mHealth App for Engagement in Care Among Youth Living With HIV: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for mHealth App for Engagement in Care Among Youth Living With HIV (NCT03587857), a na na study. The primary outcome is Feasibility: Rate of Participant Recruitment.

2. Clinical Question

3. Trial Design

This was a completed, single-group pilot study of a mobile health application for engagement in care among youth living with HIV. The registry lists the study as NCT03587857, with University of California, San Francisco as sponsor. Phase is recorded as NA, allocation as NA, masking as none, and the model as single group. Those entries describe a study without a randomized control-arm comparison.

The record gives a start date of 2019-07-01 and a primary completion date of 2020-05-01. It lists enrollment as 79. The study description separately states that the six-month pilot aimed to examine feasibility and acceptability among YLWH in the San Francisco Bay Area, with N = 76. These are different registry entries; the record does not explain the relationship between the planned pilot population and the enrollment figure.

All participants who chose to enroll were to receive access to WYZ and were asked to use it for 6 months. The stated aims also included app development and formative work, including a field test of an initial release. The description refers to qualitative interviews with a subset of participants and clinical team members, with planned counts of N = 20 and N = 10, respectively. The record does not report interview findings.

Because the study has no control group, changes over time cannot be separated from other influences using a randomized between-group contrast. Its design is suited to describing feasibility and acceptability in the pilot context, but the registry record does not establish comparative efficacy.

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

Analysis population for the primary outcome, as defined in the registry: Overall Number of Participants Analyzed represents number of participants screened for study interest prior to recruitment/enrollment

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 Feasibility: Rate of Participant Recruitment, measured over 8 Months.

The primary endpoint is titled “Feasibility: Rate of Participant Recruitment.” It is measured as a count of participants, with a timeframe of 8 Months. The endpoint description sets a recruitment goal of at least 55 participants, described as 70% of the target N. It also says the overall number analyzed represents the number of participants screened for study interest prior to recruitment or enrollment. That definition matters: screening interest and enrollment are related steps, but the record does not say that the enrollment figure is the endpoint result.

Recruitment is used as a feasibility measure because it indicates whether a study can attract enough eligible or interested people to proceed with its intended activities. In a pilot, this kind of endpoint can inform whether recruitment processes appear workable in the setting studied. It does not measure app effectiveness, engagement change, adherence, viral suppression, or clinical benefit.

The registry record does not report an observed value for the recruitment endpoint, a numerator or denominator for a recruitment rate, or a result against the stated goal. The enrollment figure is 79, but it should not be substituted for the endpoint result without confirmation that it uses the endpoint's stated definition and timeframe.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The available information supports a limited statistical reading. The registry record identifies a single-group study, a participant-count primary endpoint, several secondary outcomes, and no posted statistical analyses. It does not report a statistical analysis plan, a sample-size justification, a method for handling missing data, or the results needed to assess uncertainty around the study outcomes. Those items are not reported in the registry record.

What does a single-group design permit?

In a single-group study, outcomes can be described among people who receive the intervention. Without a concurrent comparison group, there is no randomized contrast to estimate what would have happened under another intervention or under usual care. This is a design limitation, not a flaw that can be resolved by a statistical test. Statistical adjustment cannot create the missing randomized comparator from the information recorded.

The registry lists allocation as NA and masking as none, consistent with the single-group description. The record does not report a blinded outcome assessment procedure or a plan for controlling confounding. It would be inappropriate to assume either was used. General statistical principle: a control group helps distinguish intervention-associated differences from changes that might have occurred for other reasons, while random allocation can balance measured and unmeasured factors on average.

How should the recruitment endpoint be read?

The primary measure is a count of participants, not a clinical outcome or a between-group effect. The description specifies an 8 Months timeframe and a goal of at least 55 participants, identified as 70% of the target N. It further defines the analyzed count as participants screened for study interest before recruitment or enrollment. The registry enrollment is 79, but the record does not report the endpoint's actual analyzed count or clarify that the enrollment entry follows the endpoint definition. The endpoint result therefore cannot be reconstructed from the enrollment entry.

General statistical principle: a count answers how many events or people were recorded, while a rate requires a clearly defined denominator and observation period. The endpoint title uses the word “Rate,” but its listed unit is participants and the description gives a count-based threshold. Since no endpoint result or denominator is reported, a recruitment rate cannot be calculated or interpreted from the record.

What is missing from the analysis record?

The record lists 9 outcome measures and 0 analyses. It does not provide numerical results for the recruitment endpoint or the listed acceptability outcomes. No confidence intervals, standard errors, p-values, adjusted estimates, or models are reported. Without estimates and their uncertainty, there is no basis for judging precision or distinguishing a stable pattern from sampling variation.

General statistical principle: a confidence interval describes the range of values reasonably compatible with an estimate under the statistical model used. It is useful for understanding precision, but cannot repair a design that lacks a comparator. No confidence interval is reported for this study's primary endpoint in the registry record.

The statistical methods section includes planning-illustration assumptions: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of an observed effect. The record labels these as planning illustrations rather than the trial's own design. Since this study is single-group and no observed effect or analysis is reported, those generic assumptions should not be interpreted as the pilot's protocol, evidence of power, or a basis for a treatment-effect conclusion. The record does not report a study-specific sample-size justification.

General statistical principle: power calculations depend on a specified outcome, effect, variability, design, and analysis. Planning estimates describe hypothetical future study requirements under stated assumptions; they do not indicate the probability that this completed pilot detected an effect. No observed-power conclusion is warranted.

Why do outcome definitions and follow-up matter?

For counts and proportions, interpretation depends on who was eligible, who was assessed, how missing observations were handled, and the time period in which events could occur. The record gives a timeframe for the primary endpoint and describes a six-month app-use period, but does not report a participant flow, outcome-specific denominators, or missing-data procedures. These details are not reported in the registry record. General statistical principle: incomplete follow-up can alter a proportion or outcome summary when people with missing data differ from those observed.

For event counts, over-dispersion can matter when observations vary more than a simple probability model expects; a model that ignores that extra variation may give uncertainty estimates that are too narrow. This is a general statistical consideration, not a method reported for this trial. No model for count or binary outcomes is specified in the registry record.

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("Arm 1: Intervention")
n      <- c(92)
events <- c(79)
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  Arm 1: Intervention  92  79  85.9  77.0  92.3  77.3  91.6  77.3  91.5

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 9 outcome measures, including the recruitment-feasibility endpoint and secondary outcomes on retention, app experience, privacy, security, anonymity, and continuing app use. It records 0 analyses. The registry record does not report which outcomes were analyzed, whether any outcomes were designated as secondary to particular hypotheses, or whether a multiplicity adjustment was planned.

When several outcomes are tested, the chance of at least one apparently unusual result can increase if each is assessed independently at a conventional threshold. General statistical principle: a prespecified testing hierarchy or multiplicity adjustment can help control that risk. The record does not state whether either approach was used, so no claim about control of multiple testing is supported.

The record does not report missing-data counts, the number assessed for each outcome, reasons for missingness, or procedures for handling incomplete observations. It also does not describe an analysis population such as all enrolled participants or participants with complete outcome data. These details are not reported in the registry record. General statistical principle: excluding participants with missing outcomes can bias estimates if missingness is related to participant characteristics or outcomes; the direction of bias cannot be determined without information about the missing data and the analysis.

There is no reported participant flow from screening through enrollment and follow-up. The endpoint description refers to the number screened for study interest, while the registry lists enrollment as 79. Those entries do not establish the number with outcome data or the denominator used for any analysis. Accordingly, outcome-specific rates and attrition cannot be assessed from 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 0% reporting threshold.

The registry's intervention-group safety entries list 79 participants at risk for serious adverse events, 0 serious adverse events, 79 at risk for other adverse events, 0 other adverse events, and 0 deaths. No serious-event terms are listed. These are the safety counts recorded for the study, not comparative estimates against another group.

A zero count means that no event was recorded in the relevant registry entry. It does not show that the underlying event risk is zero, establish that every participant had complete safety follow-up, or rule out events that were not captured or reported. The registry record does not report event-specific follow-up duration, definitions, severity detail beyond the serious-event category, or a method for attributing events to the app. These details are not reported in the registry record.

Because the study has no control arm, the safety entries cannot establish whether event frequency differs from another care condition. The figures should be read as descriptive counts in this pilot, not as evidence that the intervention caused or prevented adverse events.

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

The registry record documents a completed pilot study of WYZ, a mobile health application intended for young people living with HIV. It describes the app-use period, the feasibility and acceptability aims, and a primary recruitment endpoint with a stated threshold. It also records enrollment as 79 and lists zero serious adverse events, zero other adverse events, and zero deaths in the intervention group. These registry entries describe the registered study and its recorded safety entries.

The record does not report the result for the primary recruitment endpoint. The endpoint definition concerns participants screened for study interest before recruitment or enrollment, whereas the enrollment figure is a separate entry. Without a reported endpoint count using the specified definition, the stated recruitment goal cannot be evaluated from the registry record. Results for the listed acceptability outcomes are also not reported.

No outcome analyses or estimates are reported. The record therefore does not show whether app use improved engagement in care, antiretroviral therapy adherence, viral suppression, or any other clinical outcome. It also cannot establish that the app caused any change. The single-group design has no randomized comparator, and the registry record does not provide outcome data that would support a before-and-after assessment.

The study's stated aims and hypotheses are not results. Likewise, the registry's enrollment and safety counts should not be treated as measures of effectiveness or as proof of safety. The available record supports describing the pilot's design and registered counts, while leaving the study's main feasibility and acceptability findings unresolved.

14. Why This Trial Matters Statistically

This trial is statistically notable because its primary question is one of feasibility rather than a comparative clinical effect. Recruitment counts can help assess whether a pilot can identify and enroll participants in its intended setting. The endpoint description makes the operational definition especially important: it refers to people screened for study interest before recruitment or enrollment, while the record separately lists enrollment as 79. Those entries should not be treated as interchangeable without an explicit link in the record.

The single-group structure also shapes what can be learned. A pilot can inform how an intervention is delivered and can collect experience and feasibility measures, but it does not supply the randomized contrast needed to estimate an intervention effect against a control condition. This distinction is essential when interpreting an intervention designed around engagement in care and adherence: the study's motivation and hypothesis do not establish that those outcomes changed.

From a reporting perspective, the record highlights the difference between a completed study and a study with interpretable posted results. It lists 9 outcome measures but 0 analyses, and it does not report the primary endpoint result or findings for the acceptability outcomes. Without estimates, denominators, and uncertainty, readers cannot assess how precisely feasibility or acceptability was measured.

The record is therefore useful for understanding the pilot's purpose, structure, and intended measures, while offering limited statistical evidence about outcomes. Clear separation of enrollment, screening, follow-up, and analysis populations would be important for interpreting any recruitment measure in this setting.

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 for statistical interpretation is the absence of posted outcome analyses. The registry lists 9 outcome measures and 0 analyses, and does not report the primary endpoint result, results for the secondary acceptability outcomes, or estimates with uncertainty. This prevents assessment of whether the study met its stated feasibility goal or how participants evaluated the app.

The primary endpoint definition and enrollment entry are not shown to be equivalent. The endpoint description concerns participants screened for study interest before recruitment or enrollment, whereas enrollment is listed as 79. The record does not report an endpoint numerator, denominator, or the screening count needed to interpret a recruitment rate. It also does not report participant flow or outcome-specific analysis populations.

The single-group design has no randomized comparator, and masking is listed as none. Any observed changes, if available elsewhere, would not by themselves isolate an app effect. The registry record does not report a statistical analysis plan, sample-size justification, missing-data procedures, multiplicity approach, or outcome models. Those details are not reported in the registry record.

The study description focuses on a particular intended population and setting: young people living with HIV in the San Francisco Bay Area, with an age range of 18-29 years stated for the pilot. The registry record does not establish how findings would generalize beyond that context. Because outcome findings are not posted in the record, even conclusions about feasibility or acceptability in that setting remain limited.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: mHealth App for Engagement in Care Among Youth Living With HIV — NCT03587857.
• Registry record last updated 2025-07-01; status last verified 2025-06.
• Results first posted 2025-07-01.
• 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

NCT03587857 is a completed, single-group study sponsored by University of California, San Francisco, evaluating the WYZ mobile health application for engagement in care among youth living with HIV. The record lists a start date of 2019-07-01, a primary completion date of 2020-05-01, and enrollment of 79. The study description says participants were asked to use the app for 6 months.

The primary endpoint concerns recruitment feasibility, with a stated goal of at least 55 participants over 8 Months. The record lists 9 outcome measures and 0 analyses. It does not report the primary endpoint result or results for the secondary acceptability outcomes. Safety entries list 0 serious adverse events, 0 other adverse events, and 0 deaths. The single-group design does not provide a randomized comparison, so the posted record does not establish a comparative clinical effect.