Tobacco Cessation at FDNY: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Tobacco Cessation at FDNY (NCT05997225), a randomized phase 4 study. The primary outcome is Enrollment.

2. Clinical Question

The trial was registered as a randomized comparison of two parallel groups. Its rationale connects lung cancer screening, tobacco use, and access to cessation support within the FDNY program. The outcome definition matters for interpreting the result: attendance at a counseling session is a measure of participation in the treatment program, not a direct measure of quitting or sustained abstinence. The posted arm counts and their stated denominators also need to be read alongside the registry’s total enrollment figure, because the relationship between those counts is not explained in the registry record.

3. Trial Design

The registry identifies this as a Phase 4, randomized, parallel-group trial with no masking. Albert Einstein College of Medicine is listed as the sponsor. The trial status is completed. Its recorded start date is 2024-05-31, and its primary completion date is 2025-10-13. The registry lists enrollment as 23.

Participants were assigned to Enhanced Care or Standard Care. Enhanced Care offered opt-out counseling enrollment and biofeedback individually tailored to chest CT and spirometry results. Standard Care offered opt-in enrollment and standard tobacco-cessation counseling. Both arm descriptions include a varenicline preloading regimen before the target quit date: 0.5 mg once a day for days 1-3, 0.5 mg twice a day for days 4-7, and 1 mg twice a day for days 8-28. Both descriptions then specify 1 mg twice a day for 12 weeks, with Standard Care explicitly placing that period after the target quit date.

The primary endpoint was measured at Baseline (Week 0) and was defined as enrollment in the tobacco-cessation program, based on informed consent and attendance at least one counseling session. The registry also lists secondary outcomes concerning retention to study end-date, counseling attendance at each timepoint, and pill-count percentage for varenicline adherence. It lists eight outcome measures, but the posted information summarized in the record does not provide results for all of them.

The primary outcome reports 156 participants in each arm, while the trial record lists enrollment as 23. The registry record does not explain how these participant counts relate to the listed trial enrollment, whether they represent a different recruitment population or measure, or how the counts were assembled. This limits interpretation of the outcome denominators and prevents treating them as a straightforward accounting of the registered enrollment. The registry lists zero analyses in its analysis count, while the posted primary comparison includes an unadjusted p-value and estimates with confidence limits. The original analysis plan, allocation details beyond randomization, and reasons for these reporting differences are not reported in the registry 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.

Before assignment: As this study was interested in understanding the effectiveness of an opt-out recruitment design, participant randomization was completed prior to recruitment procedures. Those eligible for randomization (n=312) included retired FDNY employees drawn from a separate observational study who had previously consented to be contacted for future research. After recruitment, those who consented to enroll in this trial (n=23) were eligible to receive all study assignment interventions.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Results from two distinct enrollment measures are reported: 1.) Enrollment, defined as completion of informed consent and attending at least one counseling session, and 2.) Enrollment - Informed Consent, reported in Post-Hoc outcomes, and defined as those who completed the informed consent, regardless of if they attended a counseling session. Some participants completed informed consent, but then were subsequently unable to be contacted (n=6), hence the discrepancy between outcome data totals.

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: Numbers reported in Baseline Characteristics includes all enrolled participants who completed the informed consent, regardless of their attendance at subsequent study visits.

6. Primary Endpoint

The registry lists the primary outcome as Enrollment, measured over Baseline (Week 0).

The primary endpoint is enrollment in the tobacco-cessation program. The definition requires completion of informed consent and attendance at least one counseling session with an FDNY tobacco treatment specialist. The endpoint is recorded as a count of participants and refers to Baseline (Week 0). Its purpose is to quantify whether eligible participants entered the counseling program under the assigned enrollment approach.

This endpoint is relevant to a trial comparing opt-out with opt-in enrollment because it captures an early step in engagement with cessation services. It does not itself establish whether a participant later quit smoking, maintained abstinence, completed counseling, or adhered to medication. Those are distinct outcomes. The registry lists retention, counseling attendance at timepoints, and pill-count percentage for varenicline adherence as secondary outcomes, but their numerical results are not reported in the primary result.

The posted primary counts are 12 for Enhanced Care and 5 for Standard Care, with 156 participants listed for each arm. The registry also lists total trial enrollment as 23 and describes a separate post-hoc enrollment measure based on informed consent regardless of counseling attendance. The record’s description of that post-hoc measure is incomplete, and the connection among the outcome counts, denominators, and registered enrollment is not reported in the registry record. Consequently, the endpoint definition is clear in its basic form, but the participant accounting requires caution.

Enrollment is used as an implementation outcome: it concerns whether people begin counseling, not the clinical effect of cessation treatment. Any interpretation should stay within that scope. The primary result can describe the observed enrollment counts and their statistical uncertainty, but it does not answer whether either care approach changed cessation or health outcomes.

7. Results Posted in the Registry

• Enhanced Care: 7.7% (12/156) versus 3.2% (5/156) on control; risk difference 4.5 percentage points (95% CI -0.5 to 9.5), risk ratio 2.40 (0.87–6.65); unadjusted two-proportion z-test p = 0.081.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is binary at the participant level: a participant either met the enrollment definition or did not. The registry reports counts, so the analysis compares the number meeting the definition in each arm and the corresponding arm-level risks. A risk is the proportion of participants in an arm who experience the event of interest. The posted risks are 0.077 for Enhanced Care and 0.032 for Standard Care. The registry gives the arm denominators as 156 for each group.

What does the risk difference describe?

The risk difference subtracts the comparator-arm risk from the intervention-arm risk. The reported estimate is 0.045. It expresses the absolute contrast on the risk scale, rather than a proportional change. Its confidence interval runs from -0.005 to 0.095. A confidence interval represents a range of values compatible with the data and the method used, under the model’s assumptions. The range includes zero, so the posted data do not rule out no difference at the interval’s stated confidence level. The confidence level itself is not reported in the registry record.

How do relative measures differ?

The risk ratio compares the two risks by division; the reported value is 2.4. The odds ratio compares the odds of enrollment between arms; the reported value is 2.517. The registry reports intervals of 0.866 to 6.652 for the risk ratio and 0.865 to 7.322 for the odds ratio. These measures summarize relative contrasts, whereas the risk difference summarizes an absolute contrast. The scales answer different questions, and the relative measures can be less intuitive when the event is not common. Their intervals are wide and include the no-association value for each measure. None of these estimates establishes a causal effect by itself.

What does the p-value contribute?

The unadjusted p-value is 0.081. In general, a p-value measures how unusual the observed data, or data more extreme, would be if a specified null model and its assumptions were true. It is not a measure of effect size and does not show the probability that a hypothesis is true. “Unadjusted” indicates that the reported value is not described as adjusted for other variables or multiple comparisons. The registry does not report a detailed testing procedure, covariate-adjustment strategy, or prespecified threshold for this endpoint. The p-value should therefore be read alongside the estimate and its interval, rather than as a standalone verdict.

Why does randomization matter?

Random allocation is intended to make assigned groups comparable, on average, with respect to factors that might affect an outcome. It supports a causal comparison when allocation is implemented as intended and the analysis preserves the randomized groups. However, the registry record does not report the sequence-generation method, concealment procedures, or a detailed analysis-population definition. The trial was unmasked, so participants and study staff were not reported as masked. For an enrollment outcome, awareness of the assigned approach is part of the intervention, but lack of masking can also affect how outcomes are recorded or how participants engage.

The comparison is between two care packages. Enhanced Care combines opt-out enrollment with counseling tailored to CT and spirometry results, while Standard Care uses opt-in enrollment and standard counseling. Both include a described varenicline regimen. As a result, the primary comparison cannot isolate the contribution of any single component. This is a general feature of bundled interventions: an observed difference between groups applies to the assigned packages as tested, not automatically to each element separately.

What can be said about count data and over-dispersion?

For a binary endpoint, the central quantities are the number of participants with the event and the number at risk in each group. A binomial model commonly treats each participant’s event status as a Bernoulli outcome and represents the group count as arising from those outcomes. Over-dispersion is a general concern when variation in observed counts exceeds what a simple model expects, for example because outcomes are more heterogeneous or clustered than assumed. The registry does not report a model-based dispersion estimate or a method addressing over-dispersion. The posted primary comparison is based on the listed binary counts; the analysis details beyond the reported estimates and unadjusted p-value are not reported in the registry record.

There is also an accounting question. The registry lists total enrollment as 23, but the primary outcome lists 156 participants per arm. In addition, the record distinguishes the primary enrollment definition from a post-hoc informed-consent measure. Without a complete participant-flow account or a clear mapping between these definitions and denominators, it is not possible to verify from the registry record how the analysis population was formed. This is relevant to interpreting both the estimates and their precision, and should not be resolved by assuming that one count supersedes another.

10. Confidence Intervals and Precision

The risk-difference estimate is 0.045, with a confidence interval from -0.005 to 0.095. The interval spans values on both sides of zero. That means the posted results are compatible with no difference as well as with positive contrasts in enrollment risk; the lower limit is slightly below zero. The interval does not support a sharply determined estimate of the absolute contrast. The confidence level used for the interval is not reported in the registry record, so it should not be assigned a level based on assumption.

The relative estimates are also imprecise. The risk ratio is 2.4, with limits 0.866 and 6.652, and the odds ratio is 2.517, with limits 0.865 and 7.322. Each interval covers values below and above the no-association value of one. This breadth indicates substantial uncertainty in the relative magnitude. The risk difference and relative measures are different scales, so their numeric sizes should not be compared as if they were interchangeable.

Precision is affected by how much information the analysis contains, including the number of events and the number of participants represented. The posted counts are 12 and 5, and the listed arm denominators are 156 each. The small event counts help explain why the relative estimates can have wide intervals. However, the relationship between the outcome denominators and the registry’s total enrollment of 23 is not explained. That reporting issue complicates assessment of the effective analysis population and should remain part of the interpretation.

A confidence interval is not a guarantee that the true value lies within its limits. In general, it describes the range produced by a method that, under repeated use and its assumptions, has a specified coverage property. The exact coverage level and full model details are not reported in the registry record. The interval is most useful when read together with the point estimate, outcome counts, and limitations in participant accounting, rather than as a boundary between meaningful and meaningless effects.

11. 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 describe participants per arm, not total events. They are illustrations based on the observed effect, not the trial’s original design assumptions. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect used for each illustration is a stated fraction of the observed effect. The registry record does not report the assumptions used for the trial’s original sample-size design.

The 80% power column represents the number of participants per arm that the planning calculation estimates would be needed for an 80% chance of detecting the selected effect under those assumptions, if that effect were the true one. The 90% power column gives the corresponding planning figure for a 90% chance. These are design probabilities under a hypothetical effect and model; they are not a measure of what happened in this completed trial.

For 100% of the observed effect, the figures are 401 participants per arm for 80% power and 536 for 90% power. For planning at 75% of the observed effect, they are 644 and 861 participants per arm. For planning at 50% of the observed effect, they are 1,290 and 1,727 participants per arm. Smaller effects require more participants because they are harder to distinguish from random variation. The planning figures are not observed power.

The visual planning display represents the same relationship between the selected effect size and the number of participants required under the stated assumptions. It does not establish the original target, nor does it validate the observed effect as a reliable value for future planning. The estimates depend on the observed risk difference used as their starting point, and that estimate has a confidence interval extending from -0.005 to 0.095. The registry record does not report a separate planning effect or the original sample-size justification.

12. 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 = 0.032; treatment proportion p₁ = 0.077; average p̄ = 0.054.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.3210 = 0.6291.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.3194 = 0.2688.
4. n = (0.6291 + 0.2688)² / (0.0449)² = 400.5, rounded up to 401 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 <- 0.032051282051282                          # control proportion
p1 <- 0.0769230769230769                          # 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(5997225)
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 = 401 (80% power), 536 (90% power)
 75% of observed effect: n per arm = 644 (80% power), 861 (90% power)
 50% of observed effect: n per arm = 1,290 (80% power), 1,727 (90% power)
power.prop.test: 400.5 
Simulated power at n = 401 per arm: 0.813 (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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists eight outcome measures, including the primary enrollment outcome and secondary outcomes for retention, counseling attendance, and varenicline adherence. It also lists zero analyses in its analysis count, although the posted primary comparison includes estimates and an unadjusted p-value. The relationship between that registry field and the posted comparison is not explained. The analysis plan, including which outcomes were designated for formal hypothesis testing and in what order, is not reported in the registry record.

Multiplicity arises when several outcomes, timepoints, or comparisons are tested. In general, conducting more tests can increase the chance of at least one result appearing statistically unusual even when no underlying effect exists. Methods such as prespecifying a hierarchy or adjusting significance thresholds can address that concern, but the registry record does not report whether any such approach was planned or used. The posted p-value is explicitly unadjusted, and should not be treated as accounting for other outcomes or analyses.

Missing-data handling is also not reported in the registry record. The primary outcome is defined through informed consent and attendance at a counseling session, but the record does not describe how participants with incomplete follow-up, uncertain attendance, or unavailable outcome information were handled. It does not provide a participant-flow account that reconciles the listed trial enrollment of 23 with the 156 participants per arm shown for the primary outcome. The record also distinguishes a post-hoc informed-consent measure, but its description is incomplete.

The analysis population is not fully specified. The registry does not state whether the comparison followed an intention-to-treat approach, whether participants were analyzed according to randomized assignment, or whether any participants were excluded. These details matter because excluding or reclassifying participants after randomization can affect comparability. No alternative or sensitivity analyses addressing missing outcomes or analysis-population choices are reported in the registry record. The displayed results can therefore be described as posted, but their exact participant basis and robustness to missing-data assumptions cannot be evaluated from the available record.

14. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse event figures list zero serious events among 12 participants at risk in Enhanced Care and zero among 5 at risk in Standard Care. Deaths are listed as zero in both groups. The record gives no serious adverse event terms. These entries describe the posted counts for the groups and denominators specified in the safety record; they do not establish that no other adverse experiences occurred.

The record also lists other adverse events affecting 5 of 12 participants in Enhanced Care and 2 of 5 in Standard Care. These are separate from the serious-event counts and should not be combined with them. The safety denominators differ from the primary outcome denominators of 156 per arm, and their relationship to the trial enrollment of 23 is not explained in the registry record. The record does not provide event descriptions, severity details for these other events, exposure time, or a complete account of ascertainment.

Zero reported serious events in these groups is a count, not proof that serious events cannot occur or that the treatments have identical safety profiles. Small event counts provide limited information about uncommon outcomes. These figures are descriptive and should be interpreted only within the scope of what the registry reports; they do not support medical advice or a general safety conclusion.

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

The primary result describes enrollment in counseling, not cessation. The reported counts were 12 in Enhanced Care and 5 in Standard Care, with a risk difference of 0.045 and an unadjusted p-value of 0.081. The confidence interval, from -0.005 to 0.095, includes zero and extends to positive differences. The result therefore conveys uncertainty about the size and direction of the enrollment contrast rather than a precisely settled estimate.

The arms differed in more than one feature: Enhanced Care combined opt-out enrollment with individualized biofeedback, whereas Standard Care used opt-in enrollment and standard counseling. Both descriptions include varenicline. The comparison cannot identify whether any observed enrollment difference is attributable to the enrollment default, counseling approach, or another element of the package. It is a comparison of assigned care approaches as a whole.

The result does not show whether participants quit smoking, how long any cessation lasted, or whether medication was taken as intended. The registry lists relevant secondary outcomes, but their numerical results are not reported in the primary result. The primary endpoint is an early engagement measure. It is not a substitute for clinical outcomes or for a complete assessment of the intervention.

The record’s participant accounting adds uncertainty. It lists trial enrollment as 23 and reports 156 participants in each primary-outcome arm. It also describes a distinct post-hoc measure based on informed consent. The relationship among these figures and measures is not reported in the registry record. This does not change the posted estimates, but it limits confidence about the precise analysis population and how the denominators should be interpreted.

Overall, the posted statistics show a higher observed enrollment count in Enhanced Care, with broad uncertainty around the contrast. They do not establish that one approach produces higher enrollment in the wider eligible population, and they do not answer whether either approach improves cessation or health outcomes. The result should be read as a limited, imprecise comparison of a specific enrollment endpoint in a particular program context.

16. Why This Trial Matters Statistically

This trial raises a statistical question that extends beyond whether participants were assigned to two arms: how to define and count engagement with a service. Enrollment requires informed consent and at least one counseling session, while a separately described post-hoc measure concerns informed consent regardless of counseling attendance. Those definitions capture different steps in participation. Keeping them distinct is essential when interpreting an intervention designed to change how people enter a program.

The contrast is also a bundled comparison. Opt-out enrollment and tailored counseling are introduced together in Enhanced Care, while Standard Care uses opt-in enrollment and standard counseling. Because both arm descriptions include varenicline, the primary comparison is not a medication-versus-no-medication contrast. Statistical interpretation must follow the actual randomized comparison rather than attributing an observed difference to a single component that was not separately randomized.

The estimate is informative but imprecise. The reported risk difference is 0.045, and its interval extends from -0.005 to 0.095. This range makes the limits of the evidence visible: a point estimate alone would conceal uncertainty about the contrast. The relative measures also have broad intervals. Presenting estimates with intervals is especially important when event counts are limited.

Finally, the registry’s enrollment figure of 23 does not align transparently with the primary outcome’s 156 participants per arm. The record does not explain the relationship. This illustrates a basic principle of trial reporting: a statistical estimate is only as interpretable as its outcome definition, denominator, and analysis population. Clear participant flow and analysis methods are needed to understand how randomized assignment connects to the reported result.

17. 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 important trial-specific limitation in interpreting the primary outcome is the unexplained relationship between the listed total enrollment of 23 and the 156 participants per arm reported for the outcome. The registry record does not describe whether these counts reflect different populations, recruitment stages, or data sources. The distinction between enrollment requiring counseling attendance and the post-hoc informed-consent measure adds another layer of ambiguity. Without a participant-flow explanation, the outcome denominators cannot be reconciled from the registry record.

The primary event counts are 12 and 5, and the relative estimates have wide intervals. The risk-difference interval includes zero, while the intervals for the risk ratio and odds ratio cover values below and above one. The result is therefore uncertain in magnitude. The registry does not report the confidence level, detailed statistical model, prespecified analysis plan, or a full account of missing-data handling and analysis populations.

The trial was unmasked, and the intervention combines opt-out enrollment with tailored counseling while the comparator combines opt-in enrollment with standard counseling. Consequently, the primary comparison cannot separate the effects of those components. The primary endpoint measures initial enrollment, not smoking cessation, sustained abstinence, or clinical outcomes. Although the record lists secondary measures related to retention, counseling attendance, and medication adherence, their numerical results are not reported in the primary results.

The registry record also does not report how randomization was implemented, whether outcomes were assessed using procedures protected from knowledge of assignment, or whether the analysis followed randomized assignment for every participant. No detailed multiplicity strategy is reported. The serious adverse event entries contain zero events in the listed groups, but the safety denominators and their connection to the overall enrollment are not explained. These limitations do not erase the posted estimates; they define how narrowly and cautiously those estimates should be interpreted.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Tobacco Cessation at FDNY — NCT05997225.
• Registry record last updated 2026-11-05; status last verified 2026-10.
• Results first posted 2026-11-05.
• 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.

21. Record Summary

NCT05997225, titled Tobacco Cessation at FDNY, is a completed Phase 4 randomized, parallel-group trial sponsored by Albert Einstein College of Medicine. The registry lists no masking, enrollment of 23, a start date of 2024-05-31, and primary completion on 2025-10-13. It compares Enhanced Care, with opt-out enrollment and tailored counseling, against Standard Care, with opt-in enrollment and standard counseling; both arm descriptions include varenicline.

The primary outcome is enrollment in counseling at Baseline (Week 0). The posted counts are 12 of 156 in Enhanced Care and 5 of 156 in Standard Care. The risk difference is 0.045, with a confidence interval from -0.005 to 0.095 and an unadjusted p-value of 0.081. The relationship between those arm denominators and the registry’s total enrollment of 23 is not reported in the registry record. The primary result addresses counseling enrollment, not cessation outcomes.