Association between BRINDA-corrected iron metabolism and lung function in the community: the CoLaus|PneumoLaus study.

Background: Iron metabolism and its relationship to lung volumes remains poorly understood, with inconsistent findings reported across the literature. We analysed the association of markers of inflammation and iron metabolism with lung function in a large population-based cohort.

Methods: PneumoLaus is a sub-study of CoLaus|PsyCoLaus, an ongoing prospective observational study conducted in Lausanne, Switzerland. Within PneumoLaus, participants performed spirometry and blood sampling at two time points (baseline, 2014-2017; follow-up (FU), 2018-2021). The associations between ferritin and transferrin using BRINDA correction with spirometric values were assessed by Pearson correlation. We performed multivariable linear regressions using spirometry values as dependent variable adjusted for main confounders.

Results: 3102 (women, 56%) and 1989 (women, 55%) participants were included at baseline and FU, respectively. In both surveys, ferritin levels were not associated with FEV1, FVC and MMEF, even using the adjusted model. A weak negative association was observed only at FU in women with FEV1 and FVC. In both surveys, transferrin was negatively associated with FEV1 and FVC (standardised β coefficients -0.061 to -0.102, p < 0.001) in all subjects and in women. In the adjusted model, FEV1 is reduced by 47 to 59 mL and FVC by 63 to 71 mL for 1-SD increase of transferrin levels. Transferrin saturation was not associated with spirometric values.

Conclusions: In this population-based cohort, we observed no reproductible association between ferritin levels and spirometric values. However, transferrin levels were negatively associated with FEV1 and FVC, suggesting that iron metabolism, particularly the requirement for iron in the organism, is linked to reduced lung volumes.

Trial registration: Not required. This study is not a clinical trial. This is a population based observational study. The approval number reference 16/03 13403,13405bis, 134052to5 addenda 1to4. For other approvals, see the section dedicated to page 26 and 27.