Association between birthplace, prevalence, and age of asthma onset in adults: a United States population-based study

Abstract

Background: Previous studies have found associations between region of birth and asthma prevalence.

Objective: To study the association among birthplace, US prevalence, age of onset, and disease course of adult asthma.

Methods: Data from 447,801 adults from the 1997 to 2011 National Health Interview Survey were reviewed. History of asthma was compared with birthplace using Rao-Scott χ(2) tests, survey logistic, propensity score, and Cox regression. Trends of asthma prevalence were analyzed using logistic regression. Multivariate models controlled for sociodemographics, health care access, smoking history, and body mass index.

Results: Adults born outside the United States had lower odds of ever asthma (adjusted odds ratio [OR] 0.52, 95% confidence interval [CI] 0.49-0.55) or current asthma (OR 0.50, 95% CI, 0.46-0.54). The inverse association between foreign birthplace and asthma prevalence was significant in all regions of birth (P < .0001). Adults born outside the United States who resided in the United States for longer than 10 years compared with only 0 to 4 years had higher odds of ever asthma (OR 1.28, 95% CI, 1.18-1.38) and current asthma (OR 1.70, 95% CI, .31-2.19). Foreign-born compared with US-born adults also had delayed onset of asthma (adjusted hazard ratio 0.27, 95% CI, 0.27-0.28). The US prevalence of asthma increased in a linear manner from 1997 (9.1%, 8.77%-9.37%) to 2011 (12.5%, 12.1%-12.8%, P < .0001), which paralleled the trend for US-born adults. However, the prevalence of asthma in foreign-born adults was consistently lower and increased to a lesser extent (P < .0001).

Conclusion: Foreign-born American adults from all regions of birth have a lower prevalence of asthma, which increases after prolonged US residency. Foreign-born Americans may have a higher risk of adult-onset asthma.