ENLIGHTEN: Establishing Novel Antiretroviral (ARV) Imaging for Hair to Elucidate Non-Adherence: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ENLIGHTEN: Establishing Novel Antiretroviral (ARV) Imaging for Hair to Elucidate Non-Adherence (NCT03218592), a randomized phase 4 study. The primary outcome is Hair Antiretroviral Imaging.

2. Clinical Question

3. Trial Design

ENLIGHTEN is registered as a Phase 4, randomized, unmasked, sequential study and is marked completed. The listed start date is 2017-06-28 and the primary completion date is 2018-12-03. Its stated purpose was to study antiretroviral distribution in hair, including variation within and between subjects, dose proportionality, and the influence of characteristics such as hair growth rate, race, hair color, and hair treatment. It also aimed to develop a model relating hair signal patterns to adherence patterns.

Drug arms were enrolled sequentially, beginning with maraviroc, followed by dolutegravir, and ending with tenofovir/emtricitabine. Each arm description lists 12 healthy volunteers or subjects. In Phase 1, participants took a single observed dose. Blood and hair samples were scheduled for Days 3, 7, 14, 21 and 28 after dosing. In Phase 2, participants took daily observed doses for 28 days, with blood and hair collected on the same scheduled days.

In Phase 3, participants were randomized to stop the drug or reduce dosing to one or three doses weekly. Blood and hair collection was again scheduled on the same post-dose days. The primary endpoint description focuses on Phase 3 and states that the 12 participants were divided among the three dosing categories. The study also lists plasma, whole-blood, and peripheral blood mononuclear cell antiretroviral concentrations as secondary outcomes. The duration and details of the safety follow-up are not reported in the registry record.

The registry record gives an enrollment of 36, but does not describe a statistical sample-size justification, the procedure used for randomization, or the rules for allocating participants to the Phase 3 dosing categories. Sequential enrollment across drug arms should not be read as evidence that the drug arms were randomized against one another.

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.

Phase 1: 1 Dose

Phase 2: Daily Doses x 28 Days

Phase 3: 0 Doses Per Week

Phase 3: 1 Dose Per Period

Analysis population for the primary outcome, as defined in the registry: In Phase 3, the 12 participants were divided into 3 dosing categories: either zero further doses,1 dose per week, or 3 doses per week. For the single dose Phase 1, signal abundance was not able to be observed consistently for all drug arms

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: Healthy volunteer adults across all racial, gender and ethnicity spectrums were enrolled. Pregnant or lactating women were excluded.

6. Primary Endpoint

The registry lists the primary outcome as Hair Antiretroviral Imaging, measured over Up to 28 days post dose.

The primary endpoint is hair antiretroviral imaging, reported as signal abundance in arbitrary units (au). The registry record specifies the median and inter-quartile range as the summary measures, with measurement up to 28 days after dosing. The drugs of interest are emtricitabine (FTC), tenofovir (TFV), maraviroc (MRV), and dolutegravir (DTG). Signal was to be measured using Matrix-assisted Laser Desorption Electrospray Ionization (IR-MALDESI).

The endpoint is intended to capture the amount and pattern of antiretroviral signal detectable along or within hair. The record describes signal abundance as an industry-standard unit and states that higher values represent greater signal, with the potential to relate signal to comparative concentrations. That wording does not establish that a given signal value equals a particular drug concentration, or that signal alone identifies a person's dosing behavior.

Hair is of interest in this study because the stated goal is to examine whether antiretroviral signal patterns can help characterize exposure over time. The study also collected blood samples and listed several blood-based drug concentration outcomes. Those measurements provide different kinds of exposure information; the registry record does not report a numerical relationship between hair and blood measures.

The primary-outcome description notes that signal abundance in the single-dose phase could not be observed consistently for all drug arms. Numerical endpoint summaries, including medians and inter-quartile ranges, are not reported in the registry record. Consequently, the endpoint definition can be described, but its observed values and comparative precision cannot be assessed from the recorded results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods described in the registry record concern a sequence of dosing conditions and repeated biological measurements. They do not include a reported statistical analysis plan. The distinction matters: a study can specify what it intends to measure and when samples are collected without documenting how the measurements were ultimately analyzed.

What does the median describe?

The primary endpoint is summarized using a median. In general, the median is the middle value after observations are ordered. It is less influenced by unusually high or low observations than the arithmetic mean, which can be useful when biological measurements are skewed. The registry record does not report the observed medians, so the actual location of the signal distributions cannot be assessed.

What does the inter-quartile range add?

The inter-quartile range describes the spread of the central portion of a distribution, from the lower to the upper quartile. In general, it gives information about variability among observations without relying on the most extreme values. A median and inter-quartile range are descriptive summaries; alone, they do not quantify uncertainty in a comparison between groups. The registry record does not report the inter-quartile ranges or a comparative uncertainty measure.

How should signal abundance be understood?

Signal abundance is recorded in arbitrary units. The endpoint description says that larger values mean a stronger signal and that the signal can be related to comparative concentrations. This is not the same as reporting a concentration on a calibrated scale. In general, linking an imaging signal to concentration requires a validated measurement relationship. The registry record does not report calibration results, measurement error, or a quantitative conversion between signal abundance and concentration.

IR-MALDESI is the stated imaging method. The study also planned blood measurements, including plasma, whole blood, and peripheral blood mononuclear cell antiretroviral concentrations. These are distinct biological measurements. In general, comparing measures from different biological compartments can help characterize distribution, but agreement or correlation must be demonstrated from data. The registry record does not report those comparisons.

What does repeated sampling contribute?

Blood and hair collection was scheduled at multiple post-dose times after the single observed dose, during the daily observed-dose phase, and in the phase with stopped or reduced dosing. Repeated measurements can describe how a marker changes over time within participants. In general, measurements from the same participant are correlated rather than independent; an analysis should account for that dependence when estimating trends or comparing groups. The statistical model used for repeated observations is not reported in the registry record.

The stated study purpose includes quantifying within-subject and between-subject variability, dose proportionality, and covariate influences. These are aims, not reported findings. The brief summary mentions population pharmacokinetic modeling and physiologically based pharmacokinetic approaches as intended tools for developing a model. The registry record does not report the fitted models, their assumptions, model diagnostics, covariate estimates, or validation results. It is therefore not possible to assess whether those modeling aims were achieved.

How should the dosing categories be interpreted?

Phase 3 assigned participants by randomization to stopping further doses or taking one or three doses per week. Randomization can, in general, help balance measured and unmeasured characteristics across groups, but the registry record does not give the randomization procedure or describe the allocation sequence. Nor does it identify a specific primary contrast among those categories. Because the outcome record is not reduced to one comparison, the intended estimand—the precise quantity the analysis was meant to estimate—is not reported.

The earlier drug arms were enrolled sequentially in the order described in the record. Sequential enrollment is not the same as random assignment among the three drugs. Comparisons between these drug arms could therefore reflect differences in enrollment timing or other factors as well as differences in drug, unless the analysis addresses those concerns. No such analysis is reported.

What can planning calculations establish?

In general, a sample-size planning illustration estimates the number of participants needed under stated assumptions about a target effect, variability, significance level, allocation, and statistical model. The registry record describes an illustration framework using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it says the target effect is a stated fraction of the observed effect. Such an illustration is not the trial's own design justification and is not observed power. The record does not present one reduced primary comparison or report a numerical observed effect for that comparison, so a planning illustration cannot establish what this study was designed to detect.

More broadly, inferential methods such as confidence intervals and hypothesis tests require an analysis definition and observed data. In general, a confidence interval expresses uncertainty around an estimate under specified assumptions, while a p-value describes how compatible data are with a specified null model. Neither is reported for the primary endpoint in the registry record. The trial's measurement schedule and intended modeling approaches should therefore not be mistaken for reported statistical evidence.

10. Multiplicity, Missing Data and Analysis Populations

The study lists a primary endpoint and several secondary blood concentration outcomes. It also describes measurements across drug arms, dosing phases, post-dose time points, and Phase 3 dosing categories. When many outcomes, time points, or comparisons are examined, the chance of at least one apparently notable result can increase. In general, a prespecified analysis plan can identify which comparisons are confirmatory and how multiplicity will be handled. The registry record does not report a multiplicity strategy, a hierarchy among outcomes, or a single primary comparison.

The record lists no outcome analyses. This does not establish that no analyses were conducted; it means that analysis results and their methods are not reported in the registry record. No p-values, confidence intervals, or numerical estimates are recorded for the primary endpoint.

Missing-data rules are not reported in the registry record. The primary endpoint description notes that Phase 1 signal abundance could not be observed consistently for all drug arms, but does not give the extent or reason for this limitation, nor whether missing measurements were excluded, imputed, or handled in another way. The record also does not report the number of participants with measurements at each time point.

The analysis population is not reported in the registry record. Enrollment figures and arm descriptions do not establish which participants contributed to a particular endpoint analysis. The record does not state whether analyses followed randomized assignment, required complete measurements, or used another inclusion rule. Without these details, the effects of missing observations, multiplicity, and analysis-set choices cannot be evaluated.

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 record lists serious adverse-event counts of 0 for maraviroc, dolutegravir, and Truvada. It also lists other adverse-event counts of 0 and deaths of 0 in each of those groups. Each group is listed with 12 participants at risk for the serious-event and other-event summaries.

These entries describe the recorded counts; they should not be read as proof that no adverse effects occurred. A zero count can reflect the events observed and recorded under the study's definitions and follow-up procedures. The registry record does not report the adverse-event collection period, event definitions, severity grading procedures, or details of monitoring. The brief summary says participants completed safety follow-up, but its duration and procedures are not reported in the registry record.

The listed counts are not a comparison of safety between drugs. The drug arms were enrolled sequentially, and the record does not report a statistical analysis of adverse events. With no event details or comparative estimates reported, the registry entries support only the statement that the recorded counts were zero for the listed categories in each arm. They do not quantify the possibility of uncommon events or establish equivalence between groups.

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

The study's stated aim was to characterize antiretroviral signal in hair after controlled dosing and to develop approaches for interpreting signal patterns in relation to exposure and adherence. Its design included a single observed dose, a period of observed daily dosing, and randomized Phase 3 dosing categories involving stopping or reducing doses. Hair and blood measurements were planned at repeated post-dose times.

The registry record does not report the numerical primary endpoint results. It therefore does not show how signal abundance changed across time, whether patterns differed between dosing categories, or how results varied among maraviroc, dolutegravir, and tenofovir/emtricitabine. It also does not report model results linking signal to concentrations or adherence patterns. The study's aims should not be treated as findings.

The record identifies a limitation in consistent detection of signal during the single-dose phase. It does not quantify that limitation or describe its consequences for analysis. Results from a future or unreported analysis would need to clarify measurement completeness and the relationship between signal and drug concentration before the signal could be interpreted as a measure of exposure or adherence.

In general, a biomarker's ability to measure exposure is distinct from its ability to classify an individual's behavior or predict a clinical outcome. This registry record reports no validation results establishing such uses. It also does not describe participants living with HIV/AIDS as the enrolled population; participants are described as healthy volunteers. The findings, even if numerical results were available, would need to be interpreted in light of that population and the study's controlled dosing conditions.

The results do not establish that a dosing pattern is preferable or that hair imaging can replace other measures. No medical conclusion follows from the absence of reported numerical analyses. The record supports conclusions about the planned study structure and measurement objectives, but not a quantitative conclusion about the performance of hair signal as an exposure or adherence measure.

13. Why This Trial Matters Statistically

ENLIGHTEN addresses a statistical measurement problem: whether an antiretroviral signal detectable in hair can be characterized across time and dosing conditions, and how that signal relates to other measures of drug exposure. Hair and blood represent different biological materials, so their relationship must be estimated empirically rather than assumed. The study's plan to collect both types of samples makes that relationship a relevant statistical question.

The sequential dosing phases also raise questions about within-person variability and differences between people. Repeated measures can help describe how a signal evolves within a participant, while comparisons across participants can reveal variation in measured signal. These aims require methods that respect the dependence among repeated observations and the distinct structure of drug arms and dosing categories. The registry record states these aims but does not report the models or estimates used.

Another important issue is measurement consistency. The record notes that single-dose signal could not be observed consistently across all drug arms. For a potential biomarker, the ability to obtain a usable measurement is part of its statistical performance, alongside the magnitude and precision of any association with concentration or dosing. The extent and handling of this measurement limitation are not reported.

The trial also illustrates why design descriptions and results need to be kept separate. Randomization in Phase 3 and observed dosing in earlier phases define how measurements were intended to arise; they do not by themselves show the strength of a signal, its uncertainty, or its usefulness for interpreting adherence. Without numerical results and analysis details, the statistical importance lies in the questions and measurement structure rather than in an established estimate of performance.

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.

A central limitation of the registry record is that numerical primary-outcome results are not reported. The endpoint is defined, but the medians and inter-quartile ranges needed to describe observed signal distributions are absent. There are also no reported effect estimates, confidence intervals, or hypothesis tests for comparisons among dosing categories, phases, or drug arms.

Measurement consistency is specifically flagged as an issue for the single-dose phase: signal abundance could not be observed consistently for all drug arms. The record does not explain whether this reflected assay performance, biological variation, sample availability, or another cause. It also does not report how many measurements were affected or how the issue was handled analytically.

The population consists of healthy volunteers, and the record does not describe people living with HIV/AIDS as enrolled participants. This limits what can be inferred about applying the intended measurement approach in other populations. The brief summary lists hair characteristics as potential covariates, but the record does not report whether these were measured successfully or how they influenced results.

The drug arms were enrolled sequentially, while randomization is described for Phase 3 dosing categories. The registry record does not describe allocation procedures, analysis populations, missing-data methods, or adjustment for differences over time. It does not report whether planned pharmacokinetic models were fitted or validated. These omissions prevent assessment of confounding, selection, model fit, and generalizability. Finally, the safety follow-up duration and procedures are not reported, limiting interpretation of the recorded adverse-event counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: ENLIGHTEN: Establishing Novel Antiretroviral (ARV) Imaging for Hair to Elucidate Non-Adherence — NCT03218592.
• Registry record last updated 2019-11-22; status last verified 2019-02.
• Results first posted 2019-11-22.
• 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

ENLIGHTEN (NCT03218592) is a completed Phase 4 study of antiretroviral signal in hair among healthy volunteers. It is listed as randomized, unmasked, and sequential, with enrollment of 36. Drug arms were enrolled in sequence for maraviroc, dolutegravir, and tenofovir/emtricitabine.

The primary endpoint is hair antiretroviral imaging, summarized by median and inter-quartile range in signal abundance (au) up to 28 days post dose. The study included observed single-dose and daily-dose phases, followed by randomized stopped or reduced dosing. Blood concentration outcomes were also listed.

The registry record is marked completed but does not report numerical primary-outcome results or outcome analyses. It notes that single-dose signal was not consistently observable for all drug arms. Serious and other adverse-event counts and deaths are recorded as 0 in each drug group. Details of the statistical analysis plan, missing-data handling, and safety follow-up duration are not reported in the registry record.