Osteoporosis screening in postmenopausal women aged 50-64 years: BMI alone compared with current screening tools.

Objectives: Consensus on when to initiate DXA screening for early postmenopausal women (< 65 years of age) is lacking. Low body mass index (BMI) has been proposed as one of the major risk factors for osteoporosis. This study sought to compare the predictive performance of BMI alone with 5 screening modalities (the U.S. Preventive services task force [USPSTF] FRAX threshold of 9.3%, a risk factor based approach [≥ 1 risk factors], the osteoporosis self-assessment tool [OST < 2], the osteoporosis risk assessment instrument [ORAI ≥ 9], and the simple calculated osteoporosis risk estimation [SCORE ≥ 6]) in identifying early postmenopausal women with osteoporosis.

Methods: Postmenopausal women aged 50-64 years presenting for a DXA test were recruited between January 1, 2007, and March 1, 2009. Demographic data and osteoporosis risk factors were obtained through a telephone survey. The performance of each screening tool in predicting osteoporosis was compared.

Results: Of 445 study participants, 95% were White, 38 had osteoporosis (T-score ≤ -2.5). BMI (< 28) was associated with the highest Sensitivity (95%), the lowest Negative Likelihood Ratio (LR-) of 0.14, an AUC of 0.73, and the number needed to scan (NNS) of 8. The USPSTF approach had the lowest sensitivity (24%), highest LR- (0.91), lowest AUC (0.62), and highest NNS (9). Among 5 established modalities, SCORE (≥ 6) appears to be the best (sensitivity: 92%, LR-: 0.24, AUC: 0.75, NNS: 9).

Conclusion: BMI (< 28) had a comparable numerical screening performance overall to the current screening modalities. BMI (< 28) could be considered a potential indicator when screening early postmenopausal White women for osteoporosis. However, a better osteoporosis screening tool remains to be developed.