Long-term FEV ₁ decline and bone mineral density in asthma

It is not clear yet whether airway hyperresponsiveness (AHR) and lung function decline can be associated with bone mineral density. We therefore retrospectively analyzed 34 asthmatic females (mean age 48.4±9.6;mean baseline FEV 1 %:99.4±13.1) that had performed a methacholine challenge test (10 hyperreactive subjects; median PD 20 :358µg, IQR:240-806) and bone density scan (mean femoral-t-score:-0.7±0.9; mean vertebral t-score:-1.3±1.4) at asthma onset. Furthermore, to investigate a link between FEV 1 decline and bone density changes in time, we considered the 23 asthmatics that had repeated such exam and FEV1 measurements at least 5 years later. No significant relationships were found either between baseline femoral/vertebral-t-scores (r=0.13; r=0.03; p=n.s), and PD 20 or FEV 1 decline (r=-0.09; r=-0.16; p=n.s). After 7.6±1.7 years, we found a FEV 1 decline of 52.9±42.7 ml/year and a mean difference of femoral-t-score 0.09 and vertebral-t-score 0.26 in the 23 asthmatics. When comparing both FEV 1 decline and t-score changes in hyperreactive/normoreactive subjects, no differences were found. On the contrary, we detected a significantly positive relationship between changes of femoral-t-scores and FEV 1 decline (r=0.43;p=0.04). This suggests an association between bone density impoverishment and lung function deterioration, probably due to the inhaled corticosteroids influence on bone mineral density. However, since the vitamin D level is associated both with asthma severity and osteopenia/osteoporosis, low levels of this vitamin may negatively influence both bone density loss and FEV 1 decline. Therefore, when managing asthmatics with an accelerated FEV 1 decline, a bone density scan and vitamin D integration should be considered.