A Pilot Study Of Smoking Cessation Treatment Including Varenicline In Patients Scheduled For Planned Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Pilot Study Of Smoking Cessation Treatment Including Varenicline In Patients Scheduled For Planned Surgery (NCT00889720), a non-randomized phase 4 study. The primary outcome is Percentage of Fully Compliant Participants.

2. Clinical Question

3. Trial Design

This was a completed Phase 4, multicenter, open-label, non-randomized, single-group study. The intervention was varenicline as part of a smoking-cessation program for patients scheduled for elective surgery. Enrollment was 16. There was no masking, and the record identifies no randomized comparison group. The study began in 2009-11, and primary completion was recorded as 2010-07.

The study’s stated purpose was to examine whether a cessation program including varenicline could be offered to people awaiting elective surgery, whether some participants could quit smoking for up to 4 weeks before surgery, and whether this might be associated with fewer postoperative complications such as wound infections. These are motivating questions, not reported findings. The primary endpoint instead captured a defined package of treatment completion, surgery timing, and wound-infection assessments.

That package required 12 weeks of varenicline therapy, surgery 8 weeks ±10 days after starting treatment, and wound-infection evaluations 1 to 3 days and 6 to 10 days after surgery. Thus, the primary endpoint combines several steps in the study pathway. A participant could fail to meet the endpoint because one or more required steps were not completed; the record does not report how often each individual requirement was met.

The record lists 22 outcome measures and names secondary measures concerning postoperative-complication severity, smoking reduction, abstinence at later time points, and treatment-emergent adverse events. It reports 0 analyses. The primary endpoint percentage, its denominator, and a corresponding uncertainty estimate are not reported in the registry record. No analysis plan, sample-size justification, or interim-analysis plan is reported there. The small enrollment and absence of a comparator limit what this design can establish about treatment effects.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Surgical Population: subset of Full Analysis Set; includes all participants who took at least 1 dose (including partial doses) of study medication and received their planned surgery within the study period. N = participants in surgical population.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Fully Compliant Participants, measured over Baseline through Week 12.

The primary endpoint was the percentage of fully compliant participants from baseline through Week 12. The definition required completion of 12 weeks of varenicline therapy, surgery 8 weeks ±10 days after treatment began, and wound-infection evaluations 1 to 3 days and 6 to 10 days after surgery. The endpoint therefore measures completion of a specified treatment-and-follow-up pathway, rather than smoking abstinence alone or wound infection alone.

Such a composite process measure can address whether participants complete several steps needed to carry out the planned program and collect postoperative assessments. It may be useful for evaluating feasibility: if the required steps cannot be completed, the planned follow-up process may be difficult to implement in this setting. However, the endpoint does not isolate which step was difficult, and meeting the definition does not by itself establish smoking cessation or a change in complication risk.

The registry record defines the primary population as the surgical population, a subset of the Full Analysis Set consisting of participants who took at least 1 dose of study medication and received their planned surgery within the study period. The record does not report the number in that population or the percentage meeting the endpoint. Without those results, the endpoint’s observed frequency and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the single-group design allow?

In a single-group study, participants receive the study intervention and outcomes are recorded without a randomized control group. This can document whether a program was carried out and what outcomes were observed among participants. It does not create a direct comparison with an alternative intervention or usual care. Without such a comparison, differences from an assumed baseline or from experience in other settings cannot be treated as an intervention effect.

Here, the allocation was non-randomized, masking was absent, and the model was single-group. Those features are important when interpreting both process outcomes and events. Participants and study personnel knew the intervention, and decisions or assessments may be influenced by that knowledge. The record does not describe methods intended to address these possibilities. The registry record also does not report an analysis plan, so the statistical approach to the primary endpoint is not established by the available entry.

What does a percentage endpoint mean?

A percentage summarizes the fraction of a defined group that meets an outcome. Its interpretation depends on both the numerator—the participants meeting the definition—and the denominator—the population in which the percentage is calculated. The primary endpoint requires several conditions to be satisfied, including treatment completion, surgery timing, and postoperative evaluations. The registry record describes the denominator as the surgical population, but does not report its size or the number who met all criteria. No primary percentage can therefore be interpreted from the reported endpoint description alone.

For a multi-part definition, a single overall percentage can conceal which component was not met. Separate component results can help distinguish treatment completion from scheduling or assessment completion. The registry record does not report those component results. Nor does the endpoint definition alone tell whether a participant stopped smoking or experienced a complication.

How should uncertainty be understood?

In general, an estimate is more informative when accompanied by a measure of uncertainty, such as a confidence interval. A confidence interval expresses how compatible a range of values is with the observed data and the assumptions of the analysis. It does not correct for bias, establish causation, or compensate for the absence of a suitable comparison group. The primary percentage and its uncertainty are not reported in the registry record, so its precision cannot be assessed.

Small studies commonly have limited ability to estimate event frequencies precisely. This is a general statistical point, not a new calculation about this study. With enrollment of 16, a small change in the number of participants with an outcome could materially alter a percentage. No new percentage or interval should be inferred without the endpoint numerator and denominator.

Why does a comparison design matter?

Random allocation, when used, is intended to make groups comparable on average with respect to measured and unmeasured factors. This study was not randomized and had no control arm. A comparison with a separate population would also require careful attention to differences in eligibility, clinical care, follow-up, and outcome definitions. Such a comparison is not reported in the registry record. The posted information therefore describes participants in one study group rather than an estimated contrast between treatment strategies.

The record includes a general planning illustration based on an observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. These are assumptions for an illustrative planning exercise, not a description of this trial’s design, and the stated sample sizes are not observed power. A two-arm planning framework should not be mistaken for evidence that this single-group study had a randomized comparator. The registry record does not report the trial’s own sample-size justification.

Why can event counts be difficult to interpret?

Adverse-event counts describe how many participants experienced events under the recorded definitions and follow-up. Serious events and other events are distinct categories in the record; the counts should not be added because the record does not say whether participants overlap across categories. Event counts do not establish that the study drug caused an event. Attribution requires clinical and methodological assessment, and a non-randomized single-group study cannot estimate comparative event risk on its own.

For recurrent events, the number of events can differ from the number of participants with at least one event. The posted safety figures distinguish participants affected from event terms, but the information reported does not provide a full participant-level account. The listed serious-event term and its percentage should be read as a reported safety detail, not as a comparative estimate or proof of causation.

What can be said about statistical planning?

The registry record reports 0 analyses and does not report a statistical analysis plan, interim analyses, or a justification for the enrollment target. It also does not report how missing endpoint assessments were handled. General methods such as prespecifying an endpoint, denominator, missing-data approach, and multiplicity strategy can improve transparency; whether those methods were used in this study is not reported in the registry record. No method should be attributed to this trial without a registry entry stating it.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Varenicline")
n      <- c(12)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Varenicline  12  0  0.0  0.0  26.5  0.0  24.2  0.2  24.7

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 22 outcome measures, including the primary compliance endpoint and secondary measures involving postoperative-complication severity, smoking reduction, abstinence, and adverse events. When a study examines multiple outcomes, the chance of at least one apparently notable result can increase if many statistical tests are conducted. General approaches to multiplicity include prespecifying a primary outcome, adjusting for multiple comparisons, or treating secondary findings as exploratory. The registry record does not report a multiplicity strategy, so it is not possible to determine how multiple outcomes were handled inferentially.

The record reports 0 analyses and does not give the primary endpoint result or results for most listed outcomes. It also does not describe missing-data methods, the number of participants with missing assessments, or whether any sensitivity analyses were conducted. These details are important because the primary endpoint requires treatment completion, surgery in a specified window, and two postoperative evaluations. Missing any required information could affect whether the composite definition is met, but the record does not say how such cases were classified.

The primary population is described as the surgical population, a subset of the Full Analysis Set, including participants who took at least 1 dose and received planned surgery within the study period. The size of this population is not reported in the registry record. The entry also does not report how many participants were excluded from it or provide results for other analysis populations. Therefore, the denominator and the implications of population selection cannot be 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: intestinal obstruction (6.2%).

The posted safety figures list 1 participant with a serious adverse event among 16 at risk in the varenicline group. Other adverse events were reported for 9 participants among 16 at risk. These are counts of participants affected, not counts of all event episodes, and the two categories should not be added: the record does not say whether any participant appears in both.

Intestinal obstruction is listed among the serious-event terms with 6.2%. The record does not provide a comparative group, so this figure cannot be interpreted as a comparison of risk between treatments. Nor does the listing establish that varenicline caused the event. The registry record does not report deaths.

These safety observations describe what was recorded for this study group and its reported denominators. They do not establish how frequently similar events would occur in a broader population, and they cannot support a comparative safety conclusion without an appropriate comparator and fuller context. The registry record does not give further detail about individual event timing or outcomes in the information.

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

The study addresses a practical question: can a smoking-cessation program including varenicline be offered to patients scheduled for elective surgery, with treatment and postoperative assessments organized around the planned operation? Its primary endpoint encodes completion of a defined pathway. That makes feasibility and process completion central to the endpoint’s meaning.

The record does not report the primary percentage or the number of participants meeting the full-compliance definition. Consequently, the available information cannot show whether the endpoint was achieved frequently or rarely, or how precisely it was estimated. The record’s description of the study aim—including quitting before surgery and possible reductions in postoperative complications—does not substitute for outcome results.

The endpoint also should not be read as a direct measure of smoking cessation or surgical complications. It requires completing therapy, having surgery within a time window, and attending wound-infection evaluations. The listed secondary outcomes concern smoking and complications, but their results are not reported in the registry record. No conclusion about changes in abstinence, cigarette consumption, or postoperative complications follows from the endpoint definition alone.

Because this was a non-randomized single-group study, it cannot provide a like-for-like treatment comparison. Any outcome observed in such a group may reflect factors other than the program, and the registry record does not report a comparator or an adjusted causal analysis. The safety counts are descriptive observations and likewise do not establish comparative risk or causation.

Thus, the record identifies the study structure, intended questions, primary endpoint criteria, and some safety counts. It does not establish whether the program changed outcomes, whether varenicline caused a reported event, or how the endpoint result compares with another approach. The absence of a reported primary result is not evidence that no participants met the endpoint.

14. Why This Trial Matters Statistically

This study is statistically relevant because it illustrates the distinction between a feasibility-oriented process endpoint and a clinical outcome. A composite definition can make implementation measurable by requiring treatment completion, appropriate surgery timing, and follow-up assessments. At the same time, a single summary percentage would not reveal which step determined success, and the registry record does not report component results.

Its design also highlights why a control group matters. A single-group study can document what occurred among participants, but cannot separate the effect of the program from other influences. That limitation is especially important when the underlying question connects preoperative smoking cessation with postoperative complications. A stated research aim is not an estimate of an effect, and the record does not report the primary endpoint result or results for the listed complication outcomes.

The endpoint’s population definition further matters. The primary population is restricted to participants who took at least 1 dose and received planned surgery within the study period. The size of that population is not reported, so the primary denominator cannot be checked against enrollment. This makes clear why outcome interpretation depends on transparent reporting of both the result and the analysis population.

Finally, the safety counts offer a descriptive snapshot, not a comparative assessment. Their interpretation depends on the denominator, event definitions, and follow-up, and they do not by themselves establish causation. These design and reporting distinctions are useful whenever a registry entry is used to understand what a clinical study can—and cannot—answer.

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.

The most immediate limitation is that the primary endpoint result is not reported in the registry record. Its denominator is also not given, even though the endpoint is defined for a surgical population that is a subset of the Full Analysis Set. The record therefore does not permit assessment of the endpoint frequency or its precision.

The non-randomized, single-group, open-label design has no concurrent control for estimating comparative effects. It cannot by itself separate outcomes associated with the program from other influences. The record does not describe masking, adjustment methods, or an analysis plan beyond identifying the design features noted above.

The endpoint combines completion of therapy, surgery timing, and postoperative wound-infection assessments. The record does not report results for each component, making it impossible to identify which requirements participants did or did not meet. Nor does the primary endpoint directly measure abstinence or postoperative complications. Although the registry lists related secondary outcomes, their results are not reported in the available record.

Enrollment was 16, and the registry record does not report a trial-specific sample-size justification. It also does not report missing-data handling, the number of missing assessments, an interim-analysis plan, or a multiplicity strategy. The safety information is limited to the posted counts and serious-event term; deaths are not reported in the registry record. These reporting gaps limit interpretation of both outcomes and safety, while the absence of a comparator limits causal conclusions even if outcome results were available.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Pilot Study Of Smoking Cessation Treatment Including Varenicline In Patients Scheduled For Planned Surgery — NCT00889720.
• Registry record last updated 2011-10-17; status last verified 2011-07.
• Results first posted 2011-08-25.
• 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.

19. Record Summary

The registry record describes a completed Phase 4, multicenter, open-label, non-randomized, single-group study of a smoking-cessation program including varenicline for patients scheduled for elective surgery. Enrollment was 16; the study began in 2009-11 and primary completion was recorded as 2010-07.

The primary endpoint was the percentage of fully compliant participants, defined by completion of 12 weeks of varenicline, surgery 8 weeks ±10 days after treatment began, and wound-infection evaluations 1 to 3 days and 6 to 10 days after surgery. The primary result and the size of its analysis population are not reported in the registry record. The record lists 22 outcome measures and reports 0 analyses.

Safety figures include 1 participant with a serious event and 9 with other events, each among 16 at risk. Intestinal obstruction is listed as a serious-event term with 6.2%; deaths are not reported in the registry record. The single-group design does not provide a randomized treatment comparison.