Reduction in asthma-related emergency department visits after implementation of a smoke-free law

Background: Secondhand tobacco smoke increases the risk for the development and increasing severity of asthma among adults and children. Reducing exposure to secondhand smoke decreases symptomatic exacerbations among patients with asthma. Emergency department (ED) visits for asthma were assessed before and after the implementation of smoke-free legislation in Lexington-Fayette County, Ky. Objective: To evaluate the effects of a smoke-free law on the rate of ED visits for asthma. Methods: The study included ED visits for asthma from 4 hospitals in Lexington-Fayette County, Ky. Age-adjusted rates of asthma ED visits were determined. Poisson regression analysis of ED visits from January 1, 2001, to December 31, 2006 compared the ED visit rates between prelaw and postlaw, adjusting for seasonality, secular trends over time, and differences among demographic subgroups. The actual rates were graphed with the Poisson curve showing the rates predicted by the model. A second prediction curve was generated to show the projected rates in the postlaw period if the law had not been implemented. Results: Adjusting for seasonality, secular trends, and demographic characteristics, ED visits for asthma declined 22% from prelaw to postlaw (P <.0001; 95% CI, 14% to 29%). The rate of decline was 24% in adults age 20 years and older (P <.0001), whereas the decrease among children 19 years or younger was 18% (P =.01). Conclusion: Although this study did not establish causation, the smoke-free law was associated with fewer asthma ED visits among both children and adults, with a more significant decline among adults.