Reference

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.

58/101 patients referred for investigation were diagnosed as having isocyanate-induced occupational asthma by means of history, serial peak flow records, and bronchial provocation tests (BPT). Specific IgE antibodies to isocyanates were measured in all patients by RAST. 20 patients had a RAST ratio of 2 or greater to at least one isocyanate. 13 (28%) of the 46 patients with a positive BPT response had RAST ratio of 2 or greater, and 9 (20%) had a RAST ratio of 3 or greater. Raising the RAST cut-off from 2 or greater to 3 or greater reduced its sensitivity but increased the specificity of the test to 100%. With a RAST score of 3 or greater, it is wholly specific and therefore diagnostic of isocyanate-induced asthma. The sensitivity of specific IgE measurement is highest when blood is taken less than 30 days from last exposure, which is consistent with the observed half-life (6 months). Measurement of specific IgE to isocyanates is a specific but relatively insensitive test for asthma induced by isocyanates.

BOHRF Associated Evidence Statements

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