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Vikram Khoshoo, MD, PhD; Dean Edell, MD, MPH, FCCP
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From the West Jefferson Medical Center.

Correspondence to: Vikram Khoshoo, MD, PhD, Pediatric Specialty Center, West Jefferson Medical Center, 1111 Medical Center Blvd, South 650, Marrero, LA 70072; e-mail: vkhoshoo@sbcglobal.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):741-742. doi:10.1378/chest.09-2642
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To the Editor:

The comments by Chang and colleagues are based on their experiences and data generated from a unique population. Although several practitioners can relate to their data, our population, patient selection, methods, investigation protocols, and treatment strategies are somewhat different, and hence the differences. Based on the overwhelming response we have received from pediatricians, family physicians, gastroenterologists, allergists, and pulmonologists from all over the world following the publication of our article,1 we can confidently state that numerous practitioners worldwide can relate to our data as well. We would like to clarify a few issues so that the readership can understand the differences and interpret the data accordingly.

Definition of Chronic Cough:

Chang’s group has used an arbitrary definition of chronic cough (duration > 4 weeks). Like most other board-certified pediatric pulmonologists in the United States, we use the > 8-week-duration cutoff for chronic cough, similar to the American College of Chest Physicians (ACCP)-recommended definition for adults. Technically, Chang’s group has labeled what we and others call subacute cough (3-8 weeks) as chronic cough (> 8 weeks). That is the starting point of the difference.1-3 It is then no surprise that their definition has permeated into the recommendations of the ACCP for pediatric cough authored by them. The definition has survived probably because there have been no additional data on the etiology of chronic cough in children. Hopefully, our data will help provide another perspective that the ACCP will consider for future recommendations.

Reason for Referral for Chronic Cough:

We, as subspecialists, rarely see subacute cough because the network of our primary care physicians have diagnosed, intervened, and treated infection and other common noninfectious causes before the cough becomes chronic unless there is antibiotic resistance or difficult-to-treat airway reactivity. Our patients have near-perfect immunization status, no overcrowding, high level of education, low cigarette smoke exposure, and excellent pediatric care through physicians who are well aware of current microbial sensitivity patterns. This may be somewhat different from a more rural population in which general practitioners with limited pediatric training may make subspecialty referrals earlier in the course while infection is still persisting, and thus infection as the cause would predominate in their subspecialty clinics. Briefly, it is likely that prior to referral to a specialist, pediatricians in the United States may be intervening a lot more from weeks 3 to 8 of cough to resolve the cough.

Quality of Workup:

Chang’s group performed a selective workup, introducing a selection bias and making the results of prevalence less thorough.3 Gastroesophageal reflux disease (GERD) itself is linked to higher prevalence of lower respiratory tract infections and illnesses. So in any persistent lower respiratory tract illness, it becomes important to exclude GERD. Unlike Chang’s workup, we performed the same thorough, nonselective investigation on every patient, and it is no surprise that GERD and cough-variant asthma showed up in higher proportions.1 In our study, for reliability, several of the investigations/treatments required patient cooperation, so our patient group was somewhat older.

Wet Cough May Represent Bacterial Causes:

In our setting, such patients would be filtered by the pediatricians and not reach us, the subspecialists. Additionally, a fine study by Mello et al4 has shown that neither the character nor the timing of cough is a good predictor of the cause.

The Comment on Dry Cough Is Provocative:

A number of our patients had dry cough of > 16-weeks duration, even 30-weeks duration, despite interventions. How much longer would one be expected to wait for spontaneous resolution of dry cough? The natural history of short-duration dry cough will obviously be different from an already long-duration dry cough. Our patients had already crossed the 12-weeks mark without resolution of symptoms. Obviously, none of our children had cough scores of zero after 12 weeks.

The Visual Analog Scale:

The visual analog scale is a validated tool used to quantify cough very effectively in our setting as well as several other settings.5 The patient is his or her own control. It is, at worst, a semiobjective measure. This tool works well in our setting but may not be appropriate in other settings, where cough diaries may work better.

Briefly, our data were obtained in a very thorough manner in a typical urban/suburban population in the United States with high-quality pediatric care. Thus, the population referred for subspecialty care may be different from a rural population in another country. Finally, the learning objective of this dialogue for the readership should be to most certainly understand the population characteristics in any study before allotting merit and relevance of the data to their own practice. We thank Chang and colleagues for prompting this discussion.

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]
 
Chang AB, Glomb WB. Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines. Chest. 2006;1291Suppl:260S-283S. [CrossRef] [PubMed]
 
Marchant JM, Masters IB, Taylor SM, Cox NC, Seymour GJ, Chang AB. Evaluation and outcome of young children with chronic cough. Chest. 2006;1295:1132-1141. [CrossRef] [PubMed]
 
Mello CJ, Irwin RS, Curley FJ. Predictive values of the character, timing, and complications of chronic cough in diagnosing its cause. Arch Intern Med. 1996;1569:997-1003. [CrossRef] [PubMed]
 
Irwin RS, Zawacki JK, Wilson MM, French CT, Callery MP. Chronic cough due to gastroesophageal reflux disease: failure to resolve despite total/near-total elimination of esophageal acid. Chest. 2002;1214:1132-1140. [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]
 
Chang AB, Glomb WB. Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines. Chest. 2006;1291Suppl:260S-283S. [CrossRef] [PubMed]
 
Marchant JM, Masters IB, Taylor SM, Cox NC, Seymour GJ, Chang AB. Evaluation and outcome of young children with chronic cough. Chest. 2006;1295:1132-1141. [CrossRef] [PubMed]
 
Mello CJ, Irwin RS, Curley FJ. Predictive values of the character, timing, and complications of chronic cough in diagnosing its cause. Arch Intern Med. 1996;1569:997-1003. [CrossRef] [PubMed]
 
Irwin RS, Zawacki JK, Wilson MM, French CT, Callery MP. Chronic cough due to gastroesophageal reflux disease: failure to resolve despite total/near-total elimination of esophageal acid. Chest. 2002;1214:1132-1140. [CrossRef] [PubMed]
 
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