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

We attempted to address deficiencies in administrative health service data during a study of cardiorespiratory emergency department visits. From 1994-1996, we obtained data on 9,264 visits and conducted 1,772 follow-up interviews. The median interval between symptoms and visit ranged from 0.8 days (95% CI 0-1.7) for cardiac conditions to 4.0 days for chronic obstructive pulmonary disease (COPD) (95% CI 2.7-5.3) and respiratory infections (95% CI 3.5-4.5). Infection was the most common trigger of respiratory visits. Although most had improved at follow-up, symptoms persisted following the visit for a mean of 4.5 days (95% CI 3.8-5.4) for cardiac conditions to 8.4 days (95% CI 7.2-9.5) for COPD. Among adults aged < 70, the mean number of reduced activity days per episode ranged from 4.7 (95% CI 3.9-5.4) for asthma to 6.6 (95% CI 5.9-7.4) for respiratory infections. Our data assist in interpreting epidemiological studies based on administrative data, and illustrate the broad impacts of cardiorespiratory disease episodes.