Predicting fractures in an international cohort using risk factor algorithms without BMD

Abstract

Clinical risk factors are associated with increased probability of fracture in postmenopausal women. We sought to compare prediction models using self-reported clinical risk factors, excluding bone-mineral density (BMD), to predict incident fracture among postmenopausal women. The GLOW study enrolled women aged ≥55 years were seen at 723 primary care practices in 10 countries. The population comprised 19,586 women aged ≥60 years who were not receiving anti-osteoporosis medication and were followed annually for 2 years. Self-administered questionnaires were used to collect data on characteristics, fracture risk factors, previous fractures, and health status. The main outcome measure compares the c index for models using the WHO Fracture Risk (FRAX), the Garvan Fracture Risk Calculator (FRC), and a simple model using age and prior fracture. Over 2 years, 880 women reported incident fractures including 69 hip fractures, 468 “major fractures” (as defined by FRAX) and 583 “osteoporotic fractures” (as defined by FRC). Using baseline clinical risk factors, both FRAX and FRC showed moderate ability to correctly order hip fracture times (c index for hip fracture: 0.78 and 0.76, respectively). C indices for “major” and “osteoporotic” fractures showed lower values, at 0.61 and 0.64. Neither algorithm was better than the model based on age+fracture history alone (c index for hip fracture: 0.78). In conclusion, estimation of fracture risk in an international primary care population of postmenopausal women can be made using clinical risk factors alone, without BMD. However, more sophisticated models incorporating multiple clinical risk factors including falls were not superior to more parsimonious models in predicting future fracture in this population.

Osteoporotic fracture rate among women with at least 1 year of adherence to osteoporosis treatment

“…In practice, clinicians may face a challenge in trying to introduce a second-line drug. The factors we identified as being associated with fracture while on treatment are consistent with the highest risk of fracture in untreated populations, namely, older age and having suffered a recent fragility fracture 34 . Both these factors are compatible with an advanced stage of bone deterioration with regard to mass and structure (and perhaps other components of bone strength), which the currently available therapies are not potent enough to reverse.…”

Proportion of osteoporotic women remaining at risk for fracture despite adherence to oral bisphosphonates

“…In fact, in our study, Sambrook showed that fractures could be predicted from relatively simple algorithms that performed as well as more complex ones. [28] Since older patients, non-black patients, and those with hyperparathyroidism or concomitant estrogen use tended to remain at higher risk of fracture despite being adherent to bisphosphonate treatment, these are the patients who may need to be considered early for alternative treatments or monitored more closely to decide whether they need alternative treatments. Exactly what those criteria would be beyond BMD or new fractures are uncertain, as algorithms such as FRAX are not responsive enough to therapy to reliably detect a change in risk with therapy [12].…”

Comparison between frailty index of deficit accumulation and fracture risk assessment tool (FRAX) in prediction of risk of fractures

“…Some studies argued that previous falls should be included into FRAX, since previous falls were an independent and significant risk factor for future fractures [12,28]. Nevertheless, evidence showed that models incorporating falls as a risk factor may not be superior to FRAX alone in predicting future risk of fractures [41]. In our study, a post-hoc analysis incorporating baseline falls into the models yielded similar results for both FRAX and FI to the parsimonious models (Table 2), e.g., for the per-0.01 increment the HR was 1.03 and 1.02 and the c-index was 0.61 and 0.61 for FRAX and FI respectively.…”