Beyond administrative data: Characterizing cardiorespiratory disease episodes among patients visiting the emergency department

Numerous factors contribute to morbidity from cardiorespiratory disease by causing acute episodes superimposed on the underlying chronic condition. Ad ministrative data on health service utilization have been used extensively to examine morbidity and mortality from asthma(1) and other cardiorespirato ry diseases. As a case in point, the current epidemiologic literature linki ng air pollution to effects such as death and admission to hospital relies almost exclusively on administrative data originally collected for other pu rposes. Interpretation of this literature is limited by the incomplete pict ure of disease episodes provided by these data. We attempted to address the se information gaps using data collected during a study of air pollution an d emergency department visits for cardiorespiratory conditions. In this pap er, we present a descriptive analysis of the characteristics of patients wh o visited the emergency department during the study, as well as the nature and outcome of their disease episodes.