SUN-383 Potential Impact of Using Male vs Female T-Scores for BMD Classification in Men

BACKGROUND: Osteoporosis is traditionally associated with post-menopausal women, but up to up to one-third of osteoporosis-related fractures occur in elderly men. The International Society for Clinical Densitometry (ISCD), the World Health Organization, and the Fracture Risk Assessment Tool (FRAX) all recommend using a white female reference for BMD T-score for men. However, in clinical practice and previous clinical trials, a sex-specific white male reference T-score is used. This report examines the implications of using a female versus male reference for T-score calculation in men. METHODS: We reviewed BMD findings in 703 men (age 70-85y) who experienced a proximal femur, humerus, or distal radius/ulna fracture. For this cohort, femoral neck BMD was used to calculate a BMD T-score using either the young adult male and young adult female peak values (mean BMD 0.930 ± 0.136 and 0.849 ± 0.111 g/cm2, respectively). Osteoporosis was defined by BMD T-score ≤ -2.5, and osteopenia by BMD T-score < -1.0 and > -2.5. We also calculated FRAX-estimated fracture risk for hypothetical men ages 60-85y, with and without prior fracture. We used the National Osteoporosis Foundation (NOF) recommendations for treatment based on BMD (osteoporosis by BMD, or osteopenia by BMD with a 10-year risk of hip fracture ≥ 3% or 10-year risk of major osteoporotic fracture ≥ 20%). RESULTS: The mean BMD for this cohort was 0.670 g/cm2 and the median T scores were -2.0 (male reference) and -1.7 (female reference). Using the male T-score, 29% of men were classified as having osteoporosis, while using the female T-score, only 21% were so classified. 36% of men age 70-79y and 19% of men age 80-85y with osteoporosis (using the male T-score) would be reclassified from osteoporosis to osteopenia when a female T-score is used. Hypothetical cases of men age 60-85y (height 170 cm, weight 70 kg, BMD 0.590 g/cm2 equivalent to a male T -2.5 or female T -2.2) were used to calculate 10-year hip fracture risk using FRAX. For these hypothetical cases, the calculated 10-year risk of hip fracture exceeded the NOF treatment threshold of 3% (10-year hip fracture risk) for all cases, with or without prior fracture. CONCLUSION: For elderly men with fracture with male-T osteoporosis and female-T osteopenia, the T-score reference population used does not alter treatment recommendations because the calculated hip fracture risk is already above the treatment threshold of 3%. This is also true for men age ≥70 without a prior fracture. Hence the debate pertaining to the appropriate T-score reference population for men has limited relevance for men age ≥ 70 years who are being screened for osteoporosis.