Improving the quality of peak flow measurements for the diagnosis of occupational asthma.

INTRODUCTION: Serial measurements of peak expiratory flow (PEF) are recommended in the evidence-based review list as the first stage in objective confirmation of occupational asthma. Different centres have reported widely different success in obtaining records of sufficient data quantity for diagnosis. We investigated different methods of instruction and determined the return rate and quality of the resulting record for the diagnosis of occupational asthma. METHODS: Consecutive new referrals were recruited from a specialized occupational lung disease clinic and requested to carry out serial PEFs for the assessment of suspected occupational asthma. Requests to carry out the records were either from written postal instructions or personal instruction from a PEF specialist. Record quality received from other clinicians was also analysed separating those using dedicated occupational forms, and those submitting on graph type forms. RESULTS: The postal return rate was 56% and the personal rate 85%. The number of records fulfilling all the data quality criteria were similar in the postal and personal groups (55 and 59%, respectively). Pre-existing records from other clinics plotted from graph charts (fulfilling all criteria) were only adequate in 23%, compared with 61% adequate for pre-existing records plotted from occupational forms. Failure of the record to contain consecutive work periods of > or =3 workdays was the most common failure. CONCLUSION: The return rate of PEFs for diagnosing occupational asthma is better when patients have been given specific instructions from a PEF specialist and the data quantity better when recorded on a dedicated form.

Specific IgE to colophony?

BACKGROUND: Colophony (rosin) is a natural product obtained from coniferous trees. It is used in a diverse range of products such as adhesives, ink, paints and soldering fluxes. Some workers exposed to colophony during soldering can develop occupational asthma; at present, no specific IgE test is available to assess sensitization to colophony. METHODS: Serum samples were obtained from exposed symptomatic individuals (n = 7), some with a likely diagnosis of occupational asthma, exposed asymptomatic individuals (n = 10) and unexposed individuals (n = 11). Serum was tested for specific IgE antibodies against a protein extract produced following in vitro challenge of mono-mac-6 cells with colophony extract. RESULTS: Serum from exposed symptomatic individuals showed increased binding of specific IgE antibodies to a range of colophony-cell protein conjugates [29% (2/7) of samples tested when cut-off > 0.1 or 86% (6/7) of samples tested when cut-off > 0%] compared with both the exposed asymptomatic [0% when cut-off > 0.1, or 20% when cut-off > 0% (2/10)] and the non-exposed control populations [0% when cut-off > 0.1, or 27% when cut-off > 0% (3/11)]. CONCLUSIONS: This novel approach for the production of conjugates to assess sensitization to colophony was able to detect specific IgE in colophony-exposed workers with a likely diagnosis of occupational asthma.