Diagnosis of occupational asthma should become more reliable, now that a study has shown that computer analysis of respiratory data is much more accurate than “expert” judgement.

Clinicians expert in diagnosing occupational asthma were compared for their interpretation of actual peak expiratory flow (PEF) measurements from 35 patients with suspected occupational asthma and—though they did not know it—their individual performance against computer program Oasys-2 (Occupation Asthma SYStem), a validated diagnostic aid for occupational asthma.

There was good agreement among the experts’ overall scores for “occupational effect“ and “asthma effect”, as judged by median χ score, but wide interquartile range indicated inconsistency. Comparing individual with Oasys-2 scores showed great variation, especially for four scoring categories. The experts underscored compared with Oasys-2 and missed the occupational effect. Their scores were most variable for “intermediate” PEF records.

The clinicians had an hour for the exercise. Each was given plots of peak flows and Oasys-2 summary plots. They scored each work-rest-work period and rest-work-rest period for occupational effect and gave overall scores for occupational and asthma effects (0–100). Scores were later subdivided into two categories (0–50, 51–100%) or four categories (0–25, 26–50,51–75, 76–100%) equivalent to the clinical probability of occupational asthma (negative, possible, probable, positive) according to Oasys-2.

Correct interpretation of serial PEF values is essential to diagnosing occupational asthma. Interpretation is recognised as being difficult and is confined to expert clinicians. Oasys-2 has been designed to help the diagnosis.