P240 Lung function and low bone mineral density in cystic fibrosis

ObjectivesLow bone mineral density (BMD) is a known complication in those with cystic fibrosis (CF), and worsening lung function has been associated with low BMD in COPD patients and asthma patients. Using a large national registry, we aim to explore the relationship between low bone mineral density (BMD) and lung function in patients with cystic fibrosis.MethodsUsing data from 2007–2017 from the UK CF Registry, we investigated the rates of low BMD. Bone mineral density was measured using DEXA scans at the lumbar spine, femoral neck, total hip, and total body. Z-scores were used to determine whether patients had low BMD (z-score≤-1). The population was restricted to those aged 8 and over as reference ranges are not available for younger children.ResultsThere were 9824 patients included in this analysis, with 18 037 DEXA scans in 6827 patients. Median age at first scan was 22 (IQR: 16–30). Overall, 28% (n=2752) had low BMD. BMD z-scores were lower in males than in females, and this difference increased with age. Patients with low BMD were slightly older (24, IQR: 18–33) than those with normal BMD (21, IQR:14–31) and had lower lung function than those with normal BMD (FEV1% pred. 63.7, IQR: 45.1–80.9 vs. FEV1% pred. 74.7, IQR:55.0–89.5).FEV1% pred. was correlated with BMD at the lumbar spine (LS), femoral neck (FN), total hip (TH) and total body (TB) (p