Discrepancy Between the 10-Year Probability of Major Osteoporotic Fracture with FRAX and the Actual Fracture Prevalence over 10 Years in Japanese

Background/Objectives: Comparison between the 10-year probability of major osteoporotic fracture (MOF) calculated with FRAX (pFRAX) and the actual MOF rate was conducted, and the availability of pFRAX was evaluated with a one-center cohort study. Methods: Eligible patients were followed up for 10 years. Risk factors listed as items in the FRAX, and presence of lifestyle-related diseases (LS-RDs), escalated ability to fall (Fall-ability), cognitive impairment (CI), etc., were evaluated concerning MOF. The 10-year probability and actual MOF rate were compared. Risk factors contributing to the discrepancy between the probability and the actual rate were evaluated after dividing subgroups. Results: The study included 931 patients. Factors that contributed to the significantly higher ratio for incident MOF besides items in the FRAX were LS-RD, Fall-ability, CI, and anti-osteoporotic drug intervention. The higher the number of factors presented, the higher the actual MOF prevalence compared to the probability rise. Presenting LS-RD, Fall-ability, and CI are independent of the items in the FRAX. pFRAX was overestimated in the low-risk groups and underestimated in the high-risk group compared to the actual MOF rate. These phenomena are caused by the lack of consideration of these three comorbidity risks. Conclusions: A discrepancy between pFRAX and the actual MOF rate exists. LS-RD, Fall-ability, and CI should be listed in the items of the FRAX for more concision.