Lumbar spine DXA T-score and QCT BMD cutpoint values for defining osteofrailia among older men: a framework for further refinement

Older men suffer from hip FFx (fragility fracture) at femoral neck T-score approximately 0.6 higher than older women, thus we proposed a new category of low BMD status, osteofrailia, for older Caucasian men with femoral neck T-score ≤ -2.0 (T-score ≤ -2.1 for older East Asian men) who have an increased risk of hip FFx. Around the age of 78 years, mean LS (lumbar spine) QCT BMD is around 68 mg/mL and 100 mg/mL for East Asian men and Caucasian men, respectively. For East Asian men, LS QCT BMD <68 mg/mL offers a sensitivity of 77% for detecting vertebral FFx cases, which is consistent with LS QCT BMD <80 mg/mL and < 50 mg/mL offering a vertebral FFx detection sensitivity of around 77% for Caucasian women and East Asian women, respectively. For Chinese men, T-score ≤ -2.5 predicts hip FFx risk better than other T-score values, and LS DXA T-score - 2.5 corresponds to QCT BMD 68 mg/mL. Hip FFx occur at approximately 0.5 LS T-score higher in Caucasian men than in Caucasian women. Among older Caucasian populations, for the separation of patients with FFx and without FFx, QCT BMD <100 mg/mL in older men is approximately comparable to <80 mg/mL in older women. For FFx risk prediction, we propose osteofrailia threshold LS DXA T-score to be ≤ - 2.5 and ≤ -2.0, and QCT BMD to be <68 mg/mL and < 100 mg/mL, respectively, for East Asian men and Caucasian men. The relationship between LS QCT BMD and hip FFx risk should be better investigated in the future.