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Diurnal variation


In calculating diurnal variability I'm under the impression that the oasy's group suggest change in peak flow/predicted as a marker of variability rather than % change from baseline i.e am-pm/highest if so
what do you classify as a significant effect ? 10% of predicted or ?20%
Occupational Asthma, Specialist, 10/12/2009, 10/12/2009,

We do not place much importance on diurnal variation when investigating occupational asthma. The display shows day max - day min divided by the predicted when we know what it is. Otherwise we use day max - day min divided by the mean of all the peak flows in the record. There is a line on the diurnal variation part of the graph at 20% as this is a figure a lot of people get excited about. We use the Oasys score and visual analysis of the daily and 2-hourly plots instead.
Full Text Available for Peak expiratory flow analysis in workers exposed to detergent enzymes Moore VC, Cullinan P, Sadhra S, Burge PS, Peak expiratory flow analysis in workers exposed to detergent enzymes, Occup Med, 2009;59:418-423,
Paul Cullinan, Royal Brompton Hospital, London, UK, an author of 'Peak expiratory flow analysis in workers exposed to detergent enzymes' Sherwood Burge, Oasys, an author of 'Peak expiratory flow analysis in workers exposed to detergent enzymes' Vicky Moore, Oasys, an author of 'Peak expiratory flow analysis in workers exposed to detergent enzymes' Steve Sadhra, Institute of Occupational and Environmental Health, Birmingham, an author of 'Peak expiratory flow analysis in workers exposed to detergent enzymes'

Abstract Available for Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma 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,
Sherwood Burge, Oasys, an author of 'Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma' Vicky Moore, Oasys, an author of 'Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma' Cedd Burge, Oasys, an author of 'Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma' Alastair Robertson, Selly Oak Hospital, an author of 'Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma' Maritta Jaakkola, Oulu University Finland, an author of 'Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma' Dan Park, Birmingham Heartlands Hospital, an author of 'Serial PEF measurement is superior to cross-shift change in diagnosing occupational asthma'

10/12/2009

The percentage clearly depends on the denominator, so those with low PEF have higher diunal variation if the mean or maximum is used. The most sensible denominator is the predicted PEF. If PEF is measured 2-hourly in a normal population, the 90% CI for diurnal variation % predicted is around 17.6% (Higgins BG Am Rev Resp Dis 1992;145:588). The sensitivity at this cut-off for asthma in this study was 32%. i.e. most asthmatics when measured routinely do not have increased diurnal variation outside population norms. A study of healthy frain workers with large exposres showed an upper 95% CI of 17%, levels above this seen in around 40% of workers with occupational asthma.
Full Text Available for Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial Anees W, Huggins V, Blainey D, Pantin CFA, Robertson K, Burge PS, Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial, HSE Books, 2002;450:1-14,
David Blainey, Essex, UK, an author of 'Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial' Sherwood Burge, Oasys, an author of 'Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial' Charles Pantin, Keele, UK, an author of 'Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial' Wasif Anees, Oasys, an author of 'Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial' Vicky Moore, Oasys, an author of 'Evaluation of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma in a field trial'

Abstract Available for Comparison of bronchial reactivity and peak expiratory flow variability measurements for epidemiologic studies Higgins BG, Britton JR, Chinn S, Cooper S, Burney PG, Tattersfield AE, Comparison of bronchial reactivity and peak expiratory flow variability measurements for epidemiologic studies, Am Rev Respir Dis, 1992;145:588-593,
Peter Burney, Kings College, London, an author of 'Comparison of bronchial reactivity and peak expiratory flow variability measurements for epidemiologic studies' Bernard Higgins, Newcastle-on-Tyne, an author of 'Comparison of bronchial reactivity and peak expiratory flow variability measurements for epidemiologic studies'

10/12/2009

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