Underdiagnosis and Overdiagnosis of Asthma.

Asthma is diagnosed on the basis of respiratory symptoms of wheeze, cough, chest tightness, and/or dyspnea together with physiologic evidence of variable expiratory airflow limitation. The prevalence of asthma varies widely around the world, ranging from 0.2% to 21.0% in adults and from 2.8% to 37.6% in 6- to 7-year-old children. Population-based studies in children, adults, and the elderly suggest that from 20% to 70% of people with asthma in the community remain undiagnosed and hence untreated. Underdiagnosis of asthma has been found to be associated with underreporting of respiratory symptoms by patients to physicians as well as poor socioeconomic status. On the opposite side of the spectrum, studies of patients with physician-diagnosed asthma suggest that 30-35% of adults and children diagnosed with asthma do not have current asthma, suggesting that asthma is also overdiagnosed in the community. Overdiagnosis of current asthma can occur because of physicians' failure to confirm variable airflow limitation at the time of diagnosis or when sustained clinical remission of disease goes unrecognized. In this review, we define under- and overdiagnosis and explore the prevalence and burden of under- and overdiagnosis of asthma both in patients and within healthcare systems. We further describe potential solutions to prevent under- and overdiagnosis of asthma.