Metabolic Effects of Non-Thymidine Analogue Anti-HIV Medications: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Metabolic Effects of Non-Thymidine Analogue Anti-HIV Medications (NCT00433992), a registered phase not stated study. The primary outcome is Change in Mitochondrial Activity.

2. Clinical Question

The study focuses on biological measures rather than a clinical event endpoint. Its stated primary outcome is change in mitochondrial activity, and its secondary outcome is change in fat apoptosis. The registry describes the study as enrolling participants from ACTG A5202 who were on regimens that did not include thymidine-containing anti-HIV medications.

The question is observational in the registry record. It does not describe random assignment, and it explicitly warns that the arms should not be treated as a like-for-like control comparison. Differences between the groups therefore cannot automatically be attributed to the regimen distinction alone. The record also does not report outcome estimates, so the direction and precision of any change cannot be assessed from the posted results.

3. Trial Design

The registry identifies this study as “Metabolic Effects of Non-Thymidine Analogue Anti-HIV Medications,” with an official title focused on thymidine-sparing regimens, mitochondrial metabolism, and adipocyte apoptosis. It lists HIV infections as the condition and identifies the National Institute of Allergy and Infectious Diseases as sponsor. The study status is completed. The recorded start is 2006-04, and the primary completion is 2009-10.

The brief description says participants were drawn from another study, ACTG A5202, and were on treatment regimens that did not include zidovudine, stavudine, or other thymidine-containing anti-HIV medications. One arm is described as HIV-infected subjects given Abacavir-Lamuvidine (ABC/3TC); the other as HIV-infected patients given tenofovir DF-emtricitabine (TDF/FTC). These descriptions identify the regimens but do not establish randomization or a controlled assignment process.

The registry states that allocation is not stated and cautions that the arms are not a like-for-like control comparison. The study is classified as “other,” rather than being reduced in the record to one comparison. That classification does not supply additional detail about how participants entered each arm or how the two groups were followed. Those design details are not reported in the registry record.

The primary outcome is change in mitochondrial activity, with measurements specified at Entry and Week 96. The secondary outcome is change in fat apoptosis. Although enrollment is listed as 56, the record does not provide an analysis population or explain how many participants contributed outcome measurements. It also does not describe a protocol-level statistical plan, a sample-size justification, or interim analyses. The posted results do not include analysis estimates for either outcome.

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

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 Change in Mitochondrial Activity, measured over Entry, Week 96.

The primary endpoint is change in mitochondrial activity, measured as mitochondrial DNA (mtDNA) content in adipose tissue. The registry says the tissue measurement used quantitative real-time polymerase chain-reaction. Results are specified as a median with an inter-quartile range, with measurements at Entry and Week 96.

mtDNA content serves as a biological measure related to mitochondrial activity in the tissue under study. It is not itself a measure of a clinical event or a direct measure of how a participant feels or functions. Comparing measurements over time can describe whether the measured tissue marker changed during follow-up, while the median and inter-quartile range can convey the center and spread of the observed values.

The registry does not report the median values, the inter-quartile ranges, or an estimated change for the primary endpoint. It also does not give a confidence interval or a statistical test for the endpoint. Consequently, the measurement approach and time points are identifiable, but the magnitude, direction, and precision of change are not reported in the registry record. The secondary outcome, change in fat apoptosis, is named but is not described with a measurement method or results in the posted record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry specifies a median and inter-quartile range for the primary endpoint. The median is the middle value after measurements are ordered. It describes the center of the observed measurements without requiring the data to be symmetric. The inter-quartile range describes the spread of the middle portion of those measurements. As a general matter, these summaries can be useful when measurements are skewed or include values far from the center. The registry does not report the actual summaries, so their values and variability cannot be evaluated.

What would a change estimate describe?

For a repeated-measure outcome, a change estimate describes how the measurement differs between the specified assessment times. Here, the time points are Entry and Week 96, and the measured quantity is mtDNA content in adipose tissue. The registry names the endpoint as change in mitochondrial activity but does not state a numerical change estimate or explain the exact calculation used to derive it. It is therefore not possible to tell whether the reported target was a within-participant change, a group-level contrast in change, or another summary.

How should uncertainty be assessed?

In general, a confidence interval gives a range of estimates compatible with the data under the method used to construct it. Its width reflects statistical uncertainty: a narrower interval indicates more precision under that method, while a wider interval indicates less. A confidence interval is not a guarantee that the true effect lies in the interval, and it does not resolve design limitations such as nonrandom allocation. No confidence interval for the primary endpoint is reported in the registry record.

A p-value, when reported, addresses how unusual the observed data would be under a specified null model and its assumptions. It does not measure the size or importance of an effect, and it cannot establish causation. No primary-outcome test result or p-value is reported. The registry lists no analyses, so there is no sponsor analysis to compare with a simple recalculation from posted summary statistics. No recalculated effect is available from the record.

Why does allocation matter?

Random allocation, when used and properly implemented, can help balance measured and unmeasured participant characteristics across groups on average. The registry does not state that allocation was random; it expressly cautions that the arms are not a like-for-like control comparison. This means a difference in outcomes, if one were reported, could not automatically be interpreted as an effect caused by the regimen. The record does not report adjustment methods or covariates that might address group differences.

The study’s named summaries are medians and inter-quartile ranges, but the registry does not report the method used to compare groups or time points. It also does not identify a model, a test, or assumptions for an inferential analysis. General statistical methods can be appropriate only when their assumptions and the study design are considered; the record does not provide the details needed to assess that choice.

What do the planning illustrations mean?

Planning illustrations based on an observed effect are not the same as the trial’s original sample-size justification. The registry’s stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For non-time-to-event illustrations, the result is expressed as participants per arm for 80% power or another stated planning target; time-to-event illustrations use a total number of events. These are planning quantities, not observed power and not evidence that the study had a particular probability of detecting an effect.

The registry does not report the trial’s own sample-size justification. The outcome estimates needed to interpret an observed-effect planning calculation are also not reported in the registry record. Thus, the illustration assumptions should not be mistaken for documented design decisions or for results from the completed study.

10. Multiplicity, Missing Data and Analysis Populations

The study record names a primary outcome, change in mitochondrial activity, and a secondary outcome, change in fat apoptosis. It does not report a multiplicity strategy, such as a hierarchy of tests or an adjustment for evaluating more than one outcome. Without such information, the record does not show how the investigators intended to control the chance of a false-positive finding across outcomes or analyses. Since no outcome analysis results are reported, the practical effect of any multiplicity approach cannot be assessed.

The registry does not report how missing outcome measurements were handled. It gives no analysis population, no count of participants contributing measurements at Entry or Week 96, and no description of exclusions, withdrawals, or imputation. These omissions do not establish that measurements were missing; they mean that the extent and handling of missing data are not reported in the registry record.

The record also does not identify an intention-to-treat, per-protocol, or other analysis population. Because allocation is not stated and the arms are explicitly not described as a like-for-like control comparison, the meaning of any potential group analysis would depend on details not available in the record. Readers cannot determine whether the analysis included all enrolled participants, only participants with paired measurements, or another defined subset.

These reporting gaps limit assessment of the robustness of any outcome finding. Multiplicity, missingness, and population definitions can affect how estimates and uncertainty should be interpreted. In this case, both the analysis results and the relevant methods are not reported in the registry record.

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 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: rash (3.6%), depression (3.6%).

The registry lists serious adverse event counts separately for ABC/3TC and TDF/FTC. For ABC/3TC, it reports 2 serious events among 28 at risk and 0 other events among 28 at risk, with 0 deaths. For TDF/FTC, it reports 0 serious events among 28 at risk and 0 other events among 28 at risk, with 1 death. These are descriptive registry entries; they do not by themselves show that a regimen caused or prevented an event.

The listed serious event terms include Rash and Depression, each reported as 3.6%. The record does not provide further detail about event timing, duration, severity beyond the serious-event classification, participant characteristics, or exposure time. It also does not explain the basis for the term percentages. The counts and percentages should therefore be read as recorded, without interpreting them as comparative rates or causal effects.

The arms are not a like-for-like control comparison, and allocation is not stated. Differences in reported counts cannot be interpreted as evidence of a safety difference between regimens without additional design and analysis information. The registry entries describe what was recorded, not a causal safety conclusion.

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

The record documents a study of biological measures in HIV-infected participants receiving thymidine-sparing regimens. Its primary endpoint concerns mtDNA content in adipose tissue at Entry and Week 96, and the secondary outcome concerns fat apoptosis. This makes the research question specific to tissue-level measures rather than a direct comparison of clinical events.

What the record does not establish is the observed result. The median and inter-quartile range for the primary endpoint, any estimated change, and any inferential analysis are not reported in the registry record. The record therefore cannot show whether mitochondrial activity changed, how large a change might have been, or how precisely it was estimated. It also does not provide results for the secondary outcome.

Even if group outcome values were available, the registry’s design caution would remain important. Allocation is not stated, and the arms are not a like-for-like control comparison. A difference between groups could reflect characteristics of participants or other factors, rather than the regimen alone. The record does not provide methods for adjusting for such differences.

The completed status indicates that the study is listed as completed, but completion is not the same as a reported analysis. The serious adverse event entries are also descriptive and do not establish causation. Overall, the registry supports understanding of the study’s question, treatment groups, and planned measurement approach. It does not support a conclusion that either regimen changed mitochondrial activity or fat apoptosis, nor does it establish comparative benefit or harm.

13. Why This Trial Matters Statistically

This study illustrates a recurring statistical distinction between a clearly stated biological question and a reported estimate that can answer it. The registry identifies a tissue marker, a measurement method, and assessment times. Those details help define what was intended to be measured, but they do not reveal what was observed. Without endpoint summaries or uncertainty estimates, readers cannot judge the magnitude or precision of the outcome.

It also highlights why design information matters when interpreting arm comparisons. The registry identifies two regimen groups but says allocation is not stated and warns that the arms are not a like-for-like control comparison. A statistical contrast cannot remove design-related ambiguity simply by producing a numerical difference. Causal interpretation depends on how groups were formed and on analytic details that are not reported in the registry record.

The study’s use of a median and inter-quartile range is another useful reminder that endpoint summaries should match the data and question. These statistics describe the center and spread of measurements, but interpretation still requires the actual values, a defined change estimand, and a method for quantifying uncertainty. The registry supplies the summary format, not the results or comparison method.

Finally, safety counts and planning calculations answer different questions from the primary endpoint analysis. Event counts are not causal comparisons, and sample-size planning illustrations are not observed power. Keeping these distinctions clear prevents descriptions of a completed study from being mistaken for evidence about its outcome.

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 most consequential limitation of this registry record for interpretation is that the outcome analysis is not reported. The primary endpoint is named and its measurement approach is described, but no median, inter-quartile range, change estimate, confidence interval, or test result appears in the posted record. The secondary outcome is named without a reported result or measurement detail.

The record provides limited information about the analysis population and follow-up. Although enrollment is listed as 56 and the primary time frame is Entry and Week 96, it does not state how many participants contributed measurements at either time, whether paired measurements were available, or how missing observations were handled. Attrition and the analysis population are not reported in the registry record.

Design interpretation is also constrained: allocation is not stated, and the registry expressly says the arms are not a like-for-like control comparison. The record does not describe baseline comparability, adjustment methods, or a statistical model for the outcome. It therefore does not support a causal reading of a potential group contrast.

Additional limitations include the absence of a reported multiplicity plan, sample-size justification, interim-analysis information, and details of the secondary outcome. The safety entries lack context on timing and exposure. These gaps do not show that the study lacked such procedures or data; they mean those details are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Metabolic Effects of Non-Thymidine Analogue Anti-HIV Medications — NCT00433992.
• Registry record last updated 2017-09-05; status last verified 2017-09.
• Results first posted 2017-07-31.
• 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

NCT00433992 is a completed study of thymidine-sparing anti-HIV regimens and biological measures related to mitochondrial activity and fat cell death. The record lists enrollment of 56, with a start of 2006-04 and primary completion of 2009-10. The two regimen groups are ABC/3TC and TDF/FTC.

The primary outcome is change in mitochondrial activity, measured as adipose-tissue mtDNA content by quantitative real-time polymerase chain-reaction, with assessments at Entry and Week 96 and summaries specified as median and inter-quartile range. Change in fat apoptosis is listed as a secondary outcome.

The registry does not report outcome estimates or analyses. Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. The posted information therefore describes the research question and design features, but does not establish an outcome effect or causal comparison.