PURPOSE: We conducted an ecological study to examine the relationship between salmeterol-containing products and inhaled corticosteroids (ICS) and the rates of asthma-related hospitalizations and mortality in the US.
METHODS: Annual age-adjusted rates of asthma-related hospitalization from CDC’s National Hospital Discharge Survey and asthma-related mortality from 1991 to 2002 were plotted against annual drug sales data by year. The number of prescriptions by class was estimated using Verispan VONA data (1991-2002) and measured as the number of prescriptions/category per year. We computed the Pearson correlation between sales volume and serious events to evaluate whether the trends were linear.
RESULTS: Over 12 years, a significant, negative correlation (−0.69) was observed between age-adjusted asthma hospitalization rate and increased use of inhaled corticosteroids. A significant, negative correlation (−0.47) was also observed between age-adjusted annual asthma hospitalization rate and salmeterol-containing products. Annual asthma-related mortality rates were relatively steady, ranging from 14 to 17 deaths per million persons, though increased slightly followed by a decrease over this period. The maximum rate was observed in 1999 when age-adjustment standardization changed from the 1940 to the 2000 population distribution. No significant correlations between the annual number of asthma medication prescriptions and the age-adjusted asthma-related death rate were observed (0.35 for ICS, 0.12 for salmeterol-containing products).
CONCLUSION: This study provides population-level evidence that asthma-related hospitalizations have declined over twelve years in response to improvements in asthma management including increased use of maintenance medications such as ICS and salmeterol.
CLINICAL IMPLICATIONS: If asthma-related mortality risk was strongly associated with use of salmeterol or salmeterol-containing products, one would have expected this to be reflected as an increase in the asthma mortality rate over time. However, the asthma-related mortality rate was fairly constant over this period of increasing exposure to salmeterol-containing products while asthma-related hospitalization rates declined.
DISCLOSURE: Kourtney Davis, Employee all authors are employees of GSK.