Occupational Asthma Reference

Moore VC, Jaakkola MS, Burge CBSG, Pantin CF, Robertson AS, Vellore AD, Burge PS, PEF analysis requiring shorter records for occupational asthma diagnosis, Occup Med (London), 2009;59:413-417,

Keywords: oasys, ABC, methods

Known Authors

Sherwood Burge, Oasys Sherwood Burge

Charles Pantin, Keele, UK Charles Pantin

Vicky Moore, Oasys Vicky Moore

Cedd Burge, Oasys Cedd Burge

Alastair Robertson, Selly Oak Hospital Alastair Robertson

Arun Dev Vellore, Oasys Arun Dev Vellore

Maritta Jaakkola, Oulu University Finland Maritta Jaakkola

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Abstract

Background The Oasys programme plots serial peak expiratory flow (PEF) measurements and produces scores of the likelihood that the recordings demonstrate occupational asthma. We have previously shown that the area between the mean workday and rest day PEF curves [the area between the curves (ABC) score] has a sensitivity of 69% and specificity of 100% when plotted from waking time using a cut-off score of 15 l/min/h.

Aims To investigate the minimum data requirements to maintain the sensitivity and specificity of the ABC score.

Methods A total of 196 sets of measurements from workers with occupational asthma confirmed by methods other than serial PEFs and 206 records from occupational and non-occupational asthmatics who were not at work at the time of PEF monitoring were analysed according to their mean number of readings per day. Measurements from work and rest days were sequentially removed separately and the ABC score calculated at each reduction. The sensitivity and specificity of the ABC score (using a cut-off of 15 l/min/h) was calculated for each duration.

Results Two-hourly measurements (8 readings per day) with eight workdays and three rest days had 68% sensitivity and 91% specificity for occupational asthma diagnosis. As readings decreased to 4 readings per day, 15 workdays were required to provide a specificity above 90%.

Conclusions To be sensitive and specific in the diagnosis of occupational asthma, the ABC score requires 2-hourly PEF measurements on eight workdays and three rest days. This is a short assessment period that should improve patient compliance.

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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 minimum criteria for serial measurements of peak flow to maintain a high degree of diagnostic accuracy?
burgeps Minimum requirements for the Area Between Curves (ABC) score are 2-hourly readings for 8 workdays and 3 restdays. Longer records are required if readings are less frequent
What are the sensitivity and specificity of serial measurements of peak flow in the diagnosis of occupational asthma?
burgeps The Area Between Curves (ABC) score from at leat 8 workdays and 3 restdays has a 68% sensitivity 91% specificity for 2-hourly readings against independant standards of diagnosis, mostly specific challenge testing but also 4 fold changes in NSBR or positive IgE to a well characterised antigen together with a strong history and evidence of asthma.

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