Reduced Exposure Study in Smokers Using THS 2.2 With 5 Days in a Confinement Setting.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Reduced Exposure Study in Smokers Using THS 2.2 With 5 Days in a Confinement Setting. (NCT01959932), a randomized na study. The primary outcome is Concentration of Monohydroxybutenyl Mercapturic Acid (MHBMA).

2. Clinical Question

The registry identifies MHBMA concentration as the primary endpoint and describes the geometric least-squares (LS) means as descriptive statistics. The reported inferential analysis compares THS 2.2 with conventional cigarettes using an ANCOVA-based geometric LS mean ratio. Although smoking abstinence was a separate randomized group and has a posted endpoint summary, no inferential comparison involving that group is reported for this endpoint.

This is a short-term, confined comparison of biomarker measurements, not a study of long-term health outcomes. Its primary question concerns a urinary exposure marker measured after 5 days under the assigned conditions. The registry record does not report a primary inferential analysis of THS 2.2 against smoking abstinence.

3. Trial Design

The registry describes a randomized, controlled, open-label, three-arm, parallel-group, single-center study. Its status is completed, and the listed phase is NA. Enrollment was 169. The study start is recorded as 2013-06 and primary completion as 2013-09.

Participants were assigned to THS 2.2, smoking abstinence or conventional cigarettes. The THS 2.2 group used the system ad libitum during 5 days in confinement. The abstinence group refrained from smoking for 5 days in confinement. The conventional-cigarette group used each participant’s own preferred brand ad libitum for 5 days in confinement. Masking was none, so the study was open-label.

The primary outcome was assessed at Day 5. The endpoint record gives arm summaries for 79.0 participants assigned to THS 2.2, 41.0 assigned to conventional cigarettes and 39.0 assigned to smoking abstinence. These are the analysis counts shown for the endpoint, not a restatement of enrollment. The adverse-event record separately lists 9 participants as enrolled but not randomized.

The primary analysis population is called the full analysis set (FAS). The registry says it included randomized participants with at least one post-randomization product-use experience when assigned to THS 2.2 or conventional cigarettes, and at least one valid biomarker-of-exposure measurement. The description does not fully specify the corresponding criteria for the abstinence arm.

The registry record does not report the rationale for the enrollment target, the method used to generate the randomization sequence, concealment procedures, or detailed criteria for inclusion and exclusion. It also does not give further information about the confinement procedures. Those details should not be inferred from the design label alone.

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: Enrolled and randomized population = 160 subjects * 80 subjects in THS 2.2 * 41 subjects in CC * 39 subjects in SA Number of subjects enrolled but NOT randomized (who tried the THS 2.2 at Day -2) = 9

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The analysis was performed on the full analysis set (FAS) population. The FAS consisted of all the randomized subjects who had at least 1 post randomization product use experience (if randomized to THS 2.2 or CC) and had at least 1 valid biomarker of exposure (BoExp) measurement (THS 2.2, CC, SA 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: The study population consisted of all the randomized subjects who had at least 1 post randomization product use experience (THS 2.2 or CC arms), and 1 valid biomarker of exposure (BoExp) measurement. 160 randomized subjects: 80 in THS 2.2, 41 in CC and 39 in SA 159 completers: 1 subject (THS 2.2 arm) voluntarily withdrew on Day 3

6. Primary Endpoint

The registry lists the primary outcome as Concentration of Monohydroxybutenyl Mercapturic Acid (MHBMA), measured over 5 days.

The primary endpoint is concentration of monohydroxybutenyl mercapturic acid (MHBMA) in urine at Day 5, expressed in pg/mg creat. The measurement was adjusted for creatinine. MHBMA is treated in the study as a biomarker of exposure, within the broader goal of evaluating selected harmful and potentially harmful constituents associated with smoking.

A urinary biomarker provides a measured indicator of exposure over the relevant collection period; it is not itself a clinical outcome such as disease, symptoms or survival. Creatinine adjustment is commonly used to account for differences in urine concentration. As a general statistical point, urine dilution can vary between samples, and adjustment can make concentration measurements more comparable. The registry does not provide further details about the collection protocol or the specific creatinine-adjustment procedure.

The endpoint is summarized using geometric LS means and 95% confidence intervals. The registry explicitly characterizes the geometric LS means as descriptive statistics. The posted arm summaries are 194.1 (95% CI 173.2 to 217.4) for THS 2.2, 2314.0 (95% CI 1975.0 to 2712.0) for conventional cigarettes, and 168.0 (95% CI 142.9 to 197.6) for smoking abstinence.

Because this endpoint measures a biomarker after 5 days, its interpretation is limited to the recorded short-term exposure measure. It does not directly establish a change in clinical risk or health outcomes.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a geometric LS mean describe?

The registry reports geometric least-squares means for the continuous MHBMA endpoint. A geometric mean summarizes measurements on a multiplicative scale, which can be useful when values are right-skewed or when comparisons are naturally expressed as ratios. A least-squares mean is a model-based adjusted mean. The registry calls these descriptive statistics, but does not give the transformation details or covariates used to generate them. The arm values can be read as the model-reported summaries; they should not be assumed to be ordinary arithmetic averages.

For a continuous measure, a summary of the mean does not show the full distribution of individual observations. The posted confidence intervals describe uncertainty around the reported means, not the range of participant values. The registry does not report a standard deviation or another measure of individual-level spread for these arm summaries.

How should the ratio and confidence interval be read?

The sponsor’s reported analysis is an ANCOVA comparison expressed as a geometric LS mean ratio. Ratios compare quantities multiplicatively rather than by subtracting one mean from another. The analysis reports a ratio of 8.38, with a 95% confidence interval from 6.89 to 10.20, and p <0.001. The analysis description does not state which arm is the numerator and which is the denominator. Accordingly, the ratio should not be paraphrased as a specific fold-increase or fold-reduction without that convention being confirmed. The arm summaries provide the descriptive context for the comparison.

In general, a confidence interval reflects sampling uncertainty under the model and its assumptions. A narrower interval indicates greater precision than a wider interval on the same scale, while an interval does not account for every source of uncertainty, such as measurement limitations or model misspecification. A p-value assesses compatibility with a specified null hypothesis under the analysis assumptions; it is not the probability that the null hypothesis is true, nor a measure of clinical importance. The record does not specify whether the analysis was one- or two-sided, but it reports the p-value and confidence level.

What does ANCOVA contribute?

Analysis of covariance (ANCOVA) compares groups while accounting for one or more covariates in a statistical model. In a randomized trial, adjustment can improve precision when the chosen covariates are informative and appropriately specified. The registry reports ANCOVA, but the covariates, model formula, handling of transformed measurements and diagnostic checks are not reported in the registry record. It is therefore not possible to reconstruct the sponsor’s exact model from the information recorded for this endpoint.

Randomization supports a comparison of assigned groups, but it does not remove the need to understand the analysis population, missing observations and model specification. Open-label assignment may also affect behaviors or measurement processes; the registry does not quantify such effects. The result remains a model-based comparison for the recorded endpoint and population.

Why do the arm summaries and the ratio answer different questions?

The arm summaries describe each group’s estimated endpoint level. The ANCOVA ratio is an inferential comparison between THS 2.2 and conventional cigarettes. In general, adjusted model comparisons need not equal a ratio calculated directly from displayed group summaries, because adjustment and model details can affect the estimate. The registry does not report a separate unadjusted recalculation for this endpoint. A recalculation from summary values would not replace the sponsor’s ANCOVA result.

There are three randomized groups, but the reported inferential analysis for the primary endpoint includes THS 2.2 and conventional cigarettes. The abstinence arm’s descriptive mean and interval do not supply an inferential comparison against either other arm. Statistical significance for one reported comparison cannot be extended to comparisons that are not reported.

How should planning illustrations be interpreted?

Any sample-size illustrations associated with the posted results are planning exercises based on the observed effect, not observed power and not the trial’s original design calculation. In general, such illustrations ask how many participants per arm might be needed under specified assumptions to detect an effect of a chosen size. The registry record does not report the trial’s own sample-size justification, and no planning estimate should be treated as evidence about the probability that this completed study detected an effect.

The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between the two arms and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. Those assumptions describe a hypothetical planning calculation; they do not document the trial’s randomization allocation or its original statistical plan.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s own primary comparison as an ANCOVA-based geometric LS mean ratio of 8.38 for THS 2.2 and conventional cigarettes, with a 95% confidence interval from 6.89 to 10.20 and p <0.001. The ratio’s numerator and denominator are not specified in the analysis description, so its direction should be interpreted together with the posted arm summaries rather than inferred from the ratio alone.

The arm summaries are descriptive geometric LS means: 194.1 for THS 2.2 and 2314.0 for conventional cigarettes. They are not a replacement for the adjusted ANCOVA comparison. A direct calculation from displayed summaries would be unadjusted and could differ from the sponsor’s model-based estimate. A separate recalculated comparison is not reported in the registry record, so there is no posted recalculated value to reconcile with the sponsor result.

The discrepancy indicator is false. The sponsor’s reported analysis is therefore the available inferential result, without a flagged disagreement in the record. The analysis remains subject to the unreported model details, including its covariates and missing-data handling. The registry also does not report an inferential comparison involving the smoking-abstinence arm for this endpoint.

11. Multiplicity, Missing Data and Analysis Populations

The record lists 4 outcome measures and 4 analyses. It identifies MHBMA concentration as the primary endpoint, but the multiplicity strategy across endpoints or comparisons is not reported in the registry record. In particular, the record does not say whether any adjustment was used to account for multiple statistical tests, or whether the primary comparison was designated in advance in a detailed statistical analysis plan. The reported p-value should be understood as the result for the comparison described, not as evidence that all possible outcomes or group comparisons were tested under a single prespecified procedure.

The posted inferential analysis is for THS 2.2 versus conventional cigarettes. No inferential result for the smoking-abstinence comparison is reported for this endpoint. The record also indicates that secondary posted results are absent. The absence of a posted result does not establish that an analysis was not conducted; it means the corresponding result is not reported in the registry record.

The FAS is described as including randomized participants with at least one valid biomarker-of-exposure measurement, and, for participants assigned to THS 2.2 or conventional cigarettes, at least one post-randomization product-use experience. The FAS description does not fully specify the abstinence-arm criterion. The registry does not explain how participants without a valid measurement were handled, whether any measurements were imputed, or how protocol deviations and missing data were addressed. The endpoint arm counts should not be treated as an account of all missing observations or exclusions.

The registry record does not report a detailed statistical analysis plan, the timing of any interim analyses, or a sample-size justification. These are distinct issues: multiplicity concerns interpretation across tests, missing-data handling concerns the analysis of unavailable measurements, and analysis-population rules determine which participants contribute. Without those details, the posted estimate and interval can be described, but the full set of analytic decisions cannot be independently assessed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event record reports zero serious adverse events among participants at risk in each listed group: THS 2.2, smoking abstinence, conventional cigarettes, and enrolled but not randomized. The corresponding at-risk counts are 80, 39, 41 and 9. These figures describe serious adverse events in the recorded study period; they do not establish that serious events are impossible or that groups have identical safety profiles.

The record also lists other adverse events affecting 44 participants in the THS 2.2 group, 22 in the abstinence group, 26 in the conventional-cigarette group and 9 among those enrolled but not randomized. These are event-affected counts, not a measure of severity or a treatment-effect comparison. The registry does not provide serious-event terms, with the serious-event terms list empty, and deaths are not reported in the registry record.

Because the study was open-label and confined to 5 days, these safety figures are descriptive and limited to the recorded period and groups. The registry does not provide enough detail to assess event types, timing, attribution or statistical comparisons. The counts should not be interpreted as evidence of equivalence or used to make a broader safety conclusion.

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

The posted results describe a short-term biomarker comparison after 5 days in confinement. The primary endpoint is creatinine-adjusted urinary MHBMA concentration at Day 5. The arm summaries are 194.1 pg/mg creat for THS 2.2, 2314.0 pg/mg creat for conventional cigarettes and 168.0 pg/mg creat for smoking abstinence. The sponsor’s inferential analysis compares THS 2.2 with conventional cigarettes and reports a geometric LS mean ratio of 8.38 (95% CI 6.89 to 10.20; p <0.001).

These findings speak to the measured biomarker under the study conditions. They do not show that a biomarker difference necessarily produces a difference in symptoms, disease, life expectancy or other clinical outcomes. The study does not report long-term follow-up in the registry record described for this endpoint, and the results should not be extended beyond the measurement and time period recorded.

The reported analysis does not establish a treatment effect relative to smoking abstinence. Although the abstinence group has a descriptive endpoint summary, no inferential comparison involving that arm is posted. Nor can a result for MHBMA be generalized automatically to all harmful or potentially harmful constituents, all biomarkers, or all forms of tobacco use.

Statistical evidence and clinical importance are separate questions. The reported p-value and confidence interval characterize the sponsor’s model-based comparison, while the meaning of a change in this biomarker for health is not established by the statistical output alone. The registry record does not report a clinical outcome analysis or enough information to establish long-term implications.

The record’s open-label design, single-center setting, confined duration, incomplete reporting of model details and unspecified missing-data approach are relevant when judging how broadly the result applies. These limitations do not erase the observed summaries; they define the boundaries of what those summaries can support.

14. Why This Trial Matters Statistically

This study is statistically informative because it distinguishes descriptive arm summaries from a model-based comparison. The endpoint values show the estimated MHBMA levels in each group, while the ANCOVA ratio and its confidence interval address the reported THS 2.2 versus conventional-cigarette comparison. Keeping those outputs separate avoids treating a visual difference between means as if it were the same thing as an adjusted inferential estimate.

The three-arm design also makes clear that a study may include a group without reporting every possible pairwise comparison. The smoking-abstinence arm contributes useful descriptive context, but the registry’s primary inferential result concerns THS 2.2 and conventional cigarettes. A conclusion about the reported comparison cannot automatically be transferred to the unreported comparison.

The endpoint illustrates a broader point about surrogate or exposure biomarkers: a precisely measured difference in a biomarker is not itself a clinical outcome. Statistical precision describes uncertainty in the estimate under the model; it does not answer whether the difference changes health outcomes. That distinction is especially important for a short-term endpoint measured in confinement.

Finally, the record shows why transparent reporting matters. The FAS is described, but some arm-specific population details and the handling of missing measurements are not. The ANCOVA method is named, but its covariates and full specification are not. Reporting those details would help readers assess reproducibility and the sensitivity of the result to analytic choices. The posted result can be interpreted as reported while recognizing that its full analytic context is not documented.

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.

This study has limitations specific to its setting and reporting. It was open-label, single-center and conducted in confinement for 5 days. These features constrain how well the results represent use and measurements under other conditions or over longer periods. The registry does not report whether observed behavior in confinement differed from behavior outside the study setting.

The primary endpoint is a biomarker of exposure rather than a clinical health outcome. The registry record does not establish how the measured MHBMA concentration relates to a later health effect. The endpoint’s timing at Day 5 also means the result is limited to that assessment; persistence after the confinement period is not reported.

The only posted inferential comparison for the primary endpoint is THS 2.2 versus conventional cigarettes. The abstinence group has a descriptive summary, but an inferential comparison involving that group is not reported in the registry record. The ratio’s numerator and denominator are also not specified in the analysis description, so its directional interpretation requires care.

Important analysis details are absent. The ANCOVA covariates and full model specification are not reported, nor are the method for handling missing endpoint measurements, the complete FAS criteria for the abstinence arm, or any multiplicity procedure. The registry does not report the original sample-size justification or interim-analysis plan. These omissions limit independent reproduction and assessment of the analysis, but they do not alter the values that the registry reports.

The adverse-event summaries are also brief: serious-event counts are reported, but serious-event terms are not listed and deaths are not reported in the registry record. The safety figures therefore provide limited detail about the nature and timing of events.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Reduced Exposure Study in Smokers Using THS 2.2 With 5 Days in a Confinement Setting. — NCT01959932.
• Registry record last updated 2020-03-12; status last verified 2020-03.
• Results first posted 2016-10-13.
• 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

NCT01959932 is a completed, randomized, open-label, three-arm, parallel-group, single-center study of THS 2.2 use, smoking abstinence and conventional-cigarette use during 5 days in confinement. Enrollment was 169. The primary endpoint was creatinine-adjusted urinary MHBMA concentration at Day 5.

The registry reports geometric LS means and 95% confidence intervals for all three groups, and an ANCOVA geometric LS mean ratio comparing THS 2.2 with conventional cigarettes: 8.38 (95% CI 6.89 to 10.20; p <0.001). No inferential comparison with the abstinence group is reported for this endpoint. The record does not fully specify the model, missing-data handling or multiplicity approach.