PURPOSE: Risk factors for mortality in asthma are incompletely understood as prior studies were retrospective and included limited sociodemographic and health status information. We examined risk factors for mortality in a prospective cohort study of 865 adults with severe asthma in a closed-panel managed-care organization.
METHODS: We used structured telephone interviews to assess sociodemographics, prior asthma history, and health status. Subjects were followed until death or end of study, with an average follow-up time of two years. We searched the National Death Index to confirm mortality. We used Cox proportional hazards regression to evaluate the impact of sociodemographics, smoking, and validated measures of perceived asthma control, physical health status, and asthma severity (scored on the basis of symptoms, medications and prior health care utilization) on the subsequent risk of death.
RESULTS: We confirmed 123 deaths, a mortality rate of 6.7% per person-year. In multivariate analysis adjusted for sociodemographics and health status, higher severity-of-asthma (adjusted hazard ratios [HR], 1.11 per one-half standard deviation [SD] increase in severity-of-asthma score; 95% confidence interval [CI], 1.01 –1.23) and lower perceived asthma control scores (adjusted HR, 0.91 per one-half SD increase in perceived asthma control; 95% CI, 0.83 –0.99) were each associated with prospective risk of death. There was a suggestion that African American race was associated with a lower risk of death relative to white race, but the confidence interval included no association (adjusted HR 0.63; 95% CI 0.35 –1.12).
CONCLUSION: Greater asthma severity and poorer perceived asthma control are each associated with increased prospective risk of death among adults with severe asthma. In a healthcare system in which access to care has been established, African American patients with severe asthma are not at increased risk of death relative to other racial groups.
CLINICAL IMPLICATIONS: Further research should explore the role of the severity-of-asthma score on clinical risk stratification and the potential to improve outcomes by improving perceived asthma control. Efforts to reduce racial disparities should make improving healthcare access a priority.
DISCLOSURE: Theodore Omachi, No Financial Disclosure Information; No Product/Research Disclosure Information