Development of a Tailored HIV Prevention Intervention for Young Men: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Development of a Tailored HIV Prevention Intervention for Young Men (NCT02842060), a randomized na study. The primary outcome is Number of Participants With Change in Number of Risky Sexual Partnerships.

2. Clinical Question

The study is presented as a pilot randomized controlled trial. Its stated aims include assessing feasibility and acceptability and gathering preliminary behavioral data to inform a subsequent application. The central statistical question is therefore not just whether the groups differ, but how the intervention and comparison were evaluated and what the registry record allows readers to conclude. The record reports no analysis results for the primary outcome, so it cannot establish the direction or size of any group difference, or how precisely such a difference was estimated.

Assessments were planned at 30, 60, and 90 days after the intervention. The primary outcome description specifically refers to baseline and 90-day follow-up, while the title refers more broadly to change in risky sexual partnerships. Those formulations leave the exact outcome definition and the way repeated assessments were handled unclear. The registry record does not report detailed eligibility criteria, participant characteristics, or the statistical comparison used for the primary question.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group pilot study of myDEx versus non-tailored HIV prevention (NTHP). It records an enrollment of 180. The brief summary describes planned allocation as N=120 to myDEx and N=60 to NTHP. The record does not explain how the randomization sequence was generated, how assignment was concealed, or who was masked. The meaning of single masking is therefore not specified in the registry record.

Both interventions are web-based and have 6 sessions. myDEx is described as tailored and interactive, with session duration designed to be no more than 20 minutes and smartphone delivery considered. NTHP is intended to match myDEx in time and attention while presenting non-tailored, non-interactive content. The record says NTHP includes HIV/STI information currently available on sex education websites. It does not report how adherence to sessions was measured or whether participants completed the intended content.

The study is marked completed. The registry records a start of 2016-11 and primary completion of 2017-05. Follow-up assessments were planned at 30, 60, and 90 days post-intervention. The registry record does not establish how many participants completed each assessment, whether follow-up timing varied, or how incomplete observations were addressed.

The stated purpose was to examine feasibility and acceptability and collect preliminary behavioral data to inform a subsequent application. Secondary outcomes include change in self-efficacy motivations to engage in HIV prevention behaviors and changes in psychological well-being. The record lists 4 outcome measures but reports 0 analyses. It does not include a detailed statistical analysis plan, an account of recruitment or retention, or a description of the procedures used to measure feasibility and acceptability. The planned enrollment and allocation do not, by themselves, establish the precision of any behavioral estimate.

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 Number of Participants With Change in Number of Risky Sexual Partnerships, measured over Count of participants from baseline to 90-day follow-up reported.

The primary endpoint is titled “Number of Participants With Change in Number of Risky Sexual Partnerships.” Its description says investigators estimated the change in the total number of participants who reported engaging in condomless anal intercourse from baseline to 90-day follow-up. The timeframe is described as a count of participants from baseline to 90-day follow-up. These registry descriptions connect a count of participants with a change in a number of partnerships, but do not fully specify the outcome’s operational definition.

This kind of outcome can be used to describe reported behavior over follow-up and to compare whether patterns changed in the intervention groups. Because the registry describes a count of participants reporting condomless anal intercourse, the result would need to make clear what qualified as a change, how repeated reports were treated, and whether the analysis compared groups or only described change over time. Those details are not reported in the registry record.

The endpoint is relevant to the study’s stated aim of gathering preliminary behavioral data. However, the record does not report the observed counts, an effect estimate, a confidence interval, or a statistical test for this outcome. It is therefore not possible to assess the direction, magnitude, or precision of the primary outcome from the registry record. The title and description also use different formulations—risky sexual partnerships in the title and condomless anal intercourse in the description—so the record leaves some uncertainty about the exact endpoint being counted.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does randomization contribute? In general, randomization assigns participants to study groups by chance. When implemented and maintained appropriately, it can reduce systematic differences between groups at baseline, making a comparison more informative. The registry identifies the allocation as randomized but does not report sequence generation, concealment, or implementation details. The label alone does not establish that these procedures were adequate.

The parallel model means that the registry describes participants as being assigned to an intervention group or a comparison group, rather than describing a crossover design. The record does not provide further detail on how assignment was carried out. It also labels masking as single but does not specify who was masked. Without that information, readers cannot determine how masking could have affected intervention delivery, outcome reporting, or assessment.

What would a group comparison estimate?

In general, a comparative analysis estimates how an outcome differs between assigned groups, according to a defined analysis population and outcome definition. A change-from-baseline analysis can compare changes within groups, but a difference in within-group changes is not automatically the same as a clearly specified randomized group contrast. The estimand should state what outcome is compared, at what time, and for which participants. The registry describes change in participants reporting condomless anal intercourse between baseline and 90-day follow-up, but does not report the precise estimand or analysis method.

For a binary outcome, such as whether a participant meets a clearly defined reporting criterion, a group result might be expressed as a count or proportion, and a comparison could quantify a difference between groups. General statistical practice is to report an effect estimate with uncertainty, not rely on a significance test alone. However, the registry describes the primary outcome as a count of participants with change and does not report a group-specific outcome result, uncertainty interval, or test. No effect estimate can be reconstructed from the record.

Why does outcome definition matter?

In general, an outcome must identify what is measured, how it is recorded, and how observations over time contribute to the analysis. The primary outcome title emphasizes a change in the number of risky sexual partnerships, whereas the description emphasizes the number of participants reporting condomless anal intercourse. These formulations leave unresolved whether partnership counts, participant counts, or a binary report of behavior was the analysis target. The registry record does not state a threshold for change, the unit of comparison, or how multiple reports from the same person were summarized.

The planned assessments at 30, 60, and 90 days offer repeated opportunities to measure behavior, while the primary endpoint description names baseline and 90-day follow-up. General methods for repeated measurements can account for correlation among observations from the same participant, but the registry does not say whether repeated-measures methods were used or whether only selected assessments entered the primary analysis. No statistical model or method for handling within-participant correlation is reported.

What would a confidence interval add?

In general, a confidence interval communicates the uncertainty around an estimated effect under the assumptions of a statistical method. A narrower interval indicates greater precision, while a wider interval indicates more uncertainty. Its interpretation depends on the outcome definition, analysis method, and data included. The registry record does not report a primary effect estimate or confidence interval, so precision cannot be evaluated. A p-value, even if reported, would not show the size or practical meaning of an effect by itself; no primary p-value is recorded.

How should planning calculations be read?

The registry describes planning illustrations based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It specifies that non-time-to-event illustrations refer to participants per arm and time-to-event illustrations refer to total events. These are general design assumptions, not evidence from the trial about an outcome. A planning calculation describes the sample size associated with chosen assumptions; it is not observed power and does not establish that an effect exists. The record does not report a numeric primary effect estimate that would permit readers to assess the basis or relevance of such illustrations.

In general, assumptions about effect size, outcome variability, allocation, and analysis method influence a planning calculation. A calculation based on an observed effect can be unstable when the estimate is preliminary or imprecise. The registry record does not report a sample-size justification, a protocol-based power calculation, or details of interim analyses. Those design and monitoring procedures should not be inferred from the fact that planning assumptions are listed.

What does over-dispersion mean in general?

For count outcomes, over-dispersion means that the observed variation exceeds what a chosen count model assumes. If unaddressed, this mismatch can make standard errors too small and confidence intervals too narrow. Whether this issue applies depends on the actual outcome distribution and the model. The registry record does not report the outcome distribution, a dispersion estimate, or a count model, so no claim about over-dispersion in this trial is possible.

More broadly, statistical methods cannot be evaluated separately from data quality and endpoint definition. The registry identifies a count-oriented primary endpoint but does not report how counts were obtained, how missing responses were handled, or what model was used. These omissions prevent readers from checking whether the analysis matched the stated outcome and study design.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists secondary outcomes for change in self-efficacy motivations to engage in HIV prevention behaviors and changes in psychological well-being. It also records 4 outcome measures and 0 analyses. It does not report which outcomes were tested, whether any testing hierarchy was specified, or whether a multiplicity adjustment was planned. When multiple outcomes or time points are examined, general statistical practice recognizes that the chance of at least one apparently unusual result can increase. Methods such as prespecifying a primary comparison or adjusting for multiple testing can address particular concerns, but no such plan is reported in the registry record.

Assessments were planned at 30, 60, and 90 days after intervention, while the primary outcome description names baseline to 90-day follow-up. The record does not say whether the intermediate assessments were analyzed for the primary question, secondary outcomes, or descriptive purposes. It also does not report whether the primary endpoint was finalized before outcomes were examined. The multiplicity implications cannot be assessed without this information and the analysis plan.

Missing-data handling is not reported in the registry record. The entry does not state how many participants posted outcome data at each follow-up, why data might be missing, whether missingness differed between arms, or how incomplete records were handled. General approaches include analyzing observed data, imputing missing values, or conducting sensitivity analyses under different assumptions. These choices can affect estimates, especially when missingness is related to outcome or treatment assignment. No specific approach can be attributed to this study from the registry entry.

The analysis population is also not reported. The record does not say whether results were intended to follow randomized assignment, include only participants who completed intervention sessions, or use another population. Those choices define which participants contribute to an estimate and can affect the interpretation of a randomized comparison. With 0 analyses reported, there is no registry result to assess for population definition, exclusions, multiplicity control, or missing-data sensitivity.

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.

The registry reports zero serious adverse events and zero other adverse events in the myDEx arm, with deaths recorded as zero. It reports the same event counts in the non-tailored HIV prevention arm, with deaths recorded as zero. The registry lists 120 at risk in the myDEx arm and 60 at risk in the comparison arm for both serious and other adverse events.

These figures describe the adverse-event counts recorded in the registry. Zero recorded events should not be interpreted as proof that no event occurred or that an intervention is free of risk. The record does not list serious-event terms, describe how events were collected or classified, or give follow-up duration for safety reporting. It also does not provide a narrative of non-serious events beyond the reported zero counts.

Counts at risk do not establish that every participant was observed for the same length of time or that all participants completed follow-up. The registry record does not report event ascertainment procedures, withdrawals, or missing safety information. The safety entry is therefore a limited registry summary, not a comprehensive estimate of comparative safety or a basis for medical advice.

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

The registry record establishes that this was a randomized, single-masked, parallel pilot comparing a tailored online prevention program with a non-tailored attention control. It describes the interventions, the planned follow-up schedule, and a behavioral primary outcome. It also records that the study is completed and gives enrollment and planned arm allocation information. These features identify the research question and design, but they do not show what happened to the primary outcome.

No primary outcome analysis is reported. There are no group-specific behavioral counts, estimates of change, confidence intervals, or test results in the registry entry. It is therefore not possible to conclude from this record that myDEx improved, worsened, or had no effect on the reported behavior relative to NTHP. An absent result is not a null result. It is also not possible to judge whether a potential effect was large enough to matter or estimated with adequate precision.

The study was described as a pilot intended to assess feasibility and acceptability and gather preliminary behavioral data. Those aims are distinct: feasibility concerns whether study and intervention procedures can be carried out, while acceptability concerns participant response to them. The record does not report findings for either aim. It likewise does not report the secondary outcome results for self-efficacy motivations or psychological well-being.

The primary endpoint description needs clarification because its title refers to change in risky sexual partnerships and its detailed description refers to participants reporting condomless anal intercourse. Without a precise definition and analysis, even a numerical result could be difficult to interpret. The registry does not report participant flow, completion, missing-data handling, or the analysis population, which are also needed to understand how any estimate should be generalized.

The reported adverse-event counts are zero in both arms, but the registry summary is not sufficient to establish that no adverse events occurred. The record does not describe event ascertainment or follow-up completeness. Overall, the entry documents a trial design and an intended evaluation, not evidence that permits a conclusion about intervention effects, feasibility, acceptability, or comparative safety.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it combines an intervention-development goal with a randomized pilot comparison. The intervention is tailored and interactive, while the comparator is designed as an attention control with non-tailored, non-interactive content. That structure aims to distinguish the tailored approach from exposure to a web-based prevention program with time and attention matched. The registry describes that rationale but does not report whether the intended matching was achieved in practice.

The record also illustrates why a clear endpoint definition matters. “Change in number of risky sexual partnerships” and “change in the total number of participants” reporting condomless anal intercourse do not necessarily describe the same statistical quantity. A well-defined measure supports a clear estimand, an appropriate analysis, and an interpretable result. The registry does not resolve this wording difference, and it reports no outcome analysis.

Repeated follow-up assessments make timing part of the question. The stated schedule includes 30, 60, and 90 days after intervention, while the primary outcome description focuses on baseline and 90-day follow-up. The registry does not explain the role of intermediate measurements or whether repeated observations informed the analysis. This matters because the timing and use of measurements determine what change a result represents.

Finally, a pilot’s stated purpose should shape expectations. The record describes feasibility, acceptability, and preliminary behavioral data as aims, rather than documenting a definitive behavioral result. Without reported analyses, the entry cannot answer those aims statistically. It can, however, highlight the information needed for a useful report: explicit outcome definitions, analysis populations, missing-data procedures, effect estimates, and uncertainty measures.

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 main limitation of interpreting this trial from the registry record is that no analysis results are reported. The record lists 0 analyses, leaving no primary outcome estimate, confidence interval, or test result to evaluate. The study is marked completed, but completion status does not supply evidence about the intervention’s behavioral effects, feasibility, or acceptability.

The primary endpoint wording is not fully consistent. Its title describes participants with change in the number of risky sexual partnerships, whereas the outcome description refers to change in the number of participants reporting condomless anal intercourse. The record does not explain how “change” was defined or whether the unit was participants, partnerships, or reports. That ambiguity limits interpretation even before considering the absence of results.

Detailed participant characteristics and eligibility criteria are not reported. The entry also does not report participant flow, follow-up completion, missing observations, analysis populations, randomization procedures, masking details, or the statistical analysis plan. These omissions limit assessment of representativeness, potential bias, and precision. The planned assessments at 30, 60, and 90 days are described, but the role of each assessment in the analyses is not given.

The interventions are described at a broad level, but the registry record does not report whether participants completed sessions, how tailoring operated in practice, or whether the comparison matched myDEx in time and attention as intended. Finally, the adverse-event summary lists zero events but does not describe ascertainment or event terms. These limitations are specific to the information recorded and should not be mistaken for evidence that the underlying study did or did not collect additional details.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Development of a Tailored HIV Prevention Intervention for Young Men — NCT02842060.
• Registry record last updated 2019-07-16; status last verified 2019-06.
• Results first posted 2019-07-16.
• 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

The registry identifies a completed randomized, single-masked, parallel pilot of myDEx versus non-tailored HIV prevention (NTHP). The study concerns HIV infections and describes enrollment of 180, with planned allocation of N=120 to myDEx and N=60 to NTHP. The myDEx program is tailored and interactive; NTHP is described as a non-tailored, non-interactive attention control.

The primary outcome concerns change in reported condomless anal intercourse from baseline to 90-day follow-up, though the outcome title instead refers to change in risky sexual partnerships. Follow-up assessments were planned at 30, 60, and 90 days. Secondary outcomes concern self-efficacy motivations for HIV prevention behaviors and psychological well-being. The stated aims include feasibility, acceptability, and preliminary behavioral data.

The registry reports 0 analyses and provides no primary outcome result. It records zero serious adverse events, zero other adverse events, and zero deaths in each arm. Detailed participant characteristics, endpoint clarification, analysis methods, and missing-data handling are not reported in the registry record.