Bone mineral density (BMD) assessment of central skeletal sites from peripheral BMD and ultrasonographic measurements: an improved solution employing age and weight in type 3 regression

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.

Calcaneal quantitative ultrasound and phalangeal radiographic absorptiometry alone or in combination in a triage approach for assessment of osteoporosis: a study of older women with a high prevalence of falls

Background

The objective of this study was to investigate if application of United Kingdom National Osteoporosis Society (UK-NOS) triage approach, using calcaneal quantitative ultrasound (QUS), phalangeal radiographic absorptiometry (RA), or both methods in combination, for identification of women with osteoporosis, would reduce the percentage of women who need further assessment with Dual Energy X-ray Absorptiometry (DXA) among older women with a high prevalence of falls.

Methods

We assessed 286 women with DXA of hip and spine (Hologic Discovery) of whom 221 were assessed with calcaneal QUS (Achilles Lunar), 245 were assessed with phalangeal RA (Aleris Metriscan), and 202 were assessed with all three methods. Receiver operator characteristics (ROC) curve for QUS, RA, and both methods in combination predicting osteoporosis defined by central DXA were performed. We identified cutoffs at different sensitivity and specificity values and applied the triage approach recommended by UK-NOS. The percentage of women who would not need further examination with DXA was calculated.

Results

Median age was 80 years (interquartile range [IQR]) [75–85], range 65–98. 66.8% reported at least one fall within the last 12 months. Prevalence of osteoporosis was 44.4%. Area under the ROC-curve (AUC) (95% confidence interval (CI)) was 0.808 (0.748-0.867) for QUS, 0.800 (0.738-0.863) for RA, and 0.848 (0.796-0.900) for RA and QUS in combination. At 90% certainty levels, UK-NOS triage approach would reduce the percentage of women who need further assessment with DXA by 60% for QUS, and 43% for RA. The false negative and false positive rates ranged from 4% to 5% for QUS and RA respectively. For the combined approach using 90% certainty level the proportion of DXAs saved was 22%, the false negative rate was 0% and false positive rate was 0.5%. Using 85% certainty level for the combined approach the proportion of DXAs saved increased to 41%, but false negative and false positive values remained low (0.5%, and 0.5% respectively).

Conclusions

In a two-step, triage approach calcaneal QUS and phalangeal RA perform well, reducing the number of women who would need assessment with central DXA. Combining RA and QUS reduces misclassifications whilst still reducing the need for DXAs.