Tracking emergency department (ED) asthma visits is an important part of asthma surveillance, as ED visits can be preventable and may represent a failure of asthma control efforts. When using limited clinical ED datasets for secondary purposes such as public health surveillance, it is important to employ a standard approach to operationally defining ED visits attributable to asthma. The prevailing approach uses only the primary ICD-9-CM diagnosis assigned to the ED visit; however, doing so may underestimate the public health impact of asthma. We conducted this pilot study to determine the value of including ED visits with asthma-related diagnoses in secondary or tertiary positions. For example, for an ED visit with a primary diagnosis of upper respiratory infection and secondary diagnosis of asthma, it is possible that the infection triggered the asthma exacerbation and the visit could be attributed to both infection and asthma.
Determine operational definition of ED visits attributable to asthma for public health surveillance purposes.