Abstract

Objectives: To assess diagnostic agreement for occupational asthma (OA) by physicians within and between clinical disciplines, and to identify case and rater characteristics associated with making an OA diagnosis.

Methods: Anonymised summaries for 19 possible OA cases were sent to 51 occupational physicians (OPs) and 53 respiratory physicians (RPs). In phase 1, raters were asked to assign a likelihood score (0-100%) of OA for 4 case histories; in phase 2, raters were asked again after seeing investigative procedures/results for 2 of their cases. Interclass correlation coefficients were calculated as statistical measures of reliability for OA scores. Comparisons between mean scores for OPs and RPs were assessed for statistical significance using tests based on multilevel models. Relative risks were calculated to summarise effects of raters' demographics on OA diagnosis, and of supplying investigative procedures/results.

Results: OA scores from OPs and RPs were not systematically different. Mean overall OA scores from phase 1 were 52.1% (OPs) and 50.0% (RPs), the difference (OPs'-RPs'mean) was 2.1% (95%CI: -2.6,6.8 p=0.37). In phase 2, mean overall OA scores for OPs and RPs were 46.1% and 41.5%; the difference (OPs'-RPs'mean) was 4.6% (95%CI: -3.5,12.5 p=0.27). Raters with GMC registration ≥1986 were more likely to give a positive OA diagnosis, and in phase 2 males were much more likely to label a case as OA than females RR=4.5 (95%CI;3.3-6.0).

Conclusions: The RR of a positive OA diagnosis was not affected by clinical specialty (OP/RP), however there was only limited agreement between physicians within each group. Further work on what triggers physicians to consider a case as OA will assist better diagnosis and prevention of this disease.