This page separates the information reported in the ClinicalTrials.gov record from statistical interpretation of the study design. The registry provides the official trial record.
1. Trial at a Glance
ACTG 076 was a completed phase 3 clinical study examining the safety and effectiveness of zidovudine in HIV-infected pregnant women and their infants. The registry identifies HIV infections and pregnancy as the conditions under study and lists treatment as the primary purpose.
| Feature | ACTG 076 |
|---|---|
| Study acronym | ACTG 076 |
| ClinicalTrials.gov identifier | NCT00000960 |
| Official study title | The Safety and Effectiveness of Zidovudine in HIV-Infected Pregnant Women and Their Infants |
| Phase | Phase 3 |
| Status | COMPLETED |
| Conditions | HIV Infections; Pregnancy |
| Primary purpose | TREATMENT |
| Enrollment | 1496 |
| Intervention | Zidovudine (drug) |
| Lead sponsor | National Institute of Allergy and Infectious Diseases (NIAID) |
| Sponsor type | NIH |
2. Clinical Question
The clinical question identified by the registry is whether zidovudine is safe and effective in HIV-infected pregnant women and their infants.
Population
HIV-infected pregnant women and their infants.
Intervention
Zidovudine, listed in the registry as a drug intervention.
Comparator
The ClinicalTrials.gov information available for this record does not identify a comparator arm.
Primary question
What is the safety and effectiveness of zidovudine in HIV-infected pregnant women and their infants?
3. Trial Design
The registry identifies ACTG 076 as a phase 3 treatment study with an enrollment of 1496. It does not provide a registered primary endpoint list or posted statistical analysis for the study in the record represented here.
The registry does not report additional design characteristics such as allocation ratio, masking, comparator treatment, stratification factors, crossover, factorial structure, or interim-analysis procedures.
4. Endpoints
The ClinicalTrials.gov record represented here contains an empty registered-primary-endpoint field. Consequently, no endpoint definition or assessment time frame is reported in that record.
| Endpoint information | Registry record |
|---|---|
| Registered primary endpoints | None reported |
| Endpoint definitions | Not reported in the registered-primary-endpoint information |
| Endpoint time frames | Not reported in the registered-primary-endpoint information |
5. Planned Analysis
No formal statistical analyses are posted to ClinicalTrials.gov for this record. The registry therefore provides no posted treatment-effect estimate, confidence interval, p-value, event count, or endpoint-specific analysis result.
The registry identifies the study as a phase 3 treatment investigation of zidovudine in HIV-infected pregnant women and their infants, with safety and effectiveness named in the study title. For a treatment study of this general type, the statistical analysis would ordinarily begin by defining prespecified efficacy and safety endpoints, specifying the analysis population, and comparing outcomes according to the randomized or assigned treatment groups if the study used a comparative design.
For binary outcomes, an analysis would commonly summarize event proportions and compare groups using an appropriate risk-based measure such as a risk difference, risk ratio, or odds ratio. For continuous outcomes, group means or other distributional summaries could be compared using a prespecified regression or comparison model. For time-to-event outcomes, Kaplan-Meier estimation and a model such as the Cox proportional-hazards model could be appropriate when the endpoint and censoring structure call for them.
Those methods are general statistical frameworks rather than reported ACTG 076 analyses. The registry information represented here does not identify which endpoint types were actually prespecified or which statistical models were used.
6. Statistical Methodology
Why the phase matters
A phase 3 designation places a study within the confirmatory stage of clinical development. Statistically, phase 3 studies generally require clearly specified endpoints, a prespecified analysis plan, defined error-control procedures, and an analysis population appropriate to the study design. The phase designation alone, however, does not specify any particular statistical test.
Safety and effectiveness require distinct statistical definitions
The study title uses both safety and effectiveness. These concepts should not automatically be collapsed into a single statistical endpoint. Safety may involve adverse events, laboratory measurements, discontinuations, or other harms, while effectiveness may involve a disease or treatment outcome. Each endpoint requires its own definition and analysis strategy.
Analysis populations
A rigorous analysis distinguishes the population defined by treatment assignment from populations defined by treatment exposure or evaluability. In a randomized comparative study, intention-to-treat analysis generally preserves the treatment comparison created by randomization, while safety analyses are often based on participants who received treatment. The appropriate populations for ACTG 076 are not specified in the registry information represented here.
Effect estimates and uncertainty
A treatment comparison should ordinarily report an effect estimate together with a measure of statistical uncertainty, such as a confidence interval. The effect estimate describes the magnitude and direction of the observed or modeled difference; the confidence interval describes uncertainty around that estimate under the specified statistical framework.
The appropriate form of the estimate depends on the endpoint. A binary endpoint, continuous endpoint, and time-to-event endpoint generally require different effect measures and corresponding confidence intervals.
Hypothesis testing
When a confirmatory treatment comparison is specified, the analysis plan ordinarily defines the null hypothesis, alternative hypothesis, significance level, and method for calculating the test statistic or p-value. The p-value is evidence against a specified null hypothesis under the statistical model; it is not itself a measure of clinical magnitude.
Multiplicity
Clinical trials may evaluate several endpoints, time points, treatment comparisons, or interim analyses. If multiple statistical tests contribute to a confirmatory conclusion, the analysis plan may need an explicit multiplicity strategy to control the probability of false-positive conclusions. The registry information represented here does not specify a multiplicity procedure for ACTG 076.
7. Statistical Methods Explained
What does a phase 3 designation tell us?
It identifies the study as phase 3, but it does not by itself tell us whether the primary endpoint was binary, continuous, or time-to-event, nor does it identify the statistical test. Those details must come from the endpoint and statistical analysis plan.
Why is the endpoint definition important?
The endpoint determines what constitutes an event or response, which participants contribute information, when follow-up ends, and which statistical model is appropriate. Without the endpoint definition, an effect estimate cannot be interpreted precisely.
Why separate safety from effectiveness?
Safety and effectiveness answer different questions. An effectiveness endpoint asks whether the treatment produces the intended clinical effect, while a safety endpoint describes undesirable outcomes or treatment-related harms. Combining them prematurely can obscure both the benefit estimate and the uncertainty surrounding safety.
Why would a confidence interval normally accompany an effect estimate?
A point estimate alone gives only one value. A confidence interval communicates the statistical precision of that estimate under the chosen model and sampling framework. Wider intervals generally indicate less precision than narrower intervals, although precision should always be considered alongside the endpoint definition and analysis design.
Why does a p-value not measure treatment effectiveness?
A p-value addresses the compatibility of the observed data with a specified null hypothesis. It does not tell us the size of the treatment effect, its clinical importance, or the probability that a treatment is effective. Those questions require the effect estimate, its uncertainty, and the clinical context.
Why can the analysis population change the interpretation?
Different populations answer different questions. An intention-to-treat analysis asks about outcomes according to treatment assignment, while an exposure-based safety analysis may ask about outcomes among participants who actually received treatment. The correct population depends on the estimand and prespecified trial design.
8. Limitations and Interpretation Issues
- No registered primary endpoints are reported: the available ClinicalTrials.gov record does not identify endpoint definitions or assessment time frames, limiting endpoint-specific statistical interpretation.
- No posted statistical analyses: the registry record contains no posted statistical analyses from which treatment-effect estimates, confidence intervals, p-values, or event counts can be described.
- Comparator not identified: the registry information represented here lists zidovudine as the intervention but does not identify a comparator arm.
- Design details are incomplete: allocation, masking, stratification, crossover, interim monitoring, and other design characteristics are not reported in the available trial information.
- Safety cannot be quantified from the registry summary: although safety is part of the study title, no safety endpoint definitions or safety results are reported in the available statistical-analysis fields.
- Effectiveness cannot be quantified from the registry summary: the study title identifies effectiveness as a focus, but no effectiveness endpoint or numerical outcome is reported in the available record.
- Statistical model selection cannot be established: without registered endpoint definitions or posted statistical analyses, a specific statistical model should not be attributed to the trial.
9. Why This Trial Matters Statistically
ACTG 076 illustrates an important principle in clinical-trial statistics: the study question, endpoint definition, analysis population, and statistical model must form a coherent chain. A phase 3 designation and a large enrollment alone do not establish what statistical conclusion a trial supports.
| Concept | How it applies to ACTG 076 |
|---|---|
| Clinical question | Safety and effectiveness of zidovudine in HIV-infected pregnant women and their infants |
| Trial phase | Phase 3 |
| Primary purpose | TREATMENT |
| Enrollment | 1496 |
| Endpoint specification | No registered primary endpoints are reported in the available record |
| Statistical analysis | No posted statistical analyses are reported in the available record |
| Effect estimation | Cannot be characterized from the available registry analysis fields |
| Safety interpretation | Requires defined safety endpoints and an appropriate exposure or assignment population |
| Effectiveness interpretation | Requires a defined clinical effectiveness endpoint and prespecified analysis |
10. Statistical Interpretation vs Clinical Interpretation
Statistical interpretation
The registry identifies a phase 3 treatment study with an enrollment of 1496 and zidovudine as the intervention, but it does not report registered primary endpoints or posted statistical analyses in the available record.
Clinical interpretation
The study addresses the safety and effectiveness of zidovudine in HIV-infected pregnant women and their infants. The available registry summary does not provide numerical outcomes from which the magnitude of safety or effectiveness can be described.
The record establishes the study identity, phase, status, sponsor, conditions, purpose, enrollment, and intervention. It does not provide an endpoint-specific statistical result in the information represented here.
A meaningful treatment-effect statement would require a defined endpoint, an appropriate comparison, an analysis population, an effect measure, and its corresponding uncertainty. Without those elements, a numerical treatment conclusion cannot be assigned to the registry record.
11. Sources
- ClinicalTrials.gov: ACTG 076, NCT00000960.
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12. Record Summary
ACTG 076 is identified in the ClinicalTrials.gov record as a completed phase 3 treatment study of zidovudine in HIV-infected pregnant women and their infants, with an enrollment of 1496. The registry identifies safety and effectiveness as the central clinical focus through the study title, but the available record contains no registered primary endpoints and no posted statistical analyses. Statistically, this makes endpoint definition and prespecified analysis methodology the critical missing components for interpreting any treatment effect. The appropriate framework is therefore to distinguish the documented study characteristics from endpoint-specific statistical conclusions.