Novel algorithm generating strategy to identify high fracture risk population using a hybrid intervention threshold

Establishment of a preliminary FRAX®-based intervention threshold for rheumatoid arthritis–associated fragility fracture: a 3-year longitudinal, observational, cohort study

Background:

To establish a FRAX®-based prediction model for rheumatoid arthritis (RA)-associated fragility fracture.

Methods:

This study is a longitudinal, real-world, registry cohort study. Patients with RA were registered to start in September 2014. The baseline demographics, bone mineral density (BMD), and risk factors of osteoporosis or fragility fracture were recorded. Subsequent fragility fractures during the 3-year observation period were also recorded. We developed a fixed intervention threshold (FITD) to identify fractures by choosing an optimal cut-off point on the receiver operating characteristic (ROC) curve and FRAX®. Several models for intervention thresholds (IT), including fixed intervention threshold (Taiwan) (FITT), age-specific individual intervention threshold (IIT), and hybrid intervention threshold (HIT), were compared to evaluate which IT model will have better discriminative power.

Results:

As of December 2020, a total of 493 RA participants have completed the 3-year observation study. The mean age of the participants was 59.3 ± 8.7, and 116 (23.5%) new fragility fractures were observed during the study period. In terms of pairwise comparisons of area under the curve ( n, 95% confidence interval) in the ROC curve, the FITD (0.669, 0.610–0.727, p < 0.001) with a value of 22% in major osteoporotic fracture and FITT (0.640, 0.582–0.699, p < 0.001) is significantly better than reference, but not for IIT (0.543, 0.485–0.601, p = 0.165) and HIT (0.543, 0.485–0.601, p = 0.165).

Conclusion:

An optimal FIT is established for intervention decisions in RA-associated fragility fractures. This model can offer an easy and simple guide to aid RA caregivers to provide interventions to prevent fragility fractures in patients with RA.

The molecular etiology and treatment of glucocorticoid-induced osteoporosis

Glucocorticoid-induced osteoporosis (GIOP) is the most common form of secondary osteoporosis, accounting for 20% of osteoporosis diagnoses. Using glucocorticoids for >6 months leads to osteoporosis in 50% of patients, resulting in an increased risk of fracture and death. Osteoblasts, osteocytes, and osteoclasts work together to maintain bone homeostasis. When bone formation and resorption are out of balance, abnormalities in bone structure or function may occur. Excess glucocorticoids disrupt the bone homeostasis by promoting osteoclast formation and prolonging osteoclasts' lifespan, leading to an increase in bone resorption. On the other hand, glucocorticoids inhibit osteoblasts' formation and facilitate apoptosis of osteoblasts and osteocytes, resulting in a reduction of bone formation. Several signaling pathways, signaling modulators, endocrines, and cytokines are involved in the molecular etiology of GIOP. Clinically, adults ≥40 years of age using glucocorticoids chronically with a high fracture risk are considered to have medical intervention. In addition to vitamin D and calcium tablet supplementations, the major therapeutic options approved for GIOP treatment include antiresorption drug bisphosphonates, parathyroid hormone N-terminal fragment teriparatide, and the monoclonal antibody denosumab. The selective estrogen receptor modulator can only be used under specific condition for postmenopausal women who have GIOP but fail to the regular GIOP treatment or have specific therapeutic contraindications. In this review, we focus on the molecular etiology of GIOP and the molecular pharmacology of the therapeutic drugs used for GIOP treatment.