Abstract
The widely used Fracture Risk Assessment Tool (FRAX) estimates a 10-year probability of major osteoporotic fracture (MOF) using age, sex, body mass index, and seven clinical risk factors, including prior history of fracture. Prior fracture is a binary variable in FRAX, although it is now clear that prior fractures affect future MOF risk differently depending on their recency and site. Risk of MOF is highest in the first two years following a fracture and then progressively decreases with time – this is defined as imminent risk. Therefore, the FRAX tool may underestimate true fracture risk and result in missed opportunities for earlier osteoporosis management in individuals with recent MOF. To address this, multipliers based on age, sex, and fracture type may be applied to baseline FRAX scores for patients with recent fractures, producing a more accurate prediction of both short- and long-term fracture risk. Adjusted FRAX estimates may enable earlier pharmacologic treatment and other risk reduction strategies. This study aimed to report the effect of multipliers on conventional FRAX scores in a clinical cohort of patients with recent non-hip fragility fractures.
After obtaining Research Ethics Board approval, FRAX scores were calculated both before and after multiplier adjustment, for patients included in our outpatient Fracture Liaison Service who had experienced a non-hip fragility fracture between June 2020 and November 2021. Patients age 50 years or older, with recent (within 3 months) forearm (radius and/or ulna) or humerus fractures were included. Exclusion criteria consisted of patients under the age of 50 years or those with a hip fracture. Age- and sex-based FRAX multipliers for recent forearm and humerus fractures described by McCloskey et al. (2021) were used to adjust the conventional FRAX score. Low, intermediate and high-risk of MOF was defined as less than 10%, 10-20%, and greater than 20%, respectively. Data are reported as mean and standard deviation of the mean for continuous variables and as proportions for categorical variables.
A total of 91 patients with an average age of 64 years (range = 50-97) were included. The majority of patients were female (91.0%), with 73.6% sustaining forearm fractures and 26.4% sustaining humerus fractures. In the forearm group, the average MOF risk pre- and post-multiplier was 16.0 and 18.8, respectively. Sixteen percent of patients (n = 11) in the forearm group moved from intermediate to high 10-year fracture risk after multiplier adjustment. Average FRAX scores before and after adjustment in the humerus group were 15.7 and 22.7, respectively, with 25% (n = 6) of patients moving from an intermediate risk to a high-risk score.
This study demonstrates the clinically significant impact of multipliers on conventional FRAX scores in patients with recent non-hip fractures. Twenty-five percent of patients with humerus fractures and 16% of patients with forearm fractures moved from intermediate to high-risk of MOF after application of the multiplier. Consequently, patients who were previously ineligible for pharmacologic management, now met criteria. Multiplier-adjusted FRAX scores after a recent fracture may more accurately identify patients with imminent fracture risk, facilitating earlier risk reduction interventions.
