Study to Compare the Efficacy and Safety of DenosumAb Versus Placebo in Males With Osteoporosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study to Compare the Efficacy and Safety of DenosumAb Versus Placebo in Males With Osteoporosis (NCT00980174), a randomized phase 3 study. The primary outcome is Lumbar Spine Bone Mineral Density Percent Change From Baseline at Month 12.

2. Clinical Question

This question concerns a measured change in bone mineral density, not fractures or other clinical events. The study’s stated purpose was to assess efficacy and safety in men with low bone mass at risk of fracture. The primary endpoint is a continuous measure: each participant’s change is represented on a percentage scale, and the comparison focuses on group means. Other listed outcomes include bone mineral density at additional skeletal sites and a serum marker. Those outcomes address related but distinct measures and do not replace the specified primary question.

3. Trial Design

The registry identifies this as a phase 3, randomized, triple-masked, placebo-controlled crossover study. Its official title describes a multicenter study in males with low bone mineral density. Enrollment was 242, and the record lists the study as completed. The recorded start date is 2009-10-01 and the primary completion date is 2011-06-21.

The treatment sequence began with a 1-year double-blind phase. One group received denosumab 60 mg by subcutaneous injection every 6 months; the other received placebo by the same schedule. In the following 1-year open-label phase, both groups received denosumab on the listed schedule. Thus, the placebo group crossed over to denosumab after the blinded comparison, while the group initially assigned to denosumab continued treatment. The registry describes the initially assigned denosumab group as receiving denosumab for a total of 2 years.

The primary endpoint was assessed from baseline to month 12, at the end of the double-blind phase. That timing corresponds to the initial randomized comparison before the placebo group’s switch. The endpoint analysis lists 118 participants for placebo and 117 for denosumab 60 mg Q6M. The record defines the endpoint population as subjects with a baseline and at least one post-baseline measurement; it does not explain the difference between enrollment and those endpoint counts.

The registry does not report the randomization ratio, sequence-generation procedure, allocation concealment details, or operational details of masking. It also does not give further information about site count or how the crossover period was handled analytically. Those features should not be inferred from the design label alone.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Subjects with baseline and at least one post baseline measurements

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Lumbar Spine Bone Mineral Density Percent Change From Baseline at Month 12, measured over From Baseline to 12 Months.

The primary endpoint is the percent change from baseline in lumbar spine bone mineral density at month 12. Bone mineral density is a continuous measurement of mineral content in bone; expressing change as a percentage relates the follow-up measurement to the participant’s baseline measurement. The endpoint summarizes the average change in each treatment group and supports a direct comparison of group means.

Lumbar spine bone mineral density was selected as the primary measure in the stated clinical hypothesis. The registry specifies that the hypothesis concerns whether the mean percent change at 12 months is greater among participants receiving denosumab than among those receiving placebo. A continuous endpoint can detect and describe shifts in a measured quantity without requiring that each participant experience a categorical event. Its interpretation remains specific to the bone-density measure and assessment time: it is not itself a count of fractures or a measure of symptoms, function, or survival.

The primary endpoint timeframe is baseline to 12 months. The endpoint population includes subjects with baseline and at least one post-baseline measurement. The registry lists the endpoint as a mean with a 95% confidence interval. It does not report the instrument or technical procedure used to obtain the bone mineral density measurements, nor does it give further detail about the endpoint’s handling of repeated measurements or missing values.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the mean represent?

A mean is the average of the observed values in a group. Here, the values are percent changes in lumbar spine bone mineral density from baseline to month 12. The posted means describe the average change among the participants included in the endpoint summaries. They do not describe the spread of individual responses, because no standard deviation or other measure of participant-level variability is reported with these arm summaries.

For a continuous endpoint, comparing means is one way to summarize how two groups differ. The registry also reports a net mean difference from an ANCOVA analysis. ANCOVA, in general, compares group outcomes while accounting for one or more covariates in a statistical model. The registry names ANCOVA but does not report which covariates were used, how they were selected, or the model specification. It is therefore possible to describe the reported method, but not to reconstruct its adjustment from the registry entries.

How should the confidence interval be read?

In general, a confidence interval expresses the statistical uncertainty around an estimated quantity under the assumptions of the analysis. The reported 95% confidence interval for the net mean difference runs from 4.0 to 5.6. A narrower interval indicates greater precision than a wider interval on the same scale, but precision depends on the data and analysis and does not by itself establish clinical importance. The interval concerns the estimated group mean difference, not a range expected to contain the change for most individual participants.

The arm-specific confidence intervals describe uncertainty around each arm’s mean. They are not interchangeable with the confidence interval for the between-group contrast. The contrast is the direct statistical comparison of interest, and the registry reports its own interval from the ANCOVA analysis.

What does the p-value convey?

In general, a p-value measures how incompatible the observed data are with a specified null hypothesis, assuming the statistical model and its assumptions apply. The reported p-value is p < 0.001. It is not the probability that treatment has no effect, and it does not measure the size or clinical importance of the difference. Interpretation is stronger when considered alongside the estimated difference and its confidence interval.

The primary hypothesis was directional, stating that the mean percent change with denosumab would be greater than with placebo. The registry’s reported analysis is categorized as superiority or other, and it reports the p-value and interval. The record does not describe whether the inferential test was one-sided or two-sided; the separate sample-size illustration assumptions do not establish the testing procedure used for the trial analysis.

Why does the design timing matter?

The study is identified as a crossover design, but its first year provides the randomized, double-blind comparison of denosumab and placebo. The primary endpoint is measured at month 12, before the placebo group switches to denosumab in the open-label phase. This timing makes the primary comparison different from a comparison of outcomes after both groups have received denosumab. The registry does not report an analysis of the open-label period in the primary result.

In general, crossover studies can require attention to treatment sequence, period effects, and carryover. Those issues concern comparisons across treatment periods. Because the primary endpoint is specified at the end of the initial blinded phase, the interpretation centers on the randomized first-year comparison. The registry does not report a detailed model for the later phase or analyses of sequence and period effects.

What is not established by these methods details?

The registry provides an endpoint population definition and identifies ANCOVA, but does not report a full statistical analysis plan, covariates, missing-data method, or analysis population beyond that endpoint description. It does not report interim analyses or a sample-size justification. General statistical considerations can explain why these details matter: model choices and missing-data assumptions can affect an estimate, and prespecified planning can clarify which analyses were intended to be confirmatory. Their absence from the registry record means those aspects cannot be evaluated from the posted information.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s ANCOVA result as a net mean difference of 4.8, with a 95% confidence interval from 4.0 to 5.6 and p < 0.001. The arm-level means are 0.9 for placebo and 5.7 for denosumab 60 mg Q6M. The ANCOVA estimate is the analysis result to use when describing the sponsor’s formal comparison; it is not necessarily identical to a simple contrast of unadjusted arm summaries, because ANCOVA can account for model covariates.

The registry does not provide the ANCOVA covariates or enough model detail to reproduce the sponsor’s analysis. Nor does it include a separate recalculated estimate in the record. Accordingly, the reported ANCOVA estimate and its interval are the available inferential results. No discrepancy is flagged between a sponsor result and a recalculation in the registry information.

The confidence interval and p-value should be read as features of that reported analysis, subject to its assumptions. The result concerns the mean difference in month-12 lumbar spine bone mineral density percent change for the endpoint population. It does not describe an individual treatment effect, establish results for the secondary endpoints, or substitute for a missing-data or sensitivity analysis that is not reported in the registry record.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and six analyses, with five secondary outcomes posted in addition to the primary endpoint. The secondary measures cover bone mineral density percent change at the total hip, femoral neck, trochanter, and distal 1/3 radius at month 12, along with serum CTX percent change at Day 15. These endpoints address multiple measures and timepoints. When several hypotheses are examined, the chance of obtaining at least one small p-value by chance can increase; statistical procedures for multiplicity can be used to control that issue.

The registry record does not report whether multiplicity adjustment was planned or applied, which outcomes were designated confirmatory, or how results across the endpoint family were interpreted. No conclusion about adjustment should be inferred from the number of listed analyses alone. The primary result can be described as reported, while claims involving multiple outcomes require information about the analysis plan that is not reported in the registry record.

The primary endpoint population is defined as subjects with baseline and at least one post-baseline measurement. This definition does not state how missing outcomes were handled, whether values were imputed, or whether participants without a post-baseline measurement were excluded. The registry record does not report the analysis population as intention-to-treat or per-protocol, and it does not explain the relation between the enrolled total and the endpoint counts. It also does not report sensitivity analyses addressing missing data.

General statistical practice treats missing-data assumptions as important because different assumptions can lead to different estimates. An analysis restricted to participants with available measurements can be affected if the availability of measurements is related to participant characteristics or outcomes. Without the missing-data method and relevant sensitivity analyses, the robustness of the posted estimate to missingness cannot be assessed from the registry record.

The record does not report a sample-size justification, interim analyses, or a full statistical analysis plan. Therefore, it is not possible to determine the intended power, prespecified testing hierarchy, or any planned interim decision rules from the registry information.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: prostate cancer (2.5%), arterial thrombosis limb (1.7%), acute myocardial infarction (0.8%), atrial fibrillation (0.8%), myocardial infarction (0.8%).

The safety record lists serious adverse events among 120 participants at risk in each group. Serious adverse events affected 10 participants in the placebo group and 11 in the denosumab 60 mg Q6M group. Other adverse events affected 27 participants in the placebo group and 23 in the denosumab group, each with 120 at risk. These are counts of affected participants as recorded, not estimates of whether a treatment caused an event.

The record also lists serious-event terms with percentages: Prostate cancer, 2.5%; Arterial thrombosis limb, 1.7%; Acute myocardial infarction, 0.8%; Atrial fibrillation, 0.8%; Myocardial infarction, 0.8%; and Skull malformation, 0.8%. The registry information does not specify the group attribution for these listed terms, so they should not be assigned to one treatment arm. The death counts are not reported in the registry record.

Safety comparisons need context beyond these summary counts. The posted figures do not give event timing, duration, severity grading beyond the serious classification, participant-level overlap, or exposure-adjusted rates. The two-year treatment sequences also differ during the first year and converge to denosumab in the open-label phase. The figures should therefore be read as registry summaries, not as a complete comparison of causation or long-term risk.

13. What the Result Does, and Does Not, Mean

The primary result describes a difference in the average month-12 change in lumbar spine bone mineral density between the randomized groups during the double-blind phase. The denosumab group’s posted mean was 5.7 and the placebo group’s was 0.9; the sponsor’s ANCOVA analysis reported a net mean difference of 4.8. The 95% confidence interval from 4.0 to 5.6 characterizes uncertainty in that estimated contrast, and the reported p-value was p < 0.001.

This is a result about a measured intermediate outcome. It does not directly show how many fractures occurred, whether fracture risk differed, or how participants felt or functioned. Although the study purpose refers to men with low bone mass at risk of fracture, the posted primary endpoint is bone mineral density change, not fracture incidence. No fracture outcome is identified among the listed secondary measures.

A group mean also does not imply that every participant experienced the same change. Individual responses may vary, but the registry does not report a measure of variability for the arm summaries or a distribution of individual changes. The confidence interval around a mean difference is not a prediction interval for individual participants.

The evidence is specific to the registry’s study population, treatment schedule, endpoint population, and month-12 assessment. The placebo group switched to denosumab during the subsequent open-label phase, so the primary comparison does not describe a continuing placebo comparison over the full study duration. The record does not provide long-term comparative efficacy results or enough detail to assess every aspect of analysis robustness.

The safety counts likewise require cautious interpretation. They describe reported event counts in the registry and cannot alone establish whether an event was caused by a treatment or whether the overall safety profiles differ. The result should be understood as statistical evidence about the primary endpoint, alongside the limitations in outcome scope, missing-data reporting, and analysis detail.

14. Why This Trial Matters Statistically

This study illustrates why identifying the estimand and assessment time is central to reading trial results. The trial is labelled as a crossover design, yet the primary comparison is made at month 12, at the end of the initial double-blind phase. The placebo group’s later switch to denosumab means the primary endpoint addresses the randomized comparison before crossover, rather than a sustained comparison of denosumab against placebo throughout the entire study.

It also illustrates the difference between arm summaries and a model-based comparison. The registry posts group means and confidence intervals, alongside an ANCOVA estimate of the net mean difference. The latter is the reported formal contrast, but the absence of covariate and model details limits independent reconstruction. Statistical interpretation should therefore make clear which result is being described and avoid treating the methods label as sufficient detail to reproduce it.

The endpoint is continuous and measured at a specified anatomical site and time. That permits a precise question about average change, but it does not answer every clinical question connected to osteoporosis or fracture risk. Distinguishing a measured surrogate or intermediate outcome from clinical events prevents overstatement.

Finally, multiplicity, analysis populations, missing data, and safety summaries affect how much can be learned from registry results. The record identifies several secondary outcomes but does not describe multiplicity procedures or missing-data methods. These gaps do not erase the reported primary estimate, but they define the limits of what can be inferred from it. A careful reading separates the clear numerical result from details that are not reported.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry reports an endpoint population consisting of subjects with baseline and at least one post-baseline measurement, but does not explain the handling of missing measurements or whether all randomized participants were included in the primary analysis. The endpoint counts are 118 for placebo and 117 for denosumab 60 mg Q6M, while enrollment is 242; reasons for the difference are not reported in the registry record.

Although the primary analysis is identified as ANCOVA, the model covariates, assumptions, and full specification are not reported. The record does not provide the randomization procedure, allocation concealment details, or operational masking procedures. It also does not report an analysis plan, sample-size justification, interim analyses, or multiplicity adjustment for the six listed outcome measures and analyses.

The primary endpoint is a bone mineral density measure at month 12. It is not a direct clinical event outcome, and the listed secondary outcomes do not include a fracture measure. The record does not provide individual-level variability for the arm means, detailed measurement procedures, or additional long-term comparative efficacy results. The open-label phase follows the primary endpoint and no details are reported about its analysis.

Safety information is also limited in scope. The registry lists affected-participant counts and serious-event terms, but does not report event timing, exposure-adjusted rates, or death counts. It does not specify the treatment-group attribution of the listed serious-event terms. These reporting limits prevent a full assessment of comparative safety from the registry summaries alone.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study to Compare the Efficacy and Safety of DenosumAb Versus Placebo in Males With Osteoporosis — NCT00980174.
• Registry record last updated 2018-10-17; status last verified 2018-09.
• Results first posted 2012-11-29.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

This completed phase 3 study randomized men with low bone mineral density to denosumab 60 mg Q6M or placebo during a 1-year double-blind phase, followed by a 1-year open-label phase in which both groups received denosumab. Enrollment was 242. The primary endpoint was percent change from baseline in lumbar spine bone mineral density at month 12.

Posted mean changes were 0.9 for placebo and 5.7 for denosumab. The reported ANCOVA net mean difference was 4.8, with a 95% confidence interval from 4.0 to 5.6 and p < 0.001. The endpoint population was defined as subjects with baseline and at least one post-baseline measurement. Five secondary outcomes are listed.

The registry does not report the full model specification, missing-data method, multiplicity approach, or sample-size justification. Safety summaries include serious and other adverse-event counts; death counts are not reported in the registry record.