Smoking Cessation Medications: Efficacy, Mechanisms and Algorithms: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Smoking Cessation Medications: Efficacy, Mechanisms and Algorithms (NCT00332644), a randomized phase 4 study. The primary outcome is 7-day Point Prevalence of Smoking, Biochemically (Exhaled CO) Confirmed.

2. Clinical Question

3. Trial Design

The registry describes a phase 4, randomized, double-masked trial sponsored by the University of Wisconsin, Madison. The record lists a planned enrollment of 1504, a start date of 2004-09, primary completion in 2010-08, and completed status. It lists six arms: nicotine patch, nicotine lozenge, nicotine patch plus lozenge, bupropion, bupropion plus nicotine lozenge, and placebo control.

There is a metadata inconsistency: the trial is described as randomized and lists multiple arms, while the model classification is “single group.” The registry does not explain this coding, so the “single group” label cannot be reconciled with the arm descriptions from the record alone. The record also does not describe the randomization procedure, allocation concealment, who was masked, or whether masking was maintained throughout follow-up.

The outcome is reported at 6 months post quit date. The arm-level outcome denominators and counts are posted, but no comparative analyses are included. The registry lists one outcome measure and zero analyses. The record does not report a protocol-level statistical plan, sample-size justification, planned interim analyses, analysis population, or details of how participants were assigned among the listed regimens. Those details are not reported in the registry record and cannot be inferred from the design labels or posted counts.

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

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.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as 7-day Point Prevalence of Smoking, Biochemically (Exhaled CO) Confirmed, measured over 6 months post quit date.

The primary endpoint is the number of participants with 7-day point-prevalence abstinence at 6 months post quit date, defined using a reported absence of smoking during the previous 7 days and confirmation by an exhaled carbon monoxide level below 10 ppm. Participants were asked whether they had smoked at all, even a puff, in that period. The description says smoking status was assessed both by this point-prevalence definition and by continuous abstinence since the target quit day, using a smoking calendar and timeline follow-back method. The posted primary result, however, is the point-prevalence count.

Biochemical confirmation adds a measurement independent of self-report, although it does not change the endpoint’s time window: point prevalence reflects a specified recent period, rather than smoking behavior throughout the interval since the quit date. The registry description does not say that the primary count requires continuous abstinence. It also does not report separate outcome counts for continuous abstinence.

The results give arm-specific denominators and numbers meeting the endpoint: nicotine patch, 90 of 262; nicotine lozenge, 87 of 260; nicotine patch plus lozenge, 107 of 267; bupropion, 84 of 264; bupropion plus nicotine lozenge, 87 of 262; and placebo control, 42 of 189. These are counts, not comparative effects. The registry does not report confidence intervals or tests for differences between arms.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods help distinguish an observed result from the uncertainty around a comparison. In this record, the primary results are outcome counts by arm. No analysis results, effect estimates, confidence intervals, or p-values are posted, so comparative methods cannot be attributed to the trial based on the registry entry.

What does a count show?

A count states how many participants met the outcome definition among those included in the posted denominator. Here, the endpoint is 7-day point-prevalence smoking status, confirmed by an exhaled carbon monoxide level below 10 ppm, assessed at 6 months post quit date. Counts are useful for describing what was recorded in each arm. They do not express the uncertainty around the difference between arms, and they do not show whether any apparent contrast is compatible with chance variation.

For a binary outcome such as meeting or not meeting an abstinence definition, analysts may compare the proportion meeting the outcome between arms. General methods include a difference in proportions, a relative measure such as a risk ratio, or a regression model. Each approach answers a somewhat different question and may have different assumptions. The registry does not report which, if any, was used for the posted counts. No comparative estimate should be reconstructed or assigned to the trial from the counts alone.

Why are confidence intervals useful?

In general, a confidence interval describes the uncertainty around an estimated quantity under the assumptions of the analysis. For a treatment comparison, it helps show which effect sizes remain compatible with the data and method. A narrow interval indicates greater precision than a wide interval, while an interval spanning values with different interpretations may leave the comparison uncertain. The registry does not report confidence intervals for this endpoint, so its comparative precision cannot be assessed from the posted record.

What does randomization contribute?

In general, random assignment is intended to make treatment groups comparable on average at the point of assignment, including with respect to factors that may not have been measured. This supports causal comparisons when the trial is conducted and analyzed according to appropriate methods. Randomization does not guarantee identical groups, prevent missing outcomes, or determine how participants with missing data should be handled. The registry calls the study randomized but does not report the randomization procedure, analysis population, or missing-data methods. The “single group” model classification conflicts with the multiple listed arms and randomized designation; the record does not clarify that coding.

What do masking and analysis choices mean?

Double masking indicates that the registry classified the trial as masked at two levels, but it does not specify which people were masked or how masking was implemented. Masking can reduce some sources of bias in treatment delivery and outcome assessment, but it does not replace a clearly reported analysis. For a binary endpoint, methods may account for prognostic factors or other design features, but no adjusted estimate or model is reported. It is therefore not known whether any adjustment was performed.

Multiplicity arises when investigators make several statistical comparisons or test multiple outcomes. In general, the more inferences made, the more important it is to define which comparisons are primary and how error rates are handled. Six arms permit multiple possible comparisons, but the registry does not identify a primary pairwise contrast or report a multiplicity procedure. No claim about statistical significance across comparisons can be made from the record.

How should planning calculations be read?

General sample-size calculations depend on assumptions about the target effect, variability, significance level, allocation, and analysis method. The record describes planning illustrations based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations are not the trial’s own design justification and are not observed power. The registry does not report the original sample-size justification or its assumptions. The record’s note also distinguishes planning outputs for time-to-event outcomes, which use total events under the Schoenfeld method, from other outcomes, which use participants per arm. These conventions do not supply a missing comparative result.

Overall, the posted counts support a descriptive account of the endpoint by arm. General statistical principles explain how comparative estimates and their uncertainty might be evaluated, but the registry does not report the analyses needed to apply those interpretations to this trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. It does not report a prespecified primary comparison, a multiplicity adjustment, or a hierarchy of comparisons among the six arms. Since there are several possible comparisons, the absence of a reported analysis plan prevents readers from knowing which contrasts were intended as confirmatory or how multiple testing was handled. The posted counts alone do not establish statistical significance for any comparison.

Missing-data handling is also not reported in the registry record. The arm-level denominators are 262 for nicotine patch, 260 for nicotine lozenge, 267 for nicotine patch plus lozenge, 264 for bupropion, 262 for bupropion plus nicotine lozenge, and 189 for placebo control. The record does not explain how these denominators relate to the planned enrollment or to the number randomized, whether participants without outcome measurements were excluded, or how missing outcomes were treated.

Analysis populations are not specified. The registry does not state whether the results are based on all randomized participants, participants who received treatment, participants who attended follow-up, or another population. It also does not report sensitivity analyses to assess how missing outcomes might affect the findings. These omissions limit interpretation because a count depends on which participants are included and what assumptions are made about unavailable endpoint data. The record’s randomized designation does not resolve these questions.

11. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hospitalization: respiratory (1.6%), hospitalization: cardiovascular (1.2%), hospitalization: surgical (1.1%), hospitalization: general (0.8%), pregnancy (0.5%).

The registry reports serious adverse event counts by arm, using the number at risk and the number affected. The counts affected were 5 among 262 for nicotine patch, 5 among 260 for nicotine lozenge, 5 among 267 for nicotine patch plus lozenge, 8 among 264 for bupropion, 6 among 262 for bupropion plus nicotine lozenge, and 6 among 189 for placebo control. These are reported serious adverse event counts, not comparative estimates.

The record lists respiratory hospitalization at 1.6%, cardiovascular hospitalization at 1.2%, surgical hospitalization at 1.1%, general hospitalization at 0.8%, pregnancy at 0.5%, and skin reaction at 0.4% among its top serious terms. It does not provide a comparative statistical analysis of these events by treatment, nor does it report uncertainty intervals for between-arm differences. The registry does not report death counts in the adverse-event data.

Serious adverse events are distinct from the broader “other” adverse-event counts also listed in the record. An event count does not establish that the event was caused by the assigned medication, and a count alone does not account for differences in exposure or follow-up. These figures should be read as descriptive safety reporting, not as a basis for comparing risks or attributing causation.

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

The posted results describe the number of participants in each arm who met the trial’s primary endpoint at 6 months post quit date. The endpoint combines a 7-day self-reported abstinence definition with biochemical confirmation by exhaled carbon monoxide below 10 ppm. The record also describes assessment of continuous abstinence, but the posted primary result is the point-prevalence count.

These data do not establish that one regimen is better than another. The registry provides counts and denominators, but no comparative effect estimates, confidence intervals, or statistical tests. Counts from different arms cannot be interpreted as a treatment effect without a specified comparison and an analysis of uncertainty. Nor does the record establish that any observed arm-level outcome was caused by the assigned medication.

The findings also do not describe all dimensions of smoking behavior. A 7-day point-prevalence measure concerns a recent period at follow-up; it is not equivalent to continuous abstinence since the quit date. The registry does not post the continuous-abstinence results or secondary outcomes. It does not report participant characteristics, detailed eligibility criteria, or analysis populations that would help assess how broadly the findings apply.

The record’s design labels provide context: phase 4, randomized, and double-masked. However, the “single group” model classification is inconsistent with those labels and the six listed arms, and the registry does not explain the discrepancy. The record also does not report the protocol-level analysis plan, how missing outcome data were handled, or the intended primary treatment contrast. These unknowns constrain interpretation.

Accordingly, the results support a narrow descriptive statement about the posted endpoint counts at the stated follow-up. They do not show the precision of treatment comparisons, resolve the effect of missing data, or establish comparative efficacy or safety. Those conclusions require analyses and supporting details that are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it lists several medication strategies and a placebo control while reporting a clinically interpretable binary endpoint. The endpoint has a clear time point and a biochemical confirmation criterion, and the posted counts allow readers to see the outcome as recorded in each arm. This makes the distinction between descriptive results and comparative inference especially important.

A randomized design can support comparisons when the allocation and analysis are clearly reported. Here, the registry describes the trial as randomized and double-masked, but also classifies its model as single group despite listing six arms. That mismatch illustrates why registry metadata should be interpreted as a record of coded information, not as a substitute for a full protocol or statistical analysis plan.

The record also demonstrates that arm-level outcome data are not the same as a treatment comparison. Counts alone do not communicate uncertainty, account for missing outcomes, or establish which contrasts were prespecified. In a multi-arm study, decisions about primary comparisons and multiplicity are particularly relevant, yet those details are not reported. The registry lists one outcome measure and zero analyses.

Finally, the endpoint is specific: point-prevalence smoking status during the previous 7 days, confirmed by exhaled carbon monoxide at 6 months post quit date. It is not interchangeable with continuous abstinence. A precise endpoint definition helps prevent overgeneralization, while absent comparative analyses limit conclusions about differences among the listed regimens. The statistical lesson is to keep the result tied to its measure, follow-up time, denominator, and reported level of analysis.

14. Limitations

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

Important trial details are not reported in the registry record. These include participant eligibility criteria and characteristics, the randomization procedure, allocation concealment, which groups of people were masked, and how treatment adherence was assessed. The model classification is “single group,” although the record also describes a randomized, double-masked trial with six arms; the discrepancy is unexplained.

The registry reports the primary endpoint counts but no comparative estimates, uncertainty intervals, p-values, or analysis models. It does not identify a primary pairwise comparison, describe adjustment for multiple comparisons, or state whether covariates were used. The record lists one outcome measure and zero analyses. It also does not report the trial’s own sample-size justification or interim analyses.

Missing-data methods and analysis populations are not reported. The record does not explain why the denominators differ across arms or how participants without follow-up measurements were treated. The outcome description mentions continuous abstinence, but no results for that measure are posted. Secondary outcomes are not reported in the registry entry.

These limitations restrict interpretation of both efficacy and safety. The arm-level counts are descriptive, and the serious adverse event counts are not accompanied by comparative analyses. The registry record alone cannot establish the precision of between-arm differences, the effects of missing data, or how representative the results are beyond the population described in the record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Smoking Cessation Medications: Efficacy, Mechanisms and Algorithms — NCT00332644.
• Registry record last updated 2011-11-30; status last verified 2011-10.
• Results first posted 2011-11-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes a completed phase 4, randomized, double-masked study sponsored by the University of Wisconsin, Madison, with a planned enrollment of 1504. It lists six arms: nicotine patch, nicotine lozenge, nicotine patch plus lozenge, bupropion, bupropion plus nicotine lozenge, and placebo control.

The primary outcome is the count meeting a biochemically confirmed 7-day point-prevalence smoking abstinence definition at 6 months post quit date. Arm-level denominators and counts are posted, along with serious adverse event counts. The registry lists one outcome measure and zero analyses; comparative estimates, confidence intervals, missing-data methods, and the statistical analysis plan are not reported. The record’s “single group” model classification does not align with its randomized, multiple-arm description, and that discrepancy is not explained.