Age at asthma onset and subsequent asthma outcomes among adults with active asthma.

INTRODUCTION: Little is known about the extent to which the age at which asthma first began influences respiratory health later in life. We conducted these analyses to examine the relationship between age at asthma onset and subsequent asthma-related outcomes.

METHODS: We used data from 12,216 adults with asthma who participated in the 2010 Behavioral Risk Factor Surveillance System Asthma Call-back Survey to describe the distribution of age at asthma onset. Linear regression was used to estimate associations of age at asthma onset with asthma-related outcomes, including symptoms in the past 30 days and asthma-related emergency visits.

RESULTS: Asthma onset before age 16 was reported by an estimated 42% of adults with active asthma, including 14% with onset at 5-9 years of age who reported experiencing any asthma symptoms on 21% of days in the past month. Compared to this group, the percentage of days in the past month with any asthma symptoms was 14.8% higher (95% confidence interval (CI): 5.4, 24.1) among those whose asthma onset occurred at <1 year. When age at onset occurred at 10 years or older there was little change in the prevalence of asthma-related emergency visits across age at onset categories.

CONCLUSION: Age at asthma onset may affect subsequent asthma-related outcomes.