Little Cigar and Cigarillo Warnings for Youth: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Little Cigar and Cigarillo Warnings for Youth (NCT06413797), a randomized na study. The primary outcome is Willingness to Use Little Cigars Cigarillos (LCCs).

2. Clinical Question

3. Trial Design

The registry identifies this as a randomized, parallel-group trial with no masking. Participants were assigned among three warning conditions: FDA-proposed warnings with images, FDA-proposed text-only warnings, and Surgeon General text-only warnings. The registry classifies the interventions as behavioral and the trial phase as not applicable. Total enrollment is reported as 928.

The listed condition is little cigar and cigarillo use. The registry summary describes an interest in the effect of LCC warnings on youth who currently use, have ever used, or are susceptible to using LCCs. The primary outcome was assessed at day 8, and its analysis population is described as participants responding to the measures at that time. The registry record does not report further details about the allocation process, recruitment, eligibility criteria, follow-up schedule, or whether outcome assessors were masked.

The record identifies UNC Lineberger Comprehensive Cancer Center as the sponsor and marks the study completed. The recorded start date is 2024-07-18, and the primary completion date is 2024-11-25. The primary completion date is the registry date associated with completion of primary outcome collection; the record does not establish that every participant completed every measure. The trial is registered as NCT06413797.

The two primary contrasts compare each text-only group with the image-warning group. That design addresses differences among these warning formats in the enrolled participants, but the registry record does not describe the original statistical plan, the sample-size justification, or any planned interim analyses. The number of participants contributing to each outcome is lower than the total enrollment, and the reason for those differing analysis counts 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.

Before assignment: 1,039 potential participants began the baseline survey. Of those, 9 did not consent to participate in the study, and 96 did not complete the baseline questionnaire and were not randomized, and 6 did not meet quality control criteria. 928 participants were enrolled and randomized in the study.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Participants who responded to the measures at the time point of interest, day 8

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: Everyone who enrolled in the study, consented to participate, completed the baseline questionnaire, and was randomized to each condition.

6. Primary Endpoint

The registry lists the primary outcome as Willingness to Use Little Cigars Cigarillos (LCCs), measured over Day 8.

The primary endpoint is the mean willingness-to-use score at day 8. It is calculated as the average of responses to two survey questions, each scored on a scale from 1 to 5. The scale description identifies 1 with low willingness to use LCCs and 5 with a willingness-to-use score at the high end of the scale. Thus, a higher group mean represents higher reported willingness on this measure, not observed tobacco use.

A self-reported willingness measure addresses a response about intended or considered behavior. It differs from a measure of whether a participant actually used LCCs, and the registry does not report that the score is a validated predictor of later behavior. The outcome is relevant to the study question because the trial examines responses to warning formats among youth described as current users, ever-users, or susceptible to use. It captures a short-term response at the specified assessment time rather than a long-term outcome.

The primary mean is reported with a standard deviation, which describes variation in scores among participants within an arm. The measure was recorded for participants who responded at day 8. How the two question responses were handled when one response was missing, and how missing outcome measurements were treated, are not reported in the registry record.

7. Results Posted in the Registry

• FDA Warnings Text-Only Warnings: mean 3.08 versus 2.86 on control; difference 0.22 (95% CI -0.03 to 0.47), standardized effect d = 0.15; z-test p = 0.084.
• Surgeon General Text-Only Warnings: mean 2.99 versus 2.86 on control; difference 0.13 (95% CI -0.13 to 0.39), standardized effect d = 0.09; z-test p = 0.318.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Past 7 Days Little Cigar Use

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • FDA Warnings Text-Only Warnings: mean 1.86 versus 1.92 on control; difference -0.06 (95% CI -0.51 to 0.39), standardized effect d = -0.02; z-test p = 0.796.
  • Surgeon General Text-Only Warnings: mean 1.88 versus 1.92 on control; difference -0.04 (95% CI -0.50 to 0.42), standardized effect d = -0.02; z-test p = 0.866.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between FDA Warnings Text-Only Warnings and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Surgeon General Text-Only Warnings and the control. The interval gives the range of effects that remain compatible with the data.

Past 7 Days Cigarillo Use

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • FDA Warnings Text-Only Warnings: mean 1.86 versus 1.93 on control; difference -0.07 (95% CI -0.50 to 0.36), standardized effect d = -0.03; z-test p = 0.752.
  • Surgeon General Text-Only Warnings: mean 1.82 versus 1.93 on control; difference -0.11 (95% CI -0.55 to 0.33), standardized effect d = -0.04; z-test p = 0.621.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between FDA Warnings Text-Only Warnings and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Surgeon General Text-Only Warnings and the control. The interval gives the range of effects that remain compatible with the data.

Little Cigar and Cigarillos (LCCs) Susceptibility

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • FDA Warnings Text-Only Warnings: mean 2.49 versus 2.33 on control; difference 0.16 (95% CI -0.00 to 0.32), standardized effect d = 0.17; z-test p = 0.056.
  • Surgeon General Text-Only Warnings: mean 2.46 versus 2.33 on control; difference 0.13 (95% CI -0.04 to 0.30), standardized effect d = 0.14; z-test p = 0.136.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between FDA Warnings Text-Only Warnings and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Surgeon General Text-Only Warnings and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover reported recent LCC use, susceptibility, and responses related to warning effects, including knowledge, beliefs, cognitive elaboration, and negative affect or worry. The posted numerical summaries include measures of past seven-day little cigar use, past seven-day cigarillo use, and LCC susceptibility. Across these secondary measures, the group means are generally close, and the estimates are small relative to the within-group variability. The posted intervals for the comparisons include zero.

The broad pattern does not provide a clear secondary-outcome contrast that changes the interpretation of the primary willingness result. In particular, the secondary summaries do not convert the uncertain primary difference into evidence of a clear difference in willingness, nor do they establish a change in actual use. These measures are related aspects of warning response, but they are distinct outcomes and should not be treated as interchangeable evidence about the primary endpoint.

The record lists 19 outcome measures and reports 18 secondary outcomes as posted. The registry record does not provide a full narrative tying these outcomes together or explain how they were selected for emphasis. The numerous outcomes create an opportunity for chance findings when many comparisons are examined. General explanation: the more statistical tests considered, the more likely it becomes that at least one result may appear unusual by chance, even when there is no true effect across the outcomes.

The secondary p-values are unadjusted, and no multiplicity procedure is reported. They therefore carry less weight as confirmatory evidence than outcomes interpreted under a prespecified analysis strategy with a stated approach to multiple testing. Secondary outcomes can still help describe the pattern of responses and generate questions for future work, but isolated nominal findings should not be treated as decisive. The registry record does not report a hierarchical testing plan or identify which secondary outcomes, if any, were designated as confirmatory.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Past 7 Days Little Cigar Use
• Past 7 Days Cigarillo Use
• Little Cigar and Cigarillos (LCCs) Susceptibility
• Cognitive Elaboration About Risk of Little Cigar and Cigarillo Use
• Warning Negative Affect/Worry
• Knowledge of Little Cigar and Cigarillo (LCC) Harms
• Beliefs About Little Cigar and Cigarillo (LCC) Harms
• Cognitive Elaboration About Risk of Little Cigar and Cigarillo Use

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is a numeric score with a reported mean and standard deviation in each arm. The posted summaries use the mean as the measure of central tendency and the standard deviation as the measure of spread. The mean indicates the average score among participants represented in an arm; the standard deviation describes how dispersed individual scores are around that average. These summaries do not reveal the full score distribution or how many participants selected each possible response.

What does a mean difference represent?

For each primary contrast, the mean difference is calculated as the text-only group mean minus the FDA warnings with images group mean. A positive estimate therefore means the text-only group had a higher average willingness score in the posted summaries. The two estimates are 0.22 for FDA text-only warnings and 0.13 for Surgeon General text-only warnings. These are differences in scale points, not percentages or changes in actual LCC use.

The posted standard deviations are similar in size across the primary arms, while the mean differences are smaller. A standardized effect size expresses a mean difference relative to the variability in the scores. The posted standardized estimates are 0.154 for FDA text-only warnings and 0.090 for Surgeon General text-only warnings. General explanation: standardization can help describe the magnitude of a difference on a scale that accounts for outcome variability, but it does not make a small or uncertain estimate conclusive.

How should the p-values be read?

A p-value describes how compatible the observed data are with a specified null model, under the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of a difference. The posted primary p-values are unadjusted: 0.084 and 0.318. They should be interpreted alongside the estimated differences and confidence intervals, not on their own. The registry record does not report whether the original analysis used a particular test, a model, or any adjustment for covariates.

General explanation: a confidence interval gives a range of values compatible with the data under the method used to construct it. For a difference in means, an interval that includes zero does not rule out no difference at the interval's confidence level. It also does not show that all values in the interval are equally plausible. The primary intervals both include zero, so the results do not identify a clearly separated difference.

What is and is not described about the analysis?

The record gives group summaries and comparisons but does not report the trial's own detailed statistical analysis plan. It does not report whether analysis was based on assigned groups, whether models adjusted for baseline characteristics, how missing responses were handled, or how multiplicity was handled. The population for the primary endpoint is described as participants who responded at day 8, but the record does not specify further analysis-population rules.

General explanation: an analysis restricted to observed responders can differ from an analysis that includes all randomized participants, especially if response is related to outcome or assigned group. Without missingness counts, reasons for nonresponse, or a stated analysis strategy, the impact of missing endpoint data cannot be assessed from these summaries. This is a limitation in interpreting the estimates, not evidence that missingness necessarily biased them.

Why does variability matter?

Standard deviations describe participant-to-participant variation. When outcomes vary considerably relative to the difference between group means, estimates of between-group differences tend to be less precise for a given sample size. General explanation: over-dispersion, or greater variation than a model anticipates, can make uncertainty wider than expected if the model does not account for it. The endpoint is reported with standard deviations, but the record does not report a model-based assessment of dispersion or any alternative variance procedure.

The registry's planning illustrations use the observed difference and a stated fraction of that difference, with two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation. They are not the trial's original design justification. General explanation: a power calculation asks how often a design would detect a specified effect if that effect were the true effect under the calculation's assumptions. A calculation based on an observed effect is particularly sensitive to the uncertainty of that observed estimate and should not be mistaken for evidence that the completed trial had a particular probability of success.

The record does not report interim analyses or a prespecified approach to multiple outcomes. The main statistical reading should therefore stay close to the posted means, differences, uncertainty intervals, and unadjusted p-values. More detailed claims about the analysis would require information not reported in the registry record.

11. Confidence Intervals and Precision

The primary estimates are not highly precise in the sense of sharply locating a single value for the difference. The confidence intervals for both text-only comparisons cross zero. For FDA text-only warnings compared with FDA warnings with images, the estimated difference is 0.22, with p = 0.084. For Surgeon General text-only warnings compared with FDA warnings with images, the estimated difference is 0.13, with p = 0.318. In each case, the interval includes the possibility of no difference and values on either side of zero.

General explanation: the width of a confidence interval reflects sampling uncertainty under the method used, and a narrower interval would generally locate an estimate more precisely. An interval crossing zero is not evidence that the groups are identical; it indicates that the estimate does not distinguish a nonzero difference from zero at the interval's confidence level. Conversely, a point estimate alone should not be treated as the exact underlying effect.

The reported standard deviations, between 1.39 and 1.47 across the primary arms, are large in relation to the observed differences. This indicates substantial variation in scores among participants relative to the separation of the group averages. It helps explain why the point estimates should be read with their uncertainty rather than as definitive distinctions between formats.

Precision also depends on who contributed outcome data. The primary summaries include 250, 255, and 236 participants in the three arms, while total enrollment was 928. The registry record does not report the reasons for the outcome-specific counts or the characteristics of participants without a day 8 response. Thus, the intervals describe uncertainty for the posted analysis, but do not resolve uncertainty about possible selection associated with outcome nonresponse.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures describe participants per arm for two-arm comparisons, not a total across the two arms and not total events. The primary endpoint and the posted secondary measures discussed in the record are continuous outcomes, so the illustrations use participants per arm. The sample-size assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The target effect is set to the stated fraction of the observed effect: 100%, 75%, or 50%.

The 80% power column gives the number of participants per arm that the calculation estimates would be needed for an 80% chance of detecting the specified effect under those assumptions. The 90% power column gives the corresponding per-arm number for a 90% chance. These are planning concepts: greater power means a higher chance of detecting the chosen effect if it is truly present, while the significance level sets the calculation's criterion for a positive finding under the null model.

The illustrations are based on observed effects and are not the original trial's design assumptions, which are not reported in the registry record. They are planning illustrations, not observed power. Smaller effects require more participants to detect under the same assumptions, which is why the figures increase when planning for a smaller fraction of the observed effect. The underlying relationship is general: if an effect is harder to distinguish from ordinary variability, a larger sample is usually needed to achieve the same target power.

The calculations do not account for design features or analysis procedures that are not reported, and they should not be read as a claim about the adequacy of the completed enrollment. No planning figures for the trial's original sample-size justification are reported in the registry record.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.220; pooled standard deviation σ = 1.430.
2. n = 2 × (1.96 + 0.842)² × 1.430² / 0.220² = 663.4, rounded up to 664 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.22                      # observed difference in means
sigma <- 1.43016181708981                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(6413797)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 664 (80% power), 889 (90% power)
 75% of observed effect: n per arm = 1,180 (80% power), 1,579 (90% power)
 50% of observed effect: n per arm = 2,654 (80% power), 3,553 (90% power)
power.t.test: 664.3 
Simulated power at n = 664 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record includes a primary endpoint and numerous secondary outcomes, but it does not report a statistical plan for managing multiplicity. No adjustment for multiple comparisons, hierarchy among outcomes, or prespecified testing sequence is described. The posted comparison p-values are unadjusted. When multiple outcomes or contrasts are examined, unadjusted p-values do not account for the increased chance of at least one apparently notable result arising by chance. General explanation: multiplicity procedures are used to control or describe that family-wide risk, but they can affect how strongly individual results should be interpreted.

The primary outcome has two comparisons against the FDA warnings with images group. The registry record does not say whether the original plan treated these as a single family of tests or set a procedure for interpreting them together. The same uncertainty applies to the secondary outcomes. The posted results can be described as individual estimates, but the record does not establish a confirmatory interpretation across the full set of outcomes.

The primary analysis population is described as participants who responded to measures at day 8. Outcome counts are 250, 255, and 236 across the primary arms. The registry record does not report the number of randomized participants with missing day 8 responses, reasons for missingness, or any imputation or sensitivity analysis. It also does not report a detailed participant flow that would explain the relationship between total enrollment and each outcome-specific count.

The record does not specify whether the primary analysis followed assigned groups regardless of intervention exposure, whether participants were excluded after randomization, or how protocol deviations were handled. It also does not report baseline outcome values or an adjustment strategy. These details matter because the interpretation of randomized comparisons can depend on the analysis population and handling of missing data. Their absence from the registry record is not evidence of a particular problem, but it limits assessment of robustness.

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

The posted primary result is a comparison of average day 8 willingness-to-use scores among participants represented in three warning groups. Average scores were 2.86 with FDA warnings and images, 3.08 with FDA text-only warnings, and 2.99 with Surgeon General text-only warnings. The two text-only group estimates are above the image-warning group mean, but both estimated differences have confidence intervals that include zero. The posted unadjusted p-values are 0.084 and 0.318.

These results do not establish that either text-only format produces higher willingness scores, and they do not demonstrate equivalence among the formats. A nonsignificant comparison is not proof that the true difference is zero. The intervals include a range of possible differences, and the available information does not support a more definitive conclusion.

The endpoint is a self-reported score at day 8, not observed use or a long-term behavioral outcome. The secondary summaries include reported use over the past seven days, susceptibility, and other warning-related measures, but those results likewise should be interpreted as separate outcomes. The study's summary frames the work as informing FDA implementation of LCC warnings; the posted results do not by themselves answer broader questions about long-term effects, population-level impact, or health disparities.

The findings apply to the participants contributing to the recorded outcomes. Although the trial enrolled 928 participants, the primary endpoint summaries include fewer participants in each arm, and the record does not explain the differences. Without details on nonresponse, the original statistical plan, and the handling of missing measurements, the robustness of the estimates cannot be fully evaluated. The results are best understood as uncertain short-term differences in reported willingness, not as a final ranking of warning formats or a claim about actual use.

16. Why This Trial Matters Statistically

Statistically, this trial illustrates the difference between an observed direction and a well-resolved effect. The primary means are ordered with both text-only groups above the FDA image-warning group, yet the estimated differences are modest in relation to variation among participants, and both confidence intervals include zero. Considering direction alone would overstate what the data establish; considering p-values alone would also miss the size and uncertainty of the estimates.

The design compares three warning formats, with the image-warning condition serving as the reference for the two posted primary contrasts. This makes it possible to examine whether the two text-only conditions differ from that reference on the day 8 score. The results also show why a measured response such as willingness should be kept distinct from observed use: the endpoint directly answers a question about reported willingness, not whether participants subsequently used LCCs.

The registry record lists many outcomes related to use and warning response. That breadth may be useful for describing several dimensions of response, but it makes prespecification and multiplicity handling important for distinguishing confirmatory evidence from exploratory patterns. Those analysis details are not reported in the registry record. Likewise, the outcome-specific sample counts and lack of missing-data information limit evaluation of who contributed to each estimate.

The study is statistically relevant because it links a randomized comparison of warning formats to an explicitly defined short-term mean score, while leaving clear boundaries around what can be inferred. The estimates, uncertainty, outcome definition, and analysis reporting gaps all matter together. They make the posted evidence informative about the measured day 8 responses, but not a complete account of later behavior or the broader policy questions described in the registry summary.

17. 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 are specific to the information reported for this trial. The primary outcome is a short-term willingness score at day 8, based on two survey questions. The registry does not report later follow-up for this endpoint, so the posted result cannot describe persistence of a response or whether it corresponds to later use. The score's measurement properties beyond its stated range and scoring direction are not reported in the registry record.

The primary summaries represent respondents at day 8, and outcome counts differ by arm. The record does not explain nonresponse, missingness, or the composition of participants with available scores. As a result, it is not possible to assess whether the day 8 analysis population differs systematically from the randomized participants or whether missing data could alter interpretation.

The registry record does not report detailed eligibility criteria, participant characteristics, baseline scores, intervention exposure or adherence, or the exact survey administration procedures. These omissions limit assessment of how broadly the results may apply and whether the groups were comparable on measured characteristics. Random allocation is recorded, but the allocation process and concealment details are not described.

The registry provides no reported statistical analysis plan, sample-size justification, interim-analysis plan, or multiplicity strategy. The posted p-values are unadjusted. The listed secondary outcomes cover several different constructs, which makes a prespecified interpretation especially useful. These are limits of the available record; they do not establish that the trial lacked procedures that are not documented there.

The study summary presents FDA implementation and reducing tobacco health disparities among youth as broader motivations. The posted outcomes do not directly measure changes in disparities or population-level effects. The registered endpoint summaries therefore address a narrower question than the full policy motivation.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Little Cigar and Cigarillo Warnings for Youth — NCT06413797.
• Registry record last updated 2025-12-24; status last verified 2025-12.
• Results first posted 2025-12-24.
• 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.

21. Record Summary

NCT06413797, titled Little Cigar and Cigarillo Warnings for Youth, is a completed randomized, parallel-group trial with no masking and 928 enrolled participants. UNC Lineberger Comprehensive Cancer Center is the sponsor. The recorded start date is 2024-07-18, and the primary completion date is 2024-11-25.

Three behavioral warning conditions were compared: FDA-proposed LCC warnings with images, FDA-proposed text-only LCC warnings, and Surgeon General text-only LCC warnings. The primary endpoint was the mean willingness-to-use score at day 8, measured on a scale from 1 to 5.

The posted primary mean differences compared each text-only group with the FDA warnings with images group. Both confidence intervals include zero, and the p-values are unadjusted. The registry record does not report the original sample-size justification, detailed statistical analysis plan, missing-data procedures, or multiplicity approach.