Fracture risk prediction in outpatients from Krakow Region using FRAX tool versus fracture risk in 11-year follow-up

Abstract

Introduction: FRAX is a an algorithm accepted by WHO for evaluating fragility fracture risk of women aged 40 years or more. The aim of this study was to use the FRAX tool to verify the risk of fractures in a population of women from the Cracow region in an 11-year follow-up.

Materials and methods: The study was a retrospective cohort survey evaluating the incidence of fragility fractures over 11 years of follow-up. 5,092 women aged 50 years and more were randomly chosen from a group of 100,000 female patients of the Cracow Medical Centre who came to the Centre for densitometric examination between 1997 and 2001. Finally, 1024 patients were randomized into the study. After an average of 11 years a follow-up telephone survey was conducted among a randomly selected group of patients using a questionnaire corresponding to the one applied in the first survey. 10-year fracture risk was calculated for each patient using FRAX based on the BMI (Body Mass Index) and for 886 women using FRAX based on BMD (Bone Mineral Density) at the femoral neck. The Polish version of FRAX was validated by comparing the predicted risk with the actual incidence of fractures during the 11-year follow-up.

Results: The 10-year probability of a major osteoporotic fracture calculated using FRAX based on BMI for the entire group was 5.3% (median, 1st/3rd quartile: 3.5-8.5%) and the probability of a proximal femur (hip) fracture was 1.3% (median, 1st-3rd quartile: 0.7% -2.4%). In 886 women whose BMD T-score at the femoral neck was available, the mean probability of a major osteoporotic fracture was 4.9% (3.3-7.9%) and of a hip fracture 0.9% (0.3-2.3%). The actual absolute fracture risk calculated on the basis of the number of patients who had experienced a fracture during the follow-up was surprisingly much higher than the predicted figure. The risk of a major fracture in the study group was 17.7% and of a proximal femur fracture, 3%.

Conclusion: In our opinion, FRAX is a very good screening tool, but not a precise diagnostic tool.