The effect of measurement of the contralateral hip if the spine is not included in the bone mineral density analysis

Bilateral hip DXA Reporting: 2023 Official Positions of the International Society for Clinical Densitometry

INTRODUCTION

This position development conference (PDC) Task Force examined the use and reporting of bilateral hip bone mineral density (BMD) measurements. This was deemed appropriate as increased availability of Dual-energy X-ray Absorptiometry (DXA) technology offering bilateral hip measurement resulted in more routine clinical use. The International Society for Clinical Densitometry Official Positions accept bilateral hip BMD measurement for clinical use but currently do not include recommendations for reporting those studies.

METHODS

Four key questions regarding bilateral hip reporting were proposed by the PDC Steering Committee. Relevant literature was identified using PubMed. Questions included whether bilateral hip measurements are appropriate for diagnostic classification or monitoring, as well as which bilateral hip regions of interest should be reported for diagnosis and monitoring. Additionally, the appropriate nomenclature for bilateral hip acquisition was defined.

RESULTS

The literature review demonstrated that bilateral hip measurement is appropriate and diagnostic classification should be based on the lowest T-score at the right or left side femoral neck or total hip; the mean T-score should not be used for diagnostic purposes. Mean bilateral total hip is preferred for BMD monitoring. The terms hip, or total hip were deemed appropriate nomenclature instead of femur or total proximal femur.

CONCLUSION

Bilateral hip acquisition is clinically appropriate and reporting and nomenclature standards are offered herein when a bilateral hip study is acquired. In terms of future research, the impact of discordant hips on diagnosis and monitoring was identified as a significant knowledge gap.

Establishing a Total Hip T-Score Threshold to Measure Contralateral Hip Bone Mineral Density: Avoiding Missed Diagnosis of Osteoporosis

Bone mineral density (BMD) of the hip is routinely measured unilaterally, but can differ between left and right. This study aimed to establish total hip T-score thresholds for measuring contralateral hip BMD, to avoid missing the diagnosis of osteoporosis. In 4914 participants (2709 females) in the Busselton Healthy Ageing Study, BMD of both hips and lumbar spine (L1-L4) was measured by dual-energy x-ray absorptiometry (DXA) using a GE Lunar Prodigy Pro densitometer. Least significant change (LSC) was calculated according to International Society for Clinical Densitometry recommendations. For participants whose left-right total hip BMD difference exceeded LSC, the 95th percentile of the difference in T-score was calculated, then added to -2.5 (the cut-off for osteoporosis) to derive T-score thresholds for measuring contralateral hip to avoid a missed diagnosis in 95% of individuals. Participant mean age (±SD) was 57.4 ± 5.8 years; total hip T-score was 0.7 ± 0.1 in males and -0.2 ± 1.1 in females. Left and right total hip BMD were highly correlated (r = 0.943 for males, 0.959 for females), but in 56.2% of males and 50.0% of females, the left-right difference exceeded the LSC of 0.026 g/cm². In these participants, the 95th percentile of difference in T-score between two hips was 0.872 in males and 0.742 in females. This gave T-score thresholds for measuring contralateral total hip BMD of -1.6 (males) and -1.8 (females). When total hip T-score is between -1.6 and -2.5 (males), or between -1.8 and -2.5 (females), measuring contralateral hip BMD could avoid a missed diagnosis of osteoporosis.

Dual Hip DXA. Is it Time to Change Standard Protocol?

Previous studies have examined the utility of bilateral DXA hip bone mineral density (BMD) scans. While most studies demonstrate an advantage of bilateral hip scanning, the studies have been limited by size, or have not included simultaneous lumbar spine scans. To analyse the utility of dual hip scans in a clinical environment, a large retrospective study was performed of DXA BMD of both hips, and lumbar spine, in 17,169 individuals assessed at one centre over 10 years. There was no clinically significant difference in the population mean femoral neck BMD of the left vs the right leg (0.878 vs 0.881g/cm2) or total proximal femoral BMD of the left vs the right leg (0.920 vs 0.919g/cm2). There were however discrepancies in individuals between hip t-scores. For the total hip 1,977 (11.5 %) and 147 (0.9 %) of subjects had absolute t score differences ≥ 0.50 or ≥ 1.00. respectively. For the femoral neck 3,320 (19.3%) and 337 (2.0%) of subjects had absolute t score differences ≥ 0.50 or ≥ 1.00. respectively. Of the total 17,169 individuals there were 2,776 subjects with osteoporosis (T≤ -2.5) using the lumbar spine and right hip, compared to 2,834 subjects using the lumbar spine and left hip. Using the lumbar spine and both hips identified 3,214 individuals with osteoporosis. Diagnosis based on use of the lumbar spine and right hip BMD, or lumbar spine and left hip BMD, therefore failed to identify 15.8%, or 13.4%, of osteoporotic subjects respectively. Additional scanning time required was assessed in 40 subjects prospectively. Performing lumbar spine and both hips, compared to lumbar spine and one hip, required an average additional scan time of 55 seconds. The recommendation of best practise for DXA BMD measurements should be reviewed to consider lumbar spine and dual hip DXA as standard of care.

Study of the variations of fall induced hip fracture risk between right and left femurs using CT-based FEA

Background

Hip fracture of elderly people—suffering from osteoporosis—is a severe public health concern, which can be reduced by providing a prior assessment of hip fracture risk. Image-based finite element analysis (FEA) has been considered an effective computational tool to assess the hip fracture risk. Considering the femoral neck region is the weakest, fracture risk indicators (FRI) are evaluated for both single-legged stance and sideways fall configurations and are compared between left and right femurs of each subject. Quantitative Computed Tomography (QCT) scan datasets of thirty anonymous patients’ left and right femora have been considered for the FE models, which have been simulated with an equal magnitude of load applied to the aforementioned configurations. The requirement of bilateral hip assessment in predicting the fracture risk has been explored in this study.

Results

Comparing the sideways fall and single-legged stance, the FRI varies by 64 to 74% at the superior aspects and by 14 to 19% at the inferior surfaces of both the femora. The results of this in vivo analysis clearly substantiate that the fracture is expected to initiate at the superior surface of femoral neck region if a patient falls from his/her standing height. The distributions of FRI between the femurs vary considerably, and the variability is significant at the superior aspects. The p value (= 0.02) obtained from paired sample t-Test yields p value ≤ 0.05, which shows the evidence of variability of the FRI distribution between left and right femurs. Moreover, the comparison of FRIs between the left and right femur of men and women shows that women are more susceptible to hip fracture than men.

Conclusions

The results and statistical variation clearly signify a need for bilateral hip scanning in predicting hip fracture risk, which is clinically conducted, at present, based on one hip chosen randomly and may lead to inaccurate fracture prediction. This study, although preliminary, may play a crucial role in assessing the hip fractures of the geriatric population and thereby, reducing the cost of treatment by taking predictive measure.

Correlating Whole-Body Bone Mineral Densitometry Measurements to Those From Local Anatomical Sites

Background:

Using the same cutoff points for whole-body measurements as for site-specific measurements will result in underestimation of osteoporosis.

Objectives:

We assessed the correlation between densitometry measurements for the whole body with those for the femur, lumbar spine, and forearm to evaluate the possibility of replacing site-specific values with whole-body measurements.

Patients and Methods:

In this cross-sectional study, we evaluated all patients referred to a single rheumatology clinic for bone mineral density measurements from 2009 to 2010. All patients who had bone mineral density measurements taken from the hip, lumbar spine, forearm, and whole body were enrolled in the study. Standard bone mineral density measurements were performed using a dual energy X-ray absorptiometry device (Hologic Delphi A; Hologic, Bedford, MA, USA). Bone mineral density, Z-score, and T-score were measured for all patients and all body regions.

Results:

The mean age of the 152 participating patients was 56.7 ± 12.6 years, and 97.4% were female. Pearson correlation coefficients of the whole-body bone mineral density values compared with site-specific values in patients over age 50 were 0.66 – 0.75. Using T-score cutoff points of -1 and -2.5 for osteopenia and osteoporosis, whole-body measurements underestimated the percentage of abnormal patients compared with the site-specific measurements (all P < 0.001). Using receiver operating characteristic (ROC) analysis, the whole-body bone mineral density showed respective areas under the curve of 0.96 and 0.84 for the diagnosis of abnormal hip bone mineral density and osteoporosis.

Conclusion:

Using the same cutoff points for whole-body measurements as for site-specific measurements will result in overestimation or especially underestimation of osteopenia and osteoporosis diagnosis. Choosing new and appropriate cutoff points for whole-body densitometric measurements when we want to substitutes this assessment instead of site specific measurements seems mandatory and will decrease the rate of false diagnoses of densitometric deficiencies in these anatomical sites.

Endpoint comparison for bone mineral density measurements in North Central Cancer Treatment Group cancer clinical trials N02C1 and N03CC (Alliance)

Bone mineral density (BMD) measurement can vary depending upon anatomical site, machine, and normative values used. This analysis compared different BMD endpoints in two clinical trials. Trial results differed across endpoints. Future clinical trials should consider inclusion of multiple endpoints in sensitivity analysis to ensure sound overall study conclusions.

INTRODUCTION

Methodological issues hamper efficacy assessment of osteoporosis prevention agents in cancer survivors. Osteoporosis diagnosis can vary depending upon which bone mineral density (BMD) anatomical site and machine is used and which set of normative values are applied. This analysis compared different endpoints for osteoporosis treatment efficacy assessment in two clinical studies.

METHODS

Data from North Central Cancer Treatment Group phase III clinical trials N02C1 and N03CC (Alliance) were employed involving 774 patients each comparing two treatments for osteoporosis prevention. Endpoints for three anatomical sites included raw BMD score (RawBMD); raw machine-based, sample-standardized, and reference population-standardized T scores (RawT, TSamp, TRef); and standard normal percentile corresponding to the reference population-standardized T score (TPerc). For each, treatment arm comparison was carried out using three statistical tests using change and percentage change from baseline (CB, %CB) at 1 year.

RESULTS

Baseline correlations among endpoints ranged from 0.79 to 1.00. RawBMD and TPerc produced more statistically significant results (14 and 19 each out of 36 tests) compared to RawT (11/36), TSamp (8/36), and TRef (7/36). Spine produced the most statistically significant results (26/60) relative to femoral neck (20/60) and total hip (13/60). Lastly, CB resulted in 44 statistically significant results out of 90 tests, whereas %CB resulted in only 15 significant results.

CONCLUSIONS

Treatment comparisons and interpretations were different across endpoints and anatomical sites. Transforming via sample statistics provided similar results as transforming via reference or machine-based norms. However, RawBMD and TPerc may be more sensitive to change as clinical trial endpoints.

Discrepancy of left and right hip bone mineral density (BMD) in Thai women: diagnostic agreement and misclassification

OBJECTIVE

To determine the diagnostic agreement and the degree of misclassification when using data from the left and right hips.

METHODS

The cross-sectional study of 1,943 perimenopausal and postmenopausal Thai women, who had bone mineral density (BMD) measurements at the left (non-dominant) and right hips for the screening of low bone mass (LBM) or osteoporosis (OP) in the Department of Radiology, Faculty of Medicine, Chiang Mai University from September 2008 to August 2010 was performed. The kappa statistic was used to assess diagnostic agreement. The prevalence of LBM and OP and the percentage of misclassification were reported.

RESULTS

There was a significant correlation between the left and right BMD values for the femoral neck (FN) (r (2) = 0.83; p < 0.001) and the total hip (TH) (r (2) = 0.89; p < 0.001). The diagnostic agreement of the FN and TH regions was significant in all study groups ranging from 0.69 to 0.76 (p < 0.001). For the final diagnosis, which is based on the least T-score of the FN or TH regions, the diagnostic agreement was 0.73 for all women, 0.77 for perimenopausal women, 0.73 for postmenopausal women, 0.70 for postmenopausal women age less than 65 years and 0.71 for postmenopausal women age greater than or equal to 65 years. The percentage of misclassification for all women was 16.9 %, with 3.3 % being downgraded from normal to LBM and 3.4 % from LBM to OP.

CONCLUSION

Despite the fact that good diagnostic agreement was demonstrated in this study, a significant number of diagnostic discordance between left and right hips (16.9 %) was also observed. BMD measurements of both hips are recommended for diagnosing LBM and OP in clinical practice.

Prevalence and Risk Factors of Discordance between Left- and Right-Hip Bone Mineral Density Using DXA

To determine the prevalence of significant left-right differences in hip bone mineral density (BMD), and the impact of this difference on osteoporosis diagnosis, we measured bilateral proximal femora using dual energy X-ray absorptiometry (DXA) in 3481 subjects (608 males, 2873 females). The difference between left and right hip was considered significant if it exceeded the smallest detectable difference (SDD) for any of the three hip subregions. Contralateral femoral BMD was highly correlated at all measuring sites (r = 0.92-0.95). However, significant left-right differences in BMD were common: the difference exceeded the SDD for 54% of patients at total hip, 52.1% at femoral neck, and 57.7% at trochanter. The prevalence of left-right differences was greater in participants >65 years. For 1169 participants with normal spines, 22 (1.9%) had discordant left-right hips in which one hip was osteoporotic; for 1349 patients with osteopenic spines, 94 (7%) had osteoporosis in one hip. Participants with BMI < 20 kg/m(2) were more likely to show major T-score discordance (osteoporosis in one hip and normal BMD in the other). Multiple regression analysis showed that the only significant statically parameter that persists after adjusting for all potential confounding parameters were age over 65 years.

Underestimated fracture probability in patients with unilateral hip osteoarthritis as calculated by FRAX

Osteoporosis (OP) and osteoarthritis (OA) are age-related diseases often considered to be mutually exclusive. We previously found that 25% of women with advanced OA had occult OP and that femoral neck (FN) bone mineral density (BMD) T-scores were significantly higher for osteoarthritic vs contralateral hips. The FRAX calculator incorporates clinical risk factors and FN BMD T-score to estimate 10-yr total fracture probability and hip fracture probability. In 35 women and men aged 41 yr or older with unilateral hip OA scheduled for hip replacement, we tested whether FRAX fracture probability is underestimated when using data for the OA rather than the contralateral hip. There were between-hip differences for FN BMD T-score (p<0.0001), total fracture probability (p =0.0004), and hip fracture probability (p =0.0009). Use of FN BMD T-scores resulted in OP treatment recommendations for 0% and 11% of subjects compared with 11% and 17% for total fracture probability and hip fracture probability, respectively. In 6-11% of subjects in this series, the FRAX calculator underestimated fracture probability with data for the OA hip. With the increased use of FRAX in clinical use, these data suggest that measurement of BMD at the contralateral hip may yield higher calculated FRAX total and hip fracture probabilities.

Discordance in femoral neck bone density in subjects with unilateral hip osteoarthritis

Osteoarthritis (OA) is a common disease that increases in incidence with age and currently affects an estimated 27 million Americans. To determine whether site-specific hip bone mineral density (BMD) measures are confounded by the presence of OA, we measured bilateral hip BMD by dual X-ray absorptiometry in 34 subjects (19 women and 15 men) scheduled for hip replacement for confirmed advanced unilateral hip OA. The femoral neck (FN) BMD (p=0.035) and T-score (p=0.017) for the hip with OA was higher than those of the contralateral hip. There was a difference in osteoporosis classification depending on which hip was considered: for 11 of the 34 subjects (32%), the FN T-score was normal for OA hip, but the contralateral hip was classified as osteopenic (T-score between -1.0 and -2.5). For 1 subject, the FN T-score was normal for OA hip, but the contralateral hip was classified as osteoporotic (T-score below -2.5). Discordance was also present for trochanter values and not for total hip values. These data indicate that advanced hip OA can be associated with a higher bone density at the FN and trochanter but not at total hip and that the discrepancy between hips at the FN may have an impact on patient treatment decisions.

Effect of the bilateral hip bone density measurement on clinical practice in elderly subjects

OBJECTIVES

The aim of this study was to determine whether the addition of the measurement of bilateral hip bone mineral density (BMD) has an impact on indications for osteoporosis (OP) treatment in community-dwelling elderly individuals, based on criteria from the National Osteoporosis Foundation (NOF).

METHODS

In total, 605 consecutive community-dwelling elderly individuals who were 65 years and older were evaluated. Dual energy X-ray absorptiometry was used to determine the lowest T-score in the lumbar spine+unilateral hip, the bilateral hips, and the lumbar spine+bilateral hips. Risk factors associated with the lowest T-score in these three conditions were applied to indicate treatment in accordance with NOF criteria. McNemar's test was used to assess the difference of adding bilateral hip BMD measurements.

RESULTS

There was a significant difference in the frequency of pharmacological indication using NOF criteria together with the lowest T-score for the three tests (72.8% for lumbar spine+bilateral hips and 71.2% for lumbar spine+unilateral hip; p=0.002). A higher frequency of treatment indication was also observed for lumbar spine+unilateral hip (71.2%) compared to bilateral hips (61.1%) (p<0.001). The discrepancies in treatment appeared to be more evident in women when analyzed by gender distribution.

CONCLUSION

Our finding supports the theory that evaluation of the bilateral hips with the lumbar spine seems to be more sensitive measure for identifying patients with an osteoporosis treatment indication. Furthermore, despite the well-known artifact in the lumbar spine, this site should not be excluded when determining the indication for OP treatment in elderly people.

Bilateral femoral bone mineral density measurements in Chinese women and men

The aim of this study was to assess the contralateral femoral bone mineral density (BMD) difference as measured by dual-energy X-ray absorptiometry (DXA) in mainland Chinese women and men. We measured bilateral proximal femora (i.e., total hip, femoral neck, upper femoral neck, and trochanter) using DXA in 1101 subjects (284 males, 817 females), among whom 504 were postmenopausal. Data were analyzed by descriptive statistics, Student's t-tests, and Pearson's correlation coefficients (r). With bilateral femur measurements and the acquisition of the mean BMD, precision error could be significantly reduced at the total hip, the femoral neck, and the upper femoral neck. Contralateral femoral BMD was highly correlated at all measuring sites (r=0.879-0.964). For the male group and for the postmenopausal subgroup, no significant differences in contralateral femoral BMDs were found. In the postmenopausal women, the percentage of subjects with discordance in classification (i.e., normal, osteopenia, and osteoporosis) for the left and right femora declined from 16.9% to 8.1% with precision adjustment. From a population perspective, since there may still be a considerable number of misdiagnosed cases, we therefore suggest that bilateral femur measurements may be justified for postmenopausal Chinese women.