To the best of our knowledge, this study was the first to verify the systemic BMD measurement applied to the bioelectrical impedance method in the general public. At present, although relevant theories and studies on the application of bioelectrical impedance to BMD have been proposed, actual research applied to BMD measurements remains scarce. Currently, the published verification research literature on relevant technologies and equipment is also lacking. The experimental results of this study revealed that BIA with the standing foot-to-foot model had a moderate positive correlation with total body BMD and DXA measured by the participants in this study. The Bland–Altman plots demonstrate that BIA measures total-body BMD relative to DXA and underestimates whole-body BMD. The measurement difference between the two devices decreased with an increase in whole-body BMD. The accuracy of BIA measurement of BMD still demonstrated improvement to a certain extent compared with that of DXA. Quantitative ultrasonography (QUS) measured the correlation between BMD and DXA throughout the body, and its r value was between 0.35 and 0.8014, 15. Therefore, the World Health Organization has not recognized QUS for clinical applications. Although QUS is more convenient than DXA, DXA is more convenient, safe, low-cost, and fast. Moreover, it has unique characteristics from QUS, which may make DXA more suitable for screening for BMD or osteoporosis.
Several studies have reported age as one of the main risk factors for fractures16. In addition to aging, changes in postmenopausal women are particularly evident owing to small bone loss due to changes in body composition and hormonal changes17. In addition, family history18, lifestyle19, weight20, hormones21, chronic diseases, and long-term use of certain drugs22 would affect bone density. The existing standard method for evaluating BMD is DXA. However, DXA has some shortcomings, including limited availability and high costs10. Thus, DXA is unsuitable for use in screening.
Currently, DXA is used to measure BMD to assess osteoporosis in the lumbar spine, proximal femur, and forearm. Although the measurement results of systemic BMC were used as a clinical diagnostic reference, most of them were in pediatric patients because the measurement results of systemic BMD were highly reproducible for the examination of systemic bone condition. Systemic BMD can provide a comprehensive and integrated evaluation basis, and systemic BMD testing can provide personalized treatment policies for patients. BMD in different parts of the body may differ; therefore, systemic testing can help doctors formulate targeted treatment plans more accurately to minimize the risk of fractures. Although systemic BMD is less commonly used to assess osteoporosis than the lumbar spine, proximal femur, or forearm femur, the judgment of systemic BMD for osteoporosis is heterogeneous. Peak bone mass and standard deviation calculated from the population were not suitable for all individuals. At present, no evidence that BMD is the best reference location has been reported23. The whole-body BMD of the participants in this study was still highly positively correlated with the BMD of the lumbar spine, proximal femur, and forearm bone (r = 0.81–0.90, data not shown). The BMD in specific parts can provide independent information on fracture risk. Systemic BMD is typically considered a more comprehensive indicator.
Preventive measures and raising public awareness on bone health are important to reduce the prevalence of osteoporosis24. Specifically, proper calcium and vitamin D intake is required. Appropriate physical activity is essential to ensure good bone health. Quitting smoking and limiting alcohol intake are important factors in maintaining healthy bones. Regular physical examinations and medical guidance can help individuals understand their bone health. Regular bone density testing is performed, especially for high-risk groups such as postmenopausal women, patients who use glucocorticoids for a long time, and individuals with osteoporosis in the family. The measurement results of whole-body BMD of the equipment discussed in this study are better than those of ultrasonic BMD detection25–27, which is convenient for application in family health care. BIA can detect osteoporosis at an early stage, and can be conducive to the early adoption of prevention and treatment measures that are not provided by existing BMD measurement equipment.
Osteoporosis symptoms were not evident. In the face of possible patients, the best prevention method is to use bone healthcare and related examinations, including daily medical examinations or general initial screening28. Otherwise, the importance of diagnostic examination and treatment may still be difficult to understand when considering only "symptoms of early aging". Thus, an effective, safe, and convenient method or tool is necessary to measure bone density that is different from the present. For example, the convenient BIA method, if it has undergone large-scale verification research, can prove that its accuracy is useful for screening for osteoporosis, thus suggesting its application and promotion value.
This study has some limitations. First, the study participants were adults who could stand and walk independently in Taiwan. Thus, the results cannot be inferred from other age groups or physiological conditions. Second, the BIA device discussed in this study is a standing foot-to-foot BIA with a BMD measurement function. Therefore, it cannot be inferred from other brands, models, or body composition analyzers. Lastly, the number of participants included in the study was limited. In the future, relevant research should be conducted on other ethnic groups under different physiological conditions.
Currently, the application of BIA for BMD measurements is relatively limited7. BIA is mainly used to measure electric current flow through the human body to estimate body composition, rather than directly measuring bone density. The electrical characteristics of the current flowing through the bones, muscles, and other tissues need to be further studied. However, continuous progress in scientific research and technology may lead to new application directions for BIA in this regard. For example, integrating other biological measurements and combining BIA with other biological measurement methods could improve the accuracy of BMD estimation to establish a more comprehensive model and further improve the evaluation of BMD. In the future, new electrodes and measurement technologies may be developed to improve BIA's sensing and measurement capabilities of bone tissues. This includes improvements in the frequency, waveform, and electrode design of the current. It is used to increase the estimation of BMD in various parts of the body. In addition, more in-depth research should be conducted on specific groups of people such as children, elderly, and patients with osteoporosis. Alternatively, deep learning and artificial intelligence technology can be used to extract complex patterns from vast data to further optimize BIA's BMD evaluation model.