The health impact of undiagnosed airflow obstruction in a national sample of United States adults.

To determine the health and functional impact of undiagnosed airflow obstruction for subjects in the general population, we used data obtained as part of the Third National Health and Nutrition Examination Survey (NHANES III). Categories of diagnosed and undiagnosed airflow obstruction were defined using questionnaire responses and spirometric results. Health and functional impact of airflow obstruction was assessed from responses to questions about general health status, walking 1/4 mile, lifting or carrying something as heavy as 10 lb, or needing help with personal care. Undiagnosed airflow obstruction (12.0%) was more common than doctor-diagnosed chronic obstructive pulmonary disease (COPD) (3.1%) or asthma (2.7%). Although undiagnosed airflow obstruction was usually very mild, approximately 5% of the entire sample had an FEV(1) less than 75% predicted. After adjusting for smoking, obesity, and comorbid conditions, the risk of impaired health and functional status with undiagnosed airflow obstruction was independently associated with severity of FEV(1) impairment. For males and females, ever smoking was strongly associated with all types of airflow obstruction, diagnosed or not. However, among females with airflow obstruction, 12.2% to 35.2% never smoked. Undiagnosed airflow obstruction is common in the general population of the United States and is associated with impaired health and functional status. airflow obstruction; spirometry; health impact; screening