VAIL, 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. “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, and 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 asthmalike wheezing, and that percentage was no different from those in a comparison control group (Pediatr. Pulmonol. 1998;26:256–61).
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.