Spine–hip discordance and fracture risk assessment: a physician-friendly FRAX enhancement

Abstract

A simple procedure that incorporates the offset between the LS and FN T-scores can enhance fracture risk prediction under the FRAX system.

Interpretation and use of FRAX in clinical practice

“…Fracture outcomes were available over a 10-year time frame. There was an approximately 10% change in fracture risk for each unit of T-score discordance [85].…”

Pitfalls in the external validation of FRAX

“…The impact of spine/femoral neck T-score discordance has recently been explored in a large BMD-referral population from Manitoba, Canada categorised according to Canadian guidelines [14,22] (Table 4). Fracture outcomes were available over a 10-year time frame.…”

A comparative study of using non-hip bone density inputs with FRAX®

“…The IOF-ISCD positions specifically state that measurements other than BMD or T-score at the femoral neck obtained by DXA should not be used with FRAX. The IOF-ISCD Task Force also concluded that FRAX may underestimate or overestimate major osteoporotic fracture risk when lumbar spine T-score is much lower or higher (>1 SD discrepancy) than femoral neck T-score, and that the offset adjustment described earlier (based upon the difference between the lumbar spine and femoral neck Tscores) could be used to enhance fracture prediction in the current version of FRAX [20]. The current study found that the weighted mean T-score input to FRAX was equivalent to the offset adjustment.…”

“…The tool, termed the Canadian Association of Radiologists and Osteoporosis Canada (CAROC) tool, calculates an initial risk category (low, <10%; moderate, 10-20%; high, >20% major osteoporotic fracture probability) based upon sex, age, and femoral neck T-score [17]. The offset adjustment used in the present analysis requires a continuous measure of fracture risk, and therefore, it cannot be used with CAROC [20]. However, the weighted mean T-score approach would be expected to provide an equivalent mechanism for incorporating the lumbar spine T-score into the fracture risk assessment.…”

“…The latter, denoted FRAX (weighted mean), was empirically selected based upon the observation that approximately one quarter of clinical fractures involve the spine while approximately three quarters of clinical major osteoporotic fractures are non-spine [19]. Recently, the T-score difference between the lumbar spine and femoral neck (termed offset) has been shown to predict major osteoporotic fracture risk independent of the conventional calculation of FRAX with femoral neck BMD, and an adjustment can be applied to FRAX (femoral neck) that enhances fracture prediction by reclassifying a small number of individuals in whom there is discordance between the lumbar spine and femoral neck T-scores [20]. The offset adjusted probability, FRAX (offset), was therefore included as an additional comparator.…”