title: Age-related differences in asthma outcomes in the United States, 1988-2006.
abstract: BACKGROUND
  Relatively little is known about the effect of age on asthma outcomes in adults, particularly at a national level.
  
  
  OBJECTIVE
  To investigate age-related differences in asthma outcomes in a nationally representative, longitudinal study.
  
  
  METHODS
  We analyzed data from the Third National Health and Nutrition Examination Survey (1988-1994) with linked mortality files through 2006. Adults with physician-diagnosed asthma were identified and were divided into 2 age groups: younger adults (17-54 years of age) and older adults (55 years or older). The outcome measures were both cross-sectional (health care use, comorbidity, and lung function) and longitudinal (all-cause mortality).
  
  
  RESULTS
  There were an estimated 9,566,000 adults with current asthma. Of these, 73% were younger adults and 27% older adults. Compared with younger adults, older adults had more hospitalizations in the past year, more comorbidities, and poorer lung function (eg, lower forced expiratory volume in 1 second) (P < .05 for all). During a median follow-up of 15 years, significant baseline predictors of higher all-cause mortality included older age (≥55 vs <55 years old: adjusted hazard ratio [HR], 6.77; 95% confidence interval [CI], 3.15-14.54), poor health status (fair and poor vs excellent health status: adjusted HR, 10.07; 95% CI, 3.75-27.01), and vitamin D deficiency (vitamin D level <30 vs ≥50 nmol/L: adjusted HR, 2.19; 95% CI, 1.05-4.58), whereas Mexican American ethnicity (adjusted HR, 0.31; 95% CI, 0.14-0.65) was associated with lower mortality. Controlling for age, asthma was not associated with increased all-cause mortality (adjusted HR, 1.28; 95% CI, 0.99-1.65).
  
  
  CONCLUSIONS
  Older adults with asthma have a substantial burden of morbidity and increased mortality. The ethnic differences in asthma mortality and the vitamin D-mortality link merit further investigation.
authors.affiliation: Division of Epidemiology, Human Genetics and Environmental Sciences, The University of Texas School of Public Health, Houston, Texas 77030, USA. cltsai@post.harvard.edu
authors.forename: Chu-Lin
authors.initials: CL
authors.lastname: Tsai
authors.forename: George L
authors.initials: GL
authors.lastname: Delclos
authors.forename: Jamie S
authors.initials: JS
authors.lastname: Huang
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Hanania
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001249:Asthma / Q000453:epidemiology / Q000208:ethnology / Q000401:mortality* / Q000503:physiopathology*; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D012129:Respiratory Function Tests; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States; D014808:Vitamin D Deficiency / Q000150:complications / Q000453:epidemiology; D055815:Young Adult