Assessment of asthma control and severity.

Objective: To provide a conceptual framework for defining severity and control in asthma, to describe recent advances in measuring asthma control, and to discuss the role of severity and control in asthma disease management.
Data Sources: MEDLINE was searched for relevant English-language articles published between 1998 and July 2003. Additional sources included key references cited in these articles, national and international guidelines for the diagnosis and management of asthma, and the author's personal bibliography.
Study Selection: All studies that reported on the development and validation of formal measures of asthma control, as well as the few editorials that focused on the distinction between asthma severity and control, were included. The author's professional judgment was used to select for illustrative purposes from among the many purported measures of asthma severity in the literature.
Results: Although several standardized measures of asthma control exist, no direct comparisons of the performance and properties of these control measures have been published. The available instruments appear more similar than dissimilar. All share the common trait of assessing multiple aspects of asthma control, which is believed to provide better discrimination than a single measure.
Conclusions: Asthma control is different from asthma severity and may be useful as a clinical vital sign for patients with asthma. Ultimately, no one measure may be better than any of the others or the optimal measure may depend on the intended use of the scale.