Single Dosing of Zoledronic Acid in Cancer Therapy Induced Bone Loss (CTIBL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Single Dosing of Zoledronic Acid in Cancer Therapy Induced Bone Loss (CTIBL) (NCT00712985), a na phase 3 study. The primary outcome is Number of Participants With Urine and Serum NTx and Serum CTx Within Normal Range at 12 Months.

2. Clinical Question

3. Trial Design

This was a Phase 3, single-group study of zoledronic acid in the setting of cancer therapy induced bone loss. The registry lists the condition as breast cancer and the intervention as Zometa, a drug. The treatment description specifies one 5 mg intravenous dose. No allocation method or masking was reported; the record identifies the study as having no masking and no randomized comparison.

The registry enrollment is 18. The primary-outcome description states that 17 women with early breast cancer receiving adjuvant aromatase inhibitor therapy were treated with a single dose. The record does not explain why these figures differ, whether all enrolled participants received treatment, or which participants contributed to the primary endpoint.

The stated study aim was to assess whether a once-yearly dose could suppress and maintain urine and serum NTx and serum CTx within the normal range at 12 months after dosing. The outcome description indicates measurements at baseline and month 12, while the endpoint timeframe is given as one year. The record does not describe the timing or conduct of other study assessments.

The study is listed as completed. Its start is recorded as 2005-09, and primary completion as 2011-03. These dates do not establish the duration of follow-up for any individual participant. The protocol details, eligibility criteria beyond the population description, planned analysis, and reasons for the design choices are not reported in the registry record.

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.

Before assignment: Following consent, this trial only had 1 arm \& all patients were given a one time dose of Zoledronic Acid 5 mg IV. All 17 patients were then followed for 12 months from day 1 \& their urine \& serum were collected in order to evaluate the urine N-telopeptide (NTx) \& serum NTx \& C-telopeptide (CTx) levels.

Overall Study

Reasons for not completing this period:

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.

Population: 18 patients signed consent \& 1 withdrew due to family not wishing her to continue with trial.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Urine and Serum NTx and Serum CTx Within Normal Range at 12 Months, measured over One year.

The primary endpoint is the number of participants with urine and serum NTx and serum CTx within the normal range at 12 months. NTx and CTx are bone turnover markers; the stated purpose was to assess whether marker levels were suppressed and maintained within the normal range following treatment. The outcome description says the markers were measured at baseline and month 12.

A count of participants meeting a prespecified threshold can provide an interpretable description of how many people reached a defined biomarker state at the follow-up assessment. It does not, by itself, describe the size of change in each marker, how levels varied between participants, or whether any change was attributable to treatment. Those questions require additional measurements and an analysis appropriate to them.

The registry does not report the number meeting the endpoint, marker values, the laboratory thresholds defining normal, or how the combined endpoint was applied across the markers. It is therefore not possible to assess the observed biomarker outcome from the registry record. The endpoint also concerns laboratory measurements, not a reported clinical outcome such as symptoms or disease events.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count measure?

The primary endpoint is a count: the number of participants whose urine and serum NTx and serum CTx were within the normal range at 12 months. In general, a count records how many observations satisfy a defined condition. For interpretation, the condition needs an operational definition, including threshold values and rules for combining multiple measurements. Those details are not reported in the registry record.

A count alone is not the same as a rate or proportion. A proportion requires a clearly defined denominator: the number of participants eligible for that assessment and included in the analysis. Here, the registry lists enrollment as 18 and describes 17 treated women in the endpoint description, but does not state the denominator used for an endpoint analysis. It does not report the endpoint count either, so no estimate of the proportion meeting the condition can be interpreted.

What can a single-group design establish?

In general, a single-group follow-up can describe outcomes among participants who receive an intervention and are assessed. If baseline and follow-up measurements are analyzed together, that can describe within-participant change, provided the measurement and analysis details are reported. This record mentions baseline and month 12 measurements but posts neither the measurements nor a change analysis.

Without a concurrent comparator, the design does not provide a like-for-like estimate of what would have happened over the same period without the intervention or under another treatment. A change after treatment is not, by itself, evidence that treatment caused the change. This is a general limitation of uncontrolled comparisons, not a claim about the unreported outcome in this study.

How should uncertainty be assessed?

In general, an estimate is more informative when accompanied by a measure of uncertainty. A confidence interval describes a range of values compatible with the observed data and the assumptions of the chosen method. A narrow interval indicates greater precision than a wide interval, while neither proves that an estimate is correct. The registry record does not report a confidence interval or other uncertainty measure for the primary endpoint.

A statistical test, when appropriate, addresses how compatible the data are with a specified null hypothesis under a model. A p-value does not measure the size or clinical importance of an effect. No primary-endpoint test or p-value is reported. Since the result itself is also absent, there is no basis for an effect estimate or a recalculation from posted summary statistics.

What do the planning calculations mean?

In general, a sample-size calculation is a planning exercise based on assumptions about an effect, variability or event frequency, significance level, and design. It is not an observed result and does not establish what the study found. The planning assumptions associated with this record describe an illustration based on a fraction of an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those assumptions describe a hypothetical two-arm planning framework, not the actual single-group design.

The record does not report the trial's own sample-size justification or statistical design plan. It also does not provide an observed primary result from which to assess any effect-based planning illustration. Such planning values should therefore be read as hypothetical illustrations rather than observed power or evidence about the endpoint.

Why does over-dispersion matter in general?

Over-dispersion occurs when observed variation in count data is greater than a statistical model assumes. If a model underestimates variation, its uncertainty estimates can be too small and its inferences too confident. This is a general consideration for count outcomes, but the primary endpoint is described as a count of participants meeting a condition, and the registry does not report a model or analysis. There is no basis to say whether over-dispersion was assessed or relevant to an analysis in this study.

In sum, statistical interpretation would require the endpoint count, its denominator, the definition of normal range, and an analysis with uncertainty estimates. These are not reported in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Zoledronic Acid 5 mg IV")
n      <- c(13)
events <- c(13)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Zoledronic Acid 5 mg IV  13  13  100.0  75.3  100.0  77.2  100.0  76.8  99.8

11. Multiplicity, Missing Data and Analysis Populations

The primary endpoint refers to several biomarker measurements: urine and serum NTx and serum CTx. The registry record does not explain whether the endpoint required every measurement to be within the normal range, how the marker results were combined, or whether separate marker analyses were planned. It also does not report a multiplicity strategy. In general, when several outcomes or tests are examined, the chance of at least one apparently unusual result can increase; methods to address this depend on the prespecified analysis. Whether such methods were used is not reported in the registry record.

The record lists one outcome measure and zero analyses, and does not post the primary endpoint result. It does not describe the statistical analysis plan, prespecified hypotheses, handling of repeated measurements, or any interim analyses. These elements should not be inferred from the study aim or endpoint wording.

Missing-data handling and analysis populations are also not described. The registry does not state how many participants had month 12 measurements, whether all treated participants were included in the endpoint analysis, or how absent or unusable measurements were handled. The difference between the enrollment figure of 18 and the 17 treated women described for the outcome is unexplained. These omissions prevent a reader from identifying the endpoint denominator or assessing whether missing measurements could affect the result.

In general, missing-data assumptions matter because an analysis of observed cases may represent a different group from the enrolled population. No particular missing-data method or analysis population can be attributed to this study from the registry record.

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 0% reporting threshold.

The adverse-event figures list 17 participants at risk in the zoledronic acid group and 0 participants affected by a serious adverse event. This is a report of zero serious adverse events in the listed group, not proof that the risk is absent. The registry record does not provide a confidence interval or further detail about how serious events were collected or assessed.

The deaths field is not populated, so deaths are not reported in the registry record. No serious-event terms are listed. These entries do not establish that no non-serious adverse events occurred; the figures described concern serious adverse events. They also do not provide information about the timing, duration, severity grading, or relationship of events to treatment.

Safety counts are interpreted in the context of who was followed and for how long. The registry does not report participant-level follow-up for safety or explain the relationship between the 17 people listed at risk and the enrollment figure of 18. With no comparator group and no additional safety detail, the reported figures are descriptive for the listed group, not a comparative estimate of risk.

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

This study addressed whether one dose of zoledronic acid could be followed by urine and serum NTx and serum CTx within the normal range at 12 months among women with early breast cancer receiving aromatase inhibitor therapy. The registry record describes a single-group design and the intended biomarker assessment, including measurements at baseline and month 12.

The record does not report how many participants met the primary endpoint, the actual marker values, the normal-range thresholds, or an analysis of change. It therefore does not establish from the posted information whether the endpoint was reached, how large any biomarker change was, or how precisely an outcome was estimated. The absence of a reported result should not be mistaken for a result of no change or no effect.

Even if a within-group change had been reported, a single-group design would not by itself show that the intervention caused that change. A concurrent comparator would help separate changes associated with treatment from changes over time or other influences. No such comparator is described in the registry record.

The endpoint is a laboratory measure, and the record does not report a clinical outcome linked to the marker findings. Biomarker status at follow-up cannot be treated as evidence about symptoms, cancer outcomes, or other benefits or harms. Those outcomes are not reported as results in this record.

The appropriate conclusion is limited: the registry describes the research question, treatment, and intended follow-up endpoint, but the endpoint result and its statistical uncertainty are not reported. The available information is insufficient to draw a conclusion about the observed biomarker outcome.

14. Why This Trial Matters Statistically

This study illustrates why the design and the completeness of outcome reporting are central to statistical interpretation. The question is framed around a measurable biomarker state at a defined follow-up, but a clearly named endpoint is not enough to evaluate the evidence. Readers also need the result, denominator, measurement thresholds, and uncertainty around the estimate.

The single-group structure is especially important. Descriptive results from participants receiving an intervention can characterize what was observed in that group, but without a comparator they cannot isolate the treatment's contribution. This distinction applies even when measurements are planned both before and after treatment. A baseline value offers a reference point, but causal interpretation depends on design and analysis, not simply on the presence of two measurements.

The registry also shows how enrollment and outcome descriptions can raise questions about the analysis population. It lists enrollment as 18 and describes 17 treated women for the primary endpoint, without explaining the difference. Reporting who was assessed and how missing measurements were handled would allow readers to understand what population an endpoint count represents.

Finally, the record distinguishes a biomarker question from a clinical outcome question. The study aim concerns marker levels within a normal range; the record does not report whether that status translated into a clinical outcome. Statistical interpretation should remain aligned with the outcome actually measured and 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 principal limitation for interpretation is that the registry record does not report the primary endpoint result or any analysis. The outcome description identifies the intended count at 12 months, but provides no count, marker values, uncertainty estimate, or test result. The reader therefore cannot assess the magnitude or precision of the observed outcome.

The endpoint definition is incomplete in the record. It does not give the normal-range thresholds, specify whether all listed markers had to meet those thresholds, or describe how individual measurements were combined into the participant count. These details are necessary to interpret what meeting the endpoint means.

The design has no comparator group, and allocation is listed as not applicable. The record also lists no masking. The single-group design can describe participants' outcomes, but cannot by itself support a like-for-like treatment comparison. The registry does not explain the difference between its enrollment figure of 18 and the 17 treated women described for the outcome, or state the denominator used for endpoint assessment.

Further limitations include unreported missing-data procedures, analysis populations, statistical methods, and sample-size justification. The record does not state whether all participants had month 12 measurements or how any unavailable measurements were handled. It also does not provide the protocol details needed to assess whether the reported endpoint and analyses match prespecified plans. These are limitations of the information available in the registry record; they should not be taken as evidence that a particular procedure was or was not followed.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Single Dosing of Zoledronic Acid in Cancer Therapy Induced Bone Loss (CTIBL) — NCT00712985.
• Registry record last updated 2014-04-24; status last verified 2014-03.
• Results first posted 2014-04-24.
• 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

The registry record describes a completed Phase 3, single-group study of one 5 mg intravenous dose of zoledronic acid in women with early breast cancer receiving aromatase inhibitor therapy. It lists enrollment as 18 and describes 17 treated women in the primary-outcome description. The stated primary endpoint is the number of participants with urine and serum NTx and serum CTx within the normal range at 12 months, with measurements described at baseline and month 12.

No comparator group is described. The primary endpoint result, marker thresholds, analysis, uncertainty estimate, missing-data approach, and analysis population are not reported in the registry record. The listed serious adverse-event figures are 0 affected among 17 at risk; deaths are not reported. The record describes the question and design, but does not provide results sufficient to evaluate the biomarker endpoint.