Coordinated diagnostic approach for adult obstructive lung disease in primary care

To present an age-stratified approach to the diagnosis of obstructive lung disease based on asthma and COPD guidelines and epidemiology.

Asthma guidelines emphasize the role of the history and physical examination, with pulmonary function used primarily to confirm the diagnosis. COPD guidelines begin with symptoms and risk exposure, presenting spirometry as the primary diagnostic maneuver. Data from the National Health Interview Survey and the Third National Health and Nutrition Examination Survey illustrate relationships in prevalence of asthma and COPD in nationally representative samples.

Asthma prevalence in adults declines with age from 5-10% at age 20-40 to 4-8% above age 60. COPD is uncommon in adults under age 40 but increases with age, surpassing asthma in older adults.

These trends suggest that asthma screening is most useful in adults up to age 40, after which COPD screening and differential diagnosis are of comparable or greater utility.