When can personal best peak flow be determined for asthma action plans?
- Correspondence to:
Dr H K Reddel
P O Box M77, Missenden Road, Camperdown, NSW 2050, Australia; hkrwoolcock.org.au
- Received 25 May 2004
- Accepted 24 June 2004
Abstract
Background: Written asthma action plans based on personal best peak expiratory flow (PEF) consistently improve health outcomes, whereas those based on predicted PEF do not. Guidelines state that personal best PEF should be assessed over 2–3 weeks during good asthma control, but it is unclear how long to wait after commencing or changing treatment.
Methods: Electronically recorded spirometric data from 61 subjects with initially poorly controlled asthma from a 72 week budesonide study were analysed. For each week, average morning pre-bronchodilator PEF was calculated and personal best PEF was determined as the highest PEF in the previous 2 weeks. The time to plateau was defined as the week beyond which no further improvement occurred.
Results: At baseline, average morning PEF was 61% predicted and personal best PEF was 87% predicted. Personal best PEF from twice daily monitoring increased to a plateau of 95% predicted (p<0.0001) after only 3 weeks of budesonide treatment. However, average morning PEF continued to improve for 3 months and “as needed” reliever use for 7 months.
Conclusions: Personal best PEF is a useful concept for asthma self-management plans when determined as the highest PEF over the previous 2 weeks. With twice daily monitoring, personal best PEF reaches plateau levels after only a few weeks of corticosteroid treatment.
Footnotes
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This work was supported by the Asthma Foundation of NSW, the National Health and Medical Research Council of Australia, AstraZeneca Sweden and AstraZeneca Australia.
