Scott B Going

PMID: 16720746;Abstract:

Background. Lower bone mineral density (BMD) has been documented in clinically depressed populations, and depression is the second most common chronic medical condition in general medical practice. Therefore, the purpose of this study was to determine whether depressive symptoms, vitality, and body weight changes were related to 1-year BMD changes after accounting for covariates. Methods. Healthy postmenopausal women (n = 320; 40-65 years) were recruited, and 266 women completed the study. Participants were 3-10 years postmenopausal, sedentary, and either taking hormone replacement therapy (1-3.9 years) or not taking it (at least 1 year). Exclusion criteria were: current smoking status, history of fractures, low BMD, body mass index >32.9 or 19.0, or use of bone altering medications. Regional BMD was measured from dual-energy x-ray absorptiometry at baseline and 1 year. Self-reported depressive symptoms and vitality were measured using standard questionnaires. Results. Both the vitality and depressive symptoms scores were related to BMD changes at the femur neck but not at the greater trochanter or spine. Weight change was a predictor of BMD changes in the trochanter and spine but not in the femoral neck. Weight change and vitality and/or depressive symptoms had differential and site-specific effects on BMD changes at the hip. Vitality and depressive symptoms related to femoral neck changes and weight change related to greater trochanter changes. Conclusions. The negative impact of depressive symptoms on BMD in this population of postmenopausal women was independent of body weight or other behavioral factors such as calcium compliance or exercise. Copyright 2006 by The Gerontological Society of America.

Peripheral quantitative computed tomography (pQCT) is an essential tool for assessing bone parameters of the limbs, but subject movement and its impact on image quality remains a challenge to manage. The current approach to determine image viability is by visual inspection, but pQCT lacks a quantitative evaluation. Therefore, the aims of this study were to (1) examine the reliability of a qualitative visual inspection scale and (2) establish a quantitative motion assessment methodology. Scans were performed on 506 healthy girls (9-13 years) at diaphyseal regions of the femur and tibia. Scans were rated for movement independently by three technicians using a linear, nominal scale. Quantitatively, a ratio of movement to limb size (%Move) provided a measure of movement artifact. A repeat-scan subsample (n = 46) was examined to determine %Move's impact on bone parameters. Agreement between measurers was strong (intraclass correlation coefficient = 0.732 for tibia, 0.812 for femur), but greater variability was observed in scans rated 3 or 4, the delineation between repeat and no repeat. The quantitative approach found ≥95 % of subjects had %Move 25 %. Comparison of initial and repeat scans by groups above and below 25 % initial movement showed significant differences in the >25 % grouping. A pQCT visual inspection scale can be a reliable metric of image quality, but technicians may periodically mischaracterize subject motion. The presented quantitative methodology yields more consistent movement assessment and could unify procedure across laboratories. Data suggest a delineation of 25 % movement for determining whether a diaphyseal scan is viable or requires repeat.

PMID: 1537738;Abstract:

The purposes of this study were to develop and cross-validate the 'best' prediction equations for estimating fat-free body mass (FFB) from bioelectrical impedance in children and youth. Predictor variables included height²/resistance (RI) and RI with anthropometric data. FFB was determined from body density (underwater weighing) and body water (deuterium dilution) (FFB-DW) and from age-corrected density equations, which account for variations in FFB water and bone content. Prediction equations were developed using multiple regression analyses in the validation sample (n = 94) and cross-validated in three other samples (n = 131). R² and standard error of the estimate (SEE) values ranged from 0.80 to 0.95 and 1.3 to 3.7 kg, respectively. The four samples were then combined to develop a recommended equation for estimating FFB from three regression models. R² and SEE values and coefficients of variation from these regression equations ranged from 0.91 to 0.95, 2.1 to 2.9 kg, and 5.1 to 7.0%, respectively. As a result of all cross-validation analyses, we recommend the equation FFB-DW = 0.61 RI + 0.25 body weight + 1.31, with a SEE of 2.1 kg and adjusted R² of 0.95. This study demonstrated that RI with body weight can predict FFB with good accuracy in Whites 10-19 yr old.

PMID: 7738683;Abstract:

This study determined relationships among total energy intake, nutrient intake, body composition, exercise group status, and annual rates of change (slopes) in bone mineral density in 66 Caucasian premenopausal women (mean age, 34.4 ± 2.7) taking calcium supplements. Body composition components measured by dual-energy X-ray absorptiometry included fat mass, soft tissue lean mass, and bone mineral density (g/cm²) of total body, spine (lumbar vertebrae 2-4), and three femur sites measured at baseline, 5, 12, and 18 mo. Nutrients were not significant variables in regression models predicting bone mineral density slopes (rates of change) at any femur site. The only significant variable in models predicting Ward's triangle bone mineral density slope was the initial fat mass and, for trochanter, exercise. Significant variables (P 0.05) in models predicting total body bone mineral density slope included the initial fat mass and fat mass slope plus either vitamin A, carotene, fiber, magnesium, or phosphorus (R² from 0.31 to 0.25) and fat mass slope plus sodium (R² = 0.24). The significant variable in the model predicting L2-4 slope was energy intake (R² = 0.17, P 0.05). We conclude that nutrient intake, exercise, and body composition are related to bone mineral density rate of change and that relations among these variables vary by bone site.