Methacholine challenge testing in Reserve Officer Training Corps cadets.
OBJECTIVE
To determine the prevalence of positive results for methacholine challenge tests in asymptomatic Reserve Officer Training Corps (ROTC) cadets with no history of asthma.


METHODS
Prospective, blinded cohort comparison study.


METHODS
Pulmonary diseases clinic in a US Army tertiary-care medical center.


METHODS
One hundred three college students who were undergoing a physical examination before entering active duty. Group 1 subjects, 58 men and 5 women with an average age of 22.7 years, had no symptoms or personal history of asthma. Group 2 patients, 34 men and 6 women with an average age of 22.2 years, had a history or recent suggestive symptoms of asthma.


METHODS
Methacholine challenge testing using concentrations of 0.025, 0.25, 2.5, 10, and 25 mg/mL for a total dose of 188 inhalation units or until FEV(1) had declined by 20%.


RESULTS
Group 2 had significantly more patients with positive results for methacholine challenge tests or reversible airflow obstruction at baseline (23 of 40 patients [57.5%]) than group 1 (8 of 63 patients [12.7%]; p < 0.05). The cadets in group 1 with positive results for methacholine challenge tests reacted with a 20% decline in FEV(1) at the following concentrations: 25 mg/mL (188 IU), 2 patients; 10 mg/mL (64 IU), 4 patients; and 2.5 mg/mL (13.8 IU), 2 patients. Using values calculated for the provocative concentration of a substance causing a 20% fall in FEV(1) and the new American Thoracic Society criteria, four patients would have borderline bronchial hyperresponsiveness (4 to 16 mg/mL) and three patients (4.8%) would have mild bronchial hyperresponsiveness (1 to 4 mg/mL).


CONCLUSIONS
Asymptomatic US Army ROTC cadets with no history of asthma have possible false-positive responses to methacholine at concentrations > 0.25 mg/mL.
From the Pulmonary/Critical Care Service , Department of Medicine, Soldier Care Service, Madigan Army Medical Center, Tacoma, WA 98431, USA. Bernard.J.Roth@NW.amedd.army.mil
B J
BJ
Roth
L M
LM
Hammers
T A
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Dillard
D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000453:epidemiology; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D016022:Case-Control Studies; D015331:Cohort Studies; D005189:False Positive Reactions; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008889:Military Personnel; D015995:Prevalence; D011446:Prospective Studies; D014481:United States
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride