Six-month Study to Compare the Effects of Volume- and Pressure-Guided Adjustments on Weight Loss and Satiety: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Six-month Study to Compare the Effects of Volume- and Pressure-Guided Adjustments on Weight Loss and Satiety (NCT00960843), a randomized na study. The primary outcome is Percent Excess Weight Change at Day 180.

2. Clinical Question

The question is about the adjustment method, not a comparison between having a gastric band and not having one: both groups were described as patients with an implanted band. The main statistical comparison is between group means at the stated follow-up, as recorded for the primary endpoint. The title and study purpose also mention satiety and comfort, but the posted outcome list identifies percent excess weight change as primary and pressure and weight-loss rate as secondary. Those listed measures therefore define what the posted numerical results can address.

3. Trial Design

The registry describes a randomized, controlled, parallel-group study with no masking. It was listed as a six-month study, and the primary endpoint timeframe runs from screening to Day 180. The study status is completed. The registry lists enrollment of 51 participants, while the primary endpoint analysis is identified as a per-protocol population and has 10 participants in the conventional arm and 11 in the intraband-pressure arm. Those analysis counts are not the same as overall enrollment; the number analyzed for this endpoint is smaller.

One arm received conventional band adjustments, described as standard of care and potentially based on volume or hunger. The other arm had adjustments guided by intraband pressure readings. The comparison is therefore between two adjustment strategies applied to patients with implanted bands. The registry lists Ethicon Endo-Surgery as sponsor. The recorded study start is 2009-07 and primary completion is 2010-11.

Random allocation is intended, in general, to reduce systematic differences between groups at the point of assignment. In a parallel design, participants remain in their assigned group rather than crossing between approaches. No masking was recorded, so participants or study personnel may have known the assigned approach; the registry does not describe further procedures for limiting possible influence on assessments or care.

The registry identifies the primary analysis population as participants without major protocol violations affecting the validity of pressure or non-pressure data. It does not report the number excluded for particular reasons, a full participant flow, or an intention-to-treat analysis. The phase is listed as not applicable. Details of the randomization procedure, allocation concealment, and original sample-size justification 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Per Protocol Population - all randomized subjects without major protocol violations affecting the validity of pressure or non-pressure data.

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as Percent Excess Weight Change at Day 180, measured over Screening to Day 180.

The primary endpoint is percent excess weight change at Day 180, with the timeframe defined as screening to Day 180. The registry says it is calculated for each participant using the difference between screening weight and Day 180 weight, divided by excess weight at screening, and multiplied by 100%. Excess weight is defined as screening weight minus ideal body weight. Ideal body weight is based on sex and height, using the upper limit of the medium-frame range from the 1983 Metropolitan Life reference.

This scale expresses weight change relative to the participant’s excess weight at screening rather than as an unscaled amount of weight. In general, a standardized measure can help describe change in relation to a defined starting reference. The registry reports group means and standard deviations, so the posted primary comparison concerns average values and their dispersion, not the response of every participant.

The recorded mean is -13.2 in the conventional arm and -24.2 in the intraband-pressure arm. Because the registry’s formula and the signs of the posted results should be read together, the values are best reported as recorded rather than translated into an unstated clinical direction. The registry does not give a clinical threshold for an important difference on this measure. It also does not report a separate primary endpoint for satiety or comfortability, despite those topics in the study title and purpose.

7. Results Posted in the Registry

• Intraband Pressure Arm: mean -24.20 versus -13.20 on control; difference -11.00 (95% CI -23.42 to 1.42), standardized effect d = -0.74; z-test p = 0.083.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Mean Static Intraband Pressure at Day 180

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intraband Pressure Arm: mean 15.80 versus 0.70 on control; difference 15.10 (95% CI 3.23 to 26.97), standardized effect d = 1.11; z-test p = 0.013.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Intraband Pressure Arm than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Rate of Weight Loss kg/wk at Day 180

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intraband Pressure Arm: mean 0.43 versus 0.18 on control; difference 0.25 (95% CI 0.05 to 0.45), standardized effect d = 1.03; z-test p = 0.014.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Intraband Pressure Arm than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes provide a consistent direction of separation in their posted summaries, but they measure different features of the study. Mean static intraband pressure concerns a Day 180 pressure measurement, while rate of weight loss concerns a rate over the screening-to-Day 180 timeframe. They are not interchangeable with the primary measure of percent excess weight change, and a pattern in secondary outcomes cannot substitute for the primary comparison.

Both secondary comparisons have recalculated confidence intervals that exclude zero, and both have registry-reported two-sided p-values below 0.05. These findings may help describe how the adjustment approaches differed on the additional measured outcomes. They do not, by themselves, establish that the primary endpoint is conclusive or resolve the uncertainty in its estimate. Nor do they provide a direct numerical result for satiety or comfortability, which are not listed as posted outcome measures.

Unadjusted secondary results carry less weight because multiple outcomes create more opportunities to observe apparently notable differences by chance. General explanation: when several hypotheses are tested without an adjustment or a prespecified hierarchy, the chance of at least one false-positive finding across the set can increase. The registry does not report a multiplicity adjustment, a hierarchy for interpreting outcomes, or a plan for controlling the overall error rate. The secondary p-values should therefore be treated as exploratory evidence rather than as independent confirmation of the primary finding.

The registry lists three outcome measures in total: the primary endpoint and two secondary outcomes. However, the record does not report whether additional outcomes were measured but not posted, or whether any outcomes were changed during the study. The secondary results add context about pressure and weight-loss rate, but they do not fill the reporting gap for the title’s satiety and comfort themes. Their interpretation remains conditional on the small analyzed groups and the absence of reported multiplicity procedures.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Mean Static Intraband Pressure at Day 180
• Rate of Weight Loss kg/wk at Day 180

9. Statistical Interpretation

10. Statistical Methods Explained

The registry identifies the primary measure as continuous and reports a mean and standard deviation for each arm. A mean describes the average recorded outcome in a group. A standard deviation describes how spread out individual values are around that group mean; it is not the uncertainty of the mean itself. In these results, the group sizes are small, so both the estimated means and the spread around them matter when judging how precisely the group contrast is known.

What does the mean difference represent?

The recalculated mean difference compares the intraband-pressure arm with the conventional arm, subtracting the conventional mean from the pressure-guided mean. For the primary outcome, the estimate is -11.0. This is a difference in the endpoint’s percentage units, not a percentage reduction in risk and not a ratio. The sign records the direction of the arithmetic contrast under that arm ordering. Interpretation of the endpoint’s direction should also respect the registry’s stated calculation and the fact that the reported group means are negative.

For a continuous outcome, a difference in means is a direct way to describe the average separation between groups. It does not show how much participants’ values overlap, whether all individuals changed in the same direction, or whether a difference would be important to patients. The registry does not provide an established clinically important threshold for this endpoint.

How should a confidence interval be read?

General explanation: a confidence interval gives a range of values compatible with the observed data under the statistical model and its assumptions. Its width communicates precision: a narrower interval indicates a more precise estimate, while a wider one allows a larger range of possible values. The 95% interval for the primary recalculation is -23.42 to 1.421. Since zero is within that interval, the data do not rule out no mean difference under this interval-based comparison. The interval also includes values in both directions, making the direction and size of the underlying contrast uncertain.

A confidence interval is not a statement that there is a 95% probability that the fixed true effect lies inside this particular interval. In general, the stated confidence level describes the long-run coverage behavior of the procedure under its assumptions. It also does not account for sources of uncertainty that are not represented by the calculation, such as selective outcome reporting or missing-data mechanisms that are not described.

What does the p-value add?

The registry reports a two-sided t-test for the group comparison. General explanation: a two-sided test evaluates departures in either direction from a null hypothesis of no difference. A p-value measures how unusual the test result would be if the null model and test assumptions held. It is not the probability that the null hypothesis is true, nor does it quantify the magnitude or practical importance of the outcome.

The sponsor’s reported primary p-value is 0.052; a simple unadjusted recalculation gives 0.083. The posted results do not explain why the test results differ. The registry does not report the full test specification, such as whether a variance adjustment was used, nor does it provide its own numerical confidence interval for the primary contrast. A reader should therefore distinguish the sponsor’s reported test from a separate summary-statistic recalculation rather than treating them as interchangeable analyses.

Why can dispersion matter?

General explanation: greater variability within groups makes it harder to estimate a group mean and a difference between means precisely, particularly when the number of observations is limited. Unequal variability across groups can also affect the behavior of some tests if their assumptions do not accommodate that difference. The primary standard deviations are 11.1 and 17.5, and the arm sizes are 10 and 11. Those summaries show that the observed dispersion is not identical, but the registry does not specify the variance assumptions used in its t-test. The recalculation uses the posted summary statistics and is not a substitute for access to participant-level data or the sponsor’s analysis details.

In general, over-dispersion means that observed variability is greater than a statistical model expects. That can make model-based standard errors too small and intervals too narrow if the extra variation is not accounted for. The registry does not identify an over-dispersion model or report count outcomes for the primary endpoint; the endpoint is continuous, so over-dispersion is not the main issue for interpreting this mean comparison. The more immediate concern is the imprecision associated with the small analyzed groups and the observed spread.

How does randomization relate to the analysis?

General explanation: randomization can support a fair comparison by balancing measured and unmeasured baseline factors on average across repeated assignments. In a particular study, chance imbalances can remain, especially with limited group sizes. The registry records randomized allocation, but baseline characteristics and the allocation procedure are not reported in the details available for this analysis. The primary results are identified as per protocol, which means the reported analysis population excludes participants with major protocol violations affecting data validity according to the registry description. This differs from an analysis that retains every randomized participant in the group originally assigned.

The posted primary result is therefore an estimate for the analyzed per-protocol groups. Without a reported participant flow, reasons for exclusions, or an intention-to-treat result, it is not possible to assess how the analytic population may differ from the randomized population. Such details are relevant because exclusions after randomization can weaken the protection that random allocation is intended to provide.

11. Confidence Intervals and Precision

The recalculated primary mean difference is -11.0, with a 95% confidence interval from -23.42 to 1.421. This interval spans zero, so the recalculation is compatible with no mean difference as well as with contrasts in either direction. It allows a wide range of possible values relative to the estimate, which indicates limited precision. The group means are based on 10 and 11 analyzed participants, and the standard deviations are 11.1 and 17.5.

General explanation: confidence intervals combine the estimated contrast with its sampling uncertainty. A larger interval may result when the sample is small, when outcomes vary substantially between participants, or both. The interval does not capture every potential source of bias or uncertainty. In particular, it cannot correct for exclusions, incomplete outcome recording, or selective reporting when those processes are not represented in the statistical calculation.

The registry’s own primary analysis reports a two-sided p-value of 0.052 but does not report a numerical confidence interval for that analysis. The recalculated interval is therefore a separate estimate based on the posted group summaries, not a confidence interval attributed to the registry’s test. The sponsor’s reported test and the recalculation should be kept distinct.

The interval should not be read as a range of likely individual outcomes or as a threshold for clinical importance. It concerns the group mean contrast under the recalculation’s assumptions. The registry does not report a minimally important difference for percent excess weight change, so statistical precision cannot by itself establish whether any value within the interval would be meaningful to patients.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations based on observed effects, not the original trial design. For these continuous outcomes, the figures are participants per arm, not total events. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; each planning scenario uses the stated fraction of the observed effect as the effect to detect. The trial’s own original sample-size justification and assumptions are not reported in the registry record.

The 80% power column gives the estimated number of participants per arm for a design that would have an 80% probability of detecting the selected effect under the planning assumptions, if that effect were the true effect and the assumptions held. The 90% power column gives the corresponding number per arm for a higher target probability of detection. These are design calculations, not descriptions of what happened in this completed study. They are not observed power.

The rows compare planning around 100%, 75%, and 50% of the observed effect. As the effect to detect becomes smaller, more participants are needed to distinguish it from random variation with the stated power target. For example, the primary-outcome illustration lists 29 participants per arm for 80% power when planning for 100% of the observed effect, 51 per arm for 75%, and 114 per arm for 50%. These values are illustrations based on this study’s observed estimate, which itself is uncertain because the analyzed groups were small.

The planning numbers should not be treated as a recommendation for a future study or as proof that the original study was adequately or inadequately sized. They do not incorporate assumptions beyond those listed, and they do not establish that the observed effect is a reliable estimate of the effect a later study would encounter. The original protocol rationale is not reported in the registry record.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -11.000; pooled standard deviation σ = 14.817.
2. n = 2 × (1.96 + 0.842)² × 14.817² / -11.000² = 28.5, rounded up to 29 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -11                      # observed difference in means
sigma <- 14.8171131501809                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(960843)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 29 (80% power), 39 (90% power)
 75% of observed effect: n per arm = 51 (80% power), 68 (90% power)
 50% of observed effect: n per arm = 114 (80% power), 153 (90% power)
power.t.test: 29.5 
Simulated power at n = 29 per arm: 0.797 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry’s own primary analysis is a two-sided t-test with p = 0.052. The simple unadjusted recalculation from the posted group means, standard deviations, and analyzed sample sizes gives a mean difference of -11.0, a 95% confidence interval from -23.42 to 1.421, and p = 0.083. The registry does not provide its own numerical confidence interval or full test details for the primary outcome.

The recalculation is a separate analysis of summary statistics, not a reproduction of the sponsor’s complete analysis. The registry does not report enough methodological detail to identify the reason for the p-value difference. The sponsor’s result should be identified as the registry-reported analysis, while the recalculated estimate and interval offer an additional unadjusted view of the posted summaries. Neither result should be described as resolving the clinical importance of the contrast.

The registry does not flag a discrepancy between the reported analysis and the recalculation. Even so, the two p-values are not identical and should not be conflated. The reported test is the sponsor’s own analysis; the recalculation is useful for illustrating the estimate and its uncertainty from the available summary statistics. The registry’s analysis population is per protocol, and the available record does not report a corresponding intention-to-treat analysis for comparison.

15. Multiplicity, Missing Data and Analysis Populations

The registry reports a primary endpoint and two secondary outcomes, with two-sided tests listed for each comparison. It does not report a multiplicity adjustment or a testing hierarchy. When multiple outcomes are tested, the chance of at least one apparently positive result due to chance can rise if each is interpreted using an unadjusted threshold. General explanation: multiplicity procedures or a prespecified sequence can help define how evidence across multiple tests should be interpreted. Without a reported plan, the primary comparison should remain the central result, and the secondary p-values should be read cautiously.

The record describes the primary endpoint population as per protocol: randomized participants without major protocol violations affecting the validity of pressure or non-pressure data. This clarifies that the primary comparison is not simply described as including every randomized participant. The number excluded, the reasons for exclusion, and the group assignment of excluded participants are not reported in the registry record. An intention-to-treat analysis is also not reported.

The primary analysis includes 10 participants in the conventional arm and 11 in the intraband-pressure arm. The secondary pressure outcome includes 10 participants in each arm, while the rate-of-weight-loss outcome includes 10 and 11. These varying analysis counts indicate that the outcome-specific analyzed groups are not identical. The registry does not explain the differences in counts, give missingness by reason, or describe how missing measurements were handled.

Missing-data methods matter because results can be biased if the probability of missingness is related to participants’ outcomes or assigned groups. General explanation: complete-case estimates describe participants with observed measurements, and their relevance to all randomized participants depends partly on why other measurements are absent. The available record does not allow that process to be assessed. It also does not report interim analyses, stopping rules, or a statistical analysis plan. Those details should not be inferred from the posted tests or from the planning illustrations.

16. 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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: medical device complication (3.8%).

The registry reports serious adverse events for 0 of 25 participants at risk in the conventional adjustment group and 1 of 26 participants at risk in the intraband-pressure arm. These counts describe participants with at least one serious adverse event as recorded in the registry, not the total number of distinct event episodes. The registry also lists medical device complication at 3.8% among the top serious event terms, but does not give a group-specific breakdown for that term in the available results.

Other adverse events are reported for 6 of 25 participants in the conventional group and 11 of 26 in the intraband-pressure group. These are separate registry counts and should not be combined with the serious-event figures. The registry does not provide enough detail in this record to assess event timing, duration, severity beyond the serious classification, or the relationship of each event to the adjustment strategy. Deaths are not reported in the registry record.

These counts are descriptive and involve small groups. They do not establish that one approach is safer or less safe. The absence of a recorded serious event in one group is not proof that such events cannot occur, and the difference in counts does not by itself identify a causal effect. Safety interpretation also depends on complete and consistent event collection, details not reported in the registry record.

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

The posted primary results describe the average percent excess weight change recorded by Day 180 in the two per-protocol groups. The recalculated contrast is -11.0, with a 95% confidence interval from -23.42 to 1.421. That interval includes zero and permits a range of possible group differences, so the estimate is not precise enough to establish the direction or size of a mean difference confidently. The sponsor’s reported two-sided test gives p = 0.052, while the unadjusted recalculation gives p = 0.083.

These statistics do not determine whether the approaches are clinically equivalent. A non-significant or borderline test does not demonstrate equivalence; that requires an appropriate design, a prespecified equivalence margin, and an analysis directed at that question. No equivalence or noninferiority framework is reported in the registry record. Likewise, the observed mean difference does not establish that a difference is important to patients because a clinical-importance threshold is not reported.

The study title and purpose refer to satiety and comfort, but the posted outcomes do not include a named satiety endpoint or a distinct comfort measure. The available results therefore cannot quantify those experiences. The secondary outcomes concern intraband pressure and rate of weight loss; their unadjusted results are additional descriptive evidence, not replacements for a direct measure of satiety or comfort.

The results are limited to the analyzed groups and the stated follow-up. The registry lists total enrollment of 51, but the primary endpoint analysis includes 10 and 11 participants. The reasons for this difference, missing-data handling, and an intention-to-treat result are not reported. Accordingly, the estimates should not be generalized beyond what the record supports. They describe this randomized comparison and its uncertainty; they do not provide individual predictions or treatment advice.

18. Why This Trial Matters Statistically

This trial illustrates why an estimated effect and its uncertainty are more informative than a p-value alone. The primary contrast is reported as a mean difference with a confidence interval, which makes visible the range of values compatible with the summary data. Here that interval includes zero and spans values in both directions. The sponsor’s p-value and the recalculated p-value also differ, which is a reminder to distinguish the registry’s reported analysis from a simple recalculation using posted summaries.

The analysis population is another important part of the statistical story. Although allocation was randomized, the primary result is reported for a per-protocol population rather than all randomized participants. Without a participant flow and an intention-to-treat result, readers cannot evaluate how exclusions may have affected the comparison. The outcome-specific analysis counts also differ, while the record does not explain why.

The study also demonstrates the interpretive challenge created by multiple outcomes. The secondary comparisons have notable unadjusted results, but no multiplicity plan is reported. Treating every unadjusted p-value as independent confirmation would overstate the evidence. A prespecified outcome hierarchy and transparent missing-data reporting would help readers understand how each finding fits the analysis plan.

Finally, planning illustrations based on the observed effect can be useful for understanding how target effect size and desired power relate to sample requirements. They are not the trial’s original justification, and the observed estimate is uncertain. Keeping those planning calculations separate from the trial’s actual design assumptions is essential to avoid reading retrospective illustrations as evidence about the study’s original adequacy.

19. 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 analyzed groups are small: 10 participants in the conventional arm and 11 in the intraband-pressure arm. The observed standard deviations are 11.1 and 17.5, and the recalculated primary interval is broad and includes zero. This limits precision and makes the estimated group contrast sensitive to the outcomes of a small number of participants.

The primary result is reported for a per-protocol population. The record does not provide a complete participant flow, reasons for exclusions, an intention-to-treat analysis, or a detailed account of missing measurements. The secondary outcomes also have outcome-specific analysis counts, and the reasons for those counts are not reported. These omissions make it difficult to assess the effect of post-randomization exclusions or missing data.

The registry does not report a multiplicity plan, a statistical analysis plan, the test’s full specification, or the sponsor’s numerical confidence interval for the primary analysis. It also does not report the original sample-size justification, interim analyses, or stopping rules. The planning illustrations based on observed effects cannot fill those gaps.

The title and study purpose refer to satiety and comfortability, but the posted outcome list includes neither a named satiety measure nor a distinct comfort outcome. The listed results therefore do not directly answer those parts of the study purpose. No clinical threshold for an important primary-endpoint difference is reported, making it difficult to relate the numerical estimate to a patient-centered threshold. These are limitations of what can be interpreted from the registry record, not evidence that unreported procedures or measurements did not occur.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Six-month Study to Compare the Effects of Volume- and Pressure-Guided Adjustments on Weight Loss and Satiety — NCT00960843.
• Registry record last updated 2012-08-20; status last verified 2012-08.
• Results first posted 2012-04-03.
• 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.

23. Record Summary

The registry describes a completed, randomized, controlled, parallel-group study with no masking, comparing conventional gastric-band adjustments with adjustments guided by intraband pressure readings. It lists enrollment of 51 and a six-month timeframe. The primary endpoint is percent excess weight change from screening to Day 180, analyzed in a per-protocol population.

The primary group means were -13.2 for the conventional arm and -24.2 for the intraband-pressure arm. The recalculated mean difference is -11.0, with a 95% confidence interval from -23.42 to 1.421 and an unadjusted p-value of 0.083. The registry-reported two-sided test gives p = 0.052. Two secondary outcomes are posted, but no multiplicity procedure is reported. Satiety and comfortability outcomes are not reported in the registry record.