Bone Mineral Density and Trabecular Microarchitecture Screening in Lung Transplant Candidates

Lung transplant candidates routinely undergo dual-energy x-ray absorptiometry (DXA) screening due to increased risk of osteoporosis secondary to comorbidities and prolonged immunosuppression. Nonetheless, postoperative insufficiency fractures have been well documented, even in patients with normal bone mineral density (BMD). This study investigated the added value of trabecular bone score (TBS) as a complementary screening index of bone microarchitecture.

A retrospective review of 143 lung transplant candidates who underwent preoperative DXA screening was performed. TBS was calculated from DXA of the lumbar spine. DXA and TBS measurements were standardized using T-scores with reference to established population-based datasets.

Differences in the observed rates of osteopenia (36.4%), osteoporosis (11.2%), partially degraded bone (35.0%), and degraded bone (35.0%) were statistically significant (P < .001). Abnormal trabecular microarchitecture was significantly more prevalent than abnormal BMD (69.9% versus 47.6%; P < .001). TBS T-scores (mean = -1.98, SD = 1.39) were, on average, significantly lower than DXA T-scores (mean = -0.80, SD = 1.57; t[142] = 9.09; P < .001). Hispanic patients (mean = -1.25, SD = 1.28) had significantly lower DXA T-scores compared with White (mean = -0.28, SD = 1.14) or Black patients (mean = -0.30, SD = 1.31; F[2, 109] = 8.28; P < .001). By contrast, TBS T-scores did not differ by race or ethnicity (F[2, 109] = 0.26; P = .78).

Impaired trabecular microarchitecture is extremely common among lung transplant candidates, with a substantial proportion at risk of fracture through degraded bone despite normal BMD. TBS offers promise as a simple, robust, inexpensive, and noninvasive screening adjunct to DXA in this unique and vulnerable population.