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Cortical bone parameters predict fracture risk in older men
In older men, cortical area and cortical bone mass are associated with fracture risk independent of areal bone mineral density measurements used in the WHO fracture risk assessment tool, according to a prospective study.
“Although [areal] BMD, measured using 2-dimensional DXA, is a robust and clinically useful predictor of fracture risk, it cannot determine the cortical and trabecular bon compartments separately or analyze the cortical porosity, requiring 3-dimensional [high-resolution peripheral quantitative CT] analyses,” Claes Ohlsson, MD, PhD, of the Center for Bone Research at the Sahlgrenska Academy, University of Gothenburg, Sweden, and colleagues wrote. “We, herein, demonstrate that cortical area and cortical bone mass were independently of [areal] BMD associated with fracture risk and that fracture reclassification was significantly improved when either of these bone parameters were added to [fracture risk assessment tool] models with [areal] BMD.”
Ohlsson and colleagues analyzed data from 456 Swedish participants in the osteoporotic fractures in men study (MrOS; mean age, 80 years). Researchers assessed cortical area, cortical bone mass, trabecular bone volume fraction and cortical porosity at the tibia using high-resolution peripheral quantitative CT (HR-pQCT). Patients underwent DXA measurements to assess areal BMD. Researchers used Cox proportional hazard models to evaluate associations between areal BMD and cortical and trabecular bone parameters with incident fracture.
Within the cohort, 71 men (15.6%) sustained a fracture during a mean 5.3 years of follow-up; 50 men sustained a major osteoporotic fracture; all fractures were verified by X-ray.
After adjusting for age and BMI, researchers found that cortical bone mass was a robust predictor of incident fracture (HR per standard deviation [SD] increase = 2.07; 95% CI, 1.58-2.7) as was cortical area (HR per SD increase = 2.05; 95% CI, 1.58-2.65); trabecular bone volume fraction was found to be a moderate predictor of incident fracture (HR per SD increase = 1.61; 95% CI, 1.26-2.07). Cortical porosity did not significantly predict fracture risk, according to researchers, who noted similar associations when evaluating osteoporotic fractures separately.
In models adjusted for fracture risk assessment tool (FRAX) that included areal BMD measurements, cortical area was a predictor of any fracture risk (HR = 1.95; 95% CI, 1.44-2.66), as was cortical bone mass (HR = 1.99; 95% CI, 1.45-2.74).
Researchers observed an improvement in national reclassification improvement index and integrated discrimination improvement when adding both cortical area and bone mass to FRAX models with areal BMD.
“Importantly, addition of these bone traits to FRAX models with [areal] BMD revealed that reclassification was significantly improved as a result of both a correct upward reclassification of those with a fracture and a correct downward reclassification of those without a fracture,” the researchers wrote.
They proposed “simpler and less expensive, single-slice pQCT” be used in clinic to measure cortical area and cortical bone mass in patients.
“We propose that HR-pQCT measurement of either cortical area or the composite trait of cortical bone mass might add clinically useful information to improve the identification of individuals at high risk for fracture,” the researchers wrote. – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.