A US study found that obesity measures and white blood cell counts were associated with greater asthma risk among women.
Body mass index (BMI), body roundness index (BRI), and white blood cell counts (WBC) were each independently tied to higher odds of self-reported asthma. Per-unit increases in BMI, BRI, and WBC were linked to 4%, 13%, and 8% higher risks, respectively. Threshold effects were noted at 25.3 kg/m² for BMI, 3.84 for BRI, and 4.8 × 10⁹/L for WBC. Women in the highest quartile of BRI had nearly double the odds of asthma compared with those in the lowest quartile. Mediation testing showed that WBC partially explained the obesity–asthma association, accounting for 9% of the effect for BMI and 11% for BRI.
“WBC, as a marker of systemic inflammation, not only reflects airway inflammatory activity but may also contribute directly to asthma pathogenesis,” wrote lead study author Chen Jie, MD, of the Department of Gynecology at Affiliated Provincial People’s Hospital of Fujian University of Traditional Chinese Medicine, and colleagues.
The analysis included 3,729 women from the National Health and Nutrition Examination Survey (NHANES) between 2009 and 2018. Asthma status was identified through self-reported physician diagnosis on the NHANES medical conditions questionnaire. Researchers examined anthropometric measures, complete blood counts, and reproductive histories, using weighted logistic regression models adjusted for demographic, lifestyle, and reproductive factors. Restricted cubic spline models were applied to assess non-linear associations and thresholds. Receiver operating characteristic curve analysis showed modest predictive ability, with areas under the curve of 0.59 for BMI, 0.59 for BRI, and 0.56 for WBC. Sensitivity analysis excluding current smokers showed consistent results.
Limitations included the cross-sectional design, reliance on self-report, and potential residual confounding. Findings were specific to US women, limiting generalizability.
The study was supported by the National Administration of Traditional Chinese Medicine’s High-Level Traditional Chinese Medicine Key Discipline Construction Project, Integrative Traditional Chinese and Western Medicine Clinical Project. The authors reported no competing interests.
Source: BMC Pulmonary Medicine
