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Correspondence |

The Plea for Rigorous Studies on Cough in Children FREE TO VIEW

Anne B. Chang, MBBS, MPHTM, PhD; Lou I. Landau, MBBS, MD; Peter P. van Asperen, MBBS, MD; I. Brent Masters, MBBS, PhD; Craig M. Mellis, MBBS, MD
Author and Funding Information

From the Queensland Children’s Respiratory Centre, Royal Children’s Hospital (Drs Chang and Masters); School of Paediatrics and Child Health, University of Western Australia (Dr Landau); Department of Respiratory Medicine, The Children’s Hospital at Westmead (Dr van Asperen); and Central Clinical School (Dr Mellis), University of Sydney.

Correspondence to: Anne Chang, MBBS, MPHTM, PhD, Department of Respiratory Medicine, Royal Children’s Hospital, Herston, QLD, Australia 4029; e-mail: annechang@ausdoctors.net


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestpubs.org/site/misc/reprints.xhtml).


© 2010 American College of Chest Physicians


Chest. 2010;137(3):741. doi:10.1378/chest.09-2204
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To the Editor:

Although we applaud Khoshoo et al1 on performing such a comprehensive series of investigations in these 40 children with chronic cough, as reported in a recent issue of CHEST (September 2009), we have major reservations with their conclusions. In particular, we question the assumption that the improvement in cough (assessed at 8 weeks by parent on a subjective visual analog scale cough score) was caused by the respective interventions. In the absence of a control group, this improvement after 8 weeks could simply be due to a period effect2 and/or a placebo effect.3,4 This is particularly likely when the clinicians have taken such a great interest in the child’s cough and have carried out an elaborate series of investigations. This problem is further exacerbated by the manner in which the subjective nature of their outcome measure was measured. Clearly, given the open nature of the intervention, any assessment of outcome must be objective. This time-period effect with cough was well described in the 1980s by Evald and colleagues.2 Indeed, the placebo effect is reported to be as high as 80% in cough studies.4

Thirty-six children in the study by Khoshoo et al1 had a nonproductive cough. According to the American College of Chest Physicians (ACCP)5 and Australian6 guidelines, in children with nonproductive cough, a “watch, wait, and review” approach should be considered. We have demonstrated that a nonproductive (dry) cough in children spontaneously totally resolves (as opposed to just a reduction in cough score) by 8 weeks in 69%.3 Unfortunately, Khoshoo et al have also misinterpreted the ACCP guidelines; these do not advocate the use of antibiotics for all children with chronic cough but only those with a productive (wet) cough. Children with wet cough are likely to have protracted bronchitis, as documented in a number of clinical studies, including those using BAL with quantitative bacterial counts.7

This study by Khoshoo et al1 highlights the need for high-quality randomized controlled trials to determine an evidence-based approach to children with chronic cough as we have consistently reiterated. There is always a need to balance any risk of late diagnosis with that of over-servicing. Although the study by Khoshoo et al is interesting, clinicians need to be aware of the major flaws in the methodology used, and the potential for misleading information regarding the best approach to managing children with chronic cough.

Khoshoo V, Edell D, Mohnot S, Haydel R Jr, Saturno E, Kobernick A. Associated factors in children with chronic cough. Chest. 2009;1363:811-815. [CrossRef] [PubMed]
 
Evald T, Munch EP, Kok-Jensen A. Chronic non-asthmatic cough is not affected by inhaled beclomethasone dipropionate. A controlled double blind clinical trial. Allergy. 1989;447:510-514. [CrossRef] [PubMed]
 
Marchant JM, Masters IB, Taylor SM, Chang AB. Utility of signs and symptoms of chronic cough in predicting specific cause in children. Thorax. 2006;618:694-698. [CrossRef] [PubMed]
 
Eccles R. The powerful placebo in cough studies? Pulm Pharmacol Ther. 2002;153:303-308. [CrossRef] [PubMed]
 
Chang AB, Glomb WB. Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines. Chest. 2006;1291suppl:260S-283S. [CrossRef] [PubMed]
 
Chang AB, Landau LI, van Asperen PP, et al; Thoracic Society of Australia and New Zealand Thoracic Society of Australia and New Zealand Cough in children: definitions and clinical evaluation. Med J Aust. 2006;1848:398-403. [PubMed]
 
Chang AB, Faoagali J, Cox NC. A bronchoscopic scoring system for airway secretions-airway cellularity and microbiological validation. Pediatr Pulmonol. 2006;419:887-892. [CrossRef] [PubMed]
 

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References

Khoshoo V, Edell D, Mohnot S, Haydel R Jr, Saturno E, Kobernick A. Associated factors in children with chronic cough. Chest. 2009;1363:811-815. [CrossRef] [PubMed]
 
Evald T, Munch EP, Kok-Jensen A. Chronic non-asthmatic cough is not affected by inhaled beclomethasone dipropionate. A controlled double blind clinical trial. Allergy. 1989;447:510-514. [CrossRef] [PubMed]
 
Marchant JM, Masters IB, Taylor SM, Chang AB. Utility of signs and symptoms of chronic cough in predicting specific cause in children. Thorax. 2006;618:694-698. [CrossRef] [PubMed]
 
Eccles R. The powerful placebo in cough studies? Pulm Pharmacol Ther. 2002;153:303-308. [CrossRef] [PubMed]
 
Chang AB, Glomb WB. Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines. Chest. 2006;1291suppl:260S-283S. [CrossRef] [PubMed]
 
Chang AB, Landau LI, van Asperen PP, et al; Thoracic Society of Australia and New Zealand Thoracic Society of Australia and New Zealand Cough in children: definitions and clinical evaluation. Med J Aust. 2006;1848:398-403. [PubMed]
 
Chang AB, Faoagali J, Cox NC. A bronchoscopic scoring system for airway secretions-airway cellularity and microbiological validation. Pediatr Pulmonol. 2006;419:887-892. [CrossRef] [PubMed]
 
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