[The fracture risk assessment tool (FRAXTM), where are we in Tunisia?]. / Le score FRAX®, ou on est en Tunisie.

BACKGROUND: The fracture risk assessment tool (FRAXTM), published in February 2008, is developed based on the use of clinical risk factors with or without bone mineral density tests. AIM: To calculate the FRAX tool in a cohort of Tunisian patients in whom bone mineral density (BMD) was assessed by dual X ray absorptiometry (DXA); to correlate this score to osteoporotic fracture and to BMD assessment and to propose a threshold for therapeutic intervention. METHODS: In a cross sectional study of 582 patients older than 40 years, in whom a BMD measurement by DXA has been performed between January 2006 and December 2009, clinical risk factor for osteoporotic fracture and the occurrence of a prior fragility fracture were assessed. The French version of the FRAX tool was used. Threshold for pharmacological intervention was evaluated by ROC curve. RESULTS: Patients were aged 62.3 ± 10.4 years. They were female in 91.2% of cases. BMD measurement was under 2.5 standard deviation in 53.2%. Osteopenia was noted in 29.2% of cases and BMD was normal in 17.4 % of cases. Osteoporotic fractures were observed in 38.2% of cases. Major osteoporotic fractures (FOM) (hip, vertebra, radius occurred in 82% of cases. The FRAX® score calculated with T-score was 8.55 ± 8.54% for the FOM and 3.02 ± 6.37% for femoral neck (FN), while it was 7.81 ± 6.45% for the FOM and 2.58 ± 3.97% for the FN if calculated without T-score with a significant difference (p <10-3). For the patients having T-score under 2.5 SD, FRAX score was 11.39 ± 10.32% for the FOM and 4.74 ± 8.13% for the FN if calculated with T-score and it was 9.18 ± 6.95 % for the FOM and 3.19 ± 4.11 % if calculated without T-score. The score FRAX was correlated to BMD (r=0,53, p <10-3) and to fracture prevalence (p < 10-3). The threshold of therapeutic intervention was fixed to 30% for the FOM and 7% for the FN. CONCLUSION: Our study confirms the usefulness of the FRAX score in the prediction of fracture risk in Tunisian population. The determination of therapeutic threshold intervention requires other prospective and larger studies with medico-economic analyses.