American women ages 18 to 44 reported rising asthma prevalence rates during a 15 year period, with prevalence varying according to clinical and demographic characteristics, according to study results published in the Journal of Asthma.

Past estimates of asthma prevalence in pregnant women and women of childbearing age may not reflect current realities, partially owing to rapidly shifting US demographics. Thus, in order to identify high-risk groups and better understand the asthma burden in this population, updated estimates are needed. Investigators sought to characterize rates of asthma and asthma medication use by drawing on data from the National Health and Nutrition Examination Survey (NHANES).

Since 1999, NHANES has collected data biannually on US individuals’ health via physical exams and interviews. Using records from 2001 to 2016, researchers identified a total of 11,383 women age 18 to 44, of whom 1245 were pregnant at the time of the survey based on self-report. Age-adjusted asthma prevalence and prevalence rates for asthma medication use were estimated, stratified by year and demographic and clinical characteristics. Adjusted prevalence rates and 95% CIs were calculated.

Of all women of childbearing age (n=11,383), 1085 (9.5%) were diagnosed with asthma; in the pregnant subset (n=1245), 135 women (10.8%) reported asthma. Following age-adjustment, 15-year asthma prevalence rates were 9.9% (95% CI, 9.2%-10.7%) in all women of childbearing age and 10.9% (95% CI, 7.2%-14.6%) in the subset of pregnant women. Asthma attack prevalence rates in the same categories were 5.4% (95% CI, 4.9%-6.0%) and 5.7% (95% CI, 3.2%-8.2%), respectively. In all women with asthma, 38.3% (95% CI, 34.5%-42.1%) had used asthma medication of any type within the preceding 30 days.

When considering race/ethnicity, non-Hispanic white (10.9%; 95% CI, 9.8%-11.9%) and non-Hispanic black (10.6%; 95%CI, 9.3%-11.9%) women of childbearing age demonstrated the highest asthma prevalence rates.

Overall rates of prevalence across 15 years were lowest during the 2-year period from 2003 to 2004 (8.6%; 95% CI, 6.4%-10.8%) and highest in 2015 and 2016 (12.0%; 95% CI, 9.8%-14.3%), demonstrating a significant linear (P <.01), but not quadratic (P =.29), increase over time. Upon stratification, over time, the highest asthma prevalence rates were seen in women age 18 to 44 who were obese (14.4%; 95% CI, 12.9%-15.8%), current smokers (12.8%; 95% CI, 11.4%-14.2%), had Medicaid or State Children’s Health Insurance Program insurance (16.8%; 95% CI, 14.5%-19.2%), or had ever been diagnosed with hypertension (16.6%; 95% CI, 14.2%-19.0%) or diabetes (18.7%; 95% CI, 12.1%-25.2%).

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Study limitations included the small sample size, potential medication use underestimation, possible lower participation by pregnant vs non-pregnant women, use of self-reports that might underestimate prevalence, non-identification of temporal variations in prevalence and medication use, inability to evaluate disease and medication changes during pregnancy, lack of stratification by asthma severity, and uncertainty regarding corticosteroid administration routes.

“The results of the current study together with data from earlier time periods indicate a temporal trend of increasing asthma prevalence among women of childbearing ages in the United States,” noted the investigators. They recommended that future research explore additional factors that might be having an effect on prevalence estimates.

Reference

Flores KF, Bandoli G, Chambers CD, Schatz M, Palmsten K. Asthma prevalence among women aged 18 to 44 in the United States: National health and nutrition examination survey 2001–2016 [published online April 24, 2019]. J Asthma. doi:10.1080/02770903.2019.1602874