Population-based case-finding to identify subjects with undiagnosed asthma or COPD

Area of Science:

• Pulmonology
• Epidemiology
• Public Health

Background:

• Undiagnosed airflow obstruction, including asthma and COPD, affects an estimated 5-10% of adults.
• A population-based strategy is needed to identify undiagnosed cases among symptomatic individuals.

Purpose of the Study:

• To develop and evaluate a case-finding strategy for undiagnosed airflow obstruction (asthma or COPD) in adults with respiratory symptoms in Canada.

Main Methods:

• Recruitment of adults without prior lung disease history via random digit-dialling.
• Symptom assessment followed by validated questionnaires (ASQ, COPD-DQ, CAT) for those with symptoms.
• Pre- and post-bronchodilator spirometry for individuals scoring high on questionnaires to diagnose asthma or COPD.

Main Results:

• 20% of enrolled participants (184/910) had undiagnosed obstructive lung disease (73 asthma, 111 COPD).
• Individuals with undiagnosed disease reported more severe symptoms and lower quality of life.
• Descriptive variables (age, BMI, sex, pack-years) showed better predictive value (ROC area=0.68) than questionnaires (ROC area ≤ 0.64).

Conclusions:

• A significant proportion (20%) of symptomatic Canadians have undiagnosed asthma or COPD.
• Current screening questionnaires have limitations in accurately identifying individuals with undiagnosed obstructive lung disease.
• A combination of symptom reporting and basic demographic data may be more effective for case-finding than questionnaires alone.