LAGB as a Treatment for Morbid Obesity in Adolescents: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for LAGB as a Treatment for Morbid Obesity in Adolescents (NCT01045499), a na na study. The primary outcome is Percentage of Excess Weight Change (EWL).

2. Clinical Question

3. Trial Design

The registry describes a completed, single-group study of laparoscopic adjustable gastric banding in adolescents with morbid obesity. Enrollment is listed as 137. The intervention is a device procedure, the Allergan Lap Band. The brief description frames the study around whether the procedure could assist selected adolescents between 14 and 17 years of age with weight loss, and whether it could be performed safely in that age group. These statements describe the study's rationale and hypothesis, not a reported finding.

There is no randomized allocation: allocation is listed as NA, masking as none, and the model as single group. Consequently, the study does not include a concurrent randomized control arm for a like-for-like comparison. The arm description says that weight, BMI, and co-morbidity data are compared with patients' pre-operative values. A comparison with a participant's own earlier measurement can describe change over time, but it does not control for other influences on change in the way a randomized concurrent comparison is intended to do.

The registry lists the study start as 2005-09-13, primary completion as 2016-07-31, and status as completed. The primary endpoint timeframe is baseline and up to 5 years from the start of the study. The primary analysis population is described as individuals with confirmed band status at 5 years after surgery. The record does not explain how band status was confirmed, how the outcome population was assembled, or how observations at different follow-up times were handled.

The registry lists two outcome measures and zero analyses. It identifies percentage of excess BMI change as a secondary outcome, but provides no numerical outcome findings in the record. Details such as eligibility criteria beyond the brief age and condition descriptions, the statistical analysis plan, and any 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.

Before assignment: The age range for the enrolled adolescents at the time of surgery was 14-19 years of age since some aged from the time of consent to surgery.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Includes individuals with confirmed band status at 5 years after surgery.

5. Baseline Characteristics

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

Population: adolescents with morbid obesity 14-18yr

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Excess Weight Change (EWL), measured over Baseline and up to 5 years from start of study..

The primary endpoint is percentage of excess weight change, described in the registry as excess weight loss (EWL). It is a continuous measure, summarized as a mean with a standard deviation. The endpoint timeframe is baseline and up to 5 years from the start of the study, while the stated outcome population includes individuals with confirmed band status at 5 years after surgery.

In general, an excess-weight measure expresses weight change relative to a reference amount of weight above a specified target. Reporting change as a percentage can make the result easier to interpret against that reference than reporting only a change in weight units. However, the registry record does not define the target weight, the calculation formula, or the precise baseline reference used for EWL. Those details should not be inferred from the endpoint label alone.

A mean describes the average outcome in the analyzed population, while a standard deviation describes how dispersed individual measurements are around that average. The standard deviation is not the same as a confidence interval: it describes variation among measurements rather than the precision of the estimated mean. The registry record states the intended summary but does not report the mean, standard deviation, confidence interval, or a test result. It therefore does not show the numerical magnitude or precision of the primary endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods can be understood only to the extent that the registry record describes them. It identifies the study as single-group, the primary measure as continuous, and the planned primary summary as a mean with standard deviation. It does not report a full analysis plan, a primary-outcome estimate, a confidence interval, or a test result. The explanations below describe general statistical principles; they are not claims about analyses performed in this study.

What does a mean and standard deviation convey?

In general, a mean summarizes the central level of a continuous outcome across the observations included in an analysis. A standard deviation describes how spread out those observations are around the mean. A relatively broad spread indicates that participants' outcomes vary substantially; a narrow spread indicates more clustering around the average. Neither statistic alone conveys the uncertainty in the estimated mean. A confidence interval is used for that different purpose: it gives a range of values compatible with the data and the method's assumptions, reflecting uncertainty about the estimate.

The registry record specifies mean and standard deviation for EWL but does not provide their values. It also does not say whether a confidence interval was calculated. The outcome description does not give a distributional summary beyond those planned statistics. It would therefore be inappropriate to infer the size, spread, or precision of the observed outcome.

What does a pre-operative comparison show?

In general, comparing follow-up measurements with a person's baseline can quantify change over time in the measured group. It is a within-group description, not a randomized treatment contrast. Without a concurrent control group, changes can also reflect natural history, other care, changes in measurement, or differences in who remains observed. These are general considerations for interpreting before-and-after data, not evidence that any particular influence occurred in this study.

The arm description states that weight, BMI, and co-morbidity data are compared with pre-operative values. The record does not specify the statistical test, whether the comparison used paired observations, how repeated measurements were modeled, or how missing follow-up values were handled. The endpoint timeframe covers baseline and up to 5 years, but the record does not define which follow-up visit posted the primary analysis value or how observations across that period were combined.

What does a single-group design imply?

In general, randomization helps make treatment groups comparable with respect to measured and unmeasured characteristics, on average. A single-group study has no such between-group comparison. Its outcome can describe what was observed among participants, but attributing that change to the intervention requires assumptions that are not secured by a concurrent randomized control. The registry lists allocation as NA and masking as none, consistent with its single-group description. It does not report a causal analysis designed to address the absence of a control group.

How should the planning illustrations be understood?

In general, a sample-size calculation is a planning exercise that asks what study size might be needed to detect a specified effect under stated assumptions. The registry's planning description refers to a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of an observed effect. It also distinguishes total events for time-to-event planning from participants per arm for other planning calculations. These are planning assumptions, not evidence that this single-group study was designed or analyzed as a two-arm trial.

A planning calculation based on an observed effect is not observed power and does not establish that the underlying effect is real, clinically important, or precisely estimated. Planning values depend on the assumed effect and statistical model. The registry says that the illustration is not the trial's own design. No trial-specific sample-size justification or statistical plan is reported in the registry record.

What can p-values and confidence intervals say?

In general, a p-value assesses how compatible data are with a specified null hypothesis under a statistical model; it does not measure the probability that the null hypothesis is true, nor does it measure clinical importance. A confidence interval communicates uncertainty about an estimated quantity under its method's assumptions. Reading both the estimate and its interval is generally more informative than relying on a threshold alone. No primary-outcome p-value or interval is reported in the registry record, so neither statistical significance nor precision can be evaluated for EWL from the record.

The outcome is continuous and the planned summary includes a standard deviation. In general, unusual distributions, influential observations, and incomplete follow-up can affect the usefulness of a mean-based summary. Statistical approaches can account for some such features, but the choice depends on the data and analysis plan. The registry record does not report diagnostics, transformations, model specifications, or sensitivity analyses, so no such method should be attributed to this study.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Laparoscopic Gastric Banding")
n   <- c(127)
m   <- c(-35.5)
sp  <- c(39.4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Laparoscopic Gastric Banding  127  -35.500  39.400  -42.419  -28.581

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: percentage of excess weight change as the primary outcome and percentage of excess BMI change as a secondary outcome. It describes a primary endpoint timeframe extending from baseline and up to 5 years from the start of the study. Assessing multiple outcomes or timepoints can raise a multiplicity question: when many statistical tests are performed, the chance of at least one apparently notable result can increase. In general, a prespecified hierarchy or an adjustment can help address that issue. The registry record does not report whether such a plan was used, how many comparisons were tested, or whether any adjustment was made.

The registry lists zero analyses, and it does not provide numerical results for the outcome measures. A statistical analysis plan, definitions of analysis populations, handling of repeated observations, and any interim-analysis plan are not reported in the registry record. It is therefore not possible to determine which planned comparisons were performed or how outcome estimates were selected for reporting.

Missing-data handling is also not reported. The primary population is described as individuals with confirmed band status at 5 years after surgery, but the record does not state how many had confirmed status, how people without confirmation were treated, or whether missing outcome values were imputed or excluded. In general, missingness can affect an estimate if the observed participants differ systematically from those without outcome data. Sensitivity analyses can examine how conclusions change under different assumptions, but the record does not describe any such analyses.

The registry's stated primary population and absent missing-data details leave uncertainty about how broadly any eventual estimate would apply. The record does not report whether the primary analysis followed an intention-to-treat principle or another population definition. No specific analysis population should be assumed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: band removal (24.1%), weight loss procedure (conversion) (11.7%), port displacement (8.0%), gastric herniation (band slippage) (7.3%), band removal due to dysphagia, reflux or heartburn (2.2%).

The registry lists serious adverse events for the laparoscopic gastric banding group with 137 at risk and 63 affected. For other adverse events, it lists 137 at risk and 137 affected, and it records 3 deaths. These are distinct registry entries; the record does not explain the operational definitions or how the categories relate to each other. It does not state whether affected refers to people, events, or a particular reporting window, so the counts should be read as posted rather than reinterpreted.

The serious-event terms listed include Band removal at 24.1%, Weight loss procedure (conversion) at 11.7%, Port displacement at 8.0%, Gastric Herniation (band slippage) at 7.3%, Band removal due to dysphagia, reflux or heartburn at 2.2%, and Hiatal hernia repair at 0.7%. The registry record does not specify the denominator behind each listed percentage, whether categories overlap, or whether these are participant-level proportions or event-level summaries. They should not be added together or treated as a mutually exclusive breakdown.

The record does not provide event timing, severity criteria, relatedness assessments, or details of how deaths were classified. The fact that deaths are listed does not establish that they were caused by the intervention. The counts and terms describe the safety entries in the registry; by themselves, they do not establish comparative risk because there is no control group described.

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

The registry record identifies a clinically relevant question: whether laparoscopic adjustable gastric banding was studied as a way to assist selected adolescents with morbid obesity, with attention to weight change and associated conditions. It records a completed single-group study and defines percentage of excess weight change as its primary endpoint. It also describes pre-operative values as the reference for weight, BMI, and co-morbidity data. These design details help explain what the study set out to observe.

However, the registry record does not report a numerical primary-outcome result. No EWL mean, standard deviation, confidence interval, or test result is available in the record. The study's size and completion status do not substitute for those outcome statistics. The record also does not give numerical findings for the secondary outcome or the co-morbidity and psychological assessments described in the study summary.

Even if a pre-operative-to-follow-up change were reported, a single-group comparison would describe change over time rather than isolate a causal effect. Without a concurrent control group, explanations other than the intervention could contribute to observed change. The record also leaves the primary outcome population dependent on confirmed band status at 5 years, without reporting the number meeting that condition or the handling of people without confirmation.

The safety entries provide counts, listed terms, and percentages, but their definitions and denominators are not fully described. They do not establish whether an event was caused by the device or procedure, and there is no randomized comparator for interpreting relative risk. The listed deaths likewise cannot be attributed to the intervention from the registry entries alone.

Accordingly, the record establishes that the study was conducted and how the primary endpoint was defined, but it does not support a quantitative conclusion about the primary outcome or its precision. It also does not establish that the procedure caused any observed change or adverse event. Those are limits on what can be concluded from the registry record, not a claim about results that might be available elsewhere.

14. Why This Trial Matters Statistically

This study is statistically notable for the gap between a clearly named clinical endpoint and the absence of a numerical endpoint result in the registry record. The primary measure is specified as mean percentage of excess weight change with a standard deviation, and its timeframe extends from baseline to up to 5 years. Yet the record does not report the estimate or its uncertainty. Naming a measure helps define the research question, but does not show what the data found.

The single-group design is another important statistical feature. Comparing participants' follow-up measurements with their own pre-operative values can describe observed change, but it does not create the counterfactual comparison needed to distinguish intervention-related change from other influences over time. The registry's allocation and model entries clarify that no randomized control comparison is described. This design constraint remains even if within-group measurements are complete.

The stated primary population also draws attention to follow-up and analysis-population definitions. Inclusion depends on confirmed band status at 5 years after surgery, but the record does not report how many participants met that definition or how unconfirmed status and missing outcome data were handled. In general, such details matter because the people included in an analysis may differ from those not included. Without these details, the reach and potential selection of the analyzed population cannot be assessed.

Safety reporting offers specific event labels and counts, while leaving definitions, denominators, timing, and attribution unclear. The figures can be described as registry entries, but they do not provide a controlled estimate of comparative risk. Together, these features illustrate why statistical interpretation depends not only on the endpoint name or enrollment, but also on numerical results, analysis populations, uncertainty measures, and design. Several of those elements are not reported in the registry record.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this record affect interpretation. First, it is a single-group study with no randomized comparator. The registry describes comparison with pre-operative values, which can show within-group change but cannot by itself establish what would have happened over the same period without the intervention. Masking is listed as none. The record does not describe procedures intended to reduce measurement or assessment bias.

Second, the primary endpoint population is defined by confirmed band status at 5 years after surgery. The record does not report the number of participants in that population, how confirmation was determined, or what happened to individuals without confirmed status. It also does not report missing outcome counts, reasons for missingness, or methods for handling missing observations. These omissions limit assessment of possible selection effects and the representativeness of the analyzed group.

Third, the registry record does not provide the numerical primary endpoint result or results for the secondary outcome. The planned summary statistics are named, but their values and any confidence interval or test result are absent. The analysis plan, methods for repeated measurements, and sensitivity analyses are also not reported. Consequently, neither the magnitude nor the precision of the primary outcome can be assessed from this record.

Finally, safety entries have limited interpretive detail. Definitions, event timing, attribution, and the denominators for the listed percentages are not reported. The relationship between event categories is unclear, and no control group is available for comparative safety interpretation. These are limitations of the registry information and design; they do not establish that unreported analyses or details do not exist elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: LAGB as a Treatment for Morbid Obesity in Adolescents — NCT01045499.
• Registry record last updated 2020-04-13; status last verified 2020-03.
• Results first posted 2020-04-13.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry describes a completed, single-group study of laparoscopic adjustable gastric banding in adolescents with morbid obesity. Enrollment is listed as 137, allocation as NA, and masking as none. The primary endpoint is percentage of excess weight change, summarized as a mean with a standard deviation, from baseline and up to 5 years from the start of the study. Its stated population includes individuals with confirmed band status at 5 years after surgery.

The registry lists percentage of excess BMI change as a secondary outcome and gives adverse-event entries for the intervention group. It does not report numerical primary or secondary outcome results, the statistical analysis plan, or details of missing-data handling. The single-group design does not provide a randomized concurrent comparison, so pre-operative comparisons would describe change over time rather than a controlled treatment contrast.