Baseline airway dysfunction and small-airway abnormality burden are longitudinally associated with adverse ultradistal radial bone density outcomes in a 5-year cohort

Abstract

Impaired pulmonary function has been linked to lower bone mineral density and higher fracture risk, but longitudinal evidence on airway dysfunction and subsequent peripheral bone-density outcomes remains limited. We investigated whether baseline airway dysfunction, FEV1/FVC, and small-airway abnormality burden were associated with 5-year ultradistal radial bone-density outcomes in an orthopaedic outpatient cohort. This hospital-based retrospective longitudinal cohort included 328 adults with baseline pulmonary function testing and right-side or dominant-side ultradistal radial DXA in 2020 and follow-up DXA in 2025. The primary estimand was the adjusted association of baseline FEV1/FVC and any airway dysfunction with follow-up ultradistal radial T-score, conditional on baseline ultradistal radial T-score and prespecified core confounders. Secondary continuous outcomes included 5-year change in T-score, follow-up Z-score, and 5-year change in Z-score. Radial DXA-defined low bone mass, osteoporosis, and SQ-defined vertebral fractures were summarized descriptively because adjusted binary-outcome models were statistically unstable. Small-airway dysfunction was defined as at least two of MMF, V50, and V25 below 65% predicted. Primary multivariable models adjusted for age, sex, body mass index, smoking burden, sustained inhaled corticosteroid use, asthma history, and baseline osteoporosis medication history, whereas exercise-habit variables were examined in sensitivity analyses. The mean age was 55.97 years, and 40.2% of participants were male. Any airway dysfunction was associated with lower follow-up T-score, less favorable 5-year change in T-score, and lower follow-up Z-score, but not with 5-year change in Z-score. FEV1/FVC showed the most consistent continuous respiratory associations with follow-up T-score and 5-year change in T-score. A graded association was observed across FEV1/FVC quartiles, with higher quartiles associated with more favorable T-score-based outcomes. Increasing small-airway abnormality burden was associated with progressively less favorable T-score- and Z-score-based radial bone-density outcomes. Binary radial bone classifications and SQ-defined vertebral fractures were summarized descriptively. The sparse fracture event counts did not support adjusted fracture-risk inference. Baseline airway dysfunction was associated with less favorable 5-year ultradistal radial bone-density outcomes in this cohort. However, these findings should be interpreted as peripheral skeletal associations. FEV1/FVC and small-airway abnormality burden may provide complementary respiratory markers of peripheral bone-density trajectory, while axial skeletal and fracture implications require further validation.