Occupational Asthma. An assessment of diagnostic agreement between physicians.

Abstract

Objectives: To investigate levels of agreement between expert respiratory physicians when making a diagnosis of occupational asthma (OA). Methods: 19 cases of possible occupational asthma were identified as part of a larger national observational cohort. A case summary for each case was then circulated to 12 physicians, asking for a percentage likelihood from the supplied information, that this case represented OA. The resulting probabilities were then compared between physicians using Spearman Rank correlation and Cohen’s kappa coefficients. Results: Agreement between the 12 physicians for all 19 cases was generally good as assessed by Spearman Rank correlation. For all 66 physician / physician interactions, 45 were found to correlate significantly at the 5% level. Agreement assessed by Kappa analysis was more variable, with a median kappa value of 0.26, (range –0.2 to +0.76), although 7 of the physicians agreed significantly (p<0.05) with 5 or more of their colleagues. Only in one case did the responses for probability of OA all exceed the “on balance” 50% threshold, although 12 of the 19 cases had an interquartile range of probabilities not including 50%, implying “on balance” agreement. Median probability values for each physician (all assessing the identical 19 cases) varied from 20 to 70%. Factors associated with a high probability rating were the presence of a positive serial PEF OASYS-2 chart, and both the presence of bronchial hyperreactivity, and significant change in reactivity between periods of work and rest. Conclusions: Despite the importance of the diagnosis of OA and reasonable physician agreement, certain variations in diagnostic assessment were seen between UK expert centres when assessing paper cases of possible occupational asthma. Whilst this may reflect the absence of a normal clinical consultation in part, a more unified national approach to these patients is required.