Evaluation of FRAX to characterise fracture risk in Poland

Summary The UK FRAX model was evaluated retrospectively in Polish women assessed 11 years previously for fracture risk. Results were compared with fracture risk observed during follow-up. The UK model can be used to stratify risk, but caution is required in interpretation of absolute fracture risk. Introduction In the absence of a FRAX® model for Poland, the UK FRAX tool has been widely used. The aim of this study was to evaluate the validity of the surrogate model in a Polish setting. Methods We studied a convenience sample of 501 women who had been referred for the assessment of bone mineral density and clinical risk factors 9–12 years previously. Incident fractures in the intervening period were selfreported by telephone interview. Fracture probabilities, calculated using the UK FRAX tool, were compared to the incidence of new fractures during follow-up. Results Incident fractures were reported in 106 women. Incident fractures of the major osteoporotic fractures were reported in 89 women. The observed incidence of fractures rose progressively in women according to percentile of fracture probability. Between the 10th and 90th percentiles, hip fracture probability computed with bone mineral density (BMD) differed 49-fold. The range was fivefold in the case of a major osteoporotic fracture. The observed/ expected ratio for fracture was significantly greater than unity when the expected number was calculated without BMD (1.79; 95% confidence interval=1.44–2.21) and when BMD was included in the FRAX calculation (1.94; 95% confidence interval=1.45–2.54). Conclusion The UK FRAX tool categorised fracture risk well in this Polish cohort but significantly overestimated fracture risk. The UK model can be used to stratify risk in the population, but caution is required in interpretation of absolute risk.