PubMed · 6624708
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J Lee, L N Kolonel. 1983. Body mass indices: a further commentary.. https://doi.org/10.1093/ajcn%2F38.4.660
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The bioelectrical impedance analysis (BIA) method is an attractive tool for use in the clinical assessment of human body composition. Factors such as ease of use, relatively low cost, noninvasive nature, high degree of reproducibility, and safety of operation provide an impetus for the general application of this method. The preponderance of the published applications of BIA focused on applications in healthy populations and indicated a qualitative validity of the method. More recent applications have augmented the quantitative values of the BIA approach and have reported very good specificity and sensitivity. One potential limitation of the BIA approach is the reliance on regression models, derived in restricted samples of human subjects, which restricts the usefulness of the derived model in other patients who differ from the original sample in which the model was developed. Other investigational approaches that use different physical models (bioelectrical impedance spectroscopy and parallel model) have yielded successful and useful measures of human body composition in clinical studies. If BIA is to gain acceptance in clinical diagnosis and evaluation of therapeutic interventions, further efforts will be needed to ascertain more fully the validity, sensitivity, and specificity of biological parameters estimated with the new BIA approaches, and to establish the prognostic values of the BIA estimates of body composition.
An approach to determine intra- and extracellular conduction on the basis of Bode analysis is presented. Estimation of the ratio between intra- and extracellular conduction could be performed by phase measurement only, midrange in the bandwidth of interest. An important feature is that the relation between intra- and extracellular conduction can be continuously monitored by phase measurement and no curve fitting whatsoever is required. Based on a two-frequency measurement determining Re at 4 kHz and phi max at 64 kHz, it proved possible to estimate extracellular volume (ECV) in 23 patients. Reference values on ECV were determined by sodium bromide. The results show a good correlation (r = 0.90) with the reference method. The average error of ECV estimation was -3.6% (SD 8.4).
OBJECTIVE: In 1990 we initiated a 20 year, partly randomised study (Danish Osteoporosis Prevention Study, DOPS) in order to (a) evaluate clinical, biochemical and osteodensitometric variables as predictors of low bone mass and future osteoporotic fractures, and (b) test the hypothesis, that hormone replacement therapy (HRT) initiated shortly after menopause reduces the risk of later osteoporotic fractures. This report describes study design and baseline characteristics of the DOPS-cohort. METHODS: The study design is pragmatic, attempting to mimic the normal clinical situation. Several HRT alternatives are available according to clinical need. It was considered futile, impractical and unethical to use placebo for 20 years. Instead the study focus on hard endpoints (fractures) confirmed by independent persons (peripheral fractures) or by methods which allow investigator blinding (spinal X-rays). Statistical evaluation will focus on intention to treat analyses evaluating the decision of HRT and it's feasibility. With a compliance of 60% we will have sufficient statistical power (88%) to detect a fracture reduction of 40% in the treatments group. Clinical risk factors, current daily intakes of macronutrients, vitamins and minerals, anthropometric variables, biochemical variables (including bone markers and 25-hydroxyvitamin D), regional bone mineral density (BMD) and total body composition were assessed in all participants at entry and at various follow up intervals. RESULTS: 2016 study participants were recruited by direct mailing to a random sample of 45-58 years old women. In the randomised arm 501 were allocated to HRT and 505 to no treatment. In the non-randomised arm 219 preferred HRT and 791 preferred no treatment. Post-randomisation analysis revealed a slight but significant difference in age (50.01 versus 50.44 years) but no difference in menopausal age, prevalence of hysterectomy, educational level, BMI, serum bone alkaline phosphatase, serum osteocalcin, urine hydroxyproline or serum 25-hydroxyvitamin D. In the non-randomised arm women preferring HRT were closer to menopause, had a higher prevalence of hysterectomy, were better educated, were leaner, and had lower bone turnover than the women, who refused HRT. CONCLUSION: It is possible to include a sufficient number of perimenopausal women in a randomised 20 year study on the antifracture effect of HRT.