"Evidence-based" or "logic-based" medicine?

Low trauma fractures are the cardinal manifestation of osteoporosis. Their occurrence supersedes bone mineral density in deciding whether specific therapy is warranted. We therefore disagree with the notion that a densitometric threshold for treatment should be applied to patients over age 50 who suffer low trauma distal radius fracture.

DXA-based hip structural analysis of once-weekly bisphosphonate-treated postmenopausal women with low bone mass.

SUMMARY: DXA-based hip structural analysis from 947 individuals completing two large osteoporosis clinical trials was pooled and analyzed. Treatment with once-weekly (OW) ALN or OW RIS resulted in significant improvements from baseline in geometric parameters at all three HSA ROIs. Improvements were generally greater with OW ALN than OW RIS. INTRODUCTION: BMD can be altered by changes in distribution and quantity of bone and changes in mineralization. These effects cannot be distinguished with conventional measurements of BMD. Currently, tissue composition is evaluated only by invasive means. Structural geometry of the proximal femur, however, can be measured in vivo by several methods, including dual energy X-ray absorptiometry (DXA) using specialized hip structure analysis (HSA) software. METHODS: DXA-based HSA was obtained and analyzed in a subset of 947 subjects participating in the Fosamax Actonel Comparison Trials. Data were pooled to evaluate treatment effects on the structural geometry of the proximal femur by once-weekly alendronate (ALN) 70 mg and risedronate (RIS) 35 mg in postmenopausal women with low bone mass. RESULTS: Both ALN and RIS treatment over 2 years resulted in improvements in HSA-derived geometry at all three HSA regions of interest (ROI). The largest treatment effects were seen at the intertrochanteric ROI. Consistently greater treatment effects were seen with ALN compared with RIS at all three HSA-ROIs. CONCLUSIONS: HSA offers insight into the potential mechanisms of fracture risk reduction from pharmacologic intervention. In the current study, treatment with once-weekly bisphosphonates resulted in significant improvements in hip geometric parameters.

Importance of precision in bone density measurements.

Bone densitometry, regardless of the specific technique, is not perfectly reproducible even when consistently performed in exact accordance with the manufacturer's recommendations. Precision must be quantified at each densitometry facility in precision studies of the various skeletal sites used for monitoring. The precision, as the root-mean-square standard deviation or root-mean-square coefficient of variation, is then used to determine the change in bone density that constitutes the least significant change and the minimum interval between follow-up measurements. Until precision studies are performed, the least significant change cannot be determined for any level of statistical confidence, making the interpretation of serial studies impossible.

Bone health and osteoporosis.

Good bone health is important to everyone, regardless of age. Osteoporosis is a preventable disease, and steps for increasing bone mass should begin at an early age. To increase bone mass, much of the recent evidence suggests that the best time for intervention with calcium or exercise may be during the prepubertal years. In the older female athlete, BMD is typically well above normal, but even young amenorrheic athletes can have bone density values equal to that of an elderly osteoporotic woman. Myriad treatment options are available for the person with low bone mass, but prevention is a much more preferable alternative.

Lumbar bone mineral density in adolescent female runners.

BACKGROUND: The purpose of this study was to determine if there were significant differences in lumbar bone mineral density (L2-L4, g/cm2) or several hormones among 3 groups of adolescent females: 10 amenorrheic runners, 10 eumenorrheic runners, and 10 eumenorrheic controls. EXPERIMENTAL DESIGN: comparative. SETTING: Cooper Clinic, Aerobics Center, Dallas, Texas. PATIENTS OR PARTICIPANTS: The subjects were white, non-smokers, aged 15.1-18.8 years, who were not taking birth control pills. All amenorrheic runners had less than 5 menstrual period in the past year, averaging 2,4 periods. The runners averaged approximately 36 miles/week (58.1 km) during the last 9 months of their training season and had been running for 1-5 years. INTERVENTIONS: None. MEASURES: Lumbar bone mineral density (BMD), 10 hormones, percentage of body fat, and dietary intake were measured. RESULTS: Mean lumbar BMD (g/cm2) did not differ significantly among groups (amenorrheic runners = 1.134, eumenorrheic runners = 1.165, controls = 1.148). However, expected trends were observed. Compared to the controls, the amenorrheic runners tended to have lower lumbar BMD and the eumenorrheic runners, higher. Although there were significant differences in concentrations of five serum hormones measured, all mean hormonal values were within normal ranges. Calcium intakes were low for all groups. CONCLUSIONS: In this study, with its small number of subjects and great variability within each group, it was concluded that there is no significant difference among amenorrheic runners, eumenorrheic runners, and controls in lumbar BMD. However, a longer period of amenorrhea might result in significantly lower BMD for the amenorrheic runners.

The challenges of peripheral bone density testing: which patients need additional central density skeletal measurements?

Lower cost, portable, peripheral bone mass measurement devices are being increasingly utilized for widespread bone mass testing. These devices are being placed in traditional medical settings as well as nontraditional settings, such as pharmacies and grocery stores. Increased bone mass testing is appropriate at menopause in women who are undecided whether to begin systemic estrogen replacement. Women may decide to begin estrogen replacement if they are aware they have low bone mass and understand that bone mass will predictably decline after the menopause (1). With the approval of alendronate and raloxifene for the prevention of osteoporosis, even women who cannot or will not utilize estrogen replacement may be offered preventive interventions if they are identified as having low bone mass. More accessible bone mass measurements and more approved pharmacologic interventions will shift the focus of osteoporosis management to strategies that emphasize the reduction of lifetime fracture risk as well as current fracture risk. It will also be an impetus to focus on earlier identification and intervention (2-4).

Bone mineral density and dietary intake in patients with Crohn's disease.

Individuals diagnosed with Crohn's disease are at an increased risk for developing low bone density. The exact cause of low bone mineral density in Crohn's disease patients has not been determined. The purpose of this study was to assess the incidence of low bone mineral density in premenopausal women with Crohn's disease and to determine the role diet plays in bone mineral density for this population. Bone mineral density of the lumbar spine (L2-L4), proximal femur, and forearm was measured in 51 female controls and 50 females with Crohn's disease using dual energy X-ray absorptiometry (Lunar DPXPlus, Madison, WI). Dietary intake for all Crohn's disease participants was analyzed using both 3-d dietary records and a food frequency questionnaire. When compared to healthy controls, bone mineral density values of Crohn's disease participants were decreased for all sites, particularly the spine (1.169 +/- 0.114, p = 0.054), Ward's area (0.831 +/- 0.128, p = 0.052), and the femoral neck (0.927 +/- 0.100, p = 0.01). Factors associated with lower bone density in Crohn's participants were weight, corticosteroid usage, length and age of diagnosis, history and length of resection, and dietary intakes of magnesium, copper, magnesium, vitamin K, and zinc. The results of this study indicate for the first time that diet plays a role in the development of low bone density in premenopausal women with Crohn's disease.

Dissimilar spine and femoral Z-scores in premenopausal women.

The purpose of this study was to determine if differences exist in premenopausal women between z-scores for lumbar spine and proximal femoral bone mineral densities (BMD). Participants were 237 women ranging in age from 20 to 45 years. BMDs of the lumbar spine and proximal femur (femoral neck, Ward's area, and trochanter) were assessed using dual-energy X-ray absorptiometry (Lunar DPX). Mean (+/-SD) age, height, and weight of the participants were 29.4 +/- 6.9 years, 164.4 +/- 6.1 cm, and 64.9 +/- 12.1 kg, respectively. Lumbar spine BMD and BMD at the femoral neck, Ward's area, and trochanter were significantly correlated with large SEEs (r = 0.59-0. 65; SEE = 0.09-0.11). No positive correlation with age and BMD at any site was seen in this population but a significant negative correlation with age was seen in the proximal femur beginning at age 30. Twenty to 24% of the 20-29-year-olds exhibited a difference in z-scores of greater than 1 between the spine and sites in the proximal femur. This percentage increased to 32-46% in the 30-45-year-olds but the nature of the observed differences changed. The differences in spine and proximal femoral z-scores that are seen in the older age group appear to be the result of the earlier onset of bone loss in the proximal femur rather than an initial difference in peak bone mass which has been maintained.

Clinical utility of bone mass measurements in adults: consensus of an international panel. The Society for Clinical Densitometry.

Low bone mass predicts future fracture risk as well as high cholesterol or high blood pressure can predict the risk of heart disease or stroke. Prevention of the first fracture should be a clinical goal. In patients without fractures, osteopenia and osteoporosis can be diagnosed based on the extent of reduction in bone mass below mean peak bone mass of young healthy individuals. As bone mass decreases, fracture risk increases exponentially. Clinical situations in which an assessment of bone mass and fracture risk affects therapeutic decisions include estrogen deficiency, vertebral abnormalities, radiographic osteopenia, asymptomatic primary hyperparathyroidism, and long-term corticosteroid therapy. Serial measurements can also be used to monitor the effects of osteoporosis treatments. The appropriate technique and skeletal site for bone mass measurements should be chosen based on the patient's circumstances and the precision of measurement. A clinical interpretation can enhance the value of computer-generated bone mass measurement reports and improve decision making.

Right and left proximal femur analyses: is there a need to do both?

The purpose of this study was to determine if differences existed between right and left proximal femur bone mineral density (BMD) in a group of women. Participants for the study were 198 women ranging in age from 16 to 73 years. Bone mineral densities of both proximal femurs (femoral neck, Ward's area, and trochanter) were assessed using dual energy X-ray absorptiometry (Lunar DPX). Mean (+/-SD) age, height, and weight of the participants were 32.9 +/- 18 years, 164 +/- 7.4 cm, and 64.9 +/- 12.1 kg, respectively. Significant differences between right and left femoral BMDs were found only in the trochanter. Overall, mean differences in BMD were low (neck = 0. 7%, Ward's = 0.2%, and trochanter = 1.9%) but individual variations were as high as 22%. Based on BMD z-scores of <-1.0, 84 women were classified as "at risk" for osteoporosis. When right and left z-scores were compared, misclassifications of at risk women were 4, 15, and 11 for neck, Ward's area, and trochanter, respectively. In conclusion, analyses of both right and left proximal femurs may not be necessary for either the researcher or the clinician.

Consensus of an international panel on the clinical utility of bone mass measurements in the detection of low bone mass in the adult population.

Low bone mass, in the asymptomatic patient, predicts future fracture risk as well as high cholesterol or high blood pressure predicts the risk of heart disease or stroke. In patients without fractures, osteoporosis can be diagnosed based on the extent of reduction in bone mass below mean peak bone mass of healthy young individuals. As bone mass decreases, fracture risk increases exponentially. Prevention of the first fracture is a clinical goal. Clinical situations in which an assessment of bone mass and fracture risk affects therapeutic decisions include estrogen deficiency, vertebral abnormalities, radiographic osteopenia, asymptomatic primary hyperparathyroidism, and longterm corticosteroid therapy. Serial measurements can also be used to monitor the effects of osteoporosis treatment in certain situations. The appropriate technique and skeletal site for bone mass measurements should be chosen based on the patient's circumstances. A clinical interpretation can enhance the value of computer-generated bone mass measurement reports and enhance decision making.

Associations of body fat distribution, circulating sex hormones, and bone density in postmenopausal women.

The associations of body fat distribution, sex hormone levels, and bone mineral density (BMD) were examined in 52 postmenopausal Caucasian women. Body fat distribution was assessed by waist to hip ratio (WHR) and abdominal fat weight (between the iliac crest and L1), as determined by dual energy x-ray absorptiometry. Bone mineral densities were determined by dual energy x-ray absorptiometry, and total estradiol, total testosterone, and sex hormone-binding globulin (SHBG) levels were determined by RIA. Subjects taking hormone replacement had significantly greater total estradiol and SHBG concentrations and a lower free androgen index. BMDs tended to be higher in subjects taking estrogen replacement after adjustment for body weight. There was no difference between subjects taking hormone replacement or not taking hormone replacement in WHR or abdominal fat weight. Subjects with a gynoid (lower body) distribution of body fat had higher SHBG concentrations than subjects with a more android (upper body) distribution of body fat. Subjects with an android distribution of body fat had greater BMDs than subjects with a gynoid distribution of body fat. Abdominal fat weight and WHR were significant predictors in regression models for all BMD parameters. The results of this study suggest that there is an association between body fat distribution and BMD, with the android distribution having higher BMDs.

Relationship of regional body composition to bone mineral density in college females.

The purpose of this study was to examine relationships between regional body composition and bone mineral density (BMD) in college females. Subjects were 12 nonathletic females (< 3 h.wk-1 of exercise) and 46 female varsity athletes: basketball (N = 14), volleyball (N = 13), gymnastics (N = 13), and tennis (N = 6). Dual energy x-ray absorptiometry was used to determine BMD and body composition. The mean (+/- SD) age, height, weight, and menarche for the subjects were 19.9 +/- 2.1 yr, 167.9 +/- 9.4 cm, 62.1 +/- 9.0 kg, and 13.6 +/- 1.7 yr, respectively. Mean lumbar (1.327 g.cm-2), femoral neck (1.172 g.cm-2), and total body (1.200 g.cm-2) BMD of the athletes were significantly greater than nonathletes (P < 0.05) but did not differ among the teams. Significant correlations were found between regional leg BMD and leg lean tissue mass (LTM) (r = 0.59, P < 0.001) and between arm LTM and arm and lumbar BMD (r = 0.47 and 0.56, respectively). Significant correlations were also found between leg fat mass and leg BMD (r = 0.40). However, only regional LTM was a significant predictor of BMD using stepwise multiple regression. In summary, regional LTM appears to be a better predictor of BMD than regional fat mass.

The effects of gymnastics training on bone mineral density.

The purpose of this study was to examine the effect of 27 wk of gymnastics training on bone mineral density (BMD), body composition, insulin-like growth factor I (IGF-I), and osteocalcin. Subjects were 11 female intercollegiate gymnasts and 11 controls. Dual energy x-ray absorptiometry (Lunar DPX) was used to determine BMD (L2-L4 and femur) and to assess body composition. The gymnasts were significantly lower in weight (53.9 and 60.8 kg) and % body fat (22.6 and 30.6) compared with controls. After training, body weights of gymnasts remained the same but there was a significant increase in lean tissue mass of 2.9 kg (6.7%, P < 0.05). No changes in body composition were observed in the controls. The gymnasts had significantly higher mean lumbar (1.321 vs 1.225), and femoral neck (1.163 vs 1.079) BMD (g.cm-2) than the controls. Lumbar BMD increased significantly (1.3%) in gymnasts following training but femoral neck BMD did not increase. No BMD changes occurred in the control group. Regarding serum IGF-I, no differences were seen between the groups or across time. Serum osteocalcin values were significantly higher in the gymnasts than the controls, but no differences were found across time. In conclusion, gymnasts had significantly higher BMDs than controls, and a significant increase in lumbar BMD was seen in the gymnasts following 27 wk of training.