Peak Expiratory Flow Monitoring in Older Patients with Asthma: An Aid to Management?

The development of self-management plans was undertaken in the 1970s when general practitioners and lung specialists tried to develop better methods to deliver asthma care and reduce associated morbidity and mortality. Self-management plans are now recommended in the long-term management of adult asthma, focusing on the early recognition of unstable or deteriorating asthma by monitoring peak expiratory flow (PEF) and/ or symptoms. The use of PEF measurements has a potential advantage since it provides an objective marker of airway obstruction. Written guidelines enable patients to determine when it is necessary to adjust therapy or obtain medical assistance. International asthma guidelines recommend the use of PEF monitoring for the assessment of asthma severity and response to treatment (1, 2). Long-term monitoring is advised for patients with severe asthma, patients with poor subjective assessment of their condition, and after hospitalization, as well as for short-term monitoring to optimize adjustment of medication dose or to permit identification of triggers and management of exacerbations. The study by Buist and colleagues (3) in this issue of the Journal (pp. 1077-1087) helps to identify whether implementation of objective PEF measurements in an extensive management plan provides better asthma outcome than the same management plan without either twice-daily or "as needed" PEF measures. Results show that, in older adults with asthma, PEF monitoring appears not to add any additional advantage with respect to health care utilization, lung function, and quality of life. These findings may simplify the approach to asthma management in clinical practice.

Gibson and Powell (4) reported a meta-analysis of 26 studies that examined the effect of written action plans and their components on asthma outcome (hospital admissions, emergency treatments, lung function). In 17 of these studies, guidelines were provided on how and when to change treatment. There was striking variation in action plans, which prevented clear messages as to the optimal plan and its use. In general, these plans had two to four action points, based on either PEF alone or on symptoms and/or PEF. Again, use of such action plans was not simple, since PEF-based plans require calculation of the level of PEF below which treatment adjustments should be made. This level can be either calculated from personal best PEF or from predicted PEF. Whichever was used, the action plans incorporating PEF monitoring reduced hospital admissions. In contrast, plans based on personal best PEF values reduced emergency department visits and improved PEF, suggesting that this approach provides better customization of the action plan to the patient. In a recent review, Reddel (5) suggested that current use of PEF data is limited by the burden that monitoring incurs for the patient and the continuing use of interpretative tools (e.g., personal best PEF) that were originally developed for their practical feasibility rather than their clinical validity. The study of Buist and colleagues (3) confirms this, since a conservative estimate on recording of PEF showed that 76% of the twice-daily group and 37% of the as-needed group did so 1 mo after the first instruction plans, whereas only 34 and 25%, respectively, persisted in doing so after 14 mo! Thus, it is not too surprising that PEF monitoring did not add much to asthma management and outcomes.

It is well known that asthma is generally more severe in females than males. The study of Buist and colleagues (3) analyzed improvements in lung function stratified for males and females and found no difference in patients with asthma older than 50 yr. They state that they did not perform additional post hoc analyses, given the lack of overall difference in management approaches. However, by not undertaking such analyses, they may have missed an opportunity to develop better insight into sex differences in their response to asthma management programs. We have previously shown, admittedly in a different setting, that male and female adults between 50 and 70 yr of age differed in their response to air pollution (6). Males who were hyperresponsive and had increased IgE levels responded predominantly with an increase in symptoms on exposures to increasing air pollution, whereas their female counterparts responded with a drop in morning PEF values. If this happens for other stimuli that aggravate asthma, it may well have been that subgroups of females would have benefited from PEF monitoring, given their supposedly greater responsiveness in airway function.

The study by Buist and coworkers (3) shows that use of inhalers in a comprehensive management plan can be improved over time in a setting where individuals have to repeatedly show their ability to correctly use this technique. It also provides evidence that, at least in older patients with asthma, PEF monitoring does not add surplus value over symptomatic management alone. We suggest that perhaps a final study should be undertaken to provide evidence that this is the case for both males and females. If so, this would reduce the burden of remembering to perform PEF measures daily and would improve simplicity of asthma management immensely!

Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.

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