PrEP Point-of-Care Brief-Intervention for Adherence Among Young Men Who Have Sex With Men: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PrEP Point-of-Care Brief-Intervention for Adherence Among Young Men Who Have Sex With Men (NCT05353283), a randomized na study. The primary outcome is Number of Participants Indicating the Intervention Was Acceptable.

2. Clinical Question

The study addresses acceptability of a combined testing-and-counselling approach, rather than directly asking whether the approach changes HIV incidence. The registry describes PrEP adherence as the motivation for the intervention and identifies long-term adherence outcomes as a secondary outcome. However, the numerical primary-endpoint result and any numerical secondary-outcome results are not reported in the registry record. The question that can be framed from the record is therefore about what was intended to be assessed, not the size or direction of an observed effect.

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. Enrollment was 63. The study status is completed, and the recorded start and primary-completion dates are 2023-09-01 and 2025-07-01. The phase is listed as NA. The sponsor is the University of California, San Francisco.

Participants in the intervention arm were assigned to point-of-care adherence testing using a urine tenofovir assay together with motivational interviewing counselling. Participants in the standard-of-care arm received adherence counselling from their PrEP care provider. This design compares the combined intervention package with the stated usual counselling approach; it does not separately isolate the contribution of the urine test from the contribution of motivational interviewing.

The primary outcome is acceptability, assessed at 3 months. The registry also lists long-term adherence outcomes as a secondary outcome. It identifies 2 outcome measures and 0 analyses. The primary outcome description notes that one participant did not complete the study and was lost to follow-up, and that one participant was excluded from analysis because of inadequate hair samples. The registry record does not explain how these notes relate to the analysis denominator or whether the participants overlap.

Details such as the randomization method, allocation concealment, recruitment setting, eligibility criteria, follow-up schedule beyond the primary endpoint timeframe, and the statistical analysis plan are not reported in the registry record. The fact that the study is randomized describes its broad allocation design, but does not by itself establish how allocation was generated or implemented.

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: 63 participants were enrolled and randomized.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: One participant did not complete the study and was lost to follow-up. One participant was excluded from analysis due to inadequate hair samples.

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: One participant from the intervention arm did not complete the study and was lost to follow-up. One participant from the intervention arm and one participant from the standard of care arm were excluded from analysis due to inadequate hair samples.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Indicating the Intervention Was Acceptable, measured over 3 months.

The primary endpoint is the number of participants indicating that the intervention was acceptable. Acceptability was defined as a response of “somewhat” or “very” acceptable on a five-point Likert scale, with assessment at 3 months. This definition turns a graded response scale into a count of participants meeting the stated acceptability criterion. The registry record does not report the observed count or the denominator used for the primary analysis.

Acceptability is relevant to an intervention that combines a point-of-care test and counselling because participants’ reported views can describe whether the approach is experienced as acceptable. It is distinct from adherence itself, from the duration of adherence, and from HIV incidence. The record lists long-term adherence outcomes as secondary, but does not give their numerical results. Consequently, the acceptability endpoint can address participants’ reported evaluation of the intervention under the specified threshold; on its own, it cannot establish whether adherence changed or whether the intervention affected HIV prevention outcomes.

For a count endpoint, interpretation depends on both the number meeting the acceptability definition and the number assessed. A count without its analysis denominator would not show the proportion of assessed participants meeting the criterion. Neither the count nor the denominator for the primary endpoint is reported in the registry record, so its magnitude and precision cannot be described from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry is limited. It identifies a randomized parallel-group design with no masking, a count-based primary outcome, and planning assumptions for sample-size illustrations. It does not report the randomization procedure, the primary analysis method, an effect estimate, a confidence interval, a p-value, or a statistical analysis plan. The concepts below explain what these methods and omissions mean in general; they do not describe unreported analyses as if they had been conducted.

What does randomization contribute?

In general, random assignment is intended to make the comparison groups similar, on average, with respect to factors measured and unmeasured before treatment assignment. This supports interpretation of an arm comparison when the allocation process is implemented appropriately and outcome data are analyzed in a way that respects assignment. The registry identifies the trial as randomized, but the method used to generate and conceal assignments is not reported in the registry record. Randomization therefore describes the design label, not enough detail to assess the allocation process.

What does the primary count represent?

The primary outcome counts participants whose acceptability response met the stated definition. In general, a count is easier to interpret when reported with its denominator, since the same count can represent different levels of frequency in groups of different sizes. A comparison could be expressed using counts or proportions, depending on the prespecified analysis. The registry does not report the observed count, denominator, or analysis method. It is therefore not possible to identify which statistical model or comparison was used, or to assess its assumptions.

The acceptability definition combines responses of “somewhat” and “very” acceptable. This is a dichotomized use of a five-point response scale: it groups some responses together and distinguishes them from the rest. In general, dichotomizing a scale can make a threshold-based outcome straightforward to describe, but it does not retain all distinctions among response levels. The registry does not report the distribution across the five response options, so that fuller response pattern cannot be assessed.

How should estimates and uncertainty be read?

In general, an effect estimate describes the size and direction of a difference or association, while a confidence interval communicates uncertainty around that estimate under the analysis model. A p-value addresses compatibility between the data and a specified null hypothesis under model assumptions; it does not measure the size or importance of an effect. These statistics should be interpreted alongside the endpoint definition, denominator, and study design. None of these inferential results for the primary endpoint is reported in the registry record. A numerical conclusion about the arm comparison would therefore go beyond the posted registry information.

The sample-size assumptions state that illustrations use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect expressed as a fraction of the observed effect. They are described as planning illustrations computed from the observed effect, not as the trial’s own design. In general, a planning calculation asks what sample size would be needed under chosen assumptions to detect a specified effect with a chosen level of power. It is not a measure of the power actually achieved by a completed trial. The illustrations must not be interpreted as observed power. The registry record does not report the effect estimate or the specific fractional targets needed to interpret numerical planning outputs.

Why can outcome distributions matter?

General statistical context: methods that assume a particular variance structure may fit poorly when the data are more variable than the model expects. For count outcomes, over-dispersion means that variability exceeds what a basic count model would predict; ignoring it can make standard errors too small and confidence intervals too narrow. This is a general consideration, not a claim about this trial. The registry classifies the primary outcome as a participant count, but does not report its distribution or the model used. The endpoint definition is also a count of participants meeting a response threshold, so the appropriate analysis depends on how the count and its denominator were recorded.

The registry reports 0 analyses. This means that analysis results are not listed in the registry record, not that a particular model or no model was necessarily used in other materials. The statistical analysis plan, handling of missing outcomes, adjustment variables, and approach to multiple outcomes are not reported in the registry record. Those omissions limit the extent to which a reader can evaluate the analysis choices or reproduce an inferential result.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Intervention Arm")
n      <- c(40)
events <- c(37)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Intervention Arm  40  37  92.5  79.6  98.4  80.1  97.4  80.1  97.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures, including the primary acceptability outcome and long-term adherence outcomes as secondary. It lists 0 analyses. A multiplicity plan describing whether or how inference across outcomes was controlled is not reported in the registry record. In general, testing multiple outcomes can increase the chance of at least one apparently notable finding when results are interpreted without accounting for the number of tests. Whether that issue applies to reported conclusions depends on the analysis plan and which outcomes were tested; neither is available in the registry record.

Missing-data information is limited to the primary outcome description: one participant did not complete the study and was lost to follow-up, and one participant was excluded from analysis due to inadequate hair samples. The registry record does not say whether these notes overlap, how missing responses were treated, or what denominator was used. It does not report an imputation method, sensitivity analysis, or complete-case analysis. These methods are not interchangeable: in general, they rely on different assumptions about the relationship between missingness and the unobserved outcome.

The analysis population is not reported in the registry record. It is not stated whether the primary analysis included all randomized participants, only participants with observed outcomes, or another defined group. The distinction matters because the participants included in an analysis determine what comparison its estimate represents. With no reported denominator or analysis population, the primary endpoint cannot be reconstructed from the registry information.

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 0% reporting threshold.

The registry lists serious and other adverse-event figures by arm. For the intervention arm, 42 participants are listed as at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. For standard of care, 21 participants are listed as at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. No top serious adverse-event terms are listed.

These are the recorded counts in the registry’s safety information. A count of 0 means that no events of that type are listed for the stated group in this record; it does not establish that the intervention has no risks or that no events occurred outside the scope of the recorded information. The registry record does not give further detail about adverse-event collection, definitions, observation time, or the method used to assess safety. The at-risk counts are safety figures and should not be treated as the primary-endpoint analysis denominators.

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

The registry record describes a randomized comparison of point-of-care urine tenofovir testing with motivational interviewing against adherence counselling from a participant’s PrEP care provider. Its primary endpoint is participant-reported acceptability at 3 months, defined by responses of “somewhat” or “very” acceptable on a five-point Likert scale. These details establish what the study set out to compare and how its primary outcome was defined.

The numerical primary result is not reported in the registry record. There is no reported count of participants meeting the acceptability definition, no analysis denominator, and no arm-specific effect estimate or measure of uncertainty. The record consequently cannot establish the level of acceptability or the size and precision of any difference between groups. Its completed status and enrollment figure do not substitute for those outcome results.

The primary endpoint also has a narrower meaning than the study’s broader prevention rationale. Acceptability is not the same as adherence, and adherence is not the same as HIV incidence. The registry lists long-term adherence outcomes as secondary, but reports no numerical results for them. The study’s stated aim of supporting PrEP adherence does not, by itself, establish that adherence changed or that HIV infections were prevented. Those conclusions would require relevant outcome results and their analysis.

In general, a completed trial can still have results that are absent from a registry record. Absence of a reported result should be read as a limit on what can be concluded from that record, not as evidence that the outcome was favorable, unfavorable, or unchanged. The safety counts likewise describe the events listed, rather than proving that risk is absent. Interpretation should remain limited to the endpoints and details actually reported.

14. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between an intervention’s intended mechanism and the outcome chosen to assess it. The intervention combines a urine tenofovir test with motivational interviewing; the comparison is with standard adherence counselling. The primary endpoint asks whether participants found the intervention acceptable, while long-term adherence is listed as a secondary outcome. These questions are related but not equivalent. A favourable acceptability result, if reported, would not by itself establish a change in adherence, and an adherence result would not by itself establish an effect on HIV incidence.

The design also illustrates why complete outcome reporting matters. An endpoint definition can be clear while the result remains uninterpretable without the observed count, denominator, and an estimate of uncertainty. Here, the registry specifies the response threshold and 3-month timeframe, but does not report the primary outcome value or its analysis. Readers therefore cannot assess the magnitude or precision of the result from the registry record.

The documented notes about loss to follow-up and exclusion for inadequate hair samples make the analysis population especially important. The record does not explain how these cases relate to the primary analysis or to each other. In general, transparent reporting of exclusions, missingness, and analysis populations helps readers understand which participants contributed to each estimate and what assumptions might affect the result. This is relevant for both a count endpoint and secondary adherence outcomes.

Finally, the planning assumptions should be distinguished from evidence about trial performance. Sample-size calculations based on an observed effect are planning illustrations, not observed power. The trial’s registry record does not provide the primary effect estimate needed to understand those illustrations. Together, these reporting limits mean the record is informative about the clinical question and endpoint construction, but not about the intervention’s observed effect.

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 trial-specific details needed to assess the evidence are not reported in the registry record. The actual primary acceptability count, its denominator, arm-specific results, and an effect estimate with uncertainty are absent. Although the endpoint is defined at 3 months, the record does not describe the response distribution across the five-point scale or the statistical method used to compare arms.

The notes on one participant lost to follow-up and one participant excluded because of inadequate hair samples leave important ambiguity. The record does not say whether the participants overlap, whether the exclusion applied to a particular outcome, or how missing outcome information was handled. It also does not specify the analysis population. These gaps prevent a reader from reconstructing who contributed to the primary endpoint or evaluating the sensitivity of the result to missing data.

The registry identifies the trial as randomized and unmasked, but the randomization procedure, allocation concealment, and the roles of participants and study staff in outcome assessment are not described. Since acceptability is participant-reported and masking was absent, the record does not allow assessment of how knowledge of assignment may have shaped responses. This is a design consideration, not evidence that responses were biased.

Long-term adherence is listed as a secondary outcome, but no numerical results or measurement details are reported in the registry record. The record also does not report a multiplicity plan or a statistical analysis plan. These omissions limit interpretation of secondary findings and the ability to determine whether the reported outcomes and analyses followed prespecified methods.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: PrEP Point-of-Care Brief-Intervention for Adherence Among Young Men Who Have Sex With Men — NCT05353283.
• Registry record last updated 2026-02-13; status last verified 2026-01.
• Results first posted 2026-02-13.
• 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 randomized, unmasked, parallel-group study with enrollment of 63. The intervention paired point-of-care urine tenofovir testing with motivational interviewing counselling; standard of care was adherence counselling from the participant’s PrEP care provider. The primary endpoint assessed the number of participants reporting the intervention as “somewhat” or “very” acceptable at 3 months on a five-point Likert scale. Long-term adherence outcomes were listed as secondary.

The registry record does not report the primary outcome result, its denominator, or an inferential comparison between arms. It notes one participant lost to follow-up and one excluded because of inadequate hair samples, without explaining how these notes were handled or whether they overlap. Safety rows list 0 serious adverse events, 0 other adverse events, and 0 deaths in each arm. The analysis plan, missing-data methods, and multiplicity approach are not reported in the registry record.