This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Healthy Body, Healthy Bones After Bariatric Surgery Trial (NCT04279392), a randomized phase 1, phase 2 study. The primary outcome is Change in Hip Bone Mineral Density (BMD).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04279392 |
| Phase | Phase 1, Phase 2 |
| Condition | Bariatric Surgery Candidate, Bone Loss, Bone Resorption |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 10 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Nebraska |
| Results posted | Yes |
2. Clinical Question
Population
The primary outcome concerns study participants who completed the study after sleeve gastrectomy. The registry lists bariatric surgery candidates, bone loss, and bone resorption among the conditions. The characteristics of participants, eligibility details, and the number who did not complete the study are not reported in the registry record.
Intervention
The active arm received an intravenous infusion of zoledronic acid, 5 mg in 100 ml of saline, over 15 minutes at 6 weeks post surgery. The question is whether this intervention was associated with a different change in hip bone mineral density during the reported follow-up. The results do not establish a causal or clinical benefit.
Comparator
The comparator arm received 100 ml of saline intravenously over 15 minutes at 6 weeks post surgery. This is described as a non-active infusion. Both arms therefore had a scheduled infusion, while the active arm additionally received zoledronic acid.
Primary question
The primary outcome was change in hip bone mineral density, measured by dual-energy x-ray absorptiometry, from baseline to 10 months post-surgery. The registry reports medians and full ranges for participants who completed the study. The clinical question is about this bone-density measure, not whether the intervention changes fracture risk or another clinical outcome; such outcomes are not reported as the primary endpoint.
3. Trial Design
The Healthy Body, Healthy Bones After Bariatric Surgery Trial is listed as a randomized, quadruple-masked, parallel-group study in phase 1 and phase 2. The registry reports enrollment of 10 and a completed status. Its listed start date is 2020-09-01, and its primary completion date is 2022-12-30. The sponsor is the University of Nebraska.
The study compared an active infusion with a non-active infusion. At 6 weeks post surgery, the active arm was assigned 5 mg of zoledronic acid in 100 ml of saline, infused intravenously over 15 minutes. The other arm was assigned 100 ml of saline, infused intravenously over 15 minutes. The registry describes the study as concerning sleeve gastrectomy associated bone loss. Details about the randomization sequence, allocation concealment, and which groups of people were masked are not reported in the registry record.
The primary outcome was change in hip bone mineral density measured by dual-energy x-ray absorptiometry, with baseline and 10 months post-surgery as the stated timeframe. The primary outcome population is study participants who completed the study. The posted primary results list 2 participants in the active-infusion arm and 7 in the non-active-infusion arm. These outcome counts are not the same as the stated enrollment, and the reasons for the difference are not reported in the registry record.
The study also lists changes in lumbar spine bone mineral density, trunk lean mass, trunk fat mass, and weight as secondary outcomes. The registry does not report further details on scheduling beyond the primary timeframe, adherence, or procedures for handling incomplete observations. Its phase and feasibility context should not be read as evidence that the trial was designed to give a definitive estimate of a treatment effect.
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
| Stage | Active Infusion | Non-active Infusion |
|---|---|---|
| STARTED | 3 | 7 |
| COMPLETED | 2 | 7 |
| NOT COMPLETED | 1 | 0 |
Reasons for not completing this period:
| Reason | Active Infusion | Non-active Infusion |
|---|---|---|
| Physician Decision | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Study participants who completed the study
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.
| Characteristic | Unit | Active Infusion | Non-active Infusion | Total |
|---|---|---|---|---|
| Participants analysed | 3 | 7 | 10 | |
| Age, Continuous | years | 49.8 (43.9 to 58.7) | 43.1 (35.5 to 66.4) | 44.4 (35.5 to 66.4) |
| Sex: Female, Male: Female | Participants | 2 | 7 | 9 |
| Sex: Female, Male: Male | Participants | 1 | 0 | 1 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 2 | 0 | 2 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 1 | 7 | 8 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 3 | 7 | 10 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 3 | 7 | 10 |
| Hip BMD | g/cm2 | 1.2 (1.1 to 1.4) | 1.2 (1.2 to 1.4) | 1.2 (1.1 to 1.4) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Hip Bone Mineral Density (BMD), measured over baseline and 10 months post-surgery.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | g/cm2 |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is change in hip bone mineral density (BMD), measured in g/cm2 by dual-energy x-ray absorptiometry (DXA), from baseline to 10 months post-surgery. The reported population is participants who completed the study. The registry presents a median and full range for each arm.
As general statistical context, BMD quantifies mineral content over an area at a measured skeletal site. DXA is a method for measuring this quantity. A change score compares a participant’s measurement at follow-up with that participant’s baseline measurement; the registry does not provide individual participant data or details of the exact calculation procedure. The median describes the middle of the observed values, while the full range gives the lowest and highest reported values. A range describes the spread of observed data, not the precision of an estimated treatment contrast.
Hip BMD is a bone-related measurement relevant to a study of bone changes after surgery. It is a surrogate or intermediate measurement, not itself a fracture outcome. The registry’s primary result therefore addresses measured hip BMD change over the stated timeframe; it does not directly report whether participants experienced a change in fracture risk. No further justification for selecting the hip site as the primary endpoint is reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary results report a median hip BMD change of 0.0 g/cm2 in the active-infusion arm, with a full range from -0.01 to 0.01. This result is based on 2 participants who completed the study. In the non-active-infusion arm, the median change was -0.03 g/cm2, with a full range from -0.07 to 0.03, based on 7 participants. These are descriptive summaries of the completer data.
The reported full ranges overlap, and the registry does not provide a confidence interval for the difference between arms, a p-value, or an adjusted comparison. The summaries therefore do not establish whether the groups differ beyond the variation visible in these few observations. With so few participants, a single observed value can have substantial influence on an arm’s summary. The medians and ranges should be read as a description of the posted observations, not as a precise estimate of a broader population effect.
The registry identifies 10 participants as enrolled, while the primary outcome population is participants who completed the study and the posted arm counts are 2 and 7. The reasons for this difference, and whether missing endpoint observations differed between arms, are not reported in the registry record. Because the primary results are limited to completers, they do not by themselves show how the results might differ if all enrolled participants had contributed an endpoint value.
The outcome is a measured change in hip BMD between baseline and 10 months post-surgery. It is not a report of fractures or other clinical events. The secondary outcomes include lumbar spine BMD, trunk lean mass, trunk fat mass, and weight, but results for those outcomes are not included in the registry record for this interpretation. No conclusion about those outcomes follows from the primary result.
In general, a confidence interval describes the precision of an estimated quantity under specified assumptions. No interval for an arm contrast is reported. Likewise, a p-value would address compatibility of data with a specified statistical model and null hypothesis; the registry record does not report such a test. The available summaries do not support a definitive inferential comparison, and no claim about treatment effectiveness should be drawn from these small completer groups.
9. Statistical Methods Explained
The registry reports medians and full ranges for the primary outcome. A median is a measure of location: it identifies the center of an ordered set of observed values. It is less affected by an extreme value than an arithmetic mean, although it can still shift when the set of observations is very small. A full range gives the minimum and maximum observed values. It describes observed spread, but is not a confidence interval and does not quantify uncertainty in a treatment contrast.
The reported summaries concern change in hip BMD from baseline to 10 months post-surgery, among participants who completed the study. Change scores are used to describe how a measurement differs between a baseline assessment and a later assessment. In general, analysis of change may account for the baseline measurement by focusing on within-participant differences. The registry does not report whether the primary comparison used participant-level change scores, an adjusted model, or another analysis method. It also does not report the statistical analysis plan, model assumptions, or a method for estimating uncertainty around the between-arm contrast.
In general, randomization is intended to make assigned groups comparable in expectation, while masking is intended to reduce the influence of knowledge of assignment on care, measurement, or reporting. The registry identifies the study as randomized and quadruple-masked, but the specific people masked and the randomization procedures are not reported in the registry record. Randomization does not guarantee close balance in a very small realized sample, and it cannot remove uncertainty caused by sparse observations or incomplete outcome data.
The posted primary summaries give an outcome count of 2 for the active infusion and 7 for the non-active infusion. Such counts matter for interpreting descriptive statistics: each observed value contributes substantially when the group is small. The registry does not provide participant-level measurements, standard errors, or confidence intervals, so the spread and precision of an estimated arm difference cannot be reconstructed from the posted medians and ranges alone. No recalculated comparison is reported in the registry record for this trial.
In general, over-dispersion means that observed variability is greater than a model assumes. If a model underestimates variability, uncertainty intervals and tests can be misleading. This concept is relevant to statistical modeling broadly, but the registry does not report a model for these continuous BMD results, an assessment of dispersion, or any model diagnostics. It would therefore be inappropriate to assert that over-dispersion was present or that a particular method was used to address it.
The registry lists 7 outcome measures and 4 secondary outcomes, but reports 0 analyses. Those entries do not provide a complete account of how many statistical tests were conducted or how results were selected for posting. No p-value for the primary comparison is reported in the registry record. The record also does not describe a prespecified hierarchy of outcomes, adjustment for multiple comparisons, or interim analyses. Without those details, the posted outcome summaries should not be treated as a fully documented inferential analysis.
Sample-size planning is distinct from analysis of the observed results. In general, a sample-size calculation uses assumptions about the effect to detect, outcome variability, significance level, allocation, and desired power. The registry describes planning illustrations based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It does not report the resulting participant counts in the registry record for this trial. Such planning illustrations are not observed power and do not show the probability that the study detected an effect. They also are not evidence of the original design justification; that justification is not reported in the registry record.
For this endpoint, the registry reports medians and ranges rather than a modeled estimate with an uncertainty interval. General statistical practice distinguishes a descriptive contrast from an inferential estimate: the former compares observed summaries, while the latter quantifies uncertainty under an analysis model. The posted information supports description of the recorded completer values, but does not give enough detail to assess an inferential model or its assumptions. These methods considerations limit the strength and scope of conclusions that can be drawn from the result.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 7 outcome measures, including the primary hip BMD outcome and 4 secondary outcomes: lumbar spine BMD, trunk lean mass, trunk fat mass, and weight. It reports 0 analyses. The record does not describe a prespecified testing hierarchy, a multiplicity adjustment, or which outcomes were included in formal statistical tests. When several outcomes are examined, the chance of at least one apparently unusual result can increase; adjustment or prespecification can help address that issue. This is general statistical context, not a description of a procedure used in this trial.
Missing-data handling is not reported in the registry record. The primary outcome is defined for participants who completed the study, and the posted primary arm counts are 2 and 7, while enrollment is 10. Reasons for non-completion or absent endpoint values, and any imputation or sensitivity analysis, are not reported. In general, an analysis limited to observed completers can be affected if completion is related to outcome or assignment. The available information does not establish whether that occurred.
The analysis population beyond the stated completer population is not reported. The registry does not say whether an intention-to-treat analysis was conducted, how protocol deviations were handled, or whether any participants were excluded after randomization. It also does not report an interim analysis plan or the statistical analysis plan. These omissions make it difficult to assess the relationship between the registered outcome, the posted summaries, and any prespecified inferential analysis.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Active Infusion | 1 | 3 | 33.3% |
| Non-active Infusion | 0 | 7 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Active Infusion | 0 of 3 |
| Non-active Infusion | 0 of 7 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Active Infusion | 0 of 3 |
| Non-active Infusion | 0 of 7 |
Most frequent serious adverse event terms
| Event term | Organ system | Active Infusion | Non-active Infusion |
|---|---|---|---|
| Surgical Complication | Surgical and medical procedures | 1 of 3 | 0 of 7 |
Serious events with the highest arm-level rate: surgical complication (33.3%).
The adverse-event figures use safety populations that differ by arm: 3 participants were at risk in the active-infusion group and 7 in the non-active-infusion group. The registry reports 1 participant with a serious adverse event in the active group and 0 in the non-active group. It lists surgical complication as the top serious-event term at 33.3%. No deaths are reported. For other adverse events, the registry reports 0 affected participants in either group.
These counts describe the registry’s safety reporting and should not be confused with the primary endpoint counts, which are 2 and 7 among study completers. The serious-event figures are small and do not provide a precise comparison of event risk. The listed term and percentage should be read as registry-reported safety information, not as proof that an infusion caused an event. The record does not report further details about event timing, severity grading, relatedness to the intervention, or how the term-level percentage was calculated. The figures alone do not support a broader safety conclusion.
12. What the Result Does, and Does Not, Mean
The posted result describes hip BMD changes among study completers in a small randomized study. The active-infusion arm had a median change of 0.0 g/cm2, with a full range from -0.01 to 0.01, among 2 participants. The non-active-infusion arm had a median change of -0.03 g/cm2, with a full range from -0.07 to 0.03, among 7 participants. These summaries show the observed values in the registry record, but they do not give a precise estimate of the difference between the assigned interventions.
The result does not establish that zoledronic acid prevents bone loss, nor does it establish that it has no effect. No confidence interval or p-value for a between-arm comparison is reported. With few observed participants, uncertainty around a population-level effect is substantial, and the range in each group is not a substitute for a confidence interval. The study’s completed status does not change these limitations.
The primary endpoint is a BMD measurement, not a fracture outcome. The registry therefore does not show whether any observed difference in BMD was accompanied by a difference in fractures or other clinical outcomes. Although secondary measures are listed, their results are not reported in the registry record for this interpretation. Nor does the primary endpoint answer whether the intervention changes longer-term outcomes beyond the stated baseline-to-10-month timeframe.
The findings are also limited to the participants who completed the study. The registry reports enrollment of 10 but does not explain the difference between enrollment and the primary outcome counts, or how missing observations were handled. The result is best understood as a small descriptive record of the available completer measurements, rather than a definitive efficacy or safety assessment.
13. Why This Trial Matters Statistically
This trial raises a statistical question that is common in early or feasibility-stage clinical research: how much can be learned from a small randomized comparison when the endpoint is continuous but the posted results are descriptive? Reporting medians and full ranges makes the observed values visible in a compact form. At the same time, very small groups limit how stable those summaries are and how precisely an arm contrast can be estimated.
The distinction between a measurement and a clinical outcome is also important. Hip BMD provides a quantified measure of bone status, while fracture outcomes are not the primary endpoint. Statistical interpretation should stay aligned with the outcome actually measured and the follow-up timeframe stated in the registry. A difference in a measured endpoint would not automatically answer questions about other outcomes.
The record also illustrates why outcome counts and analysis populations matter. Enrollment is 10, whereas the primary result is reported for 2 active-arm completers and 7 non-active-arm completers. Without information about missing data, the analysis population, and the planned methods, readers cannot fully assess how the posted estimates relate to the randomized groups as a whole.
Finally, statistical reporting needs to distinguish observed summaries from inferential evidence and planning illustrations from study design justification. No formal comparison or uncertainty interval is reported for the primary result. The available information can describe what was recorded, but it cannot establish the precision or generalizability of a treatment effect. That boundary is central to responsible interpretation of small clinical trials.
14. 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 primary outcome results are based on very small completer groups: 2 participants in the active-infusion arm and 7 in the non-active-infusion arm. The registry reports enrollment of 10 but does not explain the difference between enrollment and the primary outcome population. Without reasons for non-completion, missing-data methods, or sensitivity analyses, it is not possible to assess whether completer-only summaries represent all randomized participants.
The primary outcome is reported as a median and full range. No confidence interval, standard error, p-value, or adjusted treatment comparison is reported in the registry record. The range shows observed variability, but it does not quantify precision of the between-arm contrast. The exact analysis method and statistical analysis plan are not reported, limiting assessment of assumptions and prespecification.
The registry lists secondary outcomes, but the registry entries for this interpretation do not include their results. It also reports 0 analyses and does not describe multiplicity handling. The specific masking procedures, randomization details, adherence, and protocol deviations are not reported. These gaps make it difficult to assess implementation and the completeness of statistical reporting.
The primary endpoint is hip BMD change from baseline to 10 months post-surgery. It does not directly measure fracture outcomes, and longer-term outcomes are not reported. The sample is small, and the posted summaries cannot establish whether the observed values generalize beyond the study completers. The registry’s phase 1 and phase 2 designation and feasibility context should also temper interpretation of the result as an estimate of treatment effect.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Healthy Body, Healthy Bones After Bariatric Surgery Trial — NCT04279392.
- Registry record last updated 2024-09-24; status last verified 2024-08.
- Results first posted 2024-08-29.
- 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.
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18. Record Summary
The Healthy Body, Healthy Bones After Bariatric Surgery Trial (NCT04279392) is listed as a completed, randomized, quadruple-masked, parallel-group phase 1 and phase 2 study sponsored by the University of Nebraska. Enrollment was 10. The listed start date is 2020-09-01, and the primary completion date is 2022-12-30.
The study compared an intravenous zoledronic acid infusion with a saline infusion at 6 weeks post surgery. The primary outcome was change in hip BMD, measured by DXA from baseline to 10 months post-surgery. The registry reports medians and full ranges among study completers: 2 in the active-infusion arm and 7 in the non-active-infusion arm. The record lists secondary changes in lumbar spine BMD, trunk lean mass, trunk fat mass, and weight. It does not report a formal primary comparison, confidence interval, or p-value.