Mechanisms of Lipodystrophy in HIV-Infected Pateints: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mechanisms of Lipodystrophy in HIV-Infected Pateints (NCT00457665), a randomized phase 4 study. The primary outcome is Effect of Drug Regimens on Serum Triglycerides..

2. Clinical Question

The study’s stated aims extend beyond this comparison. They concern describing metabolic abnormalities and changes in body fat distribution, developing objective criteria for defining lipodystrophy syndrome and identifying prognostic indicators, and investigating the syndrome’s molecular basis in people with HIV infection. The registry’s primary outcome listing, however, is specifically titled as the effect of drug regimens on serum triglycerides. It does not establish from the posted results how the broader aims were assessed or whether they were met.

The registry background says that the metabolic and molecular basis of lipodystrophy syndrome in HIV-infected patients was not known, and that the contributions of antiretroviral drugs, HIV infection, and reduction in viral load were unclear. Those statements describe the study rationale, not findings from the trial. The primary question should therefore be read narrowly: it concerns triglyceride measurements at the stated follow-up times, not a definitive test of every proposed mechanism or of lipodystrophy as a whole.

3. Trial Design

The registry classifies this as a randomized, triple-masked, parallel Phase 4 trial. It lists nelfinavir and efavirenz as the two drug interventions. The overall enrollment is 56. The registry does not report the randomization procedure, the meaning of each masking role, or details of how masking was maintained.

A parallel design assigns participants to different groups and follows those groups concurrently, rather than having each participant receive both interventions in sequence. Random allocation is intended to make the groups comparable on average at the point of assignment, although it does not guarantee that every characteristic will be balanced in a particular trial. These are general features of randomized parallel designs; the record does not describe the specific allocation sequence or any checks of group comparability.

The trial is marked completed. Its recorded start is 2002-02 and its primary completion is 2007-10. These dates identify the registry timeline; they do not describe the duration of follow-up for each participant. The primary outcome timeframe is listed as 12 and 24 months. The outcome description notes that some subjects dropped before 1 year and some dropped between 1-2 years, making the availability of follow-up measurements relevant to interpreting any comparison.

The arm descriptions contain no additional details. Doses, co-interventions, treatment adherence, and changes to assigned regimens are not reported in the registry record. Nor does the record describe eligibility criteria, the number assigned to each treatment arm, or the exact analysis population. The adverse-event listing gives 28 at risk in each group, but those safety risk counts alone do not establish the sample sizes used for the primary outcome analyses.

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.

12 Months

Reasons for not completing this period:

24 Months

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Some subjects dropped before 1 year and some dropped between 1-2 years.

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 Effect of Drug Regimens on Serum Triglycerides., measured over 12 and 24 months.

The primary outcome is serum triglyceride level, expressed in mg/dL, summarized as a mean with standard deviation. Triglycerides are a blood measure related to lipid metabolism. In this trial, the measure is used to compare the two drug-regimen groups at 12 and 24 months. A continuous outcome retains information about measured levels rather than reducing each participant to a category such as above or below a threshold.

A group mean describes the central level of the measurements, while a standard deviation describes how spread out individual measurements are around that mean. These are distinct quantities: the standard deviation is not the uncertainty in the estimated group mean and is not a confidence interval for the between-group comparison. General statistical interpretation of a treatment comparison would require the group results, the estimated contrast between groups, and an indication of its uncertainty.

The registry lists more than one assessment time for the primary outcome and notes that some participants dropped out before or during follow-up. The posted record does not give the mean or standard deviation for either group at either time, nor does it state a single primary contrast that combines or selects those time points. It therefore does not support a numerical conclusion about the size or precision of a difference in serum triglycerides. The registry also does not explain why this measure was selected in relation to the broader study aims.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, triple-masked, parallel trial with two drug groups and a continuous primary outcome. Understanding what those design labels generally mean helps frame the reported information, but the record does not give enough analysis detail to reconstruct the trial’s statistical methods.

What does randomization contribute?

In general, randomization uses a chance-based process to allocate participants to treatment groups. Its purpose is to reduce systematic differences between groups at assignment, including differences in measured and unmeasured characteristics. It does not ensure that groups will be identical, particularly in a particular trial, and it does not eliminate problems caused by missing follow-up or departures from assigned treatment. The registry says allocation was randomized but does not describe the sequence-generation method, concealment of the sequence, stratification, or any other allocation details.

What does a parallel design mean?

In a parallel trial, participants are assigned to a group and outcomes are compared across groups. This differs from a crossover design, in which the same participant receives more than one intervention in different periods. The record identifies a parallel model, but it does not report the treatment schedule or whether participants continued assigned treatment throughout follow-up. The intervention entries name nelfinavir and efavirenz; arm-specific dosing and regimen details are not reported in the registry record.

How should a continuous outcome be described?

Serum triglyceride level is a continuous measurement recorded in mg/dL. A mean is an average that describes the group’s central value. A standard deviation describes variation among individual measurements around that mean. The registry lists the mean and standard deviation as the outcome’s summary format. A standard deviation should not be mistaken for a standard error or for a confidence interval: it describes spread in observations, whereas standard errors and confidence intervals concern uncertainty in estimated quantities.

For a comparison of two groups, an analysis might estimate a difference in means, but the registry does not report such an estimate or specify that this was the method used. It also does not provide baseline triglyceride values or indicate whether the analysis adjusted for baseline measurements or other variables. Those choices can affect the interpretation and precision of a comparison, so they cannot be assumed from the outcome label.

Why do the two follow-up times matter?

The primary outcome timeframe lists 12 and 24 months. When an outcome is assessed at multiple times, an analysis needs to specify whether each time is treated as a separate comparison, whether change over time is modeled, or whether one time is designated as the principal comparison. These are general possibilities, not descriptions of what this trial did. The record does not identify a single comparison or explain how the two time points were incorporated. It notes that some subjects dropped before 1 year and some dropped between 1-2 years, but does not give the number of observations available at each assessment.

What can masking tell the reader?

The registry labels the trial triple-masked. In general, masking can reduce the influence of knowledge about treatment assignment on participant behavior, clinical care, outcome assessment, or analysis. Which parties were masked depends on the protocol and registry definitions. The record does not specify who was masked, what information was concealed, or whether masking was maintained. The label alone is not enough to determine how masking affected the outcome measurements.

How should uncertainty be assessed?

A confidence interval for a treatment contrast would communicate both the estimated difference and its statistical precision. A wider interval generally indicates less precision than a narrower interval, although interpretation also depends on the outcome scale and analysis. A p-value is a measure calculated under a specified statistical model and null hypothesis; it is not the probability that a treatment is effective or ineffective. The registry does not report a confidence interval, p-value, or other inferential result for serum triglycerides, so these quantities cannot be interpreted for the primary outcome.

What do planning assumptions establish?

The registry includes a sample-size planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. This is a planning illustration, not evidence about the trial’s original design or a report of observed power. The registry does not report the numerical planning results or the trial’s own sample-size justification. Such an illustration depends on its assumptions and should not be read as proof that the trial had adequate precision for its primary question.

General statistical practice also distinguishes planning calculations from analyses of collected data. Power calculations describe performance under assumed effect sizes and variability; they do not establish whether a particular observed estimate is precise. In this record, the absence of primary outcome estimates and uncertainty measures leaves the treatment comparison unresolved, regardless of the planning assumptions.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is recorded at 12 and 24 months, so there is more than one assessment time associated with the endpoint. The registry does not state whether these times were analyzed separately, whether one was designated as primary for inference, or whether a method was used to account for multiple comparisons. The listing of one outcome measure and one analysis does not by itself resolve how multiple time points were handled. A multiplicity adjustment or a prespecified hierarchy is not reported in the registry record.

The outcome description states that some subjects dropped before 1 year and some dropped between 1-2 years. It does not report how many participants had measurements at each time, the reasons for missing measurements, or whether missingness differed between groups. No method for handling missing data is described. For example, the record does not specify whether the analysis used only available measurements, imputed missing values, or used a longitudinal model. These are general approaches, not claims about this trial.

The analysis population is also not defined. The registry does not say whether participants were analyzed according to randomized assignment, treatment received, or another population definition, and it does not describe exclusions from the primary analysis. The number assigned to each arm for the primary outcome analysis is not reported in the registry record. The safety listing’s counts at risk do not establish which participants contributed to the triglyceride analysis.

Without details on multiplicity, missing-data handling, and analysis populations, readers cannot fully assess the risk of selective emphasis across assessment times or the potential effects of incomplete follow-up. These gaps do not establish that the analysis was inappropriate; they mean the posted record does not give enough information to evaluate those aspects.

11. 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: gastritis (3.6%), vomiting and diarrhea (3.6%), spider bite (3.6%).

The registry lists serious adverse event information separately for the two groups. In the nelfinavir group, 28 participants were at risk and one had a serious adverse event; in the efavirenz group, 28 were at risk and two had serious adverse events. Deaths are listed as zero in both groups. The record also lists 20 other adverse events in each group. These counts describe the entries in the registry and should not be confused with the primary serum triglyceride outcome.

The registry’s most frequently listed serious-event terms are gastritis, vomiting and diarrhea, and spider bite, each recorded as 3.6%. The record does not explain the denominator or provide term-specific group assignments in that listing, so the percentages should be read as registry entries rather than used to infer group-specific risks. It also does not give event timing, severity details beyond the serious-event category, relatedness to study treatment, or the number of participants experiencing each term by group.

These figures are descriptive. The record does not report a statistical comparison of adverse-event rates or uncertainty around the counts. The listed counts alone do not establish whether groups differed in safety, and they should not be interpreted as evidence for or against the primary triglyceride comparison.

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

The registry record establishes that a randomized, triple-masked, parallel Phase 4 trial compared nelfinavir and efavirenz in people with HIV infection, with serum triglycerides listed as the primary outcome at 12 and 24 months. It also records a total enrollment of 56 and provides a brief note about participant dropout during follow-up. Those details describe the trial’s design and outcome framework.

The record does not report the primary outcome values, a between-group estimate, a confidence interval, or a p-value. It therefore does not show whether the groups’ triglyceride measurements differed, how large any difference was, or how precise an estimate might have been. It cannot support a conclusion that either regimen increased or decreased triglyceride levels relative to the other.

The study rationale refers to broader questions about lipodystrophy syndrome, metabolic abnormalities, body fat distribution, prognostic indicators, and molecular mechanisms. The listed primary outcome is a serum measure, and the registry does not provide results for those broader aims. A triglyceride comparison, even if reported, would not by itself establish the cause of lipodystrophy or answer all of the questions in the study rationale.

The safety entries report serious adverse event counts, other adverse event counts, and zero deaths in both groups. They do not include enough detail for a complete comparison of event patterns or their uncertainty. The counts should be interpreted as descriptive registry information rather than as a comprehensive assessment of comparative safety.

In short, the posted record describes what the trial set out to compare but does not provide the primary results needed to judge the observed serum triglyceride comparison. Trial completion and enrollment do not substitute for reporting estimates, uncertainty, and analysis details. The available information supports a description of the design and reported safety entries, not a conclusion about the relative effects of the two regimens.

13. Why This Trial Matters Statistically

Statistically, this trial illustrates the distinction between a clearly named outcome and a fully interpretable result. The registry identifies serum triglycerides, their units, the summary format, and the follow-up times. Those details help define the measurement. They are not enough to establish the estimated difference between groups or its uncertainty, which are central to interpreting a comparative trial.

The two assessment times make reporting choices important. A reader needs to know whether the analysis treats each time as a separate question or estimates a pattern across follow-up. The registry does not explain this, and its note about dropout makes the number and handling of available observations especially relevant. Without those details, the relationship between the randomized groups and the analyzed measurements is difficult to evaluate.

The record also shows why design labels and analysis reporting answer different questions. Randomization and masking describe intended safeguards in the trial design. They do not disclose the allocation procedure, the analysis population, the handling of missing observations, or the estimated outcome contrast. Likewise, a planning illustration is not an observed result and does not establish the precision of a treatment-effect estimate.

The posted safety counts provide another example of the limits of simple descriptive data. Counts can orient readers to the registry’s entries, but interpretation depends on event definitions, follow-up, attribution, and uncertainty. Those details are not fully reported. Overall, the record is useful for identifying the trial’s comparative framework and outcome, while demonstrating why outcome estimates and transparent methods are necessary for statistical interpretation.

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 central limitation for interpreting this trial from the registry record is the absence of reported primary outcome results. No group means, standard deviations, treatment contrast, confidence interval, or p-value for serum triglycerides are given. The direction, magnitude, and precision of the primary comparison therefore cannot be assessed.

The primary outcome is associated with 12 and 24 months, but the analysis across those times is not described. The record does not identify a single comparison or explain whether the times were analyzed separately or jointly. It also notes dropout before 1 year and between 1-2 years without reporting the number of missing measurements, reasons for dropout, or the method used to address missing data.

Important design and analysis details are absent. The record does not give eligibility criteria, treatment doses, the randomization procedure, the parties masked, or the primary analysis population. It does not report baseline outcome measurements or state whether adjustments were used. The trial’s own sample-size justification and a detailed statistical analysis plan are not reported in the registry record.

Safety information is limited to registry counts and a short list of serious-event terms. The record does not provide event timing, group-specific detail for the listed terms, treatment relatedness, or inferential comparisons. The brief descriptions of the arms likewise do not permit assessment of the precise treatment regimens.

These limitations concern what can be evaluated from the posted registry information. They do not establish that the trial lacked an analysis plan, that its results were not analyzed, or that its methods were inadequate. They indicate that the registry record, as posted, does not provide enough information for a detailed assessment of the primary comparison or several methodological choices.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Mechanisms of Lipodystrophy in HIV-Infected Pateints — NCT00457665.
• Registry record last updated 2019-07-18; status last verified 2019-05.
• Results first posted 2019-07-18.
• 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.

18. Record Summary

This completed Phase 4 trial is listed as randomized, triple-masked, and parallel, with nelfinavir and efavirenz as the two drug interventions. The registry records enrollment of 56 and identifies HIV infections as the condition. The recorded start is 2002-02 and primary completion is 2007-10. The sponsor is University of Texas Southwestern Medical Center.

The primary outcome is the mean serum triglyceride level in mg/dL, with standard deviation, assessed at 12 and 24 months. The outcome description notes dropout before 1 year and between 1-2 years. The registry does not report the group outcome values or a single comparison, and it does not provide a detailed account of the analysis or missing-data methods.

For safety, the record lists 28 participants at risk in each group, serious adverse events in one nelfinavir participant and two efavirenz participants, and zero deaths in either group. It also lists 20 other adverse events in each group. The posted information supports describing the trial and its registry entries, but not drawing a conclusion about the primary triglyceride comparison.