Follicular Revival in Androgenic Alopecia: Evaluating Use of Micro-needling: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Follicular Revival in Androgenic Alopecia: Evaluating Use of Micro-needling (NCT04341363), a na na study. The primary outcome is Total Area Hair Count.

2. Clinical Question

The clinical question is therefore descriptive in the available registry record: it concerns the hair-count outcome among participants receiving the device intervention, rather than a contrast between randomized groups. A single-group design can record measurements over time, but the record does not specify whether the primary outcome was analyzed as a change from baseline, as a 6-month value, or in another way. That detail is not reported in the registry record.

The registry also lists secondary outcomes relating to SALT Score, hair shaft diameter, number of follicular units, vellus hairs, and terminal hairs. These measures extend beyond the primary total area hair count, but their results and analysis details are not reported in the registry record. The condition is listed as androgenic alopecia, while the official title refers to treatment-resistant alopecia areata. That inconsistency makes it important to read the population description and outcome information carefully rather than infer a broader target population from the title alone.

3. Trial Design

The study is recorded as completed, with an enrollment of 8. The listed start date is 2021-04-09 and the primary completion date is 2022-05-02. Yale University is named as the sponsor. The phase is recorded as NA, allocation as NA, masking as none, and the model as single group. These entries describe a study without a listed randomized allocation or a separate comparator group.

The intervention is a device called a tattoo machine, used for microneedling. The arm description states that participants with androgenic alopecia will receive microneedling with a tattoo machine. The brief description gives an intent to evaluate hair regrowth over up to 6 treatments across 6 months. This describes the planned treatment approach, not confirmation that every participant received the maximum number of treatments. The number actually received, adherence, and any variation in treatment exposure are not reported in the registry record.

The primary outcome is total area hair count, recorded in hairs per cm^2, with the outcome time frame listed as 6 months. The primary outcome description defines it as the total number of hairs in an area of 1 cm^2. Five secondary outcome labels are also listed: SALT Score, Hair Shaft Diameter, Number of Follicular Units, Vellus Hairs, and Terminal Hairs. The record states that there are 6 outcome measures, but does not provide results for those measures.

Important design and conduct details are not reported in the registry record. These include eligibility criteria, recruitment methods, baseline measurements, visit schedule, treatment delivery details, protocol deviations, and the number of participants assessed at each follow-up. The record does not describe a sample-size justification for the study's actual design. The separate planning assumptions associated with an illustrative sample-size calculation should not be mistaken for the trial's design rationale or for evidence that a particular sample size was adequate.

The title and official title describe different conditions: the study title names androgenic alopecia, whereas the official title names treatment-resistant alopecia areata. The listed condition and arm description identify androgenic alopecia. The reason for the title discrepancy is not reported in the registry record.

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:

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 Total Area Hair Count, measured over 6 months.

The primary endpoint is total area hair count at the 6-month time frame. Its unit is hairs per cm^2, and the registry description defines it as the total number of hairs within an area of 1 cm^2. This is a continuous measure: it can take a range of numerical values rather than classifying participants only as having or not having an event. A count standardized to an area gives a defined unit for describing hair density at the measurement site.

As a general statistical point, a quantitative endpoint can describe the distribution of measured values in a group and, when measurements are taken at more than one time, can be used to describe changes over time. The registry record does not specify whether the planned primary analysis uses a 6-month value, a change from baseline, or another summary. Baseline hair counts and the method for selecting or measuring the area are not reported in the registry record, so those details cannot be used to interpret an observed change.

The endpoint is relevant to the study's stated interest in hair regrowth because it records a hair-count measure over a specified area. However, an outcome's relevance does not itself establish that a treatment caused a change. In a single-group study, a measured value can describe participants in that group; without a separately described comparator and a reported analysis, it cannot by itself distinguish intervention effects from other explanations for observed variation.

No mean, standard deviation, confidence interval, baseline value, or 6-month estimate for the primary endpoint is reported in the registry record. Consequently, the endpoint's observed level, variability, and precision cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a continuous outcome mean?

The primary endpoint is identified as a mean for a continuous measure, with standard deviation as its listed dispersion measure. In general, a mean describes the center of a set of numerical observations, while a standard deviation describes how spread out individual observations are around that center. They answer different questions: the mean concerns the group's average level, and the standard deviation concerns variability among measured values. The registry record does not report either statistic for the primary outcome.

A mean and standard deviation alone would not describe every feature of a distribution. General statistical interpretation: unusual observations or a skewed distribution can influence a mean, and the standard deviation does not show where individual observations fall. The record does not report the distribution of hair counts or provide participant-level measurements, so those features cannot be assessed.

What would a confidence interval add?

General explanation: a confidence interval expresses the uncertainty around an estimated quantity under a specified statistical procedure. It helps readers distinguish the estimated magnitude from its precision. A narrow interval indicates greater precision than a wide interval for the same kind of estimate, while an interval that spans a broad range can leave substantial uncertainty about the plausible magnitude. The registry record does not report a confidence interval for total area hair count, and no interval can be inferred from the enrollment count alone.

A confidence interval would need to accompany a clearly defined estimate. For this study, the record gives a 6-month time frame but does not state whether the primary quantity is a 6-month mean, a mean change from baseline, or another contrast. That analysis definition is not reported in the registry record. Without it, even a hypothetical interval could not be tied to a precise estimand, meaning the quantity the analysis is intended to estimate.

Why does the single-group design matter?

General explanation: a comparator provides a reference for interpreting an outcome. In a randomized comparison, allocation aims to make the groups comparable on average, though randomization does not guarantee identical groups in a small study. In a single-group study, there is no concurrent group in the registry design to account for changes that might occur without the intervention. A within-participant change can be described if measurements before and after treatment are collected, but the record does not specify that such an analysis was conducted or report any change estimate.

As a result, a single-group outcome can be informative descriptively but does not isolate the causal effect of treatment in the way a suitable comparative design may aim to do. Changes could relate to the intervention, natural course, measurement conditions, or other factors. This is a general limitation of interpretation, not a claim that any particular alternative explanation occurred in this study.

What do the planning assumptions mean?

The record describes a planning illustration based on an observed effect. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are assumptions for a hypothetical planning exercise, not a description of the actual single-group design. The record also distinguishes between participant counts per arm for most outcomes and total event counts for time-to-event calculations. The primary outcome is continuous, not a time-to-event outcome.

General explanation: a sample-size calculation estimates how many observations a proposed design would need under specified assumptions, including a target effect and a chosen error-rate convention. Altering the effect assumed to be worth detecting changes the planning question. A planning illustration based on an observed effect does not establish that the study was designed with that sample size, and it does not measure the probability that the completed study detected an effect. The registry record does not report the trial's own sample-size justification, and the illustrative assumptions should not be read as that justification.

The record does not provide the observed primary endpoint effect used for the illustration or numerical sample-size outputs. There is therefore no basis in the registry record to interpret a particular proposed number of participants from this planning description. Planning sample sizes are not observed power, and no observed-power claim is warranted.

Why does over-dispersion matter?

General explanation: over-dispersion occurs when variability in observed data exceeds what a chosen statistical model expects. If a model understates variability, its uncertainty estimates can be too small, which can make results appear more precise than the data support. A model should therefore be checked against the type and spread of the data rather than selected only for convenience. The registry record does not describe a model for the primary endpoint, a dispersion assessment, or an adjustment for over-dispersion. No claim about over-dispersion in this study can be made from the reported information.

Hair counts are numerical observations, but the registry identifies the primary parameter as a mean and dispersion as a standard deviation. It does not state whether the statistical analysis treated the outcome as a normally distributed measure, used a different model, or assessed model assumptions. The normal approximation named for the planning illustration does not establish which analysis method was used for trial results.

What analysis details are unavailable?

The registry lists 0 analyses. It does not report the statistical test or model for the primary endpoint, any covariate adjustment, the handling of repeated measurements, the definition of the analysis population, or the method used for missing observations. It also does not report p-values or confidence intervals. Those omissions prevent readers from evaluating the specific analysis, its assumptions, and its precision. General methodological concepts can explain what these choices mean, but they cannot substitute for an analysis that is not reported.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Microneedling")
n   <- c(6)
m   <- c(126.8)
sp  <- c(41.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Microneedling  6  126.800  41.700  83.039  170.561

11. Multiplicity, Missing Data and Analysis Populations

The record lists 6 outcome measures: total area hair count as the primary outcome, plus SALT Score, hair shaft diameter, number of follicular units, vellus hairs, and terminal hairs. When a study assesses multiple outcomes, general statistical reasoning recognizes that the chance of at least one apparently notable result can increase if many results are tested independently without an adjustment or a prespecified hierarchy. Approaches to multiplicity can include defining one primary test, adjusting for multiple tests, or using a planned sequence of tests. The registry record does not describe a multiplicity strategy, endpoint hierarchy beyond naming the primary outcome, or statistical analysis plan.

No outcome estimates or analysis results are reported in the registry record. It is therefore not possible to determine whether any multiplicity procedure was used or how it would affect interpretation. The presence of several listed outcomes does not establish that all were measured, analyzed, or tested.

Missing-data information is also not reported. The record does not give the number with observed baseline or 6-month measurements, reasons for missing observations, or methods for handling missing values. General explanation: missing data can affect an estimate when the participants with observed outcomes differ systematically from those without them. The potential direction or magnitude of such effects depends on the missingness pattern and assumptions used in analysis; neither is described.

The analysis populations are not reported in the registry record. It is unclear whether analyses, if conducted, included all enrolled participants, only those who received treatment, only those with follow-up measurements, or another defined group. Enrollment of 8 is not enough to establish the denominator used for an outcome analysis. These gaps limit assessment of both the completeness and the reproducibility of any efficacy analysis.

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.

Most frequent non-serious adverse event terms

The registry lists 8 participants at risk for serious adverse events, with 0 affected, and 8 at risk for other adverse events, with 1 affected. Deaths are listed as 0. No serious adverse-event terms are listed. These are counts in the registry record; they do not provide detail about the event recorded in the other adverse-event category, its timing, severity, relationship to microneedling, or outcome. Those details are not reported in the registry record.

The categories should be read as recorded rather than treated as a complete narrative of safety experience. A count of 0 serious events means none are entered in this record for the stated group and risk count. It does not establish that every possible event was assessed or that the intervention has no risk. Likewise, the one event in the other category cannot be interpreted without a description of what happened and how events were defined and collected.

General explanation: adverse-event counts are easier to interpret when accompanied by event definitions, follow-up duration, ascertainment procedures, and details about whether multiple events in one participant are counted separately. The registry record does not report these details. The listed risk count of 8 is consistent with the recorded enrollment, but the record does not explain whether all participants had the same safety follow-up or duration of observation.

The safety figures are descriptive and should not be used to compare risks with another treatment or population. The study has no separately listed comparator group, and the registry does not provide a comparative safety analysis.

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

The record establishes that a completed single-group study enrolled 8 participants with androgenic alopecia and used microneedling with a tattoo machine as the intervention. It identifies total area hair count at 6 months as the primary endpoint and lists several additional outcomes. It also records adverse-event counts. These details describe the study's scope and its registry entries.

What the record does not establish is the observed hair-count result. No primary endpoint estimate, standard deviation, confidence interval, or analysis result is reported. The posted information therefore cannot quantify an increase, decrease, or lack of change. Missing outcome estimates should not be interpreted as evidence for either direction.

Even if a numerical before-and-after result were available, a single-group design would require careful interpretation. General explanation: a change over time within one group does not by itself distinguish the effect of an intervention from time trends, measurement variation, or other influences. Because no separate comparator is listed, the registry design does not provide a concurrent treatment contrast. Whether participants had baseline measurements and how those measurements were analyzed are not reported in the registry record.

The enrollment of 8 also means that estimates, if reported, would need to be read with attention to uncertainty and the influence of individual observations. A group mean alone would not communicate precision; a dispersion measure and an interval estimate would help describe variability and uncertainty. Those outcome statistics are not reported.

The safety counts show 0 serious adverse events among 8 at risk, 1 other adverse event among 8 at risk, and 0 deaths in the registry entries. They do not identify the non-serious-category event or establish a complete safety profile. The available counts should not be taken as proof of safety or as a comparative risk estimate.

Thus, the registry record documents a study design and selected safety entries, but it does not report the efficacy results needed to determine what happened to the primary hair-count outcome. It supports neither a causal claim nor a conclusion about the size or precision of an intervention effect.

14. Why This Trial Matters Statistically

This study is statistically notable because it illustrates the difference between a completed study record and a record containing interpretable outcome results. The registry marks the study completed and reports an enrollment of 8, yet it does not report analyses or estimates for the primary endpoint. Completion status and enrollment describe study conduct at a high level; they do not provide the numerical evidence needed to assess the outcome.

The single-group design also makes the target of inference important. A study can measure a continuous outcome among people receiving an intervention, but a group average is not automatically a treatment effect. A treatment effect is a contrast: it requires a comparison that represents what would have happened under another condition, such as a suitable control or a defined within-participant contrast with assumptions. No comparator group or primary analysis contrast is described in the registry record.

The study also lists several outcome measures. This raises general questions about prespecification, outcome hierarchy, and multiplicity. Naming one primary endpoint is useful, but the record does not describe how the secondary outcomes relate to the primary analysis or whether any multiplicity adjustment was planned. Without analysis details and results, readers cannot assess whether findings across different measures would be consistent or how selective interpretation was prevented.

The safety entries show why event counts need context. Counts without event descriptions, collection methods, or follow-up details are limited summaries. The registry records 0 serious events, 1 event in the other category, and 0 deaths, but does not supply the information needed to characterize that event or assess completeness.

Finally, the mismatch between the study title and official title, alongside the listed condition, highlights the importance of checking population descriptions across registry fields. The registry identifies androgenic alopecia as the condition and in the arm description, while the official title refers to treatment-resistant alopecia areata. The reason for this discrepancy is not reported. Careful reading helps keep conclusions aligned with the population actually described rather than with an inconsistent title alone.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this study constrain interpretation. First, the design is listed as single group, with no allocation and no masking. There is no separate comparator group in the registry record, so the design as described cannot provide a randomized treatment-versus-control contrast. The record does not say whether any baseline-to-follow-up comparison was planned or performed.

Second, enrollment is 8, and outcome estimates are not reported. The number of participants with primary endpoint data at 6 months is not reported in the registry record. The number enrolled should not be assumed to equal the number analyzed or followed through the endpoint visit. Without outcome values and a precision measure, the size and uncertainty of any observed pattern cannot be assessed.

Third, intervention exposure is incompletely described. The study intent mentions up to 6 treatments over 6 months, but the number of treatments received by participants, treatment adherence, and any variation in delivery are not reported. The record also does not describe the measurement procedure for selecting the 1 cm^2 area, assessor training, or whether measurement was standardized or repeated.

Fourth, the registry does not report eligibility criteria, baseline characteristics, missing-data handling, analysis populations, outcome models, or multiplicity methods. It therefore does not allow assessment of how representative the group was, how incomplete observations were handled, or whether the analysis matched a prespecified plan.

Fifth, the study title and official title differ on the condition named. The condition list and arm description identify androgenic alopecia, while the official title refers to treatment-resistant alopecia areata. The reason for this discrepancy is not reported in the registry record. Finally, safety information is limited to event counts without terms for the other event or details about ascertainment and follow-up.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Follicular Revival in Androgenic Alopecia: Evaluating Use of Micro-needling — NCT04341363.
• Registry record last updated 2023-06-18; status last verified 2023-05.
• Results first posted 2023-06-18.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed, single-group device study sponsored by Yale University. It lists androgenic alopecia as the condition and microneedling with a tattoo machine as the intervention. Enrollment is 8; the recorded start date is 2021-04-09, and primary completion is 2022-05-02. The study description gives an intent to assess hair regrowth over up to 6 treatments across 6 months.

The primary outcome is total area hair count in hairs per cm^2 at 6 months, described as the number of hairs in 1 cm^2. Five secondary outcome labels are listed. The registry record does not report outcome analyses or estimates. It lists 0 serious adverse events among 8 at risk, 1 other adverse event among 8 at risk, and 0 deaths, without describing the other event.

The official title refers to treatment-resistant alopecia areata, unlike the listed condition and study title. The reason for that discrepancy, the trial's analysis plan, missing-data methods, and sample-size justification are not reported in the registry record.