Evaluation of Varenicline (Champix) in Smoking Cessation for Patients Post-Acute Coronary Syndrome (EVITA) Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Varenicline (Champix) in Smoking Cessation for Patients Post-Acute Coronary Syndrome (EVITA) Trial (NCT00794573), a randomized phase 3 study. The primary outcome is 7-Day Point Prevalence Smoking Abstinence.

2. Clinical Question

The primary endpoint required self-reported abstinence during the past week and an exhaled carbon monoxide reading of 10 ppm or lower. This makes the primary question a comparison of participants meeting a combined self-report and biochemical definition at a specified follow-up, rather than a measure of abstinence throughout the entire period after treatment began.

The registry also reports 52-week outcomes for 7-day point prevalence abstinence, continuous abstinence, and a reduction in daily cigarette consumption of 50% or greater. These give additional views of smoking outcomes at a later follow-up, but they are not interchangeable with the primary endpoint: the definitions and timeframes differ. The trial record does not report the full details of how the secondary endpoints were analyzed.

3. Trial Design

EVITA was a phase 3 randomized, quadruple-masked, parallel-group trial. The registry lists an enrollment of 302 and identifies acute coronary syndrome as the condition under study. The study status is completed. Its recorded start was 2009-09, and its primary completion was 2015-06.

Participants were assigned to varenicline or placebo. The varenicline arm description specifies 0.5 mg once a day for the first three days, then 0.5 mg twice a day for the following four days, and 1.0 mg twice a day for the remainder of the 12-week treatment. The placebo arm description gives a corresponding schedule using placebo tablets. The brief summary describes follow-up over 12 months, including telephone calls and clinic visits to assess smoking, side effects, and clinical events.

The primary outcome was assessed at 24 weeks. The posted primary counts are 70 participants in the varenicline group and 49 in the placebo group, with outcome denominators of 148 and 151, respectively. The registry describes the primary population as including all patients except those who died. It also states that participants lost to follow-up or withdrawn were treated as having returned to smoking at baseline rates for the primary analysis.

The registry record does not report the original sample-size justification, the allocation procedure in further detail, or a full statistical analysis plan. It records 12 outcome measures and no reported analyses in the available analysis listing. These omissions limit what can be established about planned analysis choices beyond the endpoint and missing-outcome assumption explicitly described in the record.

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: Includes all patients except those who died. For the primary analysis, participants who were lost to follow-up or withdrew were assumed to have gone back to smoking at baseline rates.

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 7-Day Point Prevalence Smoking Abstinence, measured over 24 weeks.

The primary endpoint is 7-day point prevalence smoking abstinence at 24 weeks. A participant met the endpoint by reporting no smoking in the past week and having an exhaled carbon monoxide reading of 10 ppm or lower. The outcome is recorded as a count of participants, so the comparison concerns how many people in each group met that definition at that follow-up.

Self-report captures whether a participant says they abstained, while exhaled carbon monoxide provides a biochemical check related to recent smoking. Using both criteria makes the endpoint more specific than self-report alone. It remains a snapshot of the past week at the assessment time, however; it does not by itself establish uninterrupted abstinence since randomization or throughout the treatment period.

A point-prevalence endpoint is useful for comparing the groups at a defined follow-up, but its meaning depends on the chosen time and the operational definition. EVITA also records continuous abstinence and later point-prevalence outcomes, which address different aspects of smoking behavior. The primary endpoint’s timeframe, definition, and stated treatment of missing follow-up are therefore important when interpreting the reported group difference.

7. Results Posted in the Registry

• Varenicline: 47.3% (70/148) versus 32.5% (49/151) on control; risk difference 14.8 percentage points (95% CI 3.9 to 25.8), risk ratio 1.46 (1.09–1.94); unadjusted two-proportion z-test p = 0.009.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

7-Day Point Prevalence Smoking Abstinence

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Varenicline: 39.9% (59/148) versus 29.1% (44/151) on control; risk difference 10.7 percentage points (95% CI 0.0 to 21.4), risk ratio 1.37 (1.00–1.88); unadjusted two-proportion z-test p = 0.051.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Varenicline and the control. The interval gives the range of effects that remain compatible with the data.

Continuous Smoking Abstinence

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Varenicline: 31.1% (46/148) versus 21.2% (32/151) on control; risk difference 9.9 percentage points (95% CI -0.0 to 19.8), risk ratio 1.47 (0.99–2.17); unadjusted two-proportion z-test p = 0.052.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Varenicline and the control. The interval gives the range of effects that remain compatible with the data.

Reduction in Daily Cigarette Consumption by 50% or Greater

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Varenicline: 57.8% (85/147) versus 49.7% (75/151) on control; risk difference 8.2 percentage points (95% CI -3.1 to 19.4), risk ratio 1.16 (0.94–1.44); unadjusted two-proportion z-test p = 0.158.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Varenicline and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes offer a broader, later view of smoking behavior than the 24-week primary endpoint. They include 52-week point-prevalence abstinence, continuous abstinence, and a reduction in daily cigarette consumption by 50% or greater. These outcomes address different definitions of smoking status, so agreement or disagreement among them can inform how consistently the observed group pattern appears across measures, while not making the outcomes interchangeable.

Across the posted secondary comparisons, the estimates favor the varenicline group. The statistical evidence is less uniform than for the primary result: the unadjusted p-values are 0.051 for 52-week point-prevalence abstinence, 0.052 for continuous abstinence, and 0.158 for cigarette reduction. Their uncertainty intervals also differ in whether they include zero. This pattern is compatible with estimates pointing in a similar direction while retaining substantial uncertainty about the size of some contrasts.

These secondary results relate to the primary finding by providing information at a later follow-up and with distinct outcome definitions. They do not independently confirm the primary result in a formal sense, because the registry record does not report a multiplicity plan or the complete statistical analysis methods. When several outcomes are examined, the chance of at least one apparently notable finding can increase. In general, adjustment or a prespecified hierarchy can address aspects of this issue, but the record does not state that either approach was used.

The registry lists 10 secondary outcomes and reports no secondary analyses in its analysis listing. The posted estimates can still be described, but their evidential weight is lower than that of a prespecified primary outcome when the number of tests and the analysis plan are not available. Interpret the secondary outcomes as context for the overall pattern, not as a collection of independent definitive tests.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• 7-Day Point Prevalence Smoking Abstinence
• Continuous Smoking Abstinence
• 7-Day Point Prevalence Smoking Abstinence
• Continuous Smoking Abstinence
• 7-Day Point Prevalence Smoking Abstinence
• Continuous Smoking Abstinence
• Reduction in Daily Cigarette Consumption by 50% or Greater
• Reduction in Daily Cigarette Consumption by 50% or Greater

9. Statistical Interpretation

10. Statistical Methods Explained

The registry presents a binary outcome: each participant either met the endpoint definition or did not. The primary arm results are counts, and the comparison is reported as a risk difference. In general, a risk difference compares the proportions with an outcome in two groups by subtracting one group’s proportion from the other. Its zero value represents equal proportions. The posted estimate of 0.148 is for varenicline relative to placebo.

What does the confidence interval describe?

A confidence interval gives a range of effect estimates compatible with the observed data under the method’s assumptions. It conveys uncertainty around the estimated risk difference; it does not mean that individual participant outcomes fall within the interval. For the primary outcome, the reported interval runs from 0.039 to 0.258. Because its endpoints are positive, the interval does not include a zero risk difference. The registry record does not state the confidence level or the method used to construct this interval, so those details are not reported in the registry record.

How should the p-value be read?

The primary unadjusted p-value is 0.009. In general, a p-value measures the compatibility of the observed data with a specified null model, given the model’s assumptions. A smaller value indicates that the observed data would be less compatible with that model. It does not quantify the probability that the null hypothesis is true, and it does not measure the importance of the result. The record identifies the value as unadjusted; no adjustment for multiple outcomes is reported.

What is the role of randomization and masking?

Random assignment is intended to make the groups comparable, on average, with respect to factors that could influence the outcome. It supports a treatment-group comparison, but does not prevent chance imbalances, missing outcomes, measurement problems, or limitations in how results apply beyond the enrolled participants. The registry lists the study as quadruple-masked. In general, masking can reduce the chance that knowledge of group assignment influences participant behavior, clinical care, or outcome assessment. The record does not provide additional detail about who was masked or how masking was maintained.

How do endpoint and population definitions matter?

The primary measure is point-prevalence abstinence: it concerns the past week at 24 weeks and combines self-report with an exhaled carbon monoxide threshold. It is different from continuous abstinence, which concerns abstinence over a specified span. The primary population excludes deaths, while lost or withdrawn participants were assumed to have returned to smoking at baseline rates. This is an explicit analysis rule, not evidence that the smoking status of every missing participant was directly observed. The registry record does not report whether alternative missing-data assumptions were examined.

What is not available about the analysis?

The record gives arm counts and an unadjusted comparison, but does not report a complete statistical analysis plan, a detailed model specification, or the method used for the confidence interval. It also does not report an adjustment strategy for multiple outcomes or a list of completed secondary analyses. Those details should not be inferred from the reported effect estimate and p-value. In general, different analysis choices can affect uncertainty estimates and the interpretation of findings, particularly when there are missing observations or several outcomes.

For binary outcomes, the event count and the number of participants contributing to the comparison determine the observed proportion in each group. The group counts help make the basis of the comparison transparent, while the risk difference gives a direct absolute contrast on the proportion scale. Relative measures such as risk ratios or odds ratios answer different questions and can express the same data on different scales; they are not substitutes for understanding the endpoint, denominators, and absolute difference.

11. Confidence Intervals and Precision

The primary risk-difference estimate is 0.148, and its confidence interval extends from 0.039 to 0.258. This interval communicates uncertainty around the comparison: values across that range remain compatible with the data under the interval method’s assumptions. The entire interval is above zero, indicating that the interval does not include equal observed proportions. The confidence level and construction method are not reported in the registry record.

Precision is not the same as importance. A narrow interval would indicate less uncertainty about the estimated contrast, while a wide interval would leave more uncertainty about its magnitude. Even when an interval excludes zero, the estimate should be considered alongside the endpoint definition, the analysis population, and how missing outcomes were handled. The primary endpoint measures abstinence during a particular week, not continuous abstinence throughout follow-up.

The 52-week secondary intervals illustrate that the degree of precision varies by outcome. The interval for 7-day point prevalence abstinence extends from < 0.001 to 0.214. The interval for continuous abstinence extends from -< 0.001 to 0.198, and the interval for reduction in daily cigarette consumption by 50% or greater extends from -0.031 to 0.194. These intervals should not be interpreted as having the same evidential status as the designated primary result, especially because the secondary p-values are unadjusted and multiplicity handling is not reported.

In general, a confidence interval describes uncertainty in an estimated group contrast, not the range of outcomes that individual participants might experience. Its practical interpretation also depends on the analysis assumptions. Since the record does not report the interval method or confidence level, precision can be discussed from the posted bounds but those methodological details cannot be established.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations based on the observed effect, not a report of the trial’s original design calculation. They assume a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is a stated fraction of the observed effect. The trial’s own original sample-size assumptions and justification are not reported in the registry record.

For these binary outcomes, the planning figures are participants per arm, not total participants across both arms and not total events. The 80% power column describes the planned number of participants per arm for a design with an 80% chance of detecting the specified effect if that effect and the planning assumptions were true. The 90% power column describes the corresponding per-arm number for a design with a 90% chance. In general, higher planned power requires more participants when the other assumptions are held fixed.

The rows represent planning for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. Smaller effects are harder to distinguish from random variation, so they require more participants per arm under these assumptions. The values are planning illustrations only; they are not observed power and do not describe the probability that the completed trial’s result is correct.

These calculations depend on assumptions about the effect size, allocation, significance level, and approximation. If the true effect differs from the value used for planning, or if the trial conditions differ from the assumptions, the resulting power would also differ. The registry record does not report the trial’s original planning calculation, so the illustration should not be treated as evidence about what the investigators used when designing EVITA.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.325; treatment proportion p₁ = 0.473; average p̄ = 0.399.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6925 = 1.3572.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6844 = 0.5760.
4. n = (1.3572 + 0.5760)² / (0.1485)² = 169.5, rounded up to 170 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.324503311258278                          # control proportion
p1 <- 0.472972972972973                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(794573)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 170 (80% power), 227 (90% power)
 75% of observed effect: n per arm = 298 (80% power), 398 (90% power)
 50% of observed effect: n per arm = 657 (80% power), 879 (90% power)
power.prop.test: 169.5 
Simulated power at n = 170 per arm: 0.805 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when investigators assess several outcomes, timepoints, or comparisons. In general, testing more hypotheses creates more opportunities for a result to appear statistically notable by chance. A prespecified hierarchy, an adjustment procedure, or a clearly designated primary outcome can help structure interpretation. The registry identifies a primary endpoint, but a multiplicity strategy for the other measures is not reported in the registry record.

The registry lists 12 outcome measures and 10 secondary outcomes. It reports no analyses in the analysis listing and no reported secondary analyses. The absence of a listed analysis does not establish that no analyses were conducted; it means their details are not reported in the registry record. The secondary estimates are labeled with unadjusted p-values, so they should not be treated as adjusted for the number of outcomes assessed.

Missing data are addressed explicitly for the primary analysis. Patients who died were excluded from the primary population. Participants lost to follow-up or withdrawn were assumed to have gone back to smoking at baseline rates. This rule makes a conservative classification for missing smoking assessments in the sense that missing participants are treated as smoking rather than abstinent, but it does not eliminate uncertainty about their unobserved status. Its consequences depend on how many assessments were missing and on whether the assumption reflects those participants’ outcomes; those details are not reported in the registry record.

The record does not report the missing-data approach for each secondary outcome or sensitivity analyses using alternative assumptions. It also does not report a detailed analysis population definition for the secondary results. Consequently, the secondary comparisons cannot be evaluated for consistency across missing-data methods from the registry record alone.

In general, missingness can affect both the estimated outcome proportions and their precision. Excluding people with missing assessments, treating them as smoking, or using another method can yield different results. Randomization does not by itself resolve this issue, because outcome availability after assignment may differ between groups. The stated primary rule is therefore central to interpreting the primary estimate, while the absence of corresponding secondary details limits comparisons across outcomes.

15. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 4% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: major adverse cardiovascular event (any) (4.6%), unstable angina (3.3%), myocardial infarction (2.0%), gastrointestinal bleed (1.3%), hospitalization for suspected unstable angina - ruled out by angiogram (1.3%).

The registry reports serious adverse events affecting 18 of 151 participants in the varenicline group and 17 of 151 in the placebo group. Other adverse events are reported for 92 of 151 and 70 of 151 participants, respectively. Deaths are reported for 3 participants in the varenicline group and none in the placebo group. These are group counts, not adjusted comparisons or proof that an event was caused by the assigned treatment.

The serious-event terms most often listed include Major Adverse Cardiovascular Event (Any), at 4.6%; Unstable Angina, at 3.3%; Myocardial Infarction, at 2.0%; Gastrointestinal Bleed, at 1.3%; Hospitalization for Suspected Unstable Angina - Ruled Out by Angiogram, at 1.3%; and Cardiovascular Death, at 1.3%. The record does not provide a causal assessment for these terms in the listed figures.

In general, adverse-event counts describe events recorded during the trial and should be interpreted in light of the number at risk, follow-up, and event definitions. The registry record does not report a statistical comparison or detailed attribution for these safety figures. They provide descriptive context and should not be read as a standalone estimate of comparative safety.

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

The posted primary result shows a higher observed proportion meeting the 24-week abstinence definition in the varenicline group than in the placebo group. The risk difference is 0.148, with an interval from 0.039 to 0.258 and an unadjusted p-value of 0.009. This describes the recorded comparison under the primary endpoint definition and its stated rule for missing follow-up.

The result does not mean every participant in the varenicline group stopped smoking, or that the group difference applies to every patient who has experienced acute coronary syndrome. The endpoint captures self-reported abstinence during the past week together with an exhaled carbon monoxide reading of 10 ppm or lower at 24 weeks. It does not establish uninterrupted abstinence over the entire follow-up period. The later continuous-abstinence outcome addresses a different question.

Nor does the primary result by itself establish effects on heart attacks, hospitalization, or other clinical events. Those events appear in the brief study description and safety reporting, but the primary endpoint is smoking abstinence. The record does not report a full analysis of clinical-event outcomes in the posted results summarized by these comparisons.

Randomization and masking are important features of the study design, but results still depend on measurement, follow-up, analysis choices, and the applicability of the enrolled population to other settings. The primary population excluded deaths, and missing or withdrawn participants were assumed to have returned to smoking at baseline rates. The original sample-size rationale and several analysis details are not reported in the registry record.

In general, statistical evidence describes compatibility between the observed data and a model; it is not a guarantee of a particular outcome for an individual. The secondary results add context but are unadjusted and are not supported by a reported multiplicity plan. The findings should therefore be described as a comparison of the recorded trial outcomes, not as a universal conclusion about treatment effects or a substitute for clinical judgment.

17. Why This Trial Matters Statistically

EVITA addresses a distinct study population: active smokers who had recently experienced acute coronary syndrome. The brief summary describes the effectiveness of varenicline in this population as an open question and frames the trial around smoking cessation after a heart attack. The registry therefore places the abstinence endpoint in a clinically specific context rather than treating smoking cessation in a general population as the only relevant question.

Statistically, the trial illustrates why the estimand and outcome definition matter. The primary result concerns point-prevalence abstinence during the past week at 24 weeks, assessed by both self-report and exhaled carbon monoxide. The registry also reports continuous abstinence and later point-prevalence outcomes. These measure related but distinct aspects of smoking behavior, so clear interpretation requires keeping the definition and follow-up time attached to every estimate.

The record also highlights the role of analysis assumptions. The primary missing-data rule treats those lost to follow-up or withdrawn as having returned to smoking, while excluding patients who died from the primary population. That rule is part of the result’s meaning, not a technical detail that can be ignored. The absence of a reported multiplicity strategy also matters when interpreting several secondary outcomes.

Finally, the planning illustrations based on the observed effect are distinct from a trial’s original design calculations. They show how the required participants per arm change with the effect targeted under stated assumptions, but the record does not report that these were the assumptions used to design EVITA. Separating observed results, planning illustrations, and unreported design decisions is essential for a disciplined statistical reading.

18. 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 registry record leaves important design and analysis details unreported. It does not give the trial’s original sample-size justification, a full statistical analysis plan, the method used to construct the confidence intervals, or the confidence level. Allocation is described as randomized, and masking as quadruple, but the record does not explain the allocation procedure or identify the masked roles. These gaps limit independent assessment of how the reported estimates were produced.

The primary outcome is a 7-day point-prevalence measure at 24 weeks, not a direct measure of uninterrupted abstinence throughout follow-up. Its definition combines self-report and exhaled carbon monoxide, but the record does not provide further details about assessment procedures or adherence to the measurement schedule. The primary analysis excludes deaths and assigns a smoking outcome to participants lost to follow-up or withdrawn; the record does not report sensitivity analyses that test alternative assumptions.

The registry lists secondary outcomes but does not report secondary analyses in its analysis listing. It also does not report whether the secondary analyses used the same missing-data approach as the primary analysis, or whether any multiplicity adjustment was applied. The unadjusted comparisons therefore require caution, particularly when considering several outcomes together.

The posted enrollment is 302, while the primary comparison has group denominators of 148 and 151. The record does not explain the difference between the enrollment figure and those denominators. The brief summary describes follow-up over 12 months, but detailed outcome-specific follow-up and missingness information is not reported. These limitations do not negate the posted comparison; they define what can be concluded from the registry record alone.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Evaluation of Varenicline (Champix) in Smoking Cessation for Patients Post-Acute Coronary Syndrome (EVITA) Trial — NCT00794573.
• Registry record last updated 2019-05-23; status last verified 2019-04.
• Results first posted 2019-05-23.
• 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.

22. Record Summary

EVITA is a completed phase 3 randomized, quadruple-masked, parallel-group trial of varenicline versus placebo in patients with acute coronary syndrome who were active smokers. The registry records enrollment of 302, with a primary endpoint of 7-day point-prevalence smoking abstinence at 24 weeks.

The primary comparison reports 70 of 148 participants meeting the endpoint in the varenicline group and 49 of 151 in the placebo group. The risk difference is 0.148, with a confidence interval from 0.039 to 0.258 and an unadjusted p-value of 0.009. The primary population excluded deaths, and participants lost to follow-up or withdrawn were assumed to have returned to smoking.

Secondary outcomes at 52 weeks cover point-prevalence abstinence, continuous abstinence, and cigarette reduction. Their analyses are unadjusted, and multiplicity handling, the original sample-size rationale, and several analysis details are not reported in the registry record.