[FRAX® thresholds to identify people with high or low risk of osteoporotic fracture in Spanish female population].

BACKGROUND AND OBJECTIVE To detect FRAX(®) threshold levels that identify groups of the population that are at high/low risk of osteoporotic fracture in the Spanish female population using a cost-effective assessment. PATIENTS AND METHODS This is a cohort study. Eight hundred and sixteen women 40-90 years old selected from the FRIDEX cohort with densitometry and risk factors for fracture at baseline who received no treatment for osteoporosis during the 10 year follow-up period and were stratified into 3 groups/levels of fracture risk (low<10%, 10-20% intermediate and high>20%) according to the real fracture incidence. RESULTS The thresholds of FRAX(®) baseline for major osteoporotic fracture were: low risk<5; intermediate ≥ 5 to <7.5 and high ≥ 7.5. The incidence of fracture with these values was: low risk (3.6%; 95% CI 2.2-5.9), intermediate risk (13.7%; 95% CI 7.1-24.2) and high risk (21.4%; 95% CI12.9-33.2). The most cost-effective option was to refer to dual energy X-ray absorptiometry (DXA-scan) for FRAX(®)≥ 5 (Intermediate and high risk) to reclassify by FRAX(®) with DXA-scan at high/low risk. These thresholds select 17.5% of women for DXA-scan and 10% for treatment. With these thresholds of FRAX(®), compared with the strategy of opportunistic case finding isolated risk factors, would improve the predictive parameters and reduce 82.5% the DXA-scan, 35.4% osteoporosis prescriptions and 28.7% cost to detect the same number of women who suffer fractures. CONCLUSIONS The use of FRAX ® thresholds identified as high/low risk of osteoporotic fracture in this calibration (FRIDEX model) improve predictive parameters in Spanish women and in a more cost-effective than the traditional model based on the T-score ≤ -2.5 of DXA scan.