Osteoporosis in lung transplantation candidates with end-stage pulmonary disease

purpose

Fractures, a common complication of cardiac and liver transplantation, have not been reported in association with lung transplantation. However, many patients with end-stage pulmonary disease have multiple risk factors for osteoporosis, and several studies have suggested that osteoporosis before transplantation may increase the risk of fracture after transplantation. Therefore, we evaluated a group of patients with end-stage pulmonary disease who were awaiting lung transplantation to determine the prevalence of osteoporosis.

methods

Seventy patients (aged 18–70 years) were evaluated consecutively with bone densitometry by dual-energy x-ray absorptiometry. The patients were predominantly Caucasian (96%). Bone mass was expressed as bone mineral density (BMD; g/cm²), as the number of standard deviations (SD) below peak bone mass (T score), and as bone mineral apparent density (BMAD; g/cm³), a measurement that minimizes the effects of bone size on BMD. Spine radiographs were obtained in a subset of 50 consecutive patients to detect vertebral compression fractures. Vitamin D status was assessed with serum concentrations of 25-hydroxyvitamin D. The patients were sorted into groups by pulmonary diagnosis: chronic obstructive pulmonary disease (COPD; n = 28); cystic fibrosis (n = 11); idiopathic pulmonary fibrosis; and other lung diseases (Other; n = 31). results: In the group as a whole, osteoporosis (T score below −2.5) was present in 30% of the patients at the lumbar spine and 49% at the femoral neck. Osteopenia (T score between −1 and −2.5) was present in an additional 35% at the lumbar spine and 31% at the femoral neck. The average femoral neck T score of patients with COPD and cystic fibrosis fell into the osteoporotic range (−2.7 ± 0.3 and −2.6 ± 0.3, respectively), significantly (P < 0.01) below that of the patients in the Other category (−1.5 ± 0.3). The average lumbar spine T score fell into the osteopenic range in all three groups. Low BMAD in patients with cystic fibrosis confirmed that their low BMD was not due to their smaller body size. The prevalence rate of vertebral fractures was 29% in patients with COPD and 25% in those with cystic fibrosis. Vitamin D deficiency (25-hydroxyvitamin D levels ≤10 ng/ml) was present in 36% of patients with cystic fibrosis and 20% with COPD and Other lung diseases. Lumbar spine BMD tended to be lower in cystic fibrosis patients with vitamin D deficiency. Patients with exposure to glucocorticoids (n = 46) had significantly more vertebral fractures (P < 0.05) and duration of exposure correlated negatively with lumbar spine BMD (r = −0.398; P = 0.008). COPD and Other patients not on glucocorticoids had mild lumbar spine osteopenia (0.972 ± 0.06 g/cm²; T = −1.2 ± 0.6). Very few of the patients on glucocorticoids were on any regimen to prevent osteoporosis.

conclusions

Osteoporosis and vitamin D deficiency are extremely common in patients with end-stage pulmonary disease. Only 34% of patients had normal lumbar spine BMD and only 22% had normal BMD at the hip. Patients with cystic fibrosis and glucocorticoid-treated patients with COPD were most severely affected. Therapies to prevent bone loss and treat established osteoporosis are uncommonly utilized in glucocorticoid-treated patients with end-stage pulmonary disease. Candidates for lung transplantation should be evaluated for osteoporosis and vitamin D deficiency at the time of acceptance to the transplant waiting list.