Evaluation of (Doravirine / Lamivudine / Tenofovir Disoproxil Fumarate) (Delstrigo®) as a New Strategy for Non-occupational Post Exposure Prophylaxis, a Prospective Open Label Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of (Doravirine / Lamivudine / Tenofovir Disoproxil Fumarate) (Delstrigo®) as a New Strategy for Non-occupational Post Exposure Prophylaxis, a Prospective Open Label Study (NCT04233372), a na phase 4 study. The primary outcome is Proportion of Participants Who Did Not Complete the 28-day PEP Regimen.

2. Clinical Question

The study also lists clinical and laboratory adverse events, adherence, maintenance of follow-up, treatment non-completion, and HIV seroconversion among its secondary outcomes. These describe different aspects of the treatment period and follow-up; they are not substitutes for a comparison group. The central statistical question is therefore descriptive: what outcomes were recorded among participants receiving this regimen in this study? The registry record does not report numerical results for the primary outcome or the listed secondary outcomes.

3. Trial Design

This was a prospective, open-label, single-group, phase 4 study sponsored by Hospital Clinic of Barcelona. The registry lists an enrollment of 399 and identifies Delstrigo as the study intervention. Participants presenting to an emergency room after possible exposure to HIV were to receive the regimen as post-exposure prophylaxis. The study is marked completed. Its recorded start date is 2020-08-27, and its primary completion date is 2022-07-28.

In a prospective study, outcomes are followed after enrollment according to the study's planned observation period. Open-label means that masking was not used, as also indicated by the registry's masking entry. The record does not report whether awareness of treatment affected outcome assessment or participant reporting, so that possibility cannot be evaluated from the registry information alone.

Single-group means the listed participants received the study intervention without a separate trial arm serving as a concurrent control. The registry lists allocation as not applicable and explicitly notes that the study is not a randomized comparison. As a result, outcomes in this study can describe what was observed among its participants, but the design does not isolate the intervention's effect from other factors through a randomized between-group contrast.

The primary outcome is framed around completion of a 28-day regimen. Non-completion is described to include death, missing visits or loss to follow-up, changing or suspending study treatment for any reason, and withdrawal of consent. The record identifies the primary population as participants who received at least one dose of prophylaxis. It does not report the detailed analysis methods, the handling of participants with incomplete outcome information, or a sample-size justification. The registry lists seven outcome measures and no posted analyses. It therefore contains design and outcome definitions, but not the numerical primary efficacy results needed to estimate completion in the enrolled group.

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: 406 subjects met PEP criteria and were visited in the emergency department of Hospital Clínic of Barcelona. 1 subject was a screening failure. 6 subjects were excluded after the initial evalution because they didn't meet the selection criteria and/or had multiple entries. 399 subjects were included and analized in the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All participants who received at least one dose of PEP (Intention-To-Treat population).

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: 399 participants were analysed for baseline characteristics

6. Primary Endpoint

The registry lists the primary outcome as Proportion of Participants Who Did Not Complete the 28-day PEP Regimen, measured over 28 days.

The primary endpoint concerns whether participants completed the 28-day post-exposure prophylaxis regimen. The registry title describes the outcome as the proportion who did not complete treatment. Its description, however, first refers to the proportion with treatment completion at day 28, then defines non-completion through events including death, missed visits or loss to follow-up, treatment change or suspension, and consent withdrawal. This wording does not make the direction of the intended reported proportion entirely clear. The registry record does not resolve that ambiguity or report an observed result.

A completion endpoint can serve as a practical summary of whether participants remained on the prescribed regimen through the planned treatment period. The listed reasons for non-completion combine distinct events: some concern treatment exposure, while others concern follow-up or consent. Combining them can be useful for describing whether the overall regimen was completed, but the total alone would not explain which circumstances contributed to non-completion. Separate counts by reason would be needed for that interpretation, and those counts are not reported in the registry record.

For a binary endpoint, the basic descriptive quantities are the number of participants meeting the defined outcome and the proportion of the analysis population meeting it. Precision is commonly conveyed with a confidence interval, which expresses uncertainty around an estimate under the assumptions of the method used. The registry record does not report the primary-outcome count, proportion, confidence interval, or an analysis method. Therefore neither the observed completion level nor its precision can be assessed from the posted record. The endpoint definition also leaves uncertainty about whether the intended headline measure is completion or non-completion, so any later interpretation should retain that distinction.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins by identifying the design, the endpoint, the analysis population, and the information actually reported. In this study, the design is prospective, open label, and single group. The primary endpoint concerns completion of a 28-day prophylaxis regimen, and the stated population is participants who received at least one dose. The registry does not report the primary endpoint estimate or a statistical analysis. Without those elements, a numerical estimate of completion and its precision cannot be assessed.

What does a single-group design estimate?

In general, a single-group study can describe the outcomes observed in the participants who received the intervention. For a binary outcome such as completion, a descriptive analysis would ordinarily identify the number meeting the endpoint and the corresponding proportion in the defined population. This characterizes the study group; it does not by itself estimate a causal difference from another treatment or from no treatment. A comparator is needed for a direct between-group contrast, and random allocation can help make groups comparable with respect to factors that might otherwise influence outcomes. Neither a concurrent comparator nor random allocation is listed for this study.

That design limitation is separate from whether the observed outcome is useful to describe. A proportion could still summarize the frequency of a clearly defined event among enrolled participants. But interpreting it as an effect of treatment would require assumptions about what would have happened to those same participants under another strategy. The study record does not provide that counterfactual comparison. It also does not report an adjusted analysis that might address measured differences against an external group.

How should a binary endpoint be read?

In general, a binary endpoint classifies each participant into one of two categories according to a prespecified rule. For this study, the listed rule treats death, loss to follow-up, treatment change or suspension, and consent withdrawal as non-completion events. These events have different meanings, even if they are combined in a single endpoint. A total non-completion count would describe the combined outcome, while reason-specific counts would help show what contributed to it. The registry does not report either type of primary-outcome count.

A proportion is a descriptive estimate, not a guarantee that the same frequency would be observed in every population. A confidence interval is a general way to communicate sampling uncertainty around an estimate. It reflects the uncertainty arising from observing a study group rather than every person in a target population, subject to the model and assumptions used. A narrow interval generally indicates greater precision than a wide interval, but neither width nor coverage can be assessed without the estimate, interval, and method. No primary-outcome confidence interval or method is reported in the registry record.

What does open-label mean statistically?

In general, open-label studies do not mask treatment assignment from participants or study personnel. Knowledge of the intervention can matter especially when outcomes involve participant reports, decisions to continue treatment, or judgments about whether an event occurred. This does not establish that bias occurred. It means that readers need information about outcome definitions, assessment procedures, and safeguards to assess possible influence. The registry identifies the study as open label but does not report detailed procedures for adjudicating or measuring the primary endpoint.

Why do endpoint wording and population definitions matter?

The primary outcome title refers to the proportion who did not complete the regimen, while the outcome description refers to treatment completion at day 28 and then defines non-completion. A statistical estimate is interpretable only if readers know which category is counted as the event. A proportion of completers and a proportion of non-completers answer different questions. The registry wording does not fully clarify which is intended as the reported endpoint. The analysis population is described as participants who received at least one dose, but the registry does not report whether all enrolled participants met that definition or how any exclusions were handled.

In general, a prespecified analysis population helps prevent ambiguity about who contributes to an estimate. An intention-to-treat label often signals a defined population linked to treatment assignment, but the record's own wording specifies participants who received at least one dose. Since this is a single-group study, the registry's population description should be retained rather than assuming a different convention. The actual number included in the primary analysis is not reported.

What can be inferred from the listed planning assumptions?

The registry includes sample-size planning assumptions for an illustration: two-sided significance level 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of an observed effect. It also distinguishes planning quantities for time-to-event outcomes from those for other outcomes. These assumptions are not a description of this trial's single-group design, which has no randomized two-arm allocation. The record does not report a trial-specific sample-size justification or a numerical planning result for the primary endpoint. A planning illustration is not observed power and cannot replace an outcome analysis.

In general, sample-size calculations depend on assumptions about the outcome, the effect to be detected, variability or event frequency, and the testing approach. If assumptions do not match the design and outcome, the resulting planning quantity may not answer the study's actual question. Since the registry's listed illustration assumes equal allocation between two arms, it should not be interpreted as describing participant allocation in this single-group study. The record also does not report interim analyses, stopping rules, or a detailed statistical plan.

Finally, statistical significance and clinical interpretation are not interchangeable. A p-value, when reported, concerns the compatibility of data with a specified statistical model or null hypothesis; it does not state the probability that a treatment is effective. An estimate and its precision, endpoint definition, population, design, and possible biases all contribute to interpretation. No primary p-value, effect estimate, or confidence interval is reported in the registry record, so significance-based conclusions are unavailable.

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("Delstrigo")
n      <- c(399)
events <- c(114)
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  Delstrigo  399  114  28.6  24.2  33.3  24.4  33.2  24.4  33.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures, including the primary completion outcome and secondary outcomes concerning adverse events, treatment non-completion characteristics, adherence, follow-up, and HIV seroconversion. It reports no posted analyses. The registry record does not state whether a multiplicity strategy was planned, such as prioritizing outcomes, adjusting significance thresholds, or treating secondary outcomes as exploratory. When several outcomes are assessed, the chance of at least one apparently unusual result can increase if each is tested separately. In general, a prespecified testing hierarchy or other multiplicity approach helps clarify how multiple findings should be interpreted. No such approach is reported, and there are no posted outcome analyses to evaluate.

The primary population is described as all participants who received at least one dose of prophylaxis. The actual number included in the primary analysis is not reported. The registry also defines loss to follow-up as a reason for non-completion, but does not explain how missing endpoint data were distinguished from non-completion or otherwise handled in the analysis. It does not report imputation, sensitivity analyses, or assumptions about missing outcomes. These methods matter because a missing observation can affect a proportion and its uncertainty, and different handling approaches can lead to different interpretations.

In general, missing-data methods should be considered alongside the endpoint definition and analysis population. Treating every person without a recorded outcome as a non-completer would be an analytical choice, not an automatic consequence of a missing record, unless the protocol explicitly defines it that way. Although the endpoint description includes loss to follow-up among non-completion criteria, the registry does not report how this rule was applied in the results. Details about protocol deviations, exclusions, and the distinction between withdrawal and unavailable outcome data are not reported in the registry record.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry's adverse-event summary lists 399 participants at risk for serious adverse events and 0 participants affected. It also lists 0 deaths. For other adverse events, 399 participants are listed at risk and 123 as affected. These are the posted safety counts; the registry does not give event-specific numerical results or list serious adverse-event terms.

The counts should be read as descriptive registry fields, not as a comparison between treatments. Since there is no control group, they do not estimate a difference in safety relative to another regimen. The record does not provide detailed definitions, event severity grades, observation time by participant, or whether affected participants could have experienced multiple events. It therefore is not possible to infer the number of total events from the participant count or to characterize event types beyond what is listed.

In general, the number of participants with an event and the number of events are distinct quantities: a participant may experience more than one event. Seriousness and severity are also separate concepts in safety reporting; the registry does not provide enough detail to assess severity categories. The serious-event figures describe what is recorded in this registry summary, not proof that no unrecorded or unreported events occurred. The 123 affected participants in the other-adverse-event field should not be interpreted as 123 separate events unless the record explicitly reports event counts, which it does not.

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

The record establishes that a prospective, open-label, single-group study of Delstrigo for non-occupational post-exposure prophylaxis was completed and lists 399 enrolled participants. It defines a primary outcome related to completion of a 28-day regimen and identifies a population based on receipt of at least one dose. It also provides selected safety counts. These registry entries describe the registered study and its posted information.

The record does not report the primary outcome result. It therefore does not establish the proportion who completed the regimen, the proportion who did not, or how precisely either proportion could be estimated. The endpoint wording itself alternates between completion and non-completion, adding uncertainty about the intended direction of the measure. Numerical findings for the listed secondary outcomes are also not reported. No conclusion about their observed frequency can be drawn from their presence in the outcome list alone.

Because the study has no concurrent comparison group, it cannot provide a randomized estimate of how outcomes differ from those under another strategy. A descriptive result, if available, would apply to the study group and would need to be interpreted in light of its setting, eligibility, follow-up, and missing data. It would not by itself show what would have happened to the same participants under an alternative approach.

The safety summary reports zero participants affected in its serious-adverse-event field and zero deaths, alongside 123 participants affected in the other-adverse-event field. These counts are limited to what the registry reports and do not identify event types or establish comparative safety. The absence of a posted serious-event count beyond the listed zero does not resolve possible differences in surveillance or reporting.

The appropriate interpretation is therefore bounded: the registry record offers design details, outcome definitions, and selected safety counts, but it does not supply the primary efficacy estimate or its uncertainty. Neither study completion status nor the number enrolled can stand in for those missing results. The record alone cannot establish a treatment effect or a comparative conclusion.

14. Why This Trial Matters Statistically

This trial raises several statistical issues that are important when reading clinical research. Its single-group structure makes the distinction between describing outcomes and estimating comparative effects especially visible. A study can document what happened among participants receiving an intervention, but without a concurrent comparison it cannot directly separate treatment effects from other influences on outcomes. That distinction is central to interpreting registry results without overstating what a design can support.

The primary outcome also illustrates why clear endpoint wording matters. A completion measure and a non-completion measure refer to opposite categories, while the definition combines events such as loss to follow-up, treatment changes, and consent withdrawal. Clear operational definitions allow readers to understand what counts as an event and whether the endpoint reflects treatment exposure, follow-up, or both. In this record, the title and description do not fully align, and no result is posted to clarify the reporting choice.

The record also highlights the difference between a registered outcome and a reported result. Listing outcomes indicates what the study intended to assess, but does not tell readers how often those outcomes occurred or how uncertain an estimate may be. For meaningful statistical interpretation, results need a defined analysis population, an estimate, and a measure of precision, along with enough information to understand missing data and the analysis method. Those details are not reported for the primary endpoint.

Finally, safety summaries require attention to whether counts refer to participants or events and to how categories are defined. The posted counts distinguish participants affected by serious and other adverse events, but do not provide event-level detail or a comparator. These limits do not erase the descriptive information; they define what it can and cannot answer. The study is statistically informative as an example of why design, endpoint definition, result reporting, and uncertainty must be considered together.

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.

The principal limitation of the registry record for statistical interpretation is the absence of posted primary-outcome results. Although the primary endpoint and its timeframe are described, no count, proportion, confidence interval, or analysis result is reported. The listed secondary outcomes likewise lack numerical results. The record therefore cannot support an estimate of regimen completion or non-completion, or an assessment of precision.

The primary endpoint description is not fully consistent with its title. The title refers to participants who did not complete treatment, whereas the description refers to treatment completion at day 28 and then defines non-completion criteria. The record does not clarify which category was treated as the primary event for reporting. In addition, the listed non-completion reasons combine events with different meanings, and reason-specific results are not reported.

The single-group design has no concurrent comparator, and allocation is listed as not applicable. Consequently, the study cannot provide a randomized between-group estimate. Open-label status may also matter for outcomes influenced by participant reporting or study decisions, but the registry does not describe outcome assessment procedures in enough detail to evaluate that possibility.

The analysis population is described, but the number actually analyzed and the handling of missing outcome information are not reported. This is relevant because loss to follow-up is included among non-completion criteria, yet the application of that rule in the results is unavailable. The record does not report a trial-specific sample-size justification, a full statistical analysis plan, interim analyses, or multiplicity procedures. Its planning assumptions describe a two-arm illustration and do not match the listed single-group design.

The safety summary is also limited: it provides participant-level counts but not event terms for serious events, severity grades, detailed observation time, or a comparative group. These omissions restrict interpretation to the recorded summary rather than a comprehensive characterization of safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of (Doravirine / Lamivudine / Tenofovir Disoproxil Fumarate) (Delstrigo®) as a New Strategy for Non-occupational Post Exposure Prophylaxis, a Prospective Open Label Study — NCT04233372.
• Registry record last updated 2025-09-10; status last verified 2025-07.
• Results first posted 2025-09-10.
• 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

NCT04233372 is a completed, prospective, open-label, single-group, phase 4 study sponsored by Hospital Clinic of Barcelona. It evaluated Delstrigo as non-occupational post-exposure prophylaxis among people presenting after possible HIV exposure. The registry lists 399 enrolled participants; the recorded study dates are 2020-08-27 and 2022-07-28 for study start and primary completion.

The primary outcome concerns completion of the 28-day regimen in participants who received at least one dose. Its title and description differ on whether completion or non-completion is the reported measure. The registry lists seven outcome measures and no posted analyses, and does not report the primary outcome result or its precision.

The safety summary lists 0 participants affected by serious adverse events, 0 deaths, and 123 participants affected by other adverse events. No randomized comparator is listed. The record supports a description of study design and posted safety counts, but not a comparative treatment-effect conclusion.