asthmatic symptoms. In subjects with a positive occupational asthma case history, a negative MC test result can almost rule out a positive specific challenge test result. Hence, the MC test can reduce performance of the laborious specific challenge test.

BOHRF Associated Evidence Statements

The BOHRF occupational asthma guidelines state that this reference is associated with the following evidence statements

In the clinical setting questionnaires that identify symptoms of wheeze and/or shortness of breath which improve on days away from work or on holiday have a high sensitivity, but relatively low specificity for occupational asthma.

Free histories taken by experts have high sensitivity, but their specificity may be lower.

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2++

A large number of concordant studies from different centres using different methodologies demonstrated that increased non-specific reactivity is often found in workers with occupational asthma. There are however many reports of normal methacholine or histamine reactivity within 24 hours of exposure in workers with confirmed occupational asthma.

Non Bohrf Information

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