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Cough-variant asthma diagnosed too often in children, expert says.

VALE, COLO. -- Cough-variant asthma is "markedly overdiagnosed" in children, Dr. Carolyn M. Kercsmar said at a meeting sponsored by the American Academy of Pediatrics.

These children sometimes end up being treated with a number of different asthma drugs they do not need because nothing works, said Dr. Kercsmar, director of the children's asthma center at Rainbow Babies and Children's Hospital, Cleveland.

Some of the overdiagnosis results from the fact that children presumed to have cough-variant asthma are not evaluated for evidence of airway obstruction. And, while some children with cough-variant asthma do not have wheezing obstruction, if a physician cannot demonstrate airway obstruction with abnormal spirometry testing results, or if the child does not respond to a bronchodilator, then the physician should not diagnose cough-variant asthma, she said.

Physicians can institute a trial of an inhaled corticosteroid, but

it should only be given 2 weeks to work, she added.

"If that cough is not gone in 1-2 weeks, it is not asthma," she said.

Most children with asthma will have a strong family history of either asthma or allergy in a first-degree relative; that also can be an important piece of information to use for diagnosis.

A methacholine challenge test "can be useful, but not entirely diagnostic" because 10% of normal, nonasthmatic individuals react to a challenge, she said.

A study conducted by investigators at the University of Leicester (England) suggested how uncommon cough-variant asthma may be among children with a chronic cough, Dr. Kercsmar noted.

The study followed 125 preschool children with a reported recurrent cough for between 2 and 4 years. Over the follow-up period, 56% of the children lost their cough and 37% had continued chronic cough. But, only 7% went on to develop asthma-like wheezing, and that percentage was no different from those in a comparison control group (Pediatr. Pulmonol. 1998;26:256-61).

Population estimates of asthma suggest that anywhere from 6% to 15% of children will have asthma at some time, but only about 5%-10% of children with asthma will have cough primarily, Dr. Kercsmar said.

Instead of asthma, chronic cough in adults often is caused by gastroesophageal reflux or postnasal drip, Dr. Kercsmar said in a later interview. Children may be the same or they may be different. They have not been studied as well as adults in this area. If you are concerned about investigating the possibility of reflux, you can measure the pH of breath condensate to determine whether the child has it.

Other potential causes of chronic cough range from psychogenic cough, to persistent bacterial bronchitis, to cystic fibrosis, she said.

BY TIMOTHY F. KIRN

Sacramento Bureau

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Title Annotation:Clinical Rounds
Author:Kirn, Timothy F.
Publication:Pediatric News
Geographic Code:1USA
Date:Apr 1, 2007
Words:437
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