Association between serum albumin and asthma in the general population of the United States: a retrospective study based on NHANES 2003-2018.

Background: Serum albumin (Alb) is an essential indicator of human physiological function, which can reflect the functionality of multiple organs, including the liver and kidneys. Presently, numerous studies have indicated that levels of blood albumin serve as important biomarkers for a range of respiratory illnesses. These findings can better guide clinical practice and disease prevention. However, there have been few investigations into the correlation between serum albumin and asthma. Therefore, this study aims to explore the relationship between serum albumin and the onset of asthma.

Methods: Data from the 2003 to 2018 National Health and Nutrition Examination Survey (NHANES) were used in this observational study. Alb was measured using the bichromatic digital endpoint method. Univariate and multivariate logistic regression analyses of the potential correlation between Alb and asthma were performed. The non-linear relationship was characterized by restricted cubic spline (RCS) curve. We also conducted subgroup and interaction analyses.

Result: In this study, we included 29,336 individuals with a mean age of 38.13 ± 17.98 years. Both univariate and multivariate logistic regression analyses show a significant association between serum albumin levels and asthma and higher Alb levels were associated with a lower risk of asthma (OR = 0.64, 95%CI: 0.43-0.96,  = 0.032). RCS curve validated that serum albumin and asthma showed a biphasic correlation. The results of the subgroup analysis showed that a significant interaction between serum albumin and alcohol consumption, Alb was associated with reduced asthma risk only in the subgroup of non-alcohol drinkers (OR = 0.8, 95% CI: 0.7-0.93,  < 0.001).

Conclusions: In the general population in the United States, asthma is associated with Alb, with asthma patients exhibiting lower albumin concentrations. This provides new insights into the management of asthma patients, suggesting that greater attention should be paid to their nutritional status, and further exploration of the causal relationship between the two may be warranted.