HealthMindr App to Increase Pre-exposure Prophylaxis (PrEP) Uptake and Retention Among Men Who Have Sex With Men (MSM): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for HealthMindr App to Increase Pre-exposure Prophylaxis (PrEP) Uptake and Retention Among Men Who Have Sex With Men (MSM) (NCT03763942), a randomized na study. The primary outcome is PrEP Uptake.

2. Clinical Question

The trial focuses on uptake rather than a clinical HIV outcome. Its primary question is whether assignment to the app intervention is associated with a different rate of PrEP uptake over follow-up than assignment to the control condition. The outcome description specifies assessment at 3, 6, 9, and 12 months post-randomization. Because the measure is expressed as events per 1000 person-months, the interpretation depends on both the number of uptake events and the amount of observed time contributing to the rate.

The registry identifies a randomized comparison, which is intended to make the assigned groups comparable on average at the start of a trial. Randomization alone does not establish the magnitude or precision of an outcome difference. The record does not include primary-outcome estimates for either arm, a between-arm contrast, or a confidence interval. Consequently, the clinical question can be described, but the direction and size of the observed difference cannot be characterized from the registry record.

3. Trial Design

This was a randomized, parallel-group trial with no masking reported. The study compared access to the HealthMindr app with a control condition. The registry describes the trial as completed and lists enrollment as 658. It identifies Emory University as the sponsor. The listed study start date is 2020-01-28, and the primary completion date is 2023-03-17.

Participants assigned to the intervention arm received access to the HealthMindr app and its capabilities. The described content covered HIV testing, prevention resources, and ways to locate HIV testing and PrEP services. The control arm is described in the brief summary as receiving standard of care. Its arm description adds that participants were directed to download a study app that allowed study staff to interact with them. The registry record does not provide further detail about the control condition or how staff interaction was conducted.

The primary outcome was assessed at 3, 6, 9, and 12 months post-randomization. The record says that the number analyzed at each time point depended on the number of participants able to complete the corresponding study visit. Thus, the outcome assessment schedule is clear, but the count of participants contributing to each assessment is not reported in the registry record.

The design information establishes the broad structure of the comparison, not the full conduct or analysis of the trial. The registry record does not report the randomization procedure, allocation concealment, eligibility criteria in detail, recruitment settings, adherence to app use, or the statistical analysis plan. It also does not report whether outcome assessors were blinded. These details should not be inferred from the randomized, parallel-group, and unmasked design labels.

The registry lists one primary outcome measure and no analysis entries. The absence of analysis entries means that the posted record does not provide a statistical result for the primary comparison. Completion status and enrollment describe the study record, but do not substitute for outcome estimates or information about precision.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Number of participants analyzed per different time point are based on number of patient that were able to complete the corresponding study visit.

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 PrEP Uptake, measured over 3, 6, 9, and 12 months post-randomization.

The primary endpoint is PrEP uptake, assessed at 3, 6, 9, and 12 months post-randomization. The registry describes the measure as a rate in events per 1000 person-months. The primary measure is self-report. The description also states that validation may occur through a dried blood spot self-collection kit to detect tenofovir diphosphate and/or through upload of a photo of a PrEP prescription bottle.

A rate relates the number of events to time under observation. Person-time can accommodate differences in how long participants contribute follow-up, which is relevant when outcome assessments occur at scheduled visits and not every participant completes every visit. The registry states that the number analyzed at each time point depends on who could complete the corresponding study visit. The actual person-time and numbers contributing to each assessment are not reported in the registry record.

In general, combining self-report with a potential validation measure can help distinguish reported uptake from evidence consistent with PrEP use or a prescription. The record does not specify how validation was incorporated into the endpoint definition, how discordant information was handled, or whether validation was available for every participant. Those details matter because different operational definitions can yield different event counts.

The endpoint is intended to address the study’s uptake question, rather than to measure HIV incidence or another clinical outcome. The registry record does not report the observed uptake rates, a between-arm estimate, or the associated confidence interval. The endpoint definition and schedule can therefore be described, but the size and precision of any treatment contrast cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a rate per person-time mean?

General statistical explanation: A rate uses events in relation to accumulated observation time. Person-time is the total time participants contribute while their outcome status can be assessed. This framework can be useful when follow-up duration varies. A rate is not automatically a risk or a percentage: those quantities use different denominators and answer different questions. Here the registry describes the primary measure in events per 1000 person-months, but does not post arm-specific event counts, accumulated person-time, or rate estimates.

The scheduled assessments were at 3, 6, 9, and 12 months post-randomization. The registry notes that the number analyzed at each time point depends on completion of the corresponding visit. This makes the time-specific contribution important to interpretation. A reader would need the observed events and person-time, along with a clear description of how repeat reports across visits were handled, to understand how the stated rate was formed. Those details are not reported in the registry record.

What does a confidence interval convey?

General statistical explanation: A confidence interval expresses the uncertainty around an estimate under the assumptions of the analysis. A narrower interval indicates greater precision, while a wider interval indicates less precision. Its endpoints are not a guarantee that the true effect lies within that particular interval, and it does not by itself indicate whether an effect is important. The primary outcome description lists a 95% confidence interval as its dispersion measure, but the registry record does not report an interval for the primary comparison.

A confidence interval needs to accompany a clearly defined estimate. For this trial, that would require knowing which contrast was estimated, the direction of subtraction or comparison, and the analysis population. The registry record does not post a primary-outcome contrast or an analysis population definition. It therefore does not permit an assessment of either the estimated effect or its precision.

Why can follow-up completion matter?

General statistical explanation: When outcome information is unavailable for some participants, the amount of information is reduced. More importantly, missingness can create bias if the chance of having an observed outcome is related to the outcome itself or to the assigned group. Methods for handling missing outcomes rely on assumptions; different assumptions can lead to different estimates. The record says that analysis at each time point was based on participants able to complete the corresponding visit, but it does not report time-specific completion counts, reasons for missing visits, or a missing-data method.

The endpoint description includes self-report and possible validation through a dried blood spot or a photo of a prescription bottle. In general, incomplete validation can affect how much is known about the endpoint and may create another source of missing information. The registry record does not explain whether validation was required, how unvalidated self-reports were classified, or how incomplete validation was handled.

What can be inferred from randomization?

General statistical explanation: Random assignment aims to balance measured and unmeasured characteristics between groups on average at the start of a study. It supports a causal comparison when allocation is implemented as intended and follow-up, outcome measurement, and analysis are also handled appropriately. Randomization does not guarantee that the realized groups are identical, nor does it remove bias caused by differential missing outcomes or outcome measurement.

The registry identifies allocation as randomized, masking as none, and the model as parallel. It does not report how the random sequence was generated, whether allocation was concealed, or whether the primary analysis retained participants according to assigned group. The effects of these procedures on the result cannot be evaluated from the registry record.

What analysis model was used?

The outcome is described as a rate and its dispersion as a 95% confidence interval, but the registry record does not report the statistical model, link function, covariate adjustment, handling of repeated follow-up, or method for estimating uncertainty. It would not be appropriate to infer a particular model from the rate scale alone.

General statistical explanation: Count outcomes can show over-dispersion when their variability exceeds what a simple count model assumes. If present, over-dispersion can make standard errors too small under an unsuitable model, leading to confidence intervals that are too narrow and tests that are too optimistic. A suitable analysis may account for extra variability, but the registry record does not report whether over-dispersion was assessed or how it was addressed. This general consideration is not evidence that over-dispersion occurred in this trial.

The record contains no primary-outcome analysis entries. It also does not report an effect estimate, interval, p-value, or adjusted analysis. The method used to analyze the outcome is therefore not reported in the registry record. Statistical interpretation must stop at the design and endpoint description rather than attributing an unreported method or result to the trial.

10. Multiplicity, Missing Data and Analysis Populations

The primary endpoint was assessed at 3, 6, 9, and 12 months post-randomization. Assessing an outcome at multiple times raises a general statistical issue: if several comparisons are tested, the chance of at least one apparently unusual result can increase unless the analysis plan defines how those comparisons will be interpreted or adjusted. The registry record does not report whether the time points were treated as separate tests, combined in a repeated-measures analysis, or arranged in a prespecified testing hierarchy. Any multiplicity procedure is not reported in the registry record.

The record identifies PrEP uptake as the primary outcome but contains no analysis entries for it. It does not report whether there were secondary outcomes, subgroup analyses, interim analyses, or a prespecified primary contrast beyond the general comparison of intervention and control. The statistical analysis plan and any adjustments for multiple testing are not reported in the registry record. Therefore, the multiplicity strategy cannot be evaluated.

For missing data, the registry says that the number analyzed at each time point depended on who completed the corresponding study visit. The actual visit-specific counts, reasons for noncompletion, and methods for handling missing outcomes are not reported in the registry record. It is also not reported whether participants with missing visits were included in any model or whether sensitivity analyses examined alternative missing-data assumptions.

The analysis population is not reported in the registry record. In particular, the available record does not say whether the primary analysis followed randomized assignment regardless of app use, included only participants with observed outcome data, or used another definition. These distinctions affect how the result would be interpreted. Without an analysis population, missing-data method, multiplicity plan, and primary-outcome estimates, the strength and scope of any inferential claim cannot be assessed.

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 5% reporting threshold.

The registry lists serious adverse events, other adverse events, and deaths separately for each arm. For HealthMindr App, the record lists 437 participants at risk, 0 serious adverse events, 0 other adverse events, and 0 deaths. For Control App, it lists 221 participants at risk, 0 serious adverse events, 0 other adverse events, and 0 deaths. No serious adverse event terms are listed.

These are registry counts, not estimates of comparative safety. A zero recorded count means that no events of that category were entered in this record for the listed group; it does not establish that no event occurred outside the registry’s ascertainment, reporting, or follow-up process. The record does not describe the event collection procedures, observation duration for safety, severity grading rules, or how completeness of reporting was checked.

The participant counts listed as at risk for safety should not be assumed to be the number contributing to every primary-outcome assessment. The primary outcome description says that the number analyzed at each visit depended on completion of that visit, while the safety counts are presented separately by group. The registry record does not explain any difference in the populations represented by these figures.

Because no comparative safety analysis or uncertainty estimate is reported, the counts do not establish equivalence between the arms or quantify a difference in risk. They are best read narrowly as the adverse-event counts recorded in the registry, alongside the listed group counts at risk.

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

The registry record establishes that this was a randomized, parallel-group comparison of a mobile app intervention with a control condition, with PrEP uptake as the primary outcome. It describes self-report as the primary measurement approach, possible validation methods, and assessments at 3, 6, 9, and 12 months post-randomization. These details clarify the question the trial was designed to address.

The record does not report the primary-outcome rates or a between-arm estimate. It therefore does not show the direction, size, or precision of the difference in uptake. No conclusion that HealthMindr increased uptake, reduced uptake, or had no effect can be drawn from the posted primary-outcome information. The lack of a reported estimate is a limitation of what can be interpreted, not a result showing that the groups were alike.

Even if an estimate were available, interpretation would depend on its uncertainty, the definition of uptake, follow-up completion, and the analysis population. Self-report and validation may capture different aspects of uptake, and the registry does not explain how validation evidence was used. The numbers contributing at each visit and the handling of incomplete follow-up are also not reported.

The safety counts are separate from the efficacy question. The registry records zero serious adverse events, zero other adverse events, and zero deaths in both listed groups, but it does not provide enough detail to assess event ascertainment or comparative safety. These counts do not answer the primary question about PrEP uptake.

The appropriate interpretation is consequently limited: the registry describes a completed randomized study and its planned primary outcome, but does not report the primary outcome analysis. Clinical importance, statistical significance, and precision cannot be assessed from the available record. No treatment recommendation follows from this description.

13. Why This Trial Matters Statistically

This trial illustrates why a randomized design and a clearly named endpoint are not enough to interpret a clinical study. Randomization defines the intended comparison, while the endpoint and follow-up schedule define what outcome was to be measured. To assess the result, readers also need the observed arm-level data or a treatment-effect estimate, its uncertainty, and a description of how missing follow-up and the analysis population were handled.

The endpoint is a rate per person-time rather than a simple proportion. That distinction matters because participants may contribute different amounts of observation, and the record states that time-specific analysis depends on visit completion. Without the observed rates, person-time, or visit-specific analysis counts, the magnitude and precision of the primary contrast cannot be evaluated.

The record also makes an important distinction between self-reported uptake and possible validation. The validation options could add information about reported use or a prescription, but their role in the endpoint definition is not specified. Statistical readers need operational clarity about which observations count as events, how incomplete evidence is handled, and whether these procedures were applied similarly across arms.

Finally, reporting the completed status of a trial does not itself communicate its findings. Here, the registry describes the design and outcome schedule but includes no analysis entries for the primary endpoint. This is a useful reminder that outcome definitions, results, precision, and analysis methods are separate pieces of evidence. Without the primary estimates and methods, the randomized comparison cannot be quantitatively interpreted.

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 for interpreting this trial from the registry record is that no primary-outcome treatment-effect estimate is reported. The record does not provide arm-specific uptake rates, event counts, person-time, a between-arm contrast, confidence interval, or significance test. As a result, neither the direction nor the precision of the primary comparison can be assessed.

The endpoint description leaves important operational details unspecified. Self-report is identified as the primary measure, while validation may involve a dried blood spot self-collection kit to detect tenofovir diphosphate and/or a photo of a PrEP prescription bottle. The registry does not report how validation was incorporated, how conflicting information was resolved, or how many participants completed validation. This limits assessment of outcome measurement and completeness.

The record notes that the number analyzed at each follow-up time depended on completion of the corresponding study visit. It does not report the counts at each assessment, reasons for missed visits, or methods used to handle missing outcomes. The analysis population is also not reported in the registry record. These gaps prevent evaluation of attrition and the assumptions underlying any estimate.

Other trial details relevant to interpretation are also not reported in the registry record, including the randomization procedure, allocation concealment, the statistical model, covariate adjustment, handling of repeated observations, and any multiplicity strategy. The record identifies a randomized, unmasked, parallel design, but those labels do not resolve these methodological questions. The limitations concern what can be determined from the registry record and do not establish that the trial itself lacked these procedures.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: HealthMindr App to Increase Pre-exposure Prophylaxis (PrEP) Uptake and Retention Among Men Who Have Sex With Men (MSM) — NCT03763942.
• Registry record last updated 2024-06-04; status last verified 2024-05.
• Results first posted 2024-06-04.
• 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 record describes a completed randomized, parallel-group trial comparing the HealthMindr app with a control condition among men who have sex with men. The intervention provided app access and HIV prevention resources. The control is described as standard of care, with a study app used for staff interaction. Enrollment is listed as 658.

The primary outcome was PrEP uptake, expressed as events per 1000 person-months and assessed at 3, 6, 9, and 12 months post-randomization. Self-report was the primary measure, with validation described through a dried blood spot test and/or a photo of a PrEP prescription bottle. The number analyzed at each time point was based on completion of the corresponding visit.

The record does not report the primary-outcome analysis or a treatment-effect estimate. It also does not report the statistical analysis plan, missing-data methods, or analysis population. Serious adverse event, other adverse event, and death counts are recorded as 0 in each arm, with 437 and 221 participants at risk listed for HealthMindr App and Control App, respectively. These counts do not replace the missing primary-outcome results.