Predicting the risk of fracture at any site in the skeleton: are all bone mineral density measurement sites equally effective?

Serotonin reuptake inhibitors and bone health: A review of clinical studies and plausible mechanisms

Selective serotonin reuptake inhibitors (SSRIs) are currently the treatment of choice in depression and constitute major portion of prescription in depressive patients. The role of serotonin receptors in bone is emerging, raising certain questions regarding the effect of blockade of serotonin reuptake in the bone metabolism. Clinical studies have reported an association of SSRI antidepressants which with increase in fracture and decrease in bone mineral density. This review focus on recent evidence that evaluate the association of SSRIs with the risk of fracture and bone mineral density and also the probable mechanisms that might be involved in such effects.

Using Hounsfield Units to Assess Osteoporotic Status on Wrist Computed Tomography Scans: Comparison With Dual Energy X-Ray Absorptiometry

PURPOSE

Rates of evaluation and treatment for osteoporosis following distal radius fragility fractures remain low. As a subset of patients with these fractures undergo diagnostic computed tomography (CT) scan of the wrist, utilizing bone mineral density (BMD) measurements available with this imaging can be used to detect osteopenia or osteoporosis. This information may consequently prompt intervention to prevent a subsequent fracture. The purpose of this study was to determine if Hounsfield unit (HU) measurements at the wrist correlate with BMD measurements of the hip, femoral neck, and lumbar spine and to assess the ability of these HU measurements to detect osteoporosis of the hip.

METHODS

Forty-five female patients with distal radius fractures who underwent CT scan and dual energy x-ray absorptiometry scan as part of the management of their wrist fracture were identified. Bone mineral density measurements were made using the regional cancellous bone HU value at the capitate and compared with values obtained by a dual energy x-ray absorptiometry scan.

RESULTS

Hounsfield unit values at the capitate were significantly correlated with BMD and t scores at the femoral neck, hip, and lumbar spine. An HU threshold of 307 in the capitate optimized sensitivity (86%) and specificity (94%) for detecting osteoporotic patients.

CONCLUSIONS

By demonstrating that capitate HU measurements from clinical CT scans are correlated with BMD and t scores at the hip, femoral neck, and lumbar spine, our data suggest that clinical CT scans should have a role in detecting osteopenia and osteoporosis.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

Impacts of body mass index, physical activity, and smoking on femoral bone loss: the Tromsø study

Bone mineral density (BMD) is a reflection of bone strength and lifestyles that preserve bone mass and may reduce fracture risk in old age. This study examined the effect of combined profiles of smoking, physical activity, and body mass index (BMI) on lifetime bone loss. Data were collected from the population-based Tromsø Study. BMD was measured as g/cm(2) by dual-energy X-ray absorptiometry (DXA) at the total hip and femoral neck in 2580 women and 2084 men aged 30 to 80 years in the 2001-02 survey, and repeated in 1401 women and 1113 men in the 2007-08 survey. Height and weight were measured and lifestyle information was collected through questionnaires. Data were analyzed using linear mixed models with second-degree fractional polynomials. From the peak at the age around 40 years to 80 years of age, loss rates varied between 4% at the total hip and 14% at femoral neck in nonsmoking, physically active men with a BMI of 30 kg/m(2) to approximately 30% at both femoral sites in heavy smoking, physically inactive men with a BMI value of 18 kg/m(2) . In women also, loss rates of more than 30% were estimated in the lifestyle groups with a BMI value of 18 kg/m(2) . BMI had the strongest effect on BMD, especially in the oldest age groups, but a BMI above 30 kg/m(2) did not exert any additional effect compared with the population average BMI of 27 kg/m(2) . At the age of 80 years, a lifestyle of moderate BMI to light overweight, smoking avoidance, and physical activity of 4 hours of vigorous activity per week through adult life may result in 1 to 2 standard deviations higher BMD levels compared with a lifestyle marked by heavy smoking, inactivity, and low weight. In the prevention of osteoporosis and fracture risk, the effect of combined lifestyles through adult life should be highlighted. © 2014 American Society for Bone and Mineral Research.

Genetic markers of bone and joint health and physical capability in older adults: the HALCyon programme

BACKGROUND

Good bone and joint health is essential for the physical tasks of daily living and poorer indicators of physical capability in older adults have been associated with increased mortality rates. Genetic variants of indicators of bone and joint health may be associated with measures of physical capability.

METHODS

As part of the Healthy Ageing across the Life Course (HALCyon) programme, men and women aged between 52 and 90+ years from six UK cohorts were genotyped for a polymorphism associated with serum calcium (rs1801725, CASR), two polymorphisms associated with bone mineral density (BMD) (rs2941740, ESR1 and rs9594759, RANKL) and one associated with osteoarthritis risk rs3815148 (COG5). Meta-analysis was used to pool within-study effects of the associations between each of the polymorphisms and measures of physical capability: grip strength, timed walk or get up and go, chair rises and standing balance.

RESULTS

Few important associations were observed among the several tests. We found that carriers of the serum calcium-raising allele had poorer grip strength compared with non-carriers (pooled p=0.05, n=11,239) after adjusting for age and sex. Inconsistent results were observed for the two variants associated with BMD and we found no evidence for an association between rs3815148 (COG5) and any of the physical capability measures.

CONCLUSION

Our findings suggest elevated serum calcium levels may lead to lower grip strength, though this requires further replication. Our results do not provide evidence for a substantial influence of these variants in ESR1, RANKL and COG5 on physical capability in older adults.

Osteoporosis Canada 2010 guidelines for the assessment of fracture risk

Osteoporosis Canada's 2010 Clinical Practice Guidelines for the Diagnosis and Management of Osteoporosis in Canada focus on the clinical impact of fragility fractures, and on the assessment and management of women and men at high risk for fragility fracture. These guidelines now integrate a 10-year absolute fracture risk prediction into an overall management approach by using validated risk assessment tools. There currently is a large gap between optimal practices and those that are now being provided to Canadians with osteoporosis. These guidelines are part of a concerted effort to close this gap. Key changes from the 2002 guidelines of interest and relevance to radiologists are highlighted in this report.

Official Positions for FRAX® Bone Mineral Density and FRAX® simplification from Joint Official Positions Development Conference of the International Society for Clinical Densitometry and International Osteoporosis Foundation on FRAX®

Tools to predict fracture risk are useful for selecting patients for pharmacological therapy in order to reduce fracture risk and redirect limited healthcare resources to those who are most likely to benefit. FRAX® is a World Health Organization fracture risk assessment algorithm for estimating the 10-year probability of hip fracture and major osteoporotic fracture. Effective application of FRAX® in clinical practice requires a thorough understanding of its limitations as well as its utility. For some patients, FRAX® may underestimate or overestimate fracture risk. In order to address some of the common issues encountered with the use of FRAX® for individual patients, the International Society for Clinical Densitometry (ISCD) and International Osteoporosis Foundation (IOF) assigned task forces to review the medical evidence and make recommendations for optimal use of FRAX® in clinical practice. Among the issues addressed were the use of bone mineral density (BMD) measurements at skeletal sites other than the femoral neck, the use of technologies other than dual-energy X-ray absorptiometry, the use of FRAX® without BMD input, the use of FRAX® to monitor treatment, and the addition of the rate of bone loss as a clinical risk factor for FRAX®. The evidence and recommendations were presented to a panel of experts at the Joint ISCD-IOF FRAX® Position Development Conference, resulting in the development of Joint ISCD-IOF Official Positions addressing FRAX®-related issues.

Spine-hip T-score difference predicts major osteoporotic fracture risk independent of FRAX(®): a population-based report from CAMOS

The WHO fracture risk assessment tool (FRAX(®)) estimates an individual's 10-yr major osteoporotic and hip fracture probabilities. When bone mineral density (BMD) is included in the FRAX calculation, only the femoral neck measurement can be used. Recently, a procedure was reported for adjusting major osteoporotic fracture probability from FRAX with femoral neck BMD based on the difference (offset) between the lumbar spine and the femoral neck T-score values. The objective of the current analysis was to independently evaluate this algorithm in a population-based cohort of 4575 women and 1813 men aged 50 yr and older from the Canadian Multicentre Osteoporosis Study. For women and men combined, there was a 15% (95% confidence interval 7-24%) increase in major osteoporotic fracture risk for each offset T-score after adjusting for FRAX probability calculated with femoral neck BMD. The effect was stronger in women than men, but a significant sex interaction was not detected. Among the full cohort, 5.5% had their risk category reclassified after using the offset adjustment. Sex- and age-dependent offsets (equivalent to an offset based on Z-scores) showed improved risk classification among individuals designated to be at moderate risk with the conventional FRAX probability measurement. In summary, the T-score difference between the lumbar spine and femoral neck is an independent risk factor for major osteoporotic fractures that is independent of the FRAX probability calculated with femoral neck BMD.

Twenty bone-mineral-density loci identified by large-scale meta-analysis of genome-wide association studies

Bone mineral density (BMD) is a heritable complex trait used in the clinical diagnosis of osteoporosis and the assessment of fracture risk. We performed meta-analysis of five genome-wide association studies of femoral neck and lumbar spine BMD in 19,195 subjects of Northern European descent. We identified 20 BMD loci that reached genome-wide significance (GWS; P < 5 x 10(-8)), of which 13 map to regions not previously associated with this trait: 1p31.3 (GPR177), 2p21 (SPTBN1), 3p22 (CTNNB1), 4q21.1 (MEPE), 5q14 (MEF2C), 7p14 (STARD3NL), 7q21.3 (FLJ42280), 11p11.2 (LRP4, ARHGAP1, F2), 11p14.1 (DCDC5), 11p15 (SOX6), 16q24 (FOXL1), 17q21 (HDAC5) and 17q12 (CRHR1). The meta-analysis also confirmed at GWS level seven known BMD loci on 1p36 (ZBTB40), 6q25 (ESR1), 8q24 (TNFRSF11B), 11q13.4 (LRP5), 12q13 (SP7), 13q14 (TNFSF11) and 18q21 (TNFRSF11A). The many SNPs associated with BMD map to genes in signaling pathways with relevance to bone metabolism and highlight the complex genetic architecture that underlies osteoporosis and variation in BMD.

Bone mineral densities in individuals with Gilbert's syndrome: a cross-sectional, case-control pilot study

BACKGROUND

Unconjugated bilirubin inhibits osteoblastic proliferative activity in vitro, raising the possibility that Gilbert's syndrome (GS) patients are at increased risk of osteoporosis.

OBJECTIVES

To compare bone mineral density (BMD), serum parathyroid hormone (PTH), C-telopeptide (CTX) and osteocalcin levels in GS subjects versus matched controls in a cross-sectional, case-control study.

METHODS

BMD determinations were obtained with central dual energy x-ray absorptiometry. Serum PTH, CTX and osteocalcin levels were measured by enzyme immunoassay.

RESULTS

A total of 17 GS and 30 control subjects were studied. Overall, there were no significant differences in BMD, PTH, CTX or osteocalcin levels between the two groups. However, when older (older than 40 years of age) and younger (40 years of age and younger) cohorts were considered separately, the older GS cohort had significantly decreased total hip BMD, T scores and Z scores, and femoral neck BMD, T scores and Z scores (P<0.005 for each parameter, respectively) compared with older control subjects. Serum osteocalcin levels were lower in the older versus younger GS cohort (P=0.006). An inverse correlation existed between all subjects' serum unconjugated bilirubin levels and total body BMD determinations (r=-0.42; P=0.04). On univariate analysis, the association between serum unconjugated bilirubin and total body BMD was not significant (P=0.066), nor was serum unconjugated bilirubin identified as a risk factor for low BMD when entered into multivariate analyses.

CONCLUSIONS

The results of the present pilot study warrant further research involving larger numbers of subjects and longitudinal measurements to determine whether GS is associated with decreased BMD, particularly in older GS subjects.

Evolution and predictors of change in total bone mineral density over time in HIV-infected men and women in the nutrition for healthy living study

BACKGROUND

Osteopenia is common in the era of effective antiretroviral therapy (ART), yet the etiology is unclear. We evaluated the association of host factors, disease severity, and ART to changes in total body bone mineral density (total BMD) over time in HIV-infected men (n = 283) and women (n = 96).

METHODS

Total BMD was measured annually by whole-body dual-energy absorptiometry (DXA), and medical, dietary, and behavioral history was collected. The median time from first to last DXA was 2.5 years (range 0.9-6.8 years). Using a repeated measures regression model, we identified variables independently associated with percent change in total BMD between consecutive DXA exams (n = 799 intervals), adjusted for age, race, sex, menopause, and smoking. We estimated percent change in total BMD over an average interval (1 year) standardized for representative levels of each determinant in males, premenopausal women, and postmenopausal women.

RESULTS

Median baseline age, CD4, and viral load were 42 years, 364 cells per cubic millimeter, and 2.7 log10 copies per milliliter, respectively. The estimated change in total BMD for those not on ART was -0.37% per year [95% confidence interval (CI) -0.76 to -0.02] for men, -0.08% per year (95% CI -0.49 to 0.33) for premenopausal women, and -1.07% per year (95% CI -1.86 to -0.28) for postmenopausal women. Greater loss of total BMD was associated with lower albumin, lower body mass index, prednisone/hydrocortisone use, tenofovir use, and longer duration of didanosine. Strength training and long duration of d4T and saquinavir prevented or mitigated bone loss. For those on ART for 3 years (not including the above agents), the rate of loss was -0.57% per year (95% CI -1.00 to -0.14) for men, -0.28% (95% CI -0.71 to 0.15) for premenopausal women, and -1.27% (95% CI -2.07 to -0.47) for postmenopausal women. Postmenopausal women had greater loss than premenopausal women and men.

CONCLUSIONS

Low body weight, low albumin, catabolic steroid use, and menopause may accelerate bone loss, and strength training may be protective. Tenofovir and didanosine may also have a deleterious effect on BMD.

Guidelines for the diagnosis of osteoporosis: T-scores vs fractures

The development of bone mineral densitimometry methodologies, especially central dual energy X-ray absorptiometry (DXA) methods have allowed this quantitative tool to be used to diagnose osteoporosis before the first fragility fracture has occurred. The World Health Organization osteoporosis working group set the stage for the BMD cut-off criteria development. The wide application of DXA has brought the treatment of osteoporosis to the primary care level, a very necessary step if this increasingly prevalent disease is to have a decline in its incidence. The most difficult osteoporosis cases, for which there are many and their associated difficult DXA results and interpretation will always require specialists' involvement. In particular, the embracement of the WHO absolute fracture risk validated project will take DXA to a much greater level of value in making management decisions. In particular, the WHO absolute risk data will allow physicians, health-economic policy makers, and payors of medical services to come closer together to decide which patients are at a level of unacceptable fracture risk that justifies treatment intervention. The implementation of this validated project will also remove the unacceptable subjective computer printouts on DXA reports that often lead to the over-treatment of low risk patients and at times the under-treatment of high risk patients. The evolution of the clinical interpretation of bone densitometry has been a work in progress. Challenges in the clinical measurement of bone strength remain and will also evolve. The field of osteoporosis has grown with the use of DXA and will continue to embrace this technology as other technologies to measure fracture risk become applied in clinical practice.