Letter to the Editor: “Cortical Bone Area Predicts Incident Fractures Independently of Areal Bone Mineral Density in Older Men”

We thank Claes Ohlsson et al. (1) for sharing their significant study indicating that cortical bone area predicts incident fractures independently of area bone mineral density (BMD) in older men. In this study, microstructural indications and areal BMD in 456 men were measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) and dual-energy x-ray absorptiometry (DXA), respectively. The correlations between these parameters and incident fractures were evaluated by Cox proportional hazard models and other statistical analyses. It was shown that HR-pQCT measurement of cortical area or cortical bone mass independently correlated with bone fracture risk and might add clinically useful information for the evaluation of fractures. We have several concerns about this study.

First, the authors should clarify how many patients were diagnosed with osteoporosis or evaluated as having high fracture risks by the fracture risk assessment tool (FRAX) model at the beginning of their study. Many guidelines recommend that men 50 years of age and older with T-scores of −2.5 or lower at the femoral neck, total hip, or lumbar spine by DXA, and with osteopenia (T-score between −1.0 and −2.5) as well as a 10-year hip fracture probability or a 10-year major osteoporosis-related fracture probability above the thresholds based on the country-specified FRAX model, should be given pharmacologic treatment (2, 3). Therefore, the authors should address how it is reasonable if patients needed treatment but did not take the medication.

Second, it is highly interesting that the HR-pQCT parameters of cortical bone were independently associated with the fracture risks of the FRAX model. FRAX is a computer-based algorithm that calculates the 10-year probability of both a major fracture and a hip fracture risk from age, sex, body mass index, previous fragility fracture, parental history of hip fracture, current tobacco smoking, use of long-term oral glucocorticoids, rheumatoid arthritis, alcohol consumption, and other causes of secondary osteoporosis. Femoral neck BMD can be optionally input, and if input this can improve sensitivity of fracture prediction in conjunction with age (4). The authors should clarify whether femoral neck BMD was input for their calculations. Moreover, the FRAX scores of the patients when the study was ended should also be calculated and included in the analysis. These suggestions would help the authors get further evidence to support their findings.

Acknowledgments

This work was supported by National Natural Science Foundation of China Grants 81000361 and 81471091.

Disclosure Summary: The authors have nothing to disclose.

Abbreviations:

 
• BMD

  bone mineral density

 
• DXA

  dual-energy x-ray absorptiometry

 
• FRAX

  fracture risk assessment tool

 
• HR-pQCT

  high-resolution peripheral quantitative computed tomography.

References

Author notes