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Foreign-born US adults experienced lower asthma prevalence

Foreign-born American adults had a lower prevalence of asthma compared with native-born Americans, according to recent study results.

Jonathan I. Silverberg, MD, PhD, MPH, of the department of dermatology at Northwestern University in Chicago, and colleagues reviewed data from 447,801 adults from the 1997 to 2011 National Health Interview Survey that was collected by the US Bureau of Census, with questions determining asthma history. Rao-Scott chi-square tests, survey logistic regression models, propensity score and Cox regression were used to compare asthma history with birthplace.

Jonathan I. Silverberg

Logistic regression analyzed asthma prevalence trends, and researchers used multivariate models to control for sociodemographics, BMI, health care access and smoking history.

Lower odds of ever having asthma (adjusted OR=0.52; 95% CI, 0.49-0.55) or current asthma (aOR=0.5; 95% CI, 0.46-0.54) were reported for adults born outside the US. An inverse association existed between asthma prevalence and foreign birthplace, regardless of region (P<.0001).

Foreign-born adults who resided in the US at least 10 years had higher odds for ever having asthma (aOR=1.28; 95% CI, 1.18-1.38) and current asthma (aOR=1.7; 95% CI, 0.31-2.19) compared with those who resided in the US for 0 to 4 years. Delayed onset asthma was more prevalent in foreign-born adults (aOR=0.27; 95% CI, 0.27-0.28) compared with US-born adults.

“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,” the researchers said. “However, the prevalence of asthma in foreign-born adults was consistently lower and increased to a lesser extent (P<.0001).

“Foreign-born Americans have significantly lower risk and delayed onset of asthma than their US-born counterparts,” the researchers concluded. “However, foreign-born Americans develop increased risk for asthma with prolonged residency in the United States. Further studies are needed to understand the causative factors for the development of asthma in foreign-born Americans.”

Disclosure: The researchers report no relevant financial disclosures.