Oasys score and ABC score far superior to cross shift changes in the diagnosis of occupational asthma

There is clear benefit from 2-hourly PEF records over pre and post shift changes.

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% for the diagnosis of occupational asthma. 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%.

References

	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,

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