Comparison of guideline-based control definitions and associations with outcomes in severe or difficult-to-treat asthma

Although all 3 control definitions were correlated with future control and health economic outcomes, there were striking differences in the descriptive results across the definitions, including the proportion of patients in each category of control. Differences among definitions of asthma control may lead to divergent research conclusions or treatment practices. We do not advocate for one particular definition, but we call for standardization of control definitions for specific uses.