This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Pharmacogenetics of Nicotine Addiction Treatment (NCT01314001), a randomized phase 3 study. The primary outcome is 7-day Point Prevalence Quit Rate at End-of-Treatment (EOT).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01314001 |
| Phase | Phase 3 |
| Condition | Nicotine Addiction |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 1246 |
| Arms in the primary outcome | 6 |
| Lead sponsor | University of Pennsylvania |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerned smokers classified by nicotine metabolite ratio (NMR) as slow or normal metabolizers. The primary endpoint population was the intent-to-treat population, defined in the registry record as all subjects who received at least one dose of intervention. Further eligibility details are not reported in the registry record.
Intervention
The active treatments were varenicline and transdermal nicotine, described in the registry arms as nicotine patch. Each was studied in both metabolizer groups. The study’s stated purpose was to understand whether NMR may influence a smoker’s ability to quit.
Comparator
Placebo arms were included for slow and normal metabolizers. In the arm descriptions, placebo pills and placebo patches were used in the placebo groups; active treatment groups received the assigned active medication with a matching placebo for the other formulation.
Primary question
At Week 11, what percentage of the intent-to-treat subjects in each treatment and metabolizer group met the registry definition of verified abstinence? The registry posts arm-level percentages, but a formal treatment-by-metabolizer interaction estimate or a single primary between-arm comparison is not reported in the registry record.
The clinical question is therefore about the pattern of end-of-treatment quit percentages across six treatment-by-metabolizer groups, rather than a single contrast that can be read directly from the posted results. The design permits descriptive inspection of whether the arm percentages appear different across NMR groups, but the percentages alone do not establish that NMR modifies treatment effects. That conclusion would require a prespecified statistical comparison of the treatment effect across metabolizer groups, with its estimate and uncertainty. Such an analysis is not reported in the registry record.
3. Trial Design
NCT01314001, titled “Pharmacogenetics of Nicotine Addiction Treatment,” is recorded as a phase 3, randomized, triple-masked, parallel study. The sponsor was the University of Pennsylvania. The registry lists enrollment of 1246 and a completed status. The recorded start was 2010-12, and primary completion was 2013-12.
The six arms combine treatment assignment with metabolizer classification: placebo, nicotine patch or varenicline among slow metabolizers, and the same three treatments among normal metabolizers. The arm descriptions state that participants assigned varenicline took active pills with a placebo patch, while participants assigned transdermal nicotine took placebo pills with an active patch. Treatment descriptions specify daily pills for twelve weeks and patch use for eleven weeks. The placebo arm used placebo pills and a placebo patch.
Randomization and triple masking are recorded, but the randomization method, allocation concealment details, and which parties were masked are not reported in the registry record. The record also does not report the planned allocation ratio or whether assignment was stratified by NMR group. The posted arm sizes range from 191.0 to 227.0 participants, but those observed sizes do not by themselves establish how assignment was planned.
The primary endpoint was assessed at Week 11. The trial also lists six-month quit status and repeated side-effect severity assessments among secondary outcomes. Details of recruitment, eligibility, adherence, treatment discontinuation, and protocol deviations are not reported in the registry record. The design description identifies the treatment groups and masking structure, but does not provide enough detail to reconstruct the full protocol or the analysis plan.
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: Subjects were randomly assigned to one of three treatment groups in a 1:1:1 ratio: "Placebo"; "Nicotine Patch"; or "Varenicline". Randomization was stratified by nicotine metabolite ratio - slow metabolizers of nicotine vs. normal metabolizers - and study site and blocked in blocks of 12 to maintain balance. Slow metabolizers were over-sampled.
Overall Study
| Stage | Placebo (Slow Metabolizers) | Placebo (Normal Metabolizers) | Nicotine Patch (Slow Metabolizers) | Nicotine Patch (Normal Metabolizers) | Varenicline (Slow Metabolizers) | Varenicline (Normal Metabolizers) |
|---|---|---|---|---|---|---|
| STARTED | 215 | 193 | 227 | 191 | 220 | 200 |
| End-of-Treatment Visit | 156 | 141 | 179 | 146 | 174 | 160 |
| 6-Month Follow Up Survey | 146 | 137 | 165 | 135 | 157 | 139 |
| COMPLETED | 140 | 124 | 158 | 122 | 148 | 129 |
| NOT COMPLETED | 75 | 69 | 69 | 69 | 72 | 71 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-treat population (all subjects who received at least one dose of intervention).
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 number of subjects who began treatment period in the project (intention-to-treat).
Only the first 6 of 7 groups are shown.
| Characteristic | Unit | Placebo (Slow Metabolizers) | Placebo (Normal Metabolizers) | Nicotine Patch (Slow Metabolizers) | Nicotine Patch (Normal Metabolizers) | Varenicline (Slow Metabolizers) | Varenicline (Normal Metabolizers) |
|---|---|---|---|---|---|---|---|
| Participants analysed | 215 | 193 | 227 | 191 | 220 | 200 | |
| Age, Continuous | years | 44 (SD 11) | 47 (SD 11) | 46 (SD 11) | 46 (SD 11) | 44 (SD 12) | 46 (SD 12) |
| Sex: Female, Male: Female | Participants | 83 | 91 | 88 | 94 | 88 | 99 |
| Sex: Female, Male: Male | Participants | 132 | 102 | 139 | 97 | 132 | 101 |
| Race/Ethnicity, Customized: White | participants | 97 | 128 | 117 | 119 | 99 | 133 |
| Race/Ethnicity, Customized: Black | participants | 95 | 56 | 94 | 57 | 107 | 53 |
| Race/Ethnicity, Customized: Other | participants | 23 | 9 | 16 | 15 | 14 | 14 |
| Region of Enrollment: Canada | participants | 47 | 43 | 52 | 42 | 48 | 44 |
| Region of Enrollment: United States | participants | 168 | 150 | 175 | 149 | 172 | 156 |
| Education level: High school education or lower | participants | 68 | 57 | 78 | 49 | 74 | 61 |
| Education level: Post-high school education | participants | 147 | 136 | 149 | 142 | 146 | 139 |
| Annual Income (US dollars): Greater than or equal to US$50,000 | participants | 65 | 79 | 82 | 75 | 74 | 71 |
| Annual Income (US dollars): Less than US$50,000 | participants | 150 | 114 | 145 | 116 | 146 | 129 |
| Employment Status: Not employed | participants | 79 | 84 | 69 | 71 | 88 | 75 |
| Employment Status: Employed | participants | 136 | 109 | 158 | 120 | 132 | 125 |
| FTND Score | units on a scale | 5.3 (SD 1.92) | 5.4 (SD 2.00) | 5.2 (SD 2.00) | 5.3 (SD 1.89) | 5.1 (SD 2.00) | 2.1 (SD 2.02) |
| Cigarettes per day | cigarettes per day | 17.6 (SD 7.0) | 19.6 (SD 8.7) | 17.6 (SD 7.0) | 18.5 (SD 7.0) | 16.7 (SD 5.4) | 18.4 (SD 6.3) |
6. Primary Endpoint
The registry lists the primary outcome as 7-day Point Prevalence Quit Rate at End-of-Treatment (EOT), measured over Week 11.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of ITT subjects |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the 7-day point prevalence quit rate at end-of-treatment, assessed at Week 11. It is reported as the percentage of intent-to-treat subjects who were verified as abstinent. Abstinence required no self-reported smoking, not even a puff, during at least 7 days before the telephone assessment. Participants who reported abstinence had in-person verification with breath carbon monoxide analysis; a reading of 8 parts-per-million or less confirmed abstinence. Subjects lost to follow-up were classified as smokers.
A short-window point prevalence measure captures abstinence over a defined recent period rather than continuous abstinence throughout the whole study. Verification adds an objective check for participants who self-report quitting. This combination defines the outcome more specifically than a self-report alone, while the classification of loss to follow-up as smoking makes the endpoint rule explicit for that group.
The reported percentages are calculated in the registry’s stated intent-to-treat population: subjects who received at least one intervention dose. That definition is not necessarily equivalent to including every randomized subject, because the registry’s wording makes receipt of a dose the inclusion criterion. The actual numbers of abstinent participants and the confidence intervals for the primary arm percentages are not reported in the registry record. The outcome therefore communicates the observed percentage in each arm, but does not directly show the precision of each percentage or a formal comparative effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The end-of-treatment abstinence percentages differ across the six posted arms. Among slow metabolizers, the placebo percentage was 17.2, the nicotine patch percentage was 27.7, and the varenicline percentage was 30.4. Among normal metabolizers, the corresponding percentages were 18.6, 22.5, and 38.5. The largest posted arm percentage was 38.5 for varenicline among normal metabolizers, and the smallest was 17.2 for placebo among slow metabolizers.
These are descriptive arm results. The registry record does not report a confidence interval, standard error, p-value, adjusted estimate, or formal comparison for the primary endpoint. Consequently, the differences in the displayed percentages should not be treated as evidence that one treatment is statistically superior, or that metabolizer status changes the relative effects of treatment. The record also does not report a direct estimate of the NMR-by-treatment interaction. The pattern can motivate questions for a comparative analysis, but cannot answer those questions on its own.
Interpretation also depends on the outcome definition. The percentages represent verified abstinence during the specified seven-day period at the Week 11 assessment, with loss to follow-up counted as smoking. They do not represent continuous abstinence over the full treatment period or long-term abstinence. The listed six-month quit outcome is a secondary outcome, and its results are not reported in the registry record.
The registry’s primary endpoint description identifies the denominator as the intent-to-treat population, defined as subjects who received at least one dose. Arm sizes are posted, but the numbers who were randomized, excluded from this population, or lost to follow-up are not separately reported. Without those details and uncertainty estimates, it is difficult to assess how much sampling variability may affect the observed percentages. The percentages are useful for describing the posted results, but they do not establish a causal contrast or provide a precise estimate of treatment effects.
The appropriate statistical reading is therefore restrained: the arm percentages show variation across treatment and NMR groups, while the evidence needed to quantify the uncertainty of those differences and test the pharmacogenetic question is not reported in the registry record. No treatment conclusion follows from the descriptive pattern alone.
9. Statistical Methods Explained
The primary endpoint is a binary outcome at the participant level: a subject either meets the registry’s definition of verified abstinence at the assessment or does not. Reporting the percentage meeting that definition is a natural way to summarize a binary outcome within each arm. The percentage is descriptive; a comparison between arms needs an estimate of the contrast and a measure of uncertainty. The registry record posts the percentages and arm sizes, but does not report inferential comparisons for this endpoint.
What does a confidence interval add?
In general, a confidence interval describes the range of effect estimates that are reasonably compatible with the observed data under a statistical model and its assumptions. It communicates precision: a wider interval indicates less precision than a narrower interval. It is not a guarantee that the true effect lies within the interval, nor is it the probability that a particular treatment effect is true. No confidence intervals for the primary abstinence percentages are reported in the registry record, so the precision of those percentages cannot be read from the posted primary results.
How should a p-value be read?
In general, a p-value assesses how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the analysis assumptions were correct. It does not measure the size or clinical importance of an effect, and it is not the probability that the null hypothesis is true. The registry record reports no p-values or primary endpoint comparison. A reader should not infer statistical significance from the visual ordering of arm percentages.
For the posted continuous secondary outcomes, the registry provides arm means and standard deviations, with a limited set of pairwise summaries. Those summaries are unadjusted recalculations from posted arm summary statistics, not reported sponsor analyses. The mean difference expresses the difference between the two arm means in the units of the scale. Its confidence interval describes uncertainty under the recalculation’s assumptions. A standardized effect measure expresses a mean difference relative to pooled variability; it can help compare the scale of a difference with the spread of scores, but does not replace interpretation in the original scale units.
The secondary summaries list unadjusted p-values. “Unadjusted” means that the p-values have not been adjusted to account for testing multiple outcomes or comparisons. The summaries are therefore exploratory and should not be read as confirmatory tests of a prespecified hypothesis. No reported analyses are listed in the registry record. The statistical plan, including the intended analysis model and any adjustment strategy, is not reported in the registry record.
What do the planning illustrations mean?
The planning illustrations are calculated from observed effects, rather than being the trial’s own sample-size justification. They assume a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Their rows consider planning for 100%, 75%, and 50% of the observed effect. The displayed values are participants per arm for 80% power and participants per arm for 90% power.
These values are hypothetical planning quantities. They describe sample sizes that would be required under the stated assumptions to detect the selected effect size with the specified power. They are not the number enrolled in the trial, do not establish the original design target, and are not “observed power.” Because the calculations use an effect observed in these results, they are sensitive to the uncertainty and potential over- or underestimation of that observed effect. The actual design assumptions and sample-size justification are not reported in the registry record.
More generally, over-dispersion matters when the variation in observed data is greater than a model assumes. If a model underestimates variability, standard errors may be too small and intervals too narrow; if it allows for extra variability, uncertainty may be more realistic. This is a general statistical consideration, not a feature that can be assessed for the primary binary endpoint from the posted arm percentages alone. The registry record does not report a model-based primary analysis or a dispersion assessment.
The sample-size illustrations concern pairwise planning and should not be confused with a plan for the full six-arm, biomarker-stratified design. A study designed to test whether treatment effects differ by metabolizer group would need a clearly specified interaction analysis and suitable precision for that contrast. Such a design target or analysis is not reported in the registry record. For the primary endpoint, the most defensible reading remains descriptive, while the secondary recalculations and planning illustrations should be treated as supportive statistical context rather than sponsor-reported confirmatory findings.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists multiple secondary outcomes in addition to the primary Week 11 abstinence endpoint. It does not report a multiplicity plan, such as a hierarchy of hypotheses, an adjustment method, or a distinction between confirmatory and exploratory secondary analyses. Without that information, the family of planned comparisons cannot be reconstructed, and the chance of false-positive findings across the analysis program cannot be quantified.
The posted secondary pairwise summaries are unadjusted recalculations, and no reported analyses are listed. Their p-values should therefore be interpreted as exploratory rather than as adjusted confirmatory evidence. The statistical analysis plan, including planned models, covariates, subgroup methods, handling of repeated measurements, and any interim analyses, is not reported in the registry record. Whether interim analyses were conducted is also not reported in the registry record.
For the primary outcome, the registry explicitly states that subjects lost to follow-up were considered smokers. This is a conservative and transparent endpoint rule in the sense that missing assessments do not count as abstinence. It does not reveal how many subjects were lost to follow-up in each arm or how many had other forms of missing outcome information. The handling of missing values for the secondary outcomes is not reported in the registry record.
The primary population is described as all subjects who received at least one dose of intervention. The number of randomized subjects who did not receive a dose, if any, and the disposition of those subjects are not reported in the registry record. The record does not provide a separate per-protocol population or explain whether analyses beyond the stated primary population were conducted. These omissions constrain assessment of attrition, deviations from randomized assignment, and the robustness of the findings to alternative missing-data assumptions.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Placebo (Slow Metabolizers) | 10 | 215 | 4.7% |
| Placebo (Normal Metabolizers) | 6 | 193 | 3.1% |
| Nicotine Patch (Slow Metabolizers) | 11 | 227 | 4.8% |
| Nicotine Patch (Normal Metabolizers) | 11 | 191 | 5.8% |
| Varenicline (Slow Metabolizers) | 3 | 220 | 1.4% |
| Varenicline (Normal Metabolizers) | 8 | 200 | 4.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo (Slow Metabolizers) | 194 of 215 |
| Placebo (Normal Metabolizers) | 171 of 193 |
| Nicotine Patch (Slow Metabolizers) | 206 of 227 |
| Nicotine Patch (Normal Metabolizers) | 169 of 191 |
| Varenicline (Slow Metabolizers) | 210 of 220 |
| Varenicline (Normal Metabolizers) | 185 of 200 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo (Slow Metabolizers) | Placebo (Normal Metabolizers) | Nicotine Patch (Slow Metabolizers) | Nicotine Patch (Normal Metabolizers) | Varenicline (Slow Metabolizers) | Varenicline (Normal Metabolizers) |
|---|---|---|---|---|---|---|---|
| Suicidal thoughts | Psychiatric disorders | 1 of 215 | 1 of 193 | 1 of 227 | 1 of 191 | 0 of 220 | 2 of 200 |
| Death | General disorders | 1 of 215 | 1 of 193 | 1 of 227 | 0 of 191 | 0 of 220 | 1 of 200 |
| Heart Attack | Cardiac disorders | 0 of 215 | 0 of 193 | 1 of 227 | 1 of 191 | 0 of 220 | 1 of 200 |
| Knee injuries | Musculoskeletal and connective tissue disorders | 0 of 215 | 0 of 193 | 1 of 227 | 0 of 191 | 1 of 220 | 1 of 200 |
| Stroke | Vascular disorders | 2 of 215 | 1 of 193 | 0 of 227 | 0 of 191 | 0 of 220 | 0 of 200 |
| Severe nausea/vomiting/abdominal pain | Gastrointestinal disorders | 0 of 215 | 0 of 193 | 1 of 227 | 0 of 191 | 0 of 220 | 1 of 200 |
| Gall bladder issues | Hepatobiliary disorders | 0 of 215 | 1 of 193 | 0 of 227 | 1 of 191 | 0 of 220 | 0 of 200 |
| Pneumonia | Infections and infestations | 0 of 215 | 0 of 193 | 1 of 227 | 0 of 191 | 1 of 220 | 0 of 200 |
| Broken bones | Musculoskeletal and connective tissue disorders | 2 of 215 | 0 of 193 | 0 of 227 | 0 of 191 | 0 of 220 | 0 of 200 |
| Cancer; colon | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0 of 215 | 0 of 193 | 1 of 227 | 1 of 191 | 0 of 220 | 0 of 200 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo (Slow Metabolizers) | Placebo (Normal Metabolizers) | Nicotine Patch (Slow Metabolizers) | Nicotine Patch (Normal Metabolizers) | Varenicline (Slow Metabolizers) | Varenicline (Normal Metabolizers) |
|---|---|---|---|---|---|---|---|
| Irritability | Psychiatric disorders | 125 of 215 | 123 of 193 | 130 of 227 | 119 of 191 | 128 of 220 | 114 of 200 |
| Sleep Problems | Psychiatric disorders | 109 of 215 | 81 of 193 | 103 of 227 | 100 of 191 | 118 of 220 | 109 of 200 |
| Gas | Gastrointestinal disorders | 110 of 215 | 101 of 193 | 108 of 227 | 91 of 191 | 111 of 220 | 98 of 200 |
| Agitation | Psychiatric disorders | 103 of 215 | 95 of 193 | 105 of 227 | 96 of 191 | 90 of 220 | 84 of 200 |
| Dry Mouth | General disorders | 89 of 215 | 71 of 193 | 99 of 227 | 74 of 191 | 111 of 220 | 62 of 200 |
| Abnormal Dreams | Psychiatric disorders | 68 of 215 | 64 of 193 | 94 of 227 | 88 of 191 | 97 of 220 | 89 of 200 |
| Flatulence | Gastrointestinal disorders | 82 of 215 | 77 of 193 | 85 of 227 | 69 of 191 | 94 of 220 | 81 of 200 |
| Anxiety | Psychiatric disorders | 74 of 215 | 87 of 193 | 84 of 227 | 86 of 191 | 71 of 220 | 73 of 200 |
| Fatigue | General disorders | 73 of 215 | 71 of 193 | 88 of 227 | 65 of 191 | 88 of 220 | 79 of 200 |
| Headache | General disorders | 95 of 215 | 74 of 193 | 75 of 227 | 64 of 191 | 88 of 220 | 60 of 200 |
Serious events with the highest arm-level rate: suicidal thoughts (1.0%), broken bones (0.9%), stroke (0.9%), heart attack (0.5%), pancreatitis (0.5%).
The registry posts serious adverse event counts by treatment and metabolizer group, alongside counts for other adverse events. The serious-event figures are 10 of 215 for placebo among slow metabolizers, 6 of 193 for placebo among normal metabolizers, 11 of 227 for nicotine patch among slow metabolizers, 11 of 191 for nicotine patch among normal metabolizers, 3 of 220 for varenicline among slow metabolizers, and 8 of 200 for varenicline among normal metabolizers. These are counts among the listed participants at risk, not comparative effect estimates.
Other adverse events were reported for 194 of 215, 171 of 193, 206 of 227, 169 of 191, 210 of 220, and 185 of 200 participants in the corresponding arms. The registry also lists serious-event terms including Suicidal thoughts (1.0%), Broken bones (0.9%), Stroke (0.9%), Heart Attack (0.5%), Pancreatitis (0.5%), and Tongue Swelling (0.5%). These terms and percentages do not indicate whether events were judged related to treatment.
Safety counts should be read descriptively. The registry record does not report comparative safety analyses, exposure-adjusted rates, event timing, or attribution. Death counts are not reported in the registry record. The posted counts alone do not establish that a treatment caused, prevented, or changed the risk of an event.
12. What the Result Does, and Does Not, Mean
The posted primary results describe the percentage of subjects meeting the trial’s verified abstinence definition at the Week 11 assessment in each treatment and metabolizer group. They show that the observed percentages vary across the six arms. They do not, on their own, quantify the uncertainty around those percentages or establish whether any observed difference is larger than could plausibly arise from sampling variation.
The record’s stated scientific aim concerns whether NMR may influence a smoker’s ability to quit. Showing percentages within NMR groups is relevant to that aim, but a pharmacogenetic claim requires more than noting that one subgroup has a higher percentage than another. The key statistical question is whether treatment contrasts differ across metabolizer groups. A formal interaction estimate, its uncertainty, and the analysis plan for that question are not reported in the registry record. The listed percentages cannot substitute for that analysis.
The result also has a defined time horizon and outcome meaning. It concerns verified abstinence over at least 7 days before a Week 11 assessment, with loss to follow-up counted as smoking. It does not demonstrate sustained abstinence over the entire trial or beyond treatment. Although a six-month quit outcome is listed, its results are not reported in the registry record.
Likewise, the secondary side-effect severity summaries and adverse-event counts provide context but do not prove a treatment effect on safety or explain the abstinence pattern. The unadjusted secondary comparisons have limited inferential weight, and the registry does not report the methods needed for a full comparative assessment.
In general, a registry result is most informative when the endpoint definition, analysis population, effect estimates, uncertainty, and prespecified analysis are all available. Here the endpoint and population definition are stated, and arm percentages are posted; comparative inference and primary endpoint precision are not. The results should therefore be read as descriptive registry findings, not as proof that a treatment works or does not work, or that NMR reliably selects a treatment.
13. Why This Trial Matters Statistically
This trial is statistically notable because its question concerns potential variation in treatment response by a biomarker, not only the average response to treatment. That distinction changes the target of inference. A comparison of treatments within a metabolizer group is not the same as a test of whether treatment effects differ between metabolizer groups. The latter is an interaction question and needs its own estimate and uncertainty.
The six-arm structure makes the descriptive pattern easy to organize by treatment and NMR classification, but the registry’s arm percentages do not provide a direct interaction test. A statistically sound interpretation must distinguish subgroup patterns from evidence of effect modification. Without a reported formal comparison, visual differences across groups are hypothesis-generating rather than confirmatory.
The trial also illustrates why endpoint definitions and missing-data rules matter. The primary outcome uses a short, explicitly defined abstinence window, objective verification for self-reported abstinence, and a stated rule for loss to follow-up. These details make the endpoint more interpretable than an outcome label alone. At the same time, the absence of arm-level missingness details limits assessment of how the rule affected the results.
Finally, the record offers secondary summaries and sample-size planning illustrations, but the distinction between reported analyses and recalculations is important. The secondary comparisons are unadjusted recalculations, and the planning figures are based on observed effects rather than the original design justification. Neither should be mistaken for the trial’s prespecified confirmatory analysis. This is a useful example of how registry information can support careful descriptive reading while leaving important inferential questions unanswered.
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 primary endpoint is reported as arm percentages without confidence intervals or a formal comparison. The registry record therefore does not show the precision of the primary estimates or the statistical uncertainty around treatment contrasts. The count of abstinent subjects is also not reported, limiting independent assessment of the percentages.
The central biomarker question is not answered by a reported interaction analysis. Although results are separated by slow and normal metabolizer classification, the method used to define these categories and the prespecified analysis of treatment-effect modification are not reported in the registry record. Eligibility criteria and the representativeness of participants are also not reported in the registry record, limiting assessment of generalizability.
The primary population is defined as subjects who received at least one dose, and loss to follow-up is classified as smoking. Arm-specific losses, other missingness, treatment adherence, discontinuation, and protocol deviations are not reported in the registry record. The record does not state whether sensitivity analyses were conducted for missing outcomes.
The secondary outcome information is incomplete: results for the listed six-month quit outcome and Week 4 side-effect severity measure are not reported in the registry record. The available pairwise continuous-outcome recalculations are limited in scope and unadjusted. The full statistical plan, including multiplicity control and any interim monitoring, is not reported in the registry record.
Safety results are counts rather than comparative analyses. Event attribution, timing, exposure-adjusted rates, and deaths are not reported in the registry record. These limitations do not invalidate the posted descriptions, but they constrain causal interpretation, precision, subgroup claims, and broader safety conclusions.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pharmacogenetics of Nicotine Addiction Treatment — NCT01314001.
- Registry record last updated 2016-03-03; status last verified 2016-02.
- Results first posted 2016-03-03.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT01314001 is recorded as a completed phase 3 randomized, triple-masked, parallel trial sponsored by the University of Pennsylvania, with enrollment of 1246. It studied varenicline, transdermal nicotine, and placebo in slow and normal nicotine metabolizer groups. The primary endpoint was verified 7-day point prevalence abstinence at Week 11 in subjects who received at least one intervention dose; loss to follow-up was classified as smoking.
The registry posts arm-level abstinence percentages, secondary side-effect severity summaries, and adverse-event counts. It does not report a primary comparative analysis, confidence intervals for the primary endpoint, or a formal treatment-by-metabolizer interaction. The secondary pairwise summaries are unadjusted recalculations, and the planning illustrations are not the trial’s own design justification. These results support descriptive reading, while key details needed for confirmatory inference and full assessment of missingness and safety are not reported in the registry record.