Occupational Asthma Reference

Park D, Moore VC, Burge CBSG, Jaakkola MS, Robertson AS, Burge PS, Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma, Eur Respir J, 2009;34:574-578,

Keywords: post shift, PEF, oasys, cross shift, diagnosis, occupational asthma, challenge

Known Authors

Sherwood Burge, Oasys Sherwood Burge

Vicky Moore, Oasys Vicky Moore

Cedd Burge, Oasys Cedd Burge

Alastair Robertson, Selly Oak Hospital Alastair Robertson

Maritta Jaakkola, Oulu University Finland Maritta Jaakkola

Dan Park, Birmingham Heartlands Hospital Dan Park

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Abstract

ABSTRACT:
Cross-shift measurements of peak expiratory flow (PEF) are commonly employed in the diagnosis of occupational asthma, although evidence for this approach is lacking. The current paper presents an evaluation of the technique.

Methods
Mean changes in PEF across morning/day shifts were compared between workers with occupational asthma, confirmed using specific challenge testing, and non-working asthmatics. Individuals were divided into a development set, used to identify the optimum cross-shift change
for diagnosing occupational asthma, and an evaluation set, used to test the sensitivity and specificity of this value. Comparative analysis of serial PEF records was performed using the Oasys-2 computerised system.

Results
A cross-shift decrease in PEF of 5 L/min achieved acceptable specificity in the development set. Applied to the evaluation set, this cut-off had a specificity of 90.9% and a sensitivity of 50%. Sensitivity could not be improved without unacceptable compromise to specificity. Analysis of
serial PEF records using linear discriminant analysis identified occupational asthma with a sensitivity of 83.3% and a specificity of 90.9%. Serial analysis using mean work/rest day PEF comparison had a sensitivity of 66.7% and a specificity of 100%.

Conclusion
Cross-shift changes in PEF in morning/day-shift workers have poor sensitivity in diagnosing occupational asthma, and are inferior to serial techniques.

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Associated Questions

Registered users of this website have associated this reference with the following questions. This association is not a part of the BOHRF occupational asthma guidelines.

What are the sensitivity and the specificity of pre and post shift changes in lung function in the diagnosis of occupational asthma?
burgeps This paper shows that In workers with challenge positive occupational asthma the mean change across shift of pef is very small in workers on a day or morning shift. (about 5 litres/min) because the PEF usually increases after waking due to spontaneous diurnal variation. Using a cut off of 5 litres/min gives a sensitivity of 50% and a specificity of 91%. Using Oasys analysis of the same record an Oasys score >2.5 had a sensitivity of 83% and a specificity of 91%. The Area Between th Curves (ABC) score had a sensitivity of 67% and a specificity of 100%. There is clear benefit from 2-hourly PEF records over pre and post shift changes.
What are the sensitivity and specificity of serial measurements of peak flow in the diagnosis of occupational asthma?
burgeps This paper shows that In workers with challenge positive occupational asthma the mean change across shift of pef is very small in workers on a day or morning shift. (about 5 litres/min) because the PEF usually increases after waking due to spontaneous diurnal variation. Using a cut off of 5 litres/min gives a sensitivity of 50% and a specificity of 91%. Using Oasys analysis of the same record an Oasys score >2.5 had a sensitivity of 83% and a specificity of 91%. The Area Between th Curves (ABC) score had a sensitivity of 67% and a specificity of 100%. There is clear benefit from 2-hourly PEF records over pre and post shift changes.

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