Pediatric Pulmonology 49:205–213 (2014)

State of the Art

Asthma and Cystic Fibrosis: A Tangled Web Brian D. Kent, MBBCh,1 Stephen J. Lane, PhD,1* Edwin J. van Beek, MD, PhD,2 Jonathan D. Dodd, MD,3 Richard W. Costello, MD,4 and Harm A.W.M. Tiddens, PhD5 Summary. Successfully diagnosing concomitant asthma in people with cystic fibrosis (CF) is a challenging proposition, and the utility of conventional diagnostic criteria of asthma in CF populations remains uncertain. Nonetheless, the accurate identification of individuals with CF and asthma allows appropriate tailoring of therapy, and should reduce the unnecessary use of asthma medication in broader CF cohorts. In this review, we discuss the diagnostic challenge posed by asthma in CF, both in terms of clinical evaluation, and of interpretation of pulmonary function testing and non-invasive markers of airway inflammation. We also examine how the role of crosssectional thoracic imaging in CF and asthma can assist in the diagnosis of asthma in these patients. Finally, we critically appraise the evidence base behind the use of asthma medications in CF populations, with a particular focus on the use of inhaled corticosteroids and bronchodilators. As shall be discussed, the gaps in the current literature make further high-quality research in this ß 2014 Wiley Periodicals, Inc. field imperative. Pediatr Pulmonol. 2014; 49:205–213. Key words: cystic fibrosis; asthma; inhaled corticosteroids; atopy. Funding source: Health Research Board, Ireland

INTRODUCTION

A decade ago, Balfour-Lynn and Elborn closed their seminal review of asthma in cystic fibrosis (CF) with a warning that performing quality future research in the area would be extremely difficult.1 The ensuing years have only illustrated the extent of that difficulty, as despite the huge strides made in the understanding and treatment of both CF and asthma, there has not been a great deal of exploration of how the two diseases might interact in some CF patients. Does making a reasonably secure diagnosis of asthma in people with CF even matter? Many CF patients use 1 Department of Respiratory Medicine, Adelaide & Meath Hospital, Dublin, Ireland.

medications with a solid evidence base supporting their use in asthma, but of uncertain utility in CF populations. Although generally perceived as being unlikely to cause harm to the patient, the use of these medications is not without risk, and their use adds substantially to the burden, complexity, and cost of treatment for people with CF, while potentially yielding little additional benefit. Conversely, new medications targeted to certain phenotypes of asthma may be of benefit to those CF patients with an asthmatic component. This review examines some of the major issues in identifying asthma in CF patients, evaluates the evidence behind the use of asthma treatments in populations with Conflict of interest: None. 

2

Clinical Research Imaging Centre, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK. 3 Department of Radiology, St. Vincent’s University Hospital, Dublin, Ireland. 4

Department of Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland. 5 Erasmus University Medical Center, Sophia Children’s Hospital, Rotterdam, The Netherlands.

ß 2014 Wiley Periodicals, Inc.

Correspondence to: Stephen J. Lane, Department of Respiratory Medicine, Adelaide & Meath Hospital, Dublin 24, Ireland. E-mail: [email protected] Received 20 September 2012; Accepted 6 September 2013. DOI 10.1002/ppul.22934 Published online 13 January 2014 in Wiley Online Library (wileyonlinelibrary.com).

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CF, and highlights recent advances in asthma which may help to identify asthmatic phenotypes in CF. EPIDEMIOLOGY Asthma Appears to Be a Common Problem in Patients With CF

With no established, validated criteria to confirm the diagnosis, establishing the burden of asthma in CF populations is a challenging proposition. Perhaps the best attempted characterization of asthma in CF patients was made by investigators in the North American Epidemiologic Study of Cystic Fibrosis (ESCF), where a diagnosis of asthma was suggested by a composite of clinical and laboratory features, including a personal or family history of atopy, seasonal benefit from bronchodilators, and eosinophilia.2 Using these criteria, the overall prevalence of asthma in the cohort was estimated at 19%, with roughly equal distribution between pediatric and adult subjects. A somewhat looser definition was utilized in the European Epidemiologic Registry of Cystic Fibrosis (ERCF) study, which found the prevalence of asthma-like symptoms increased with disease severity—from 14– 17% of patients with an FEV1 > 70% predicted, to 24–27% of those with an FEV1

Asthma and cystic fibrosis: a tangled web.

Successfully diagnosing concomitant asthma in people with cystic fibrosis (CF) is a challenging proposition, and the utility of conventional diagnosti...
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