Feasibility of Conducting a Pilot Telehealth Study Assessing the Removal of Filter Ventilation on Smoking Behavior and Biomarkers in Menthol Smokers Switched to Non-menthol Cigarettes: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feasibility of Conducting a Pilot Telehealth Study Assessing the Removal of Filter Ventilation on Smoking Behavior and Biomarkers in Menthol Smokers Switched to Non-menthol Cigarettes (NCT04514471), a randomized na study. The primary outcome is Percentage of Participants That Dropped Out.

2. Clinical Question

3. Trial Design

NCT04514471 was a completed, randomized, open-label, parallel-group pilot study sponsored by Masonic Cancer Center, University of Minnesota. The registry lists the phase as NA. Enrollment was 46, with 23 participants assigned to minimally ventilated non-menthol cigarettes and 23 assigned to ventilated non-menthol cigarettes. The study dates in the record are 2024-03-18 for start and 2025-06-05 for primary completion.

Eligible participants were menthol smokers who reported using menthol cigarettes at least 80% of the time. Both groups entered a 2-week period of monitoring their usual-brand smoking before randomization. After that monitoring period, participants were assigned to one of the two non-menthol cigarette groups. The study description characterizes the comparison as minimal versus moderate filter ventilation; the arm names in the results refer to minimally ventilated and ventilated non-menthol cigarettes.

The study was designed as a decentralized evaluation using telehealth visits and mailed samples. Subjective measures, alveolar carbon monoxide, blood pressure, and cigarettes smoked per day were to be collected remotely. Biological samples were to be collected at home and mailed to the clinic. These features make study conduct and retention relevant to interpreting the primary endpoint: dropping out may reflect the demands of participation as well as participants’ experience in the study.

The registry record does not report the original sample-size justification, detailed eligibility criteria, the allocation procedure, or the statistical analysis plan. It also does not describe the timing or conduct of interim analyses. The design information establishes that the groups were randomized and parallel, but does not by itself specify how missing observations or analysis populations were handled.

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 Percentage of Participants That Dropped Out, measured over Baseline through Week 4.

The primary endpoint is the percentage of participants who dropped out by Week 4, with the stated timeframe running from baseline through Week 4. It measures retention in the study, not a change in smoking, nicotine exposure, or health. The endpoint is directly relevant to a feasibility pilot because remote visits and home collection and mailing of biological samples require participants to remain engaged through follow-up.

In the minimally ventilated group, 4 of 23 participants dropped out, and the posted percentage is 17.4%. In the ventilated group, 2 of 23 dropped out, and the posted percentage is 8.7%. The comparison is expressed as the risk difference for ventilated versus minimally ventilated cigarettes: -0.087, with an interval from -0.28 to 0.106. The negative estimate indicates a lower observed dropout percentage in the ventilated group, while the interval spans values on both sides of no difference.

Retention is an operational outcome. It can help describe whether participants completed a remote study, but it does not establish why any participant left or whether the assigned cigarette type caused a dropout. Reasons for withdrawal are not reported in the registry record. The endpoint also does not, by itself, answer whether the remote procedures were acceptable or whether the planned measurements were successfully obtained for every participant.

7. Results Posted in the Registry

• Ventilated Non-menthol Cigarette: 8.7% (2/23) versus 17.4% (4/23) on control; risk difference -8.7 percentage points (95% CI -28.0 to 10.6), risk ratio 0.50 (0.10–2.47); unadjusted two-proportion z-test p = 0.381.

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.

Cotinine Change

• 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:
  • Ventilated Non-menthol Cigarette: mean 7.86 versus 4.14 on control; difference 3.72 (95% CI -116.50 to 123.94), standardized effect d = 0.02; z-test p = 0.952.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ventilated Non-menthol Cigarette and the control. The interval gives the range of effects that remain compatible with the data.

Carbon Monoxide Changes

• 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:
  • Ventilated Non-menthol Cigarette: mean 3.02 versus 0.01 on control; difference 3.01 (95% CI -3.62 to 9.64), standardized effect d = 0.26; z-test p = 0.374.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ventilated Non-menthol Cigarette and the control. The interval gives the range of effects that remain compatible with the data.

Quit Attempts

• 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:
  • Ventilated Non-menthol Cigarette: mean 0.55 versus 0.52 on control; difference 0.03 (95% CI -0.63 to 0.68), standardized effect d = 0.02; z-test p = 0.938.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ventilated Non-menthol Cigarette and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary outcomes cover a biomarker of nicotine exposure, carbon monoxide, and quit attempts. Across them, the estimated mean differences are small relative to the uncertainty reflected in their intervals, and every posted interval includes zero. The direction of the point estimates is not consistent across outcomes: the cotinine and carbon monoxide estimates favor higher averages in the ventilated group, while the quit-attempt estimate is also slightly higher in that group. Those directions should not be treated as a unified pattern of effect.

The primary endpoint is dropout, which is a measure of retention rather than smoking behavior or biomarker exposure. The secondary outcomes therefore address different questions from the primary result. Their estimates do not explain the observed dropout contrast, and the dropout result does not establish what happened to biomarkers or quit attempts. Taken together, the posted results describe several distinct aspects of the pilot without demonstrating a clear comparative pattern.

The registry record lists no reported analyses for these secondary outcomes, and the comparisons are unadjusted recalculations from group summaries. The record does not describe whether the outcomes were prespecified in a statistical plan, how multiple comparisons were to be handled, or how missing measurements were treated. In general, unadjusted secondary results carry less weight because multiple outcomes create more opportunities for chance findings and because exploratory results are not a substitute for a prespecified primary analysis.

These measures may help frame questions for a subsequent study, but their uncertainty and the unreported analysis details limit the strength of conclusions. They should be read as descriptive signals in a small pilot rather than as confirmatory evidence about the effects of either cigarette assignment.

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

• Cotinine Change
• Carbon Monoxide Changes
• Quit Attempts

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is binary at the participant level: each participant either dropped out by Week 4 or did not. The record reports a percentage for each group and the number of participants in each group. For the minimally ventilated group, 4 of 23 participants dropped out; for the ventilated group, 2 of 23 did. The comparison is described as a risk difference, which expresses the difference between the two groups’ event proportions. The direction is ventilated minus minimally ventilated, so the estimate of -0.087 corresponds to a lower observed dropout proportion in the ventilated group.

In general, a risk difference is an absolute comparison rather than a relative one. It is useful for showing the difference in event frequency between groups on the same scale as the outcome. A risk difference near zero represents similar observed proportions, while values on either side represent differences in opposite directions. The estimate is only one summary of the data; it does not capture all uncertainty or explain why the outcome occurred.

The reported interval for the risk difference runs from -0.28 to 0.106. In general, a confidence interval gives a range of values compatible with the observed data under the method used to construct it. Its width conveys precision: wider intervals indicate greater uncertainty about the underlying difference. The registry record does not identify the specific interval construction method or state its confidence level in the posted outcome information, so those details should not be assumed.

The unadjusted p-value is 0.381. In general, a p-value describes how unusual data at least as different as those observed would be under a specified null hypothesis and statistical model. It is not a measure of the probability that the null hypothesis is true, and it does not quantify the probability that a finding will replicate. The record does not report an analysis plan or sponsor-reported analyses; this p-value belongs to the unadjusted recalculation from the posted summaries.

For a binary endpoint, the number of participants with the event and the group size matter to the uncertainty of the estimated proportion. With relatively few participants, a small change in the event count can noticeably shift a percentage. In general, this is why pilot estimates based on small groups should be interpreted together with their intervals rather than as stable estimates of the rate expected in future studies.

The secondary outcomes are reported as means with standard deviations: cotinine change in ng/nL, carbon monoxide changes in ppm, and quit attempts. Their comparisons are mean differences between the ventilated and minimally ventilated groups. In general, a mean difference describes the difference between group averages, while a standard deviation describes the spread of participant values within a group. A standard deviation is not the same as a standard error or a confidence interval; it describes variability among observations, not the precision of the group mean by itself.

The recalculated mean differences are unadjusted comparisons from the posted group summaries. Their intervals are reported with each outcome, and their p-values are unadjusted. The registry record does not describe covariate adjustment, transformations, handling of repeated measurements, or a model for the secondary outcomes. It also does not report whether analyses used every randomized participant or only participants with available measurements. Therefore, the mean comparisons should not be described as adjusted treatment effects or attributed to a particular model.

General statistical context: when a study measures several outcomes, chance alone can produce apparently notable results among the collection of comparisons. A multiplicity procedure can alter how evidence is evaluated across those outcomes. No multiplicity adjustment is reported in this record. This matters especially for secondary and exploratory measures, which are not the primary endpoint and for which no analysis plan is described.

The registry record lists no reported analyses. That does not erase the posted group values or the unadjusted recalculations, but it distinguishes them from an analysis explicitly reported by the study investigators. The original statistical methods, assumptions, and approach to missing observations are not reported in the registry record. Interpretations should therefore stay close to the posted summaries and avoid attributing unreported procedures to the study.

11. Confidence Intervals and Precision

The primary dropout estimate is uncertain. The observed risk difference for ventilated versus minimally ventilated cigarettes is -0.087, and the reported interval ranges from -0.28 to 0.106. Because that range includes zero and extends in both directions, the data do not pin down the direction or size of the underlying difference. The point estimate is the observed contrast, not a precise forecast of dropout in a future study.

The group percentages are based on 23 participants per arm, with 4 and 2 observed dropouts. In general, estimates from small groups are sensitive to individual outcomes, and intervals can be wide when the amount of information is limited. The posted interval makes this imprecision more informative than the point estimate alone. The registry record does not report the method or confidence level used for that interval.

The secondary comparisons also have substantial uncertainty. The interval for cotinine mean difference is -116.5 to 123.9 ng/nL; for carbon monoxide changes it is -3.623 to 9.638 ppm; and for quit attempts it is -0.626 to 0.678. Each interval includes zero, so the posted summaries do not establish a clear difference in either direction. The size of these intervals relative to the point estimates is a reminder that the observed group averages are not precise measures of the underlying contrasts.

Precision is distinct from whether a result meets a threshold for statistical significance. A wide interval can encompass meaningfully different possibilities even when the point estimate is small. These pilot data are most useful for describing what was observed and for illustrating uncertainty; they do not offer narrow estimates of comparative effects.

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 sample-size figures are planning illustrations based on the observed effect, not the trial’s original design justification. For these non-time-to-event outcomes, the figures are participants per arm, not total participants or total events. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect equal to the stated fraction of the observed effect. The original sample-size assumptions for the trial are not reported in the registry record.

The 80% power column gives the number of participants per arm indicated by those assumptions for an 80% chance of detecting the specified effect if that effect were the true one and the assumed model applied. The 90% power column uses the same interpretation but targets a 90% chance. These are design-planning concepts, not guarantees that a future study will find a difference. The displayed values are not observed power.

Each planning row uses a different fraction of the observed effect: 100%, 75%, or 50%. A smaller effect is harder to distinguish from random variation, so the planning illustration requires more participants per arm as the target effect gets smaller. The values can be very large when the observed difference is small relative to variability, as with some secondary outcomes. They should not be read as recommendations or as evidence that the original pilot was designed to detect those effects.

The registry record does not report the investigators’ planned target sample size or the rationale for the 46 participants enrolled. The illustrations therefore answer a conditional question about sample size under the listed assumptions; they do not explain why the study enrolled its actual participants or demonstrate that it had adequate power for a particular endpoint.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.174; treatment proportion p₁ = 0.087; average p̄ = 0.130.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.4763 = 0.9335.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.4723 = 0.3975.
4. n = (0.9335 + 0.3975)² / (-0.0870)² = 234.3, rounded up to 235 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
p0 <- 0.173913043478261                          # control proportion
p1 <- 0.0869565217391304                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(4514471)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 235 (80% power), 314 (90% power)
 75% of observed effect: n per arm = 447 (80% power), 598 (90% power)
 50% of observed effect: n per arm = 1,071 (80% power), 1,433 (90% power)
power.prop.test: 234.3 
Simulated power at n = 235 per arm: 0.815 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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 primary endpoint is percentage of participants who dropped out, and the registry lists three named secondary outcomes: cotinine change, carbon monoxide changes, and quit attempts. The record gives six outcome measures in total, but the additional measures beyond the primary and named secondary outcomes are not identified in the posted information. No analysis plan is reported, so it is not possible to determine which outcomes were designated in advance for formal testing or how the investigators intended to prioritize them.

No multiplicity adjustment is reported. In general, evaluating several outcomes without an adjustment can increase the chance of obtaining at least one apparently unusual result by chance. That concern does not mean that every secondary estimate is invalid; it means the results should be interpreted with attention to their exploratory status, uncertainty, and the number of comparisons. The posted unadjusted results should not be treated as a collection of independent confirmations.

The registry record lists no reported analyses. It does not report the analysis population for each outcome, whether participants were analyzed according to randomized assignment, or how missing outcome measurements were handled. The primary endpoint concerns dropout, but reasons for dropout and the treatment of a participant who left the study in other endpoint analyses are not described. Missing-data methods, imputation, and sensitivity analyses are not reported in the registry record.

Interim analyses are also not reported. The record does not describe stopping rules, a prespecified feasibility threshold, or criteria for deciding whether to proceed to a larger study. Without these details, the posted results can be described, but they cannot establish how the investigators planned to interpret retention or manage the family of outcomes. These omissions are relevant to how much inferential weight to place on the unadjusted comparisons.

15. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hypertension (4.3%), pneumonia (4.3%).

The serious adverse event figures list 0 affected participants among 23 at risk in the minimally ventilated group and 2 among 23 at risk in the ventilated group. No deaths are listed in either group. The record names hypertension and pneumonia as serious adverse event terms, each with a posted frequency of 4.3%. The term-specific figures do not identify which treatment group each term occurred in, so they should not be assigned to a group based on the overall group counts.

Other, non-serious adverse events are listed for 5 of 23 participants in the minimally ventilated group and 10 of 23 in the ventilated group. These counts describe participants affected, not necessarily the total number of event episodes. The registry record does not provide event timing, duration, severity details beyond the serious/non-serious distinction, or an assessment of whether events were related to the assigned cigarettes or study procedures.

These figures are descriptive and involve small groups. They do not establish that one assignment is safer or less safe than the other, and they do not provide a complete account of risk outside the study. They should be read as the adverse event information posted in the registry record, with the limited detail available there.

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

The study provides a small randomized comparison of retention and selected secondary measures during a remote pilot in menthol smokers switched to non-menthol cigarettes. By Week 4, 4 of 23 participants in the minimally ventilated group and 2 of 23 in the ventilated group had dropped out. The estimated risk difference is negative for ventilated versus minimally ventilated cigarettes, but its reported interval is wide and crosses zero. The result therefore describes the observed groups without resolving whether a meaningful underlying difference exists.

The secondary outcomes similarly do not establish a clear difference. Their unadjusted intervals include zero, and the registry does not list investigator-reported analyses or a statistical plan. The findings cannot show that either cigarette assignment changed smoking behavior, nicotine exposure, carbon monoxide, or quit attempts. Nor can dropout alone identify the acceptability of the remote procedures or the reasons participants left.

Randomization is a strength of the comparative design, but the trial’s pilot scale and open-label conduct matter when interpreting the results. The study enrolled 46 participants, with 23 in each group, and participants and study staff were not masked. The registry record does not report reasons for withdrawal, analysis populations, or missing-data methods. These limits leave uncertainty about how outcomes would look in a larger study and how complete the measured data were.

The results do not prove that the two assignments have the same effects, and they do not prove that one assignment is better. A wide interval that includes no difference is not evidence of equivalence. The posted data also do not establish whether the study met a prespecified feasibility target, because such a target is not reported in the registry record.

The most defensible interpretation is descriptive: the record reports Week 4 dropout and several secondary measures from a remote randomized pilot. It offers estimates that may inform questions for future research, but not a definitive assessment of comparative effectiveness, safety, or the success of telehealth study procedures.

17. Why This Trial Matters Statistically

This trial is statistically interesting because its primary outcome is a feasibility-relevant measure: whether participants remain in a remote study through Week 4. In a decentralized design, telehealth visits and home collection and mailing of samples are part of the study process. Retention therefore describes an important operational aspect of conducting research remotely, even though it is not itself a biomarker or smoking outcome.

The randomized parallel-group structure permits a direct descriptive comparison between participants assigned to minimally ventilated and ventilated non-menthol cigarettes. The small groups also make precision a central issue. A point estimate can look directional while the interval remains broad enough to include substantially different possibilities. This is a useful setting for distinguishing an observed difference from a well-estimated difference.

The study also illustrates why a pilot’s purpose and its statistical evidence should be kept distinct. A pilot can generate information about procedures and measurements without being designed to provide a precise test of every outcome. The registry record does not report a formal feasibility threshold or the original sample-size justification, so the results cannot be judged against an unreported target. The planning illustrations based on observed effects are separate from the study’s own design rationale.

Finally, the record contains several secondary measures, but no reported analyses or multiplicity approach. That makes interpretation depend on careful attention to the primary retention outcome, the uncertainty in each estimate, and the exploratory nature of the remaining comparisons. The trial is a useful example of how design, measurement, and statistical precision shape what a small randomized pilot can establish.

18. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The most immediate limitation is the small enrollment: 46 participants, with 23 assigned to each group. The primary dropout comparison is based on 4 events in one group and 2 in the other, so the estimate is imprecise. Its interval includes both negative and positive values. The posted data therefore do not provide a stable estimate of the difference that should be expected in a future population.

The intervention comparison is open label, with no masking. The registry record does not explain whether participants’ knowledge of assignment could have affected their decision to remain in the study, their reported subjective measures, or their behavior. Reasons for dropout are not reported, which prevents distinguishing withdrawal related to study burden from other reasons.

The remote procedures are central to the study, but the record does not provide detailed completion rates for telehealth visits, mailed samples, or individual measurements. It also does not report whether all randomized participants contributed data to each outcome. Without that information and the missing-data methods, the completeness of the secondary outcome comparisons cannot be assessed from the posted summaries alone.

The analysis plan, original sample-size justification, and multiplicity approach are not reported in the registry record. No sponsor-reported analyses are listed. The available comparisons are unadjusted recalculations, and the registry gives limited detail about how the outcomes were measured or analyzed. The record also does not report participant characteristics beyond the stated menthol use criterion, limiting assessment of how representative the enrolled group may be.

Finally, the study concerns a short period through Week 4 and a specific group of menthol smokers switched to non-menthol cigarettes. The posted results should not be extended to other populations, durations, or settings. These limitations qualify both the interpretation of retention and the secondary outcomes.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Feasibility of Conducting a Pilot Telehealth Study Assessing the Removal of Filter Ventilation on Smoking Behavior and Biomarkers in Menthol Smokers Switched to Non-menthol Cigarettes — NCT04514471.
• Registry record last updated 2026-09-09; status last verified 2026-09.
• Results first posted 2026-09-09.
• 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.

22. Record Summary

NCT04514471 is a completed, randomized, open-label, parallel-group pilot study sponsored by Masonic Cancer Center, University of Minnesota. It enrolled 46 menthol smokers and compared assignment to minimally ventilated versus ventilated non-menthol cigarettes after 2 weeks of usual-brand monitoring. The study evaluated a remote approach using telehealth and home-collected, mailed biological samples.

The primary endpoint was dropout from baseline through Week 4. Dropout was 17.4% in the minimally ventilated group and 8.7% in the ventilated group. The unadjusted recalculated risk difference was -0.087, with a reported interval from -0.28 to 0.106. The uncertainty is substantial, and the result does not establish a clear difference between assignments.

The record also lists cotinine change, carbon monoxide changes, and quit attempts as secondary outcomes. Their unadjusted comparisons are imprecise. The registry record does not report the original sample-size rationale, analysis plan, missing-data methods, or investigator-reported analyses.