The Cochrane Libraryand Long-Acting Beta-agonist Treatment for Childhood Asthma: An Overview of Reviews

The evolution of a new publication type: Steps and challenges of producing overviews of reviews

BACKGROUND

To date, the Cochrane Child Health Field has published 18 overviews of reviews in our journal, Evidence-based Child Health: A Cochrane Review Journal. In this article, we highlight some of the logistical and methodological challenges of producing such syntheses. As this is a new and evolving publication type, we hope that our experience will benefit others who engage in this process. Current Methods: We discuss the process we have developed to produce overviews of reviews relevant to our mandate, including identification of the research question, establishment of the author team, selection of outcomes and included SRs, and presentation of findings. Ongoing Development: We discuss the lessons we have learned, outstanding challenges for overview authors, and the limitations of overviews.

CONCLUSIONS

Overviews of reviews are only as good as the SRs and primary studies on which they are based; gaps or lack of currency in this evidence will weaken the overview of reviews. Future directions in this work must address questions of bias and loss of information. Methods for overviews of reviews targeted for specific groups, such as children, need more elaboration. Copyright © 2011 John Wiley & Sons, Ltd.

Use and safety of long-acting β2-agonists for pediatric asthma

Asthma guidelines recommend the use of long-acting β2-agonists (LABAs) as the preferred add-on therapy for adults and children over 5 years of age when asthma is inadequately controlled by inhaled corticosteroids alone. It has been suggested that LABA use may be associated with an increased risk of morbidity and mortality; however, this view is controversial since study findings have been inconsistent. While the safety profile of LABA monotherapy has been questioned, the value of concomitant inhaled corticosteroids to eliminate possible risks remains unproven. There is a paucity of efficacy and safety data for LABA use in children, and existing evidence is not sufficiently convincing to demonstrate a clear position for LABAs in the management of childhood asthma. The main aims of this article are to place LABAs in context in the management of childhood asthma and evaluate the current evidence for safety and efficacy.

The beta-agonist saga and its clinical relevance: on and on it goes

The decision by the Food and Drug Administration to issue a "black box" warning for long-acting beta-agonists has been followed by a series of pharmacoepidemiological studies focusing on the safety of these drugs. However, these provide the clinician with mixed messages and do not offer clear guidance as to whether adverse responses to beta-agonists are a relevant consideration in individual patients. Simultaneously, there is a growing body of evidence that continuous or high dose-beta-agonist exposure is proinflammatory and that, paradoxically, airway hyperresponsiveness is enhanced, not attenuated. Also, pharmacological theory regarding the pathophysiological function of the beta-adrenoceptor is having to be revised. A recent clinical study has even suggested that beta-blockers rather than beta-agonists may be beneficial in asthma. In practice, there are individuals in whom excessive beta-agonist use contributes adversely to poor asthma control. The recommendation that concomitant use of inhaled steroids will obviate any risks associated with beta-agonists is not in fact fool-proof. Clinicians need to be aware of how to identify and manage patients for whom beta-agonist treatment is a problem rather than a solution. They constitute a small but important subgroup of patients with difficult asthma.