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 The Effect of Surgically Induced Weight Loss on Endocrine Function, Cardiovascular Function and Body Composition (NCT00686972), a na phase 2 study. The primary outcome is Insulin Secretion.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00686972 |
| Phase | Phase 2 |
| Condition | Bariatric Surgery |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 51 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johns Hopkins University |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing bariatric surgery were the population described in the study summary. The enrollment was 51, but the registry record does not report participant characteristics or confirm how many participants contributed data.
Intervention
The summary describes assessing changes as patients lose weight following bariatric surgery. The listed intervention is GLP-1, delivered at 5 ng/kg/min intravenously for 1 hour during each clamp study over 2 years. The record does not explain how that intervention relates to the comparison of surgery types described in the summary.
Comparator
No control group or randomized comparator is identified. The record classifies the study as single-group and gives allocation as not applicable. Although the summary describes comparing four types of bariatric surgery, the registry record does not provide corresponding arm details that would establish a like-for-like comparison.
Primary question
The registered primary outcome is insulin secretion, with a 2-year timeframe. The record does not report a measurement method or results. It says the study was terminated and that outcome data, if collected, are unknown because no data are available.
At the level of the stated scientific aim, the investigators sought to evaluate changes in sugar metabolism, heart function, and body composition after bariatric surgery, and to compare those changes across four surgery types. The summary also expresses a belief about which procedure might be most beneficial and safest; that is a stated expectation, not a result. The registry structure does not describe a randomized comparison or identify a control group, so the record does not establish how those planned comparisons would have been made. The primary endpoint that can be evaluated from the entry is insulin secretion over 2 years, but no endpoint observations or analysis are available. Consequently, the record establishes the intended question and some design features, but it does not answer whether insulin secretion changed or whether changes differed among procedures.
3. Trial Design
The registry identifies this as a phase 2, single-group study with no masking. Allocation is listed as not applicable, and enrollment is 51. Johns Hopkins University is named as the sponsor. The recorded start is 2007-05 and the primary completion date is 2010-10. The current status is terminated.
The study title and summary concern surgically induced weight loss and possible changes in endocrine function, cardiovascular function, and body composition. The summary describes evaluating changes as patients lose weight after bariatric surgery and comparing improvements across four types of surgery. However, the registered design details do not show separate surgery groups or a control arm. The entry lists GLP-1 as the intervention and describes an intravenous infusion of 5 ng/kg/min for 1 hour during each clamp study over 2 years. The relationship between this intervention, the clamp studies, and the surgery-type comparison is not clarified in the registry record.
The planned primary outcome is insulin secretion over 2 years. The registry record does not report the measurement instrument, operational definition, analysis scale, or planned summary statistic. It also does not provide a detailed protocol, eligibility criteria, visit schedule, or participant flow. Those details are not reported in the registry record and should not be inferred from the intervention description alone.
The termination explanation is that the principal investigator left the institution and the study was terminated because of noncompliance with the Institutional Review Board. The record explicitly says outcome measure data, if collected, are unknown because no data are available. Thus, the enrollment figure should not be read as the number with outcome observations, and the stated completion date should not be read as evidence that planned follow-up or analyses were completed. No randomized treatment contrast is described, so this entry does not support interpreting the study as a controlled estimate of comparative effects.
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 | Glucagon Like Peptide 1 -GLP-1 |
|---|---|
| STARTED | 51 |
| COMPLETED | 0 |
| NOT COMPLETED | 51 |
Reasons for not completing this period:
| Reason | Glucagon Like Peptide 1 -GLP-1 |
|---|---|
| P.I, Left institution. Study terminated | 51 |
Analysis population for the primary outcome, as defined in the registry: The PI left the institution and this study was terminated due to noncompliance with our Institutional Review Board. Outcome measure data, if collected, is unknown since no data are available.
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 | GLP-1 |
|---|---|---|
| Participants analysed | 51 | |
| Age, Customized: >=21 and <=65 | participants | 51 |
| Sex: Female, Male: Female | Participants | 43 |
| Sex: Female, Male: Male | Participants | 8 |
| Region of Enrollment: United States | participants | 51 |
6. Primary Endpoint
The registry lists the primary outcome as Insulin Secretion, measured over 2 years.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The registered primary endpoint is insulin secretion, with a timeframe of 2 years. Insulin secretion refers generally to the release of insulin by the body in response to a stimulus or metabolic demand. It is relevant to studies of sugar metabolism because the amount and pattern of insulin release are part of the body's regulation of blood glucose. In a study focused on weight loss and metabolic function, tracking insulin secretion could help characterize a physiological change over time. This is general context, not a description of the registry's measurement procedure.
The record does not specify how insulin secretion was measured, how it was summarized, whether it was assessed at baseline and follow-up, or what change was intended as the primary contrast. GLP-1 is listed as an intervention, with administration during clamp studies, but the entry does not state how the clamp measurements define the primary endpoint. The outcome description itself contains no measurement details.
Most importantly, the registry states that outcome data, if collected, are unknown because no data are available. There is therefore no posted endpoint value, estimate of change, measure of uncertainty, or test of a difference to interpret. The endpoint's scientific role can be explained in general, but the registry record does not establish what insulin secretion was among participants or whether it changed during the intended timeframe.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes an intended study, not an interpretable set of outcome findings. It names insulin secretion as the primary outcome and gives a 2-year timeframe, but it reports no outcome values and no statistical analyses. Its own explanation says that data, if collected, are unknown because no data are available. There is consequently no estimate of change, comparison between surgery types, uncertainty interval, or statistical test on which to base a conclusion about the primary endpoint.
The listed enrollment of 51 is a design-record figure. It does not establish how many participants underwent surgery, received GLP-1, completed clamp studies, reached follow-up, or contributed measurements. The record does not give a participant flow or analysis population. It would therefore be incorrect to treat enrollment as the observed sample size for an endpoint analysis.
The summary describes an aim to compare changes across four surgery types, but the registered design is single-group, with allocation not applicable and no masking. No arms for the surgery types or control group are specified in the design details. The summary's statement that investigators believed one procedure would be most beneficial and safest is a hypothesis or expectation, not a finding. The registry structure and absence of results prevent an assessment of that expectation.
The adverse-event listing shows zero participants at risk and zero events in the listed categories for the GLP-1 group. Those entries cannot be interpreted as evidence that no adverse events occurred among participants: with zero participants recorded as at risk, the listing provides no evaluable safety denominator. The record also does not provide event follow-up details or a safety analysis.
Any numerical planning illustrations associated with posted results are not estimates from this trial when no observed effect is available. In general, such calculations depend on assumptions about an effect and a design; they cannot recover missing trial data or establish observed power. The planning assumptions recorded for illustrations are not evidence that the trial used those assumptions. The registry record does not report a trial-specific sample-size justification or statistical analysis plan.
The appropriate statistical interpretation is therefore limited to describing the study's recorded aims, design labels, enrollment, and termination explanation. Effectiveness, comparative effects, and safety remain undetermined in the registry record. This absence of results is not evidence of no change, no difference, or no events; it means those quantities cannot be assessed from the posted information.
9. Statistical Methods Explained
The registry labels the design as single-group and gives allocation as not applicable. Those labels matter because statistical comparisons require a clear definition of which observations are being contrasted. In a single-group study, change over time may be described within participants if repeated measurements exist, but such a change alone does not separate the effect of an intervention from other explanations. General examples include changes in participant characteristics over time, concurrent care, measurement conditions, and natural variation. The record does not say which analyses, if any, were planned to address these issues.
What would a single-group estimate describe?
General statistical interpretation distinguishes a within-group change from a between-group contrast. A within-group change compares measurements from the same participants at different times, while a between-group contrast compares outcomes across distinct groups under specified conditions. A within-group estimate can describe what happened in the observed cohort, but without an appropriate comparator it does not by itself establish what would have happened under another intervention. In this record, there are no outcome observations with which to estimate either kind of change.
The summary refers to comparing outcomes across four surgery types, but the registry's arm and design information does not define those groups. It lists GLP-1 as the intervention and describes its administration during clamp studies. No account is given of how surgery type would enter the analysis, whether participants would receive more than one procedure category, or how measurements would be assigned to comparisons. The analysis structure is therefore not reported in the registry record. It would be inappropriate to reconstruct it from the study title or summary.
What is an uncertainty interval?
General explanation: a confidence interval is a range of values compatible with an estimate under a statistical model and its assumptions. Its width conveys precision: wider intervals indicate more uncertainty about the effect's magnitude than narrower intervals. An interval does not repair bias, missing data, or an unclear comparison. The registry contains no endpoint estimate or confidence interval for insulin secretion, so precision cannot be assessed in this study.
A p-value, in general, describes how unusual data at least as incompatible with a specified null model would be if that model and the test assumptions were correct. It does not measure the probability that a treatment works, nor does it show the clinical importance of an effect. No p-value or outcome analysis is reported for the primary endpoint. The 0.05 two-sided significance level appears in the registry's planning-illustration assumptions, not as a documented trial analysis plan. It should not be treated as evidence of a prespecified inferential procedure.
Why does the comparator matter?
General explanation: random allocation, when used and properly implemented, can help balance known and unknown participant characteristics across comparison groups. This record lists allocation as not applicable, identifies a single-group model, and does not describe masking. There is no recorded randomized comparison. These design details limit what could be inferred from a simple difference between groups even if such groups were later identified; in this entry, the necessary group definitions and outcome data are absent.
The study summary's intended comparison of four surgery types also raises a general issue of confounding. If participants receive different procedures for reasons related to their health or other characteristics, differences in outcomes may reflect those characteristics as well as procedure differences. Appropriate adjustment can sometimes address measured factors, but it cannot guarantee removal of unmeasured confounding. The registry does not report whether adjustment was planned, which factors would be considered, or whether such a comparison was performed.
What do planning calculations mean?
General explanation: sample-size calculations are design tools that estimate how much information a planned study might collect under stated assumptions. A calculation may rely on an anticipated effect, variability, a significance level, allocation, and a statistical model. If assumptions do not match the eventual study, the calculation may not describe its operating characteristics. The registry's planning-illustration description states assumptions for hypothetical calculations, including a two-sided significance level of 0.05 and equal allocation between two arms. Those are illustration assumptions, not documented features of this single-group trial. No trial-specific sample-size justification is reported in the registry record.
Power is a design property calculated for a specified effect and set of assumptions; it is not a measure of the probability that a result is true. A calculation based on an observed effect is not observed power and cannot replace an effect estimate or uncertainty interval. Since this record has no outcome effect to interpret and no posted analysis, planning calculations cannot establish what the trial found.
Finally, statistical methods are only interpretable when the outcome definition, analysis population, missing-data handling, and model are clear. The registry does not report those details. It also reports zero analyses. The absence of an analysis is distinct from a finding of no effect: there is no estimate to judge. These limitations are not technical details that can be resolved by choosing a statistical test after the fact; the unavailable observations and unreported analysis framework prevent reconstruction of the trial's inferential results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure, insulin secretion, but the study summary describes several domains: sugar metabolism, heart function, and body composition. It also describes comparisons across four surgery types. The record does not state whether these additional domains were formally designated secondary outcomes, whether multiple time points or contrasts were planned, or whether any adjustment for multiple testing was intended. Such multiplicity procedures are not reported in the registry record.
In general, when many outcomes, time points, or comparisons are tested, the chance of at least one apparently unusual result can increase. Prespecifying a primary endpoint and analysis can help clarify which inference is central, while multiplicity methods can address some families of comparisons. These general considerations cannot be applied to infer what the investigators planned, and no test results are available.
Missing-data information is also insufficient for analysis. The termination explanation says the principal investigator left the institution and the study ended because of noncompliance with the Institutional Review Board. The record says outcome data, if collected, are unknown because no data are available. It does not report the number with measurements, reasons for missingness by participant, timing of withdrawals, or any imputation or sensitivity analysis. Without those details, it is not possible to assess whether available observations would represent the enrolled participants.
The analysis population is not described. The entry does not identify an intention-to-treat population, a treated population, or a group restricted to participants with complete measurements. Because there are no reported outcome analyses, none of those populations can be associated with an estimate. The enrollment of 51 should not be substituted for an analysis denominator.
11. What the Result Does, and Does Not, Mean
The registry record establishes that investigators planned a phase 2 study concerning surgically induced weight loss and physiological outcomes, with insulin secretion named as the primary outcome and a 2-year timeframe. It also records an enrollment of 51, a single-group design, no masking, and termination. These are descriptions of the study record and its intended work, not evidence of an observed treatment effect.
The record does not show whether insulin secretion increased, decreased, or remained unchanged. It does not report comparisons among surgery types, changes in cardiovascular function or body composition, or estimates of uncertainty. The summary's expectation about a preferred surgery type is not a result. With no outcome data available, neither a favorable nor an unfavorable conclusion can be drawn from this entry.
The safety listing cannot establish that the intervention was free of adverse events. It records zero participants at risk and zero events in the listed categories, leaving no participant denominator from which to describe event frequency. Similarly, the enrollment figure alone does not establish how many people received the listed intervention or completed follow-up.
In general, an observed change in a single group would describe the participants' measured trajectory, while a controlled comparison could offer a different basis for attributing differences to interventions. Here, neither trajectory nor controlled contrast is reported. The design details also do not resolve how the four surgery types mentioned in the summary relate to the single-group registry classification.
The most defensible conclusion is about the limits of the evidence: the registry records an intended investigation but provides no analyzable endpoint results. It cannot support claims about benefit, lack of benefit, comparative effectiveness, or safety. That uncertainty reflects unavailable data and unreported analysis details, not a demonstrated absence of an effect.
12. Why This Trial Matters Statistically
This record is statistically instructive because it separates a planned research question from evidence that can answer it. The entry describes a clinically motivated aim and names a primary outcome, but it also records termination and no available outcome data. A stated objective, planned follow-up timeframe, and enrollment figure are not substitutes for an estimate, its uncertainty, and a defined analysis population.
It also illustrates why design labels and narrative summaries should be read together. The summary describes comparisons across four surgery types, while the registry identifies a single-group model and does not describe corresponding arms. The listed GLP-1 intervention and clamp-study description do not clarify that discrepancy. When the comparison structure is not specified, an analyst cannot reliably define the target contrast or determine which statistical method would address it.
The safety listing offers another useful lesson: a count of zero events is not informative without a population at risk. The record lists zero at risk, so the event entries do not establish a zero event rate or demonstrate safety. General statistical reporting requires both event counts and a relevant denominator, with enough follow-up detail to understand what was observed.
Finally, termination and missing outcomes have direct consequences for inference. No analysis can recover the endpoint results when the registry says they are unavailable. Planning calculations cannot stand in for observations, and general statistical concepts cannot resolve the absent comparison structure. The record therefore matters as an example of transparent interpretation: statistical conclusions should be limited to what the design and posted data support, while unreported information remains explicitly unresolved.
13. 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 central limitation is that no outcome data are available. The registry says data, if collected, are unknown, and reports no analyses. As a result, the primary endpoint cannot be summarized and the intended 2-year assessment cannot be evaluated.
The study was terminated after the principal investigator left the institution and because of noncompliance with the Institutional Review Board. The record does not describe when termination occurred relative to participant recruitment, intervention, or follow-up. It therefore does not establish how much of the planned study was completed.
The design information does not match the full comparison described in the summary. The record identifies a single group and lists GLP-1, while the summary refers to four surgery types. No corresponding surgery arms, control condition, or allocation method are detailed. This leaves the planned contrast unclear.
Important methods are not reported in the registry record, including participant eligibility and characteristics, the insulin-secretion measurement procedure, the primary analysis method, analysis population, missing-data strategy, and any multiplicity plan. The listed enrollment of 51 does not reveal the number with usable observations. The adverse-event entries list zero participants at risk, so they cannot support a safety assessment. These limitations are specific to the information recorded for this study and prevent estimation of its outcomes.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: The Effect of Surgically Induced Weight Loss on Endocrine Function, Cardiovascular Function and Body Composition — NCT00686972.
- Registry record last updated 2017-07-02; status last verified 2017-06.
- Results first posted 2017-07-02.
- 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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17. Record Summary
The registry describes a phase 2, single-group study sponsored by Johns Hopkins University, with enrollment of 51 and no masking. Its title concerns surgically induced weight loss and endocrine, cardiovascular, and body-composition outcomes. The summary describes comparisons across four surgery types, while the registered intervention is GLP-1, administered intravenously during clamp studies. The relationship between these descriptions is not clarified.
Insulin secretion is the primary outcome, with a 2-year timeframe. The recorded start is 2007-05, and the primary completion date is 2010-10. The study status is terminated. The stated reason is that the principal investigator left the institution and the study was terminated because of noncompliance with the Institutional Review Board.
The record says outcome data, if collected, are unknown because no data are available, and it reports no analyses. Accordingly, there are no posted estimates of the primary outcome or interpretable safety results. The entry documents the intended study and its termination, not evidence for or against an effect.