Serum insulin-like growth factor-1, asthma, and lung function among British adults

Abstract

BackgroundInsulin-like growth factor-1 (IGF-1) plays a key role in the pathogenesis of metabolic syndrome, which is in turn associated with asthma. Whether IGF-1 contributes to asthma causation or asthma severity is largely unknown. ObjectiveTo evaluate the relation between serum IGF-1 and asthma, asthma outcomes, and lung function in adults. MethodsCross-sectional study of 297,590 adults (aged 40-69 years) who participated in the United Kingdom Biobank, had no diagnosis of diabetes, and were not on insulin. Multivariable logistic or linear regression was used to analyze serum IGF-1 and physician-diagnosed asthma, current wheezing, asthma hospitalizations, and lung function measures (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and FEV1 to FVC ratio). ResultsSerum IGF-1 levels above the lowest quartile (Q1) were significantly associated with lower odds of asthma (adjusted odds ratio for fourth quartile [Q4] vs Q1 = 0.88; 95% confidence interval [CI], 0.85-0.91). Among the participants with asthma, IGF-1 levels above Q1 were significantly associated with lower odds of current wheezing (adjusted odds ratio for Q4 vs Q1 = 0.89; 95% CI, 0.83-0.96), but not with asthma hospitalizations. Serum IGF-1 was significantly and positively associated with FEV1 (b = 20.9 mL; 95% CI, 19.1-22.7) and FVC (b = 25.6 mL; 95% CI, 23.4-27.7), regardless of an asthma diagnosis; these associations were significant in men and women, with larger estimated effects in men. ConclusionIn a large study of British adults, higher serum IGF-1 levels were associated with lower odds of asthma and current wheezing and higher FEV1 and FVC. Our findings suggest potential beneficial effects of circulating IGF-1 on asthma and asthma outcomes in adults.