An Assessment of Intervention Thresholds for Very High Fracture Risk Applied to the NOGG Guidelines : A Report for the National Osteoporosis Guideline Group (NOGG)

Introduction: Guidelines for the assessment of fracture risk have begun to categorise patients eligible for treatment into high and very high risk of fracture to inform choice of therapeutic approach. The aim of the present study was to develop intervention thresholds based on the hybrid assessment model of NOGG.

Methods: We examined the impact of intervention thresholds in a simulated cross-sectional cohort of women age 50 years or more from the UK with the distribution of baseline characteristics based on that in the FRAX cohorts. The prevalence of very high risk using the hybrid model was compared with age-dependent thresholds used by the International Osteoporosis Foundation and the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (IOF/ESCEO). The appropriateness of thresholds was tested based on the populations treated with anabolic agents.

Results: With an upper intervention threshold using the IOF/ESCEO criteria, 56% of women age 50 years or more would be characterised at very high risk. This compares with 36% using the IOF/ESCEO criteria and an age-specific intervention threshold over all ages. With an upper intervention threshold of 1.6 times the pre-existing intervention threshold, 10% of women age 50 years or more would be characterised at very high risk. The data from phase 3 studies indicate that most trial participants exposed to romosozumab or teriparatide would fall into the very high-risk category.

Conclusions: Proposals for FRAX-based criteria for very high risk for the NOGG hybrid model categorise a small proportion of women age 50 years or more (10%) in this highest risk stratum. The level of risk identified was comparable to that of women enrolled in trials of anabolic agents.