Nicotine Replacement Therapy (NRT) and Bupropion Mechanisms of Effectiveness in Smokers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nicotine Replacement Therapy (NRT) and Bupropion Mechanisms of Effectiveness in Smokers (NCT01048944), a randomized phase 4 study. The primary outcome is Changes in Log Brain-wave (EEG) Activity (Power [Microvolts Squared]) From Pre-quit Baseline to 66 Days Post-quit, Assessed at 3, 24, 45, and 66 Days Post-quit..

2. Clinical Question

3. Trial Design

This was a Phase IV, randomized, double-masked trial with a factorial model, conducted by Southern Illinois University Carbondale. The registry reports enrollment of 197 and a completed status. The listed study dates are 2005-06 for start and 2013-01 for primary completion. The condition was nicotine dependence.

The brief summary describes three treatment assignments over a 45-day period: bupropion SR, nicotine patch, or placebo patches plus pills. It also describes a 3-week intensive post-treatment follow-up and a delayed-quit control group. The arm descriptions specify bupropion SR at 150 mg bid, nicotine patches at 21mg, 14mg, and 7mg, and matching placebo patch and pill. The delayed-quit group was to smoke for 67 days while the other participants had quit, then quit.

Although the registry labels the model factorial, it does not report the factorial factors, their levels, or a treatment-by-factor analysis plan. The information needed to reconstruct the allocation structure or determine precisely how treatment comparisons were organized is not reported in the registry record. The record also does not give group enrollment counts for the primary EEG analysis.

The reported EEG population was restricted to people who complied with study requirements, including biochemically verified abstinence. The registry says future analyses would include people who complied with certain critical endpoints. It does not state how this restriction was handled in the analysis or how many participants were excluded from the primary analysis. Those details matter because results in an adherent, abstinent subset do not automatically represent the randomized population as a whole.

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: After consent subjects and the completion of their first experimental session subjects were randomly assigned to one of 4 treatment arms: 197 signed the consent, 126 completed the first experimental session and were subsequently randomly assigned to a treatment condition.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: For the currently reported analyses, only individuals complying with the study requirements, including biochemically verified smoking abstinence, were assessed. Future analyses will include individuals who complied to certain critical endpoints.

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: Personality trait questionnaires, history of psychiatric disorders, SES, age, smoking and drug use history.

6. Primary Endpoint

The registry lists the primary outcome as Changes in Log Brain-wave (EEG) Activity (Power [Microvolts Squared]) From Pre-quit Baseline to 66 Days Post-quit, Assessed at 3, 24, 45, and 66 Days Post-quit., measured over Mean EEG power [microvolts squared] from at baseline, 3, 24, 45, and 66 days post-quit.

The primary endpoint concerns change in log EEG power, measured in microvolts squared, from pre-quit baseline. EEG was collected with scalp electrodes while subjects relaxed, including frontal and parietal electrode locations. A commercial brain-wave machine recorded the signal, and computer programs quantified its frequency components.

The description identifies slow-frequency bands including delta, theta-1, theta-2, and alpha-1, as well as higher-frequency waves. It says delta, alpha-1, and theta waves generally reflect deactivation of brain activity, while higher-frequency waves reflect greater activation. EEG power was transformed using the natural logarithm, and the primary focus was the change in each participant’s log theta-1, theta-2, and alpha-1 power from pre-quit baseline.

Measurements were scheduled at baseline and 3, 24, 45, and 66 days post-quit. The endpoint is a mechanistic or physiological measure: it was intended to characterize brain-activity patterns relevant to the study’s stated interest in how smoking-cessation pharmacological treatments may affect mood, attention, and brain activation. It is not, by itself, a direct measure of sustained smoking cessation or a patient’s clinical experience. The registry does not report numerical EEG results by treatment, frequency band, or follow-up time.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods describe how measured outcomes are converted into estimates and how uncertainty in those estimates is assessed. The registry identifies a continuous outcome summarized as a mean, with standard error as the dispersion measure. It does not report the fitted model, the treatment contrasts, the handling of repeated observations, or the inferential procedure used for the primary EEG analysis. The methods below explain general considerations relevant to this kind of endpoint; they are not a claim about the analysis actually conducted.

What does a mean change represent?

For a continuous outcome, a mean summarizes the average value in an analysis group. Here the outcome is a change in log EEG power relative to pre-quit baseline. A mean change therefore describes average movement in the transformed measure within a group or at a particular follow-up. To estimate a comparative treatment effect, the analysis would ordinarily need to contrast changes between groups, rather than relying only on whether a within-group mean differs from baseline.

The logarithm is part of the outcome definition. A change in log power is not the same quantity as a raw change in microvolts squared. Log transformation can make distributions more suitable for some models and can express changes on a transformed scale. The registry does not provide the numerical estimates or further detail needed to translate its outcome into a practical magnitude.

Why is the standard error relevant?

A standard error describes the precision of an estimated mean under the assumptions of the analysis. It is not a description of how variable individual participants’ EEG measurements are. A confidence interval uses an estimate and its uncertainty to show a range of values compatible with the data and the statistical model. A narrower interval indicates greater precision than a wider one, while neither interval width nor an estimate alone establishes clinical importance.

No standard errors or confidence intervals for the primary EEG results are reported in the registry record. As a result, readers cannot assess the precision of group means or treatment contrasts from the posted primary-outcome information.

Why do repeated time points matter?

Measurements at several post-quit times on the same person are correlated: a participant’s observations tend to be related because they come from the same individual. A statistical model for repeated measurements can account for that dependence and can estimate how patterns change over time. It may also distinguish an overall treatment difference from a treatment-by-time pattern. These are general concepts, not details confirmed for this trial. The registry lists assessments at 3, 24, 45, and 66 days post-quit, but does not report a repeated-measures model, covariance structure, or a treatment-by-time test.

Separate tests at each time and for each EEG band can generate many estimates. A prespecified primary contrast can make interpretation more focused; adjustment procedures can also be used when many hypotheses are tested. The registry does not state which contrasts were prespecified, whether a multiplicity adjustment was used, or how results across bands and times were interpreted.

What is the role of the randomized design?

Random allocation is intended to make treatment groups comparable at the point of assignment, on average, so that a properly analyzed between-group contrast can support a causal interpretation under the study’s assumptions. Double masking can reduce some forms of bias in treatment delivery and outcome assessment. Neither design feature alone guarantees an unbiased result. How participants were analyzed, how missing observations were handled, and whether masking was maintained are also relevant; these details are not reported in the registry record.

The registry labels the model factorial, but gives no factor definitions or analysis plan for factorial effects. Therefore, it is not possible to identify from the record whether the primary estimate was intended to represent a main effect, an interaction, or another contrast. No conclusion about those effects can be drawn without the relevant estimates and model description.

What do the planning assumptions mean?

The registry describes a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. Such a calculation concerns a hypothetical future design under assumptions; it is not evidence that the trial had a particular probability of finding an effect, and it is not observed power. Numerical planning estimates are not reported in the registry record. The registry also states that the event-total convention applies to time-to-event tables and that other planning outputs are participants per arm. No numerical estimate for this continuous EEG endpoint is available in the posted information.

There is no recalculated treatment effect to interpret because the registry outcome was not reduced to a single comparison and the necessary group summary results are not reported. The sponsor’s own analysis therefore cannot be compared with an independent recalculation using the information in the record.

10. Multiplicity, Missing Data and Analysis Populations

The primary EEG outcome spans multiple frequency bands and follow-up times. The registry identifies theta-1, theta-2, and alpha-1 as the main focus, and lists measurement at 3, 24, 45, and 66 days post-quit. This creates several possible ways to define a primary comparison. The record does not report whether a single primary contrast was chosen in advance, how the family of comparisons was defined, or whether any adjustment for multiple testing was applied. Without that information, statistical significance across any individual band or time would require careful interpretation; the numerical results themselves are not reported in the registry record.

Missing-data methods are also not reported. The registry does not state how participants with incomplete EEG measurements were handled, whether analyses used all available measurements, or whether any imputation method was applied. It also does not report the number of participants contributing data to each time point. These omissions limit assessment of how missing observations might affect estimates and uncertainty.

The analysis population is described as people complying with study requirements, including biochemically verified smoking abstinence. This is not enough to determine whether the primary analysis followed intention-to-treat, per-protocol, or another approach. The registry does not describe how compliance was defined, how the eligible analysis population was selected, or whether this population was determined before outcomes were examined.

The record reports 2 outcome measures and 1 analysis, but does not explain how those registry counts relate to the multiple EEG components and times in the primary outcome description. No statistical analysis plan, multiplicity procedure, missing-data strategy, or clear analysis-population definition is reported in the registry record.

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 non-serious adverse event terms

The registry lists serious adverse events as affecting 0 participants in each of the four groups, with 32 at risk in Bupropion SR, 38 at risk in Nicotine Patch, 35 at risk in Placebo Patch and Placebo Pill, and 21 at risk in Delayed-quit Control. The record lists no serious adverse-event terms. These entries describe the recorded serious-event counts; they do not establish that no serious events occurred outside the registry’s reporting scope or observation period.

For other adverse events, the registry reports 21 affected participants in Bupropion SR, 22 in Nicotine Patch, 19 in Placebo Patch and Placebo Pill, and 6 in Delayed-quit Control. The corresponding numbers at risk are 32, 38, 35, and 21, respectively. These are group-level registry counts, not a comparative statistical analysis. The record does not provide event-specific descriptions, severity breakdowns for these other events, or a statistical comparison between groups.

Deaths are recorded as null for each group, so death counts are not reported in the registry record. The adverse-event figures should be read separately from the EEG outcome: they do not provide evidence about treatment effects on brain-wave activity or smoking cessation.

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

The record describes a randomized, double-masked trial designed to study the mechanisms associated with bupropion SR and nicotine patch, with placebo and delayed-quit control conditions. Its primary endpoint uses changes in log EEG power across specified frequency bands and post-quit assessments. That design and outcome description clarify the scientific question, but do not supply the results needed to answer it quantitatively.

No numerical group means, treatment contrasts, confidence intervals, or p-values for the primary EEG outcome are reported in the registry record. Consequently, the posted information cannot establish the size, direction, or precision of any difference between treatment groups. It also cannot determine whether EEG changes varied by time or frequency band. The absence of a single reduced comparison is especially consequential because the outcome involves multiple components and assessment times.

The outcome is a brain-activity measure, not a direct measure of cessation success. While the study summary describes a purpose related to pharmacological treatment and quitting smoking, the primary endpoint does not itself report whether participants quit, remained abstinent, or experienced a clinical benefit. No such conclusion should be inferred from EEG measurements without the relevant outcome data and analysis.

The reported analyses were restricted to participants complying with study requirements, including biochemically verified abstinence. This means any results from that population would need to be distinguished from results for all randomized participants. The registry does not report how many people contributed to the primary analysis, how missing outcomes were handled, or whether the analysis preserved the randomized comparison.

The safety listings show recorded counts of serious and other adverse events, but do not give event-specific details or comparative tests. The figures alone do not establish a difference in safety between groups. Overall, the registry supports a description of trial design and measurement, while the principal treatment-effect conclusions remain unavailable in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically notable for its combination of a mechanistic outcome, repeated measurements, and a restricted analysis population. EEG activity was measured at multiple post-quit times and described across several frequency bands. That structure makes the choice of estimand and the method for handling within-person correlation central to interpretation. The registry does not provide those analytic details or a single primary contrast.

The study also highlights the distinction between a biological or physiological endpoint and a clinical outcome. A change in log EEG power can characterize brain activity, but it does not by itself establish an effect on quitting or a patient-important outcome. Clear reporting should connect the measured endpoint to the research question without treating a mechanistic measure as a substitute for clinical evidence.

Randomization and masking are important design features, but analysis decisions still matter. The record specifies that the current primary analyses included people who complied with study requirements, including verified abstinence. Restricting analysis after randomization can change the population represented by the estimate. Reporting how that group was defined, how many participants were analyzed, and how missing data were handled would help readers assess the consequences.

Finally, an outcome with several bands and times raises questions about multiplicity and emphasis. A clearly reported primary contrast and analysis plan help distinguish confirmatory findings from exploratory patterns. In this case, the registry gives enough detail to identify the measurement strategy, but not enough to assess treatment-effect estimates or their uncertainty. That distinction is useful when evaluating what a trial record can and cannot support.

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.

The main limitation of the registry information is that it does not report numerical primary EEG results. Without group summaries and a defined treatment contrast, the size and precision of any effect cannot be evaluated. The outcome description includes several frequency bands and multiple post-quit times, but the record does not identify a single comparison that represents the primary question.

The primary analysis population was restricted to people complying with study requirements, including biochemically verified abstinence. The number included in the EEG analysis, the criteria for compliance, and the relationship between that selected population and all randomized participants are not reported. This restricts assessment of selection effects and generalizability.

Important analytic details are also absent: the statistical model, treatment contrasts, repeated-measures method, multiplicity approach, and missing-data handling are not reported in the registry record. The factorial label is not accompanied by descriptions of the factors or the planned analysis of their effects. The record also does not state whether the reported analyses followed an intention-to-treat strategy.

The safety information is limited to counts of participants affected and at risk. Event terms and comparative safety analyses are not reported, and death counts are not reported in the registry record. Finally, the record includes planning assumptions but no numerical planning estimate for this EEG outcome. These gaps prevent a full assessment of statistical precision, robustness, and the clinical relevance of any treatment differences.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Nicotine Replacement Therapy (NRT) and Bupropion Mechanisms of Effectiveness in Smokers — NCT01048944.
• Registry record last updated 2014-11-25; status last verified 2014-11.
• Results first posted 2014-11-25.
• 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

NCT01048944 is a completed, randomized, double-masked Phase IV trial sponsored by Southern Illinois University Carbondale. The registry reports enrollment of 197 and identifies nicotine dependence as the condition. The study compared bupropion SR, nicotine patch, placebo patch and pill, and a delayed-quit control as described in the record.

The primary outcome was change in log EEG power from pre-quit baseline, with assessments at 3, 24, 45, and 66 days post-quit. The main focus was theta-1, theta-2, and alpha-1 power. The currently reported analyses were limited to participants meeting study requirements, including biochemically verified abstinence.

Numerical primary-outcome comparisons, analysis details, and the size of the EEG analysis population are not reported in the registry record. The safety listing records serious and other adverse events by group, but does not provide event-specific comparative analyses.