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 WISE (Weightloss Intervention Surgical Effects) Brain Study (NCT02137070), a registered phase not stated study. The primary outcome is Change in BOLD fMRI Signal.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02137070 |
| Phase | Phase not stated |
| Condition | Diabetes, Weightloss |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 197 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Florida |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned adults with obesity and type 2 diabetes. The surgical group consisted of participants intending to have bariatric surgery at local surgical centers or UFHEALTH & Shands Hospital. The non-surgical community group was described as healthy adults with body mass index >35 who would not undergo bariatric surgery.
Intervention
The intervention was bariatric surgery as part of usual care for participants who intended to undergo the procedure. The brief summary says the study was intended to learn about changes associated with weight loss, including changes in brain function, memory and thinking ability. It also states that the study does not cover surgery costs.
Comparator
The comparator was a non-surgical community volunteer group. This group was not described as a like-for-like control for the surgical candidates: the registry record describes different eligibility and treatment circumstances, and notes that this was not a randomized comparison. Allocation is not stated.
Primary question
Among participants completing brain imaging, what change in the BOLD fMRI connectivity measure was observed from baseline to 18 months? The outcome was defined as a mean Fisher-z transformation of connectivity. The registry record does not report the mean change or its standard deviation, so the result's direction and precision are not reported in the registry record.
3. Trial Design
The WISE (Weightloss Intervention Surgical Effects) Brain Study is a completed study sponsored by the University of Florida. The registry record lists its start as 2014-08 and primary completion as 2022-11. Enrollment is listed as 197. The study concerns obesity, weight loss and diabetes, and its brief summary describes an investigation of changes in brain function, memory and thinking ability in adults.
The registry describes two groups: Bariatric Surgery Candidates and Non surgical/Community volunteers. The first consisted of participants intending to have bariatric surgery at local surgical centers or UFHEALTH & Shands Hospital. The second consisted of healthy adults with body mass index >35 who would not undergo bariatric surgery. The registry identifies the study as not a randomized comparison, and allocation is not stated. The groups therefore should not be read as equivalent groups assigned to different treatments under randomization.
The primary outcome was change in BOLD fMRI signal, measured as connectivity Fisher-z transformation. Its timeframe was change from baseline at 18 months. The registry states that 37 individuals completed pre-surgery MRI at baseline and 18-month follow-up. This is the outcome's stated population; the record does not explain how those individuals relate to the enrollment figure or how missing follow-up information was handled.
The study is marked completed, but that status does not itself establish that every planned analysis is available in the registry. The posted record does not report the primary endpoint's numerical results or the detailed statistical analysis plan.
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 | Bariatric Surgery Candidates | Non Surgical/Community Volunteers |
|---|---|---|
| STARTED | 150 | 47 |
| COMPLETED | 76 | 29 |
| NOT COMPLETED | 74 | 18 |
Reasons for not completing this period:
| Reason | Bariatric Surgery Candidates | Non Surgical/Community Volunteers |
|---|---|---|
| Adverse Event | 12 | 3 |
| Death | 2 | 0 |
| Lost to Follow-up | 24 | 9 |
| Physician Decision | 0 | 1 |
| Protocol Violation | 18 | 4 |
| Withdrawal by Subject | 18 | 1 |
Analysis population for the primary outcome, as defined in the registry: 37 individuals completed pre-surgery MRI at baseline and 18-month follow-up.
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 | Bariatric Surgery Candidates | Non Surgical/Community Volunteers | Total |
|---|---|---|---|---|
| Participants analysed | 150 | 47 | 197 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 143 | 42 | 185 |
| Age, Categorical: >=65 years | Participants | 7 | 5 | 12 |
| Age, Continuous | years | 42.54 (SD 11.51) | 52.29 (SD 12.51) | 44.86 (SD 12.44) |
| Age, Customized: Mean by intervention condition | years | 42.54 (SD 11.51) | 52.29 (SD 12.51) | 44.86 (SD 12.44) |
| Sex: Female, Male: Female | Participants | 118 | 32 | 150 |
| Sex: Female, Male: Male | Participants | 32 | 15 | 47 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 11 | 4 | 15 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 138 | 43 | 181 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
| 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 | 35 | 14 | 49 |
| Race (NIH/OMB): White | Participants | 100 | 31 | 131 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 15 | 2 | 17 |
| Region of Enrollment: United States | participants | 150 | 47 | 197 |
| Age of study participants | years | 42.54 (SD 11.51) | 52.29 (SD 12.51) | 44.86 (SD 12.44) |
6. Primary Endpoint
The registry lists the primary outcome as Change in BOLD fMRI Signal, measured over Change from baseline at 18 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Connectivity Fisher-z transformation |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was change in BOLD fMRI connectivity from baseline to 18 months, expressed as a Fisher-z transformation of connectivity. The registry describes the z-score as a transformation of the Pearson correlation coefficient, r, between the BOLD time series of two brain regions. It identifies the frontal cortex and hippocampus as the regions of interest, but does not specify the individual connections or pairs of regions used to produce the endpoint.
The registry's interpretation guide says a value below zero suggests weakening connections between brain areas, while a value above zero suggests strengthening. It also says r=0 indicates that two brain regions were functionally disconnected. These descriptions explain the scale; they do not indicate the direction or size of the study's observed change. The record does not report the primary mean change, standard deviation, or other numerical outcome estimate.
Connectivity was used to quantify a brain-imaging feature relevant to the study's question about brain function and weight loss. A continuous measure can describe the magnitude and direction of change rather than reducing participants to categories. The registry specifies a mean as the summary measure and a standard deviation as the measure of dispersion. Without those results, the endpoint's observed pattern and its precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the primary outcome and its follow-up timeframe, but does not report the numerical estimate for change in BOLD fMRI connectivity. In particular, no mean change or standard deviation is reported in the registry record. Therefore, the endpoint cannot be interpreted as showing a strengthening, weakening, or absence of change on the basis of the posted results. The scale's stated direction rules explain how a value would be read, but they cannot substitute for the missing outcome estimate.
The stated analysis population for this endpoint is 37 individuals who completed pre-surgery MRI at baseline and 18-month follow-up. This establishes who the registry says contributed to the endpoint, but does not describe their outcome values or the distribution of those values. Enrollment is listed as 197, but the record does not explain participant flow from enrollment to the MRI follow-up population. It would be inappropriate to infer why these figures differ or to treat the endpoint population as representative of all enrolled participants without further information.
The study's groups also require cautious interpretation. Participants in the surgical group intended to have bariatric surgery, whereas the community volunteers were described as healthy adults with body mass index >35 who would not undergo surgery. The registry states this was not a randomized comparison and that allocation is not stated. Differences between groups could therefore reflect differences in who entered each group as well as differences associated with surgery. The record does not establish that the groups were comparable at baseline or describe an adjusted comparison.
No estimate of uncertainty, such as a confidence interval, or test result for the primary endpoint is reported in the registry record. A confidence interval, in general, expresses the uncertainty around an estimated quantity under the assumptions of the analysis. Without the estimate and its uncertainty, readers cannot assess how precisely the endpoint was measured or whether the data are compatible with a range of possible changes. Nor can statistical significance be judged from the available endpoint information.
The registry describes an analysis using a mean and standard deviation, but the numerical results needed to characterize that mean are not reported. Accordingly, the study's primary result cannot be quantified or compared across the groups from the registry record. The findings should be described as unavailable in this record, rather than as evidence for or against a particular change in brain connectivity.
9. Statistical Methods Explained
The registry describes the primary outcome as continuous and specifies a mean with a standard deviation. A continuous endpoint can take values along a measurement scale. Its mean describes the average observed value or change for the analyzed population, while its standard deviation describes how spread out individual measurements are around that mean. A standard deviation is not itself a measure of how precisely the mean has been estimated; precision also depends on the analysis and available observations. The record does not give the mean change or standard deviation for the primary outcome.
What does the Fisher-z measure represent?
The endpoint uses a Fisher-z transformation of connectivity derived from Pearson's r correlation between BOLD time series from brain regions. Correlation describes how two series vary together. A transformation places the correlation on a scale used for analysis. The registry's description assigns an interpretation to the sign: a value below zero suggests weakening connections, and a value above zero suggests strengthening. It states that r=0 indicates functional disconnection between two brain regions. These are descriptions of the measure, not reported findings from this study. The registry does not provide the observed connectivity values or identify every brain-region pair included in the outcome.
What can a confidence interval tell a reader?
In general, a confidence interval describes uncertainty around an estimate, under the statistical model and assumptions used. A narrower interval indicates greater precision than a wider interval for the same type of estimate. An interval also helps readers consider which effect sizes are compatible with the data, rather than relying only on a binary significance decision. No confidence interval for the primary change is reported in the registry record. It is therefore not possible to characterize the precision of the study's primary endpoint using the posted outcome information.
How should the planning assumptions be read?
The registry's sample-size assumptions describe a planning illustration based on the observed effect, not the trial's own design. The illustration assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It considers an effect to detect expressed as a stated fraction of the observed effect. These are planning assumptions, not evidence that the study was designed or conducted according to that plan. The record does not report a sample-size justification for the trial or a detailed account of the trial's own design assumptions.
Sample sizes calculated under such assumptions are planning illustrations. They are not observed power and do not establish that a study was adequately powered for its actual analysis. Interpretation also depends on the observed effect and its variability; the primary outcome estimates needed to assess those features are not reported in the registry record. The record's planning description says non-time-to-event calculations are expressed as participants per arm, while time-to-event calculations are expressed as total events. The primary endpoint is a continuous measure, not a time-to-event outcome.
Why does over-dispersion matter in general?
For outcomes that are counts, over-dispersion means that variability is greater than a simple model expects. If it is ignored, standard errors can be too small and confidence intervals too narrow, giving an overly precise impression. This general issue does not describe the primary endpoint here, which is continuous and summarized by a mean and standard deviation. The registry does not report an over-dispersion assessment or a count-outcome model for the primary endpoint.
More broadly, a statistical method should match the outcome, study design and analysis population. The registry record identifies the outcome summary but does not provide sufficient detail to reconstruct the primary analysis. It does not report whether the analysis adjusted for baseline values, included covariates, accounted for repeated measurements, or used any particular missing-data method. Those choices should not be inferred from the endpoint definition or planning assumptions.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and one analysis. That listing does not establish how the investigators handled multiplicity, including whether the primary endpoint was the only hypothesis considered, whether additional outcomes were analyzed outside the posted record, or whether any adjustment for multiple comparisons was planned. A multiplicity strategy is not reported in the registry record.
The outcome is defined as change from baseline at 18 months, and the stated endpoint population includes 37 individuals who completed MRI at baseline and follow-up. The record does not describe missing observations, reasons for non-completion, or how participants with incomplete data were handled. It does not report whether the analysis used only complete cases, imputed missing values, or applied another approach. No assumptions about missingness can be inferred from the stated follow-up population.
The registry also does not report a detailed analysis population definition beyond the statement about MRI completion. Enrollment is listed as 197, but no participant flow or reconciliation with the endpoint population is reported. Therefore, the effect of missing follow-up data on the primary estimate cannot be assessed from this record.
For this non-randomized comparison, the registry says allocation is not stated. It does not report a covariate-adjustment plan, a baseline-comparability analysis, or an approach to confounding. These omissions limit interpretation of any group contrast, even if the numerical results were available. The registry record does not provide enough information to determine whether multiplicity, missing data, or differences between groups were addressed in the 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 |
|---|---|---|---|
| Surgical Group | 5 | 150 | 3.3% |
| Control Group | 0 | 47 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Surgical Group | 2 of 150 |
| Control Group | 0 of 47 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Surgical Group | 11 of 150 |
| Control Group | 3 of 47 |
Most frequent serious adverse event terms
| Event term | Organ system | Surgical Group | Control Group |
|---|---|---|---|
| Post-surgical Symptoms | Gastrointestinal disorders | 3 of 150 | 0 of 47 |
| High BDI | Psychiatric disorders | 2 of 150 | 0 of 47 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Surgical Group | Control Group |
|---|---|---|---|
| MRI symptoms | General disorders | 4 of 150 | 2 of 47 |
| Blood draw problems | General disorders | 3 of 150 | 1 of 47 |
| Survey Questions/Cognitive questions | Social circumstances | 3 of 150 | 0 of 47 |
| Other tasks | General disorders | 1 of 150 | 0 of 47 |
Serious events with the highest arm-level rate: post-surgical symptoms (2.0%), high bdi (1.3%).
The adverse-event information is presented separately for the Surgical Group and Control Group. The registry lists 5 serious adverse events among 150 at risk in the Surgical Group and 0 among 47 at risk in the Control Group. For other adverse events, it lists 11 among 150 at risk in the Surgical Group and 3 among 47 at risk in the Control Group. The listed deaths are 2 in the Surgical Group and 0 in the Control Group. These are registry counts; they do not establish that an event or death was caused by surgery or by study participation.
The record lists Post-surgical Symptoms at 2.0% and High BDI at 1.3% among the top serious terms. These labels and percentages should be read as the adverse-event terms reported in the registry, not as a complete description of all event types or their clinical context. The record does not provide further detail about event timing, severity criteria, relatedness, or outcomes.
Group counts alone do not establish comparative safety. The registry identifies a non-randomized comparison, and the groups were described differently. No causal conclusion should be drawn from the counts without additional information about how events were collected and classified, participant characteristics, and follow-up.
12. What the Result Does, and Does Not, Mean
The study addresses a question about brain connectivity over time in adults involved in a bariatric surgery study. Its primary outcome was change in a BOLD fMRI connectivity measure from baseline to 18 months, with a mean and standard deviation specified as the summary statistics. The registry also provides a general interpretation of the transformed connectivity scale. These details identify what the study set out to measure, but do not give the observed result.
The registry record does not report the mean change, its standard deviation, a confidence interval, or a statistical test result for the primary endpoint. As a result, the posted record does not establish whether the measured connectivity changed, the direction of any change, or how precisely any estimate was determined. It also cannot support a conclusion that one group had a larger or smaller change than the other.
The design affects what a group comparison could mean. The surgical participants intended to undergo bariatric surgery, while community volunteers were described as healthy adults with body mass index >35 who would not undergo surgery. The registry states that the study was not a randomized comparison. Even if a numerical difference between groups were reported, this design would not by itself show that surgery caused the difference; group characteristics and other factors could contribute. The record does not describe an adjustment strategy that would address such differences.
The stated MRI follow-up population is 37 individuals. The record does not explain participant flow, missing outcome data, or the relation between that population and enrollment of 197. This limits assessment of how broadly the endpoint information might apply to the enrolled study population.
In short, the registry describes a completed study and its primary measurement, but not the primary numerical result. The evidence available in the record therefore supports describing the study question and design, not claiming a particular effect on brain connectivity, memory, thinking ability, or clinical outcomes.
13. Why This Trial Matters Statistically
This study illustrates why a clearly named endpoint is not the same as a fully interpretable result. The registry specifies a continuous brain-imaging measure, the transformation used to express connectivity, a follow-up timeframe, and summary statistics. Those elements tell readers what was intended to be measured. Without the observed mean change and its variability, however, the magnitude, direction and precision of the outcome remain unknown.
It also highlights the importance of distinguishing a non-randomized group comparison from a randomized trial. The surgical candidates and community volunteers had different descriptions and were not randomly allocated according to the registry record. Statistical comparisons between such groups can be affected by differences in who enters each group. The design context is essential when deciding whether an observed association could be interpreted causally.
The stated MRI population and overall enrollment are not accompanied by participant-flow details. Without information on follow-up completion and missing data, readers cannot assess how outcome availability might relate to the study population. Clear reporting of analysis populations, missing-data handling, estimates and uncertainty is important for judging the strength and limits of evidence.
Finally, planning calculations are not a substitute for trial results. The registry's assumptions describe a planning illustration based on an observed effect; they do not establish the study's original design rationale or observed power. Separating planning assumptions from actual outcome estimates helps keep statistical interpretation aligned with what the record documents.
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 principal limitation for interpreting this study from the registry record is that the numerical result for the primary endpoint is not reported. The record identifies the outcome as mean change in BOLD fMRI connectivity at 18 months, with standard deviation as the dispersion measure, but does not provide either statistic. It also does not report an interval estimate or a test result. The size, direction and precision of the primary finding therefore cannot be assessed.
The record states that 37 individuals completed pre-surgery MRI at baseline and 18-month follow-up, while enrollment is listed as 197. It does not provide a flow account explaining the relationship between those figures, reasons for missing follow-up, or the way incomplete data were handled. The potential for selection related to MRI completion cannot be evaluated.
The comparison is explicitly not randomized, and allocation is not stated. The group descriptions differ: the surgical group consisted of candidates intending to undergo bariatric surgery, while the community volunteers were described as healthy adults with body mass index >35 who would not undergo surgery. The registry does not report baseline characteristics or an adjustment plan, limiting the ability to assess comparability or confounding.
The outcome description refers to the frontal cortex and hippocampus but does not specify the exact connectivity pairs or provide further details about measurement and analysis. The record also does not report a detailed statistical plan, multiplicity handling, or missing-data methods. These limitations concern the information available in the registry record and do not establish what analyses may have been conducted outside it.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The WISE (Weightloss Intervention Surgical Effects) Brain Study — NCT02137070.
- Registry record last updated 2024-12-05; status last verified 2024-11.
- Results first posted 2024-12-05.
- 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 WISE (Weightloss Intervention Surgical Effects) Brain Study is listed as completed and sponsored by the University of Florida. The registry lists enrollment of 197, a start of 2014-08 and primary completion of 2022-11. It describes a surgical-candidate group and a non-surgical community volunteer group, and states that the study was not a randomized comparison.
The primary endpoint was change in BOLD fMRI connectivity from baseline at 18 months, expressed as a Fisher-z transformation. The registry states that 37 individuals completed MRI at baseline and follow-up. It does not report the primary numerical outcome estimate or its variability, nor does it provide details about missing-data handling, participant flow, or the statistical analysis plan. The posted record therefore defines the research question and measurement but does not permit interpretation of the primary result's direction or precision.