Phase I Study: Stop Smoking Therapy for Ontario Patients (STOP): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Phase I Study: Stop Smoking Therapy for Ontario Patients (STOP) (NCT00356993), a na na study. The primary outcome is Count of Participants Not Smoking.

2. Clinical Question

The study’s stated aim was to evaluate the methods and effectiveness of providing nicotine replacement therapy to Ontario smokers. Its broader goals included developing an evidence-based protocol, supporting faculty development in combining pharmacotherapy and behavioural interventions, and creating an evaluation framework to inform future coverage models. Those goals describe the study’s intended contribution; they are not themselves reported outcome findings.

Because there is no separate control group, the clinical question is descriptive: what outcomes were recorded among participants receiving the combined support? The record does not answer a comparative question about whether that combination changes abstinence relative to another approach. Nor can the single-group structure separate the contribution of nicotine replacement from the contribution of behavioural support.

3. Trial Design

The STOP study is registered as a completed, single-group study with enrollment of 6009. The listed arm is NRT plus Behavioural Support, described as nicotine replacement therapy plus behavioural intervention. Allocation is recorded as NA, and masking as none. The phase is recorded as NA. The sponsor is the Centre for Addiction and Mental Health.

The registry lists the study start as 2005-10 and primary completion as 2018-03-30. These dates give the registered timing of the study; they do not indicate when individual participants received treatment or completed follow-up. Participant-level treatment duration and follow-up schedules beyond the endpoint timeframe are not reported in the registry record.

A single-group design can describe outcomes among those enrolled in the arm, but without a concurrent comparison group it cannot directly distinguish an intervention-associated change from other influences. Examples of such influences in general include changes over time, selection into participation, and differences in participants’ circumstances. These are design considerations, not findings about this study.

The record describes two interventions, nicotine replacement therapy and behavioural intervention, combined in the one listed arm. It does not record separate arms for each component. Consequently, the design cannot estimate the independent contribution of either component from a between-arm comparison. Randomization procedures and allocation concealment are not reported in the registry record. Given the single-group structure, no randomized treatment contrast is presented.

The brief description places the study in the context of smoking cessation in Ontario and notes intended service and evaluation goals. Those statements explain the rationale and planned applications, but do not substitute for results on abstinence, implementation, or coverage. The registry record lists two outcome measures and zero analyses. Further detail about the statistical design, analysis populations, protocol deviations, and any planned interim analyses is 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.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Not every participant completed the 6mo and 12mo follow-up surveys

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 Count of Participants Not Smoking, measured over 6 months post treatment.

The primary measure is the count of participants not smoking at 6 months post treatment. Its description specifies 7-day point prevalence of abstinence: the outcome concerns whether a participant reports no smoking over the stated 7-day period at the 6-month assessment. It is a binary status for each participant, while the registered summary measure is a count of participants meeting that status.

In general, a point-prevalence measure captures smoking status over a defined short window at a follow-up assessment. It can provide a clear, interpretable snapshot of abstinence at that time. It does not, by itself, establish continuous abstinence throughout the period since treatment, nor does it describe outcomes after that follow-up point. Those distinctions matter when interpreting what the endpoint represents.

The registry record notes that not every participant completed the 6mo and 12mo follow-up surveys. It does not report how many completed the 6-month survey, how missing responses were handled, or the count classified as not smoking. The endpoint definition is therefore available, but the result and its uncertainty cannot be assessed from the registry record. The same named outcome is also listed among the secondary outcomes, so its placement in the record is not entirely consistent.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count outcome represent?

The primary outcome is a count of participants meeting the stated abstinence definition. In general, a count reports how many individuals experienced a specified event or status. It is different from an effect estimate comparing groups: a count alone does not quantify a treatment contrast, and its meaning depends on the population assessed and the observation process.

For interpretation, readers typically need both the number meeting the outcome and the number whose status was assessed. When follow-up is incomplete, the enrolled total and the assessed total need not be the same. The registry record says that not every participant completed the 6mo and 12mo surveys, but does not give the follow-up denominator for the primary endpoint. It also does not report the number classified as abstinent. Thus, neither the outcome count nor a proportion based on participants with known status is available.

What does a confidence interval add?

In general, a confidence interval communicates statistical uncertainty around an estimate. A narrow interval indicates greater precision under the analysis assumptions; a wide interval indicates that a broader range of values remains compatible with the observed data. An interval does not correct a biased design or missing data, and it does not turn an uncontrolled observation into a randomized comparison. No confidence interval or other measure of uncertainty for the primary outcome is reported in the registry record.

For a single-group count, uncertainty could be described for the observed outcome under an appropriate model, but this would still be a description of that group. To estimate a comparative effect, a study needs a suitable comparator and a contrast between groups. STOP has one listed arm and no allocation, so its registered structure does not support a randomized between-group estimate.

Why does the study design matter?

Randomization is a design method used in comparative trials to balance, on average, both measured and unmeasured participant characteristics across treatment groups. A control group also provides a basis for estimating outcomes under a different condition. These are general principles. The registry lists STOP as single-group and records no allocation; it does not describe a randomized comparison. Therefore, a result from the intervention arm, if reported, would not by itself show the outcome difference attributable to the combined intervention.

The intervention combines nicotine replacement therapy and behavioural support. In general, when multiple components are delivered together in a single arm, the outcome cannot separate the effect of one component from the other without additional design features or comparisons. The registry record does not list component-specific arms or analyses.

How should planning calculations be read?

In general, a sample-size calculation estimates how many participants a planned study would need under specified assumptions about the target effect, significance level, allocation, and statistical model. A planning illustration is not an observed result. It does not show that a study had a particular probability of detecting an effect after the fact, and it cannot replace a reported estimate with its uncertainty.

The recorded planning assumptions describe a two-arm calculation with equal allocation, a two-sided significance level of 0.05, and a normal approximation. The trial itself is recorded as single-group, so those assumptions are not a description of its registered allocation. The illustrations are based on fractions of an observed effect, but an observed primary outcome effect is not reported in the registry record. The trial’s own sample-size justification is not reported in the registry record. These distinctions prevent planning scenarios from being mistaken for observed evidence or for the actual design.

What is not available about the analysis?

The registry record lists zero analyses and does not describe a statistical analysis plan, an analysis population, or handling of missing outcomes. In general, an analysis plan specifies how the endpoint will be summarized, which participants are included, how incomplete observations are treated, and which comparisons or adjustments are intended. Those choices affect how results should be interpreted. They cannot be reconstructed reliably from the endpoint name alone.

Over-dispersion is a general concern in some count models when variability exceeds what the chosen model expects. If present, it can make standard errors and confidence intervals too optimistic unless addressed with an appropriate method. The registered primary endpoint is a count of participants with an event, but no dispersion estimate or count model is reported. It would therefore be inappropriate to assert that over-dispersion was present or that a particular model was used.

Similarly, adjustment for baseline variables, sensitivity analyses, subgroup analyses, and interim monitoring can affect statistical interpretation, but none is described in the registry record. Their use should not be inferred. The posted registry information supports a description of the registered design and endpoint, not a reconstruction of unreported analytic decisions.

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("NRT + Behavioural Support")
n      <- c(2088)
events <- c(766)
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  NRT + Behavioural Support  2088  766  36.7  34.6  38.8  34.6  38.8  34.6  38.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures, including the count of participants not smoking, and identifies the same named measure as primary and secondary. It does not explain this overlapping classification or report the full details of the other measure in the information available for interpretation. The number of analyses is listed as zero. A multiplicity plan, including any hierarchy among outcomes or adjustment for multiple statistical tests, is not reported in the registry record.

In general, multiplicity arises when researchers make several statistical comparisons or test multiple outcomes. Without a prespecified strategy, the chance of finding at least one apparently notable result can increase as more tests are considered. Adjustment procedures or an explicitly prioritized outcome plan can help readers understand how to interpret multiple findings. Since no analyses or multiplicity approach are reported, no claim about adjustment or control of false-positive findings can be made for this study.

Missing follow-up is directly noted: not every participant completed the 6mo and 12mo surveys. The registry record does not report the number with missing primary endpoint status, reasons for missingness, or the method used to handle those observations. In general, complete-case summaries describe participants with observed outcomes, while other approaches may make assumptions about outcomes that are missing. Different approaches can yield different interpretations, and their validity depends on assumptions that should be made explicit.

The analysis population is not reported in the registry record. It is therefore unclear from the record whether the primary measure was intended to include all enrolled participants, only participants who completed follow-up, or another defined group. No imputation method, sensitivity analysis, or missing-data assumption is reported. These omissions limit evaluation of both the representativeness of the observed outcomes and the robustness of any result.

12. 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.

The registry lists one intervention group, NRT plus Behavioural Support, with 6009 participants at risk for serious adverse events and zero affected. It also lists 6009 at risk for other adverse events and zero affected. Deaths are listed as zero. No top serious adverse event terms are listed.

These are the safety counts recorded in the registry; they are not evidence that the chance of an adverse event is zero. In general, a report of no recorded events does not rule out events that were not detected, not reported, or not captured within the applicable observation period. The record does not specify the safety observation period, event definitions, ascertainment procedures, or completeness of safety follow-up. Those details are not reported in the registry record.

The at-risk counts and event counts are registry safety summaries, not a comparison with an untreated or alternative-treatment group. They cannot establish whether the intervention changed adverse-event risk relative to another condition. They should also be kept separate from the abstinence endpoint: safety counts do not provide the missing primary outcome result.

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

The registry record establishes that STOP was a completed, single-group study of nicotine replacement therapy combined with behavioural support, and that its named primary measure concerned 7-day point prevalence of abstinence at 6 months post treatment. It also records enrollment of 6009 and notes incomplete follow-up survey completion. These details help define the setting and the intended measurement.

The record does not report the abstinence count, the number assessed for that endpoint, an effect estimate, or a statistical analysis. As a result, it does not show how many participants met the abstinence definition or how precisely that outcome was estimated. The enrollment number cannot stand in for the number with observed outcomes, particularly given the stated follow-up incompleteness.

Even a reported count from this one group would describe outcomes among participants in the intervention arm, rather than establish a causal effect. Without a comparator, observed abstinence cannot be contrasted with an outcome under another strategy. The design also cannot isolate the contribution of nicotine replacement from behavioural support, which were combined in the listed arm. Thus, no comparative effectiveness claim follows from the registry design alone.

The serious adverse event summary records zero affected among 6009 at risk, and the other adverse event summary also records zero affected among 6009 at risk. These are safety entries, not a complete account of all possible harms or an efficacy finding. The registry record does not describe the observation period or event ascertainment in enough detail to interpret the counts beyond what is recorded.

The distinction is between what the record documents and what it leaves unanswered. It documents the study structure, the endpoint definition, enrollment, and safety counts. It does not report endpoint results, analytic methods, uncertainty, or a comparison. Conclusions should remain within those boundaries.

14. Why This Trial Matters Statistically

Statistically, STOP illustrates the difference between a study’s stated objective and the evidence available for assessing it. The registry describes a goal of evaluating nicotine replacement therapy delivery and includes an abstinence endpoint, but does not report the endpoint result or its analysis. A clear outcome definition is necessary for interpretation, yet it is not sufficient without the observed data, denominators, and method of analysis.

The study also illustrates how design determines the questions an analysis can answer. A single-group study can document outcomes among participants receiving a combined intervention. It cannot directly estimate how those outcomes differ from a separate control condition. This distinction remains important regardless of the enrollment size: a larger single group does not create the missing comparison.

Follow-up completeness is another core statistical issue. The registry explicitly notes that not every participant completed follow-up surveys. Without counts of missing outcomes and a description of their handling, readers cannot judge whether the observed participants represent the enrolled group or how missingness might affect an endpoint summary. Transparent reporting of denominators and analysis decisions is therefore essential to understand outcome estimates.

Finally, the record separates safety summaries from efficacy results. Zero recorded adverse events is a reported safety count, whereas the primary abstinence result is not reported. Treating these as distinct evidence types avoids conflating absence of a recorded event with evidence about the study’s primary clinical question. The case underscores the value of complete outcome reporting, analysis detail, and alignment between the question, design, and conclusions.

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 main limitation for interpretation is that the primary endpoint result is not reported in the registry record. The count of participants not smoking at 6 months, its follow-up denominator, and any uncertainty estimate are unavailable. Therefore, the central outcome cannot be described quantitatively from the registry information.

The study is registered as single-group, with one combined intervention arm and no allocation. There is no like-for-like control comparison. As a result, the design does not support attributing an observed outcome to the intervention through a randomized contrast. Since nicotine replacement therapy and behavioural support are delivered together in the listed arm, their separate contributions are not estimable from the recorded design.

The registry notes that not every participant completed 6mo and 12mo follow-up surveys, but does not report completion counts, reasons for missingness, or the approach to missing data. The population used for analysis is also not reported in the registry record. These gaps make it difficult to assess outcome ascertainment and potential bias related to incomplete follow-up.

The analysis details are limited: zero analyses are listed, and the statistical plan, sample-size justification, analysis populations, interim analyses, and multiplicity approach are not reported in the registry record. The primary endpoint is also listed among secondary outcomes, leaving its classification in the record unclear. Finally, the safety entries do not specify the observation period or event ascertainment. Each of these limitations concerns what can be established from the registered information; none supplies an alternative result.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Phase I Study: Stop Smoking Therapy for Ontario Patients (STOP) — NCT00356993.
• Registry record last updated 2021-11-30; status last verified 2021-11.
• Results first posted 2019-05-02.
• 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

STOP is registered as a completed, single-group study sponsored by the Centre for Addiction and Mental Health, with enrollment of 6009. The study arm combined nicotine replacement therapy and behavioural support. The registry records no allocation and no masking.

The primary measure is the count of participants not smoking at 6 months post treatment, described as 7-day point prevalence of abstinence. The registry notes incomplete completion of 6mo and 12mo follow-up surveys, but does not report the primary outcome count, its denominator, or an analysis. The same named measure is also listed among the secondary outcomes.

Serious adverse events are listed as zero among 6009 at risk; other adverse events are also listed as zero among 6009 at risk, with deaths listed as zero. These safety summaries do not establish a comparative effect. The registry record does not report the study’s own statistical plan or sample-size justification.