Undiagnosed Airflow Obstruction: Prevalence and Implications
Conditions associated with airflow obstruction are often over- and underdiagnosed. Prevalence estimates of undiagnosed airflow obstruction (UDAO) range from 3 to 12%. UDAO is a nonspecific physiologic abnormality that may be caused by a number of factors (eg, cigarette smoking) and can be the manifestation of many different disorders. The higher occurrence of UDAO among men, current or former smokers, and with advancing age provide preliminary evidence on probable causes and diagnoses (ie, chronic obstructive pulmonary disease). While cigarette smoking is associated with UDAO, a substantial proportion of persons have never smoked, particularly among women. Few studies suggest that this condition is associated with increased morbidity and mortality. While there is currently no evidence to support screening for UDAO, case-finding may have a role among persons with respiratory symptoms, who have ever smoked, with a family history of respiratory disease, or with occupational exposures to dusts or fumes.
Airflow obstruction refers to an abnormal slowing of airflow from the lungs on exhalation. Physiologically, airflow obstruction is characterized by a low ratio of forced expiratory volume in 1 second (FEV1) to FVC (FEV1/FVC). Clinically, it is most often associated with the diagnoses of chronic obstructive pulmonary disease (COPD) and asthma, but is also a feature of a number of other less common disorders ( Table 1 ).
Over the past 30 years, COPD has become increasingly common, and presents a major challenge worldwide. From 1980-2000, the overall death rate for COPD in the US increased by 67%, and, among the 10 leading causes of death, COPD is the only one for which prevalence and mortality rates have increased. In 1996, approximately 16 million people were estimated to have diagnosed COPD in the US. Verbrugge and Patrick used data collected from the National Health Interview Survey, between 1983 through 1985, to calculate the prevalence of chronic conditions in the US and to determine their relative impact on functioning. Among adults aged 18 years and older, the prevalence of COPD, which included chronic bronchitis, emphysema, and asthma, was consistently among the top 10 conditions. The prevalence was highest among men and women age 65 years and older (16.7% and 12.6%, respectively), intermediate for persons aged 45-64 years (8.8% and 11.4%, respectively), and lowest for persons aged 18-44 years (5.5% and 9.3%, respectively). In addition, COPD consistently ranked among the top 10 conditions in all age groups causing limitation of job activities and other activities of daily living (see below). The total estimated costs associated with COPD in 2002 were 32.1 billion.
The large public health, clinical, and economic impact of diseases associated with airflow obstruction provides a strong rationale for a thorough understanding of diagnostic accuracy and implications of misdiagnosis. Literature relevant to this review was identified by searching PubMed using UDAO as the search term and scanning related articles and reference lists of selected articles. The emphasis of this review is on recent publications through August 31, 2002.
Conditions associated with airflow obstruction are often over- and underdiagnosed. Prevalence estimates of undiagnosed airflow obstruction (UDAO) range from 3 to 12%. UDAO is a nonspecific physiologic abnormality that may be caused by a number of factors (eg, cigarette smoking) and can be the manifestation of many different disorders. The higher occurrence of UDAO among men, current or former smokers, and with advancing age provide preliminary evidence on probable causes and diagnoses (ie, chronic obstructive pulmonary disease). While cigarette smoking is associated with UDAO, a substantial proportion of persons have never smoked, particularly among women. Few studies suggest that this condition is associated with increased morbidity and mortality. While there is currently no evidence to support screening for UDAO, case-finding may have a role among persons with respiratory symptoms, who have ever smoked, with a family history of respiratory disease, or with occupational exposures to dusts or fumes.
Airflow obstruction refers to an abnormal slowing of airflow from the lungs on exhalation. Physiologically, airflow obstruction is characterized by a low ratio of forced expiratory volume in 1 second (FEV1) to FVC (FEV1/FVC). Clinically, it is most often associated with the diagnoses of chronic obstructive pulmonary disease (COPD) and asthma, but is also a feature of a number of other less common disorders ( Table 1 ).
Over the past 30 years, COPD has become increasingly common, and presents a major challenge worldwide. From 1980-2000, the overall death rate for COPD in the US increased by 67%, and, among the 10 leading causes of death, COPD is the only one for which prevalence and mortality rates have increased. In 1996, approximately 16 million people were estimated to have diagnosed COPD in the US. Verbrugge and Patrick used data collected from the National Health Interview Survey, between 1983 through 1985, to calculate the prevalence of chronic conditions in the US and to determine their relative impact on functioning. Among adults aged 18 years and older, the prevalence of COPD, which included chronic bronchitis, emphysema, and asthma, was consistently among the top 10 conditions. The prevalence was highest among men and women age 65 years and older (16.7% and 12.6%, respectively), intermediate for persons aged 45-64 years (8.8% and 11.4%, respectively), and lowest for persons aged 18-44 years (5.5% and 9.3%, respectively). In addition, COPD consistently ranked among the top 10 conditions in all age groups causing limitation of job activities and other activities of daily living (see below). The total estimated costs associated with COPD in 2002 were 32.1 billion.
The large public health, clinical, and economic impact of diseases associated with airflow obstruction provides a strong rationale for a thorough understanding of diagnostic accuracy and implications of misdiagnosis. Literature relevant to this review was identified by searching PubMed using UDAO as the search term and scanning related articles and reference lists of selected articles. The emphasis of this review is on recent publications through August 31, 2002.
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