Smoking Cessation in Alcoholics: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Smoking Cessation in Alcoholics (NCT00963482), a randomized na study. The primary outcome is Number of Smoke-free Patients.

2. Clinical Question

3. Trial Design

This was a randomized, controlled, parallel-group trial comparing a cognitive-behavioural smoking cessation program with autogenic training among inpatient alcohol-dependent smokers. The registry records no masking. It lists the study as completed, with enrollment of 103. The study start is recorded as 2007-07 and primary completion as 2010-01.

The study summary frames the intervention as a specific smoking cessation program based on cognitive-behavioural therapy, and the control condition as treatment as usual. The arm descriptions, however, identify the control intervention as autogenic training. The registry does not explain the relationship between that arm description and the summary’s wording, so the comparison is best described using the intervention and control arm names recorded for the trial.

The primary outcome was assessed at 6 months and is labelled as an intention-to-treat analysis. The registry lists the intervention group with 46.0 participants and 0.0 smoke-free patients, and the control group with 43.0 participants and 3.0 smoke-free patients. The record does not explain why the outcome group sizes differ from each other or from the overall enrollment figure.

A secondary outcome concerned drinking in the last 7 days, assessed using patient report and a urine sample. Details about its result are not reported in the registry record. The record lists two outcome measures and one analysis. Further information about the randomization procedure, allocation concealment, treatment delivery, follow-up schedule, or prespecified statistical plan 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.

Before assignment: Out of 237 screened patients, 103 were enrolled. Intervention group(EG)=53; Control group (CG)=50.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Intention-to-treat analysis

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 Number of Smoke-free Patients, measured over 6 months.

The primary endpoint is the number of patients classified as smoke-free at 6 months, within the population described as intention-to-treat. The registry’s definition combines patient report about smoking during the last 7 days with carbon monoxide measurement and a urine cotinine sample. It specifies a carbon monoxide level below 10ppm as part of the smoke-free definition.

This endpoint uses more than self-report alone: the record describes both reported smoking behaviour and biochemical measures. Such measures can provide different kinds of information, but the registry does not state how discordant results were handled, whether all listed criteria had to be met, or how unavailable measurements were classified. Those details are not reported in the registry record.

Counting patients classified as smoke-free gives an outcome that can be compared between the randomized groups. The posted results report 0.0 smoke-free patients in the intervention group and 3.0 in the control group. This is a count-based binary outcome: each patient is classified as smoke-free or not according to the study’s definition. The outcome does not, by itself, describe changes in smoking intensity, duration of abstinence, or the timing of any return to smoking.

7. Results Posted in the Registry

• Intervention Group: 0.0% (0/46) versus 7.0% (3/43) on control; risk difference -7.0 percentage points (95% CI -14.6 to 0.6); unadjusted two-proportion z-test p = 0.068.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary at the patient level: a patient is classified as smoke-free or not under the registry’s stated definition. The posted group results are counts, and the comparison uses a risk difference. In general, a risk difference expresses the difference between the proportions experiencing an outcome in two groups. Its sign depends on the order in which groups are compared. Here, the reported comparison is intervention relative to control, so a negative estimate points toward a lower observed smoke-free proportion in the intervention group.

What does the unadjusted recalculation mean?

The recalculated comparison uses the posted outcome counts and group sizes without adjustment for other variables. It is therefore a simple, unadjusted comparison, rather than an estimate accounting for possible differences in baseline characteristics or other covariates. The registry record does not report an adjusted primary analysis. Recalculation from summary data can help readers understand the direction and uncertainty of the observed group contrast, but it cannot reproduce unreported aspects of the sponsor’s analysis.

The recalculated p-value is p = 0.068. In general, a p-value measures how unusual data at least as incompatible with a specified null model would be if that model were true. It is not a measure of the size or importance of the difference, nor is it the probability that the observed pattern arose by chance. The registry reports a Chi-squared test with p =.111. Since the record does not describe the test’s details beyond its method label, the source of the numerical difference cannot be identified from the registry information.

How should the confidence interval be read?

A confidence interval expresses uncertainty around an estimated effect under the assumptions of the method used. A wide interval indicates that the data do not pin down the effect precisely. For this risk difference, the interval includes zero and extends in both directions. It therefore does not rule out no difference, nor does it rule out effects in either direction. It should not be interpreted as a range containing every plausible value with certainty.

The observed count of smoke-free patients is low in both groups. With few outcome events, estimates and tests can be sensitive to the method used, and the available data provide limited precision. The registry does not report whether any alternative methods for sparse binary outcomes were considered. The recalculation remains a simple summary-based analysis rather than evidence that a particular method was prespecified.

What does the sample-size illustration represent?

Any sample-size figures associated with this analysis are planning illustrations based on the observed effect, not the trial’s original design. The listed assumptions describe a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect targeted is a stated fraction of the observed effect. Such calculations ask how many participants per arm might be needed under those assumptions to detect a specified effect with a chosen power. They do not tell how likely this completed trial was to detect an effect, and they are not observed power.

Planning calculations based on an effect observed in a small-outcome trial can be unstable: the observed effect may not represent the underlying effect, and changing the targeted fraction changes the planning scenario. The record does not report a sample-size justification from the original protocol, the assumptions used when designing the trial, or whether the study was intended to detect a particular clinically meaningful difference. Those design details are not reported in the registry record.

What other analysis details are missing?

The outcome is described as intention-to-treat, but the registry does not provide a detailed definition of that population or state how missing outcome components were handled. It also does not report adjustment variables, a detailed analysis plan, interim analyses, or the treatment of multiple outcomes or tests. General statistical interpretation should therefore remain focused on the posted outcome counts, the registry’s stated Chi-squared result, and the unadjusted recalculation.

10. Confidence Intervals and Precision

The confidence interval for the unadjusted risk difference extends across zero. In practical terms, the observed data do not locate the group contrast precisely enough to exclude no difference, and the interval also permits contrasts in either direction. The interval should be read alongside the small number of smoke-free outcomes, rather than as a precise estimate of the underlying effect.

Precision depends on the amount of information in the data and on the variability of the outcome. Here the binary endpoint records only a small number of smoke-free patients across the reported groups. That leaves substantial uncertainty around the comparison. An interval that includes zero is not proof that the groups are the same; it indicates that the data are compatible with a range of effects that includes no difference.

The recorded group sizes are 46.0 for the intervention group and 43.0 for the control group. The registry does not explain how these outcome denominators relate to the enrollment of 103 or whether any outcome observations were missing. This makes it difficult to assess the completeness of the primary endpoint from the registry record alone. The reported intention-to-treat label does not substitute for details about which participants were included and how unavailable measurements were treated.

The p-values also reflect uncertainty, but they compress information into a single measure and do not convey the range of effect sizes compatible with the data. The recalculated p-value and the sponsor-reported p-value differ, while both are above the listed planning significance level. Neither should be interpreted as evidence of equivalence or as a direct measure of the magnitude of any group difference.

11. Analyses Reported by the Sponsor

The registry reports a Chi-squared analysis comparing the two groups, with p =.111. The unadjusted recalculation from the posted group counts gives p = 0.068. The registry record does not explain the difference between these p-values, and it does not provide further details about the sponsor’s test implementation. The recalculation is a separate, simple analysis of the posted summary statistics and should not be presented as the sponsor’s result.

The two analyses do not produce identical p-values, but each is above the 0.05 significance level listed among the planning assumptions. This does not establish that the groups are equivalent. The confidence interval for the recalculated risk difference includes zero, and the small number of smoke-free outcomes limits precision. The sponsor’s reported analysis is the primary registry-reported analysis; the recalculation can serve only as a transparent supplementary check based on the posted counts.

The record does not report a reason for using the Chi-squared method, whether it was prespecified, or whether another test was used in the original protocol. It also does not provide enough information to determine whether differences arise from test choice, data handling, or another analysis detail. Any explanation beyond the stated distinction between the reported test and the unadjusted recalculation would be speculative.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and one analysis, and identifies a secondary outcome concerning drinking in the last 7 days. A trial may examine more than one outcome or conduct more than one statistical test; when many tests are considered, the chance of at least one apparently unusual result can increase. Whether and how to address that issue depends on the prespecified analysis plan and the role of each outcome.

The registry record does not report a multiplicity adjustment, a hierarchy of outcomes, or a detailed plan for interpreting multiple tests. It also does not provide the result for the listed secondary outcome in the information. Therefore, the scope of any multiplicity concern and its effect on interpretation cannot be determined from the record. The primary outcome should be read as the registry identifies it, while recognizing that the wider testing plan is not reported.

The primary endpoint is labelled intention-to-treat, but detailed information about the analysis population is not reported in the registry record. In particular, the record does not explain the relationship between overall enrollment of 103 and the outcome group sizes of 46.0 and 43.0. It does not state whether participants were excluded from the endpoint analysis, whether the denominators reflect available measurements, or how missing self-reports, carbon monoxide results, or urine samples were classified.

Those omissions matter because missing outcome information can affect both the observed counts and the uncertainty of a binary comparison. The record also does not describe the randomization procedure, allocation concealment, interim analyses, a statistical analysis plan, or covariate adjustment. No assumption about these procedures should be substituted for the information actually recorded.

13. 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.

The registry records zero serious adverse events among 53 at risk in the intervention group and zero among 50 at risk in the control group. It also records zero other adverse events among 53 at risk in the intervention group and zero among 50 at risk in the control group. These are the posted event counts and at-risk figures.

The registry does not report deaths for either group. It also does not list serious adverse-event terms. The record does not provide a safety follow-up timeframe or explain how the at-risk figures relate to the group sizes reported for the primary endpoint. Those details are not reported in the registry record.

Zero recorded events in these groups does not establish that no adverse events occurred outside the registry’s recorded categories, observation period, or reporting process. Nor do these figures establish a comparative safety profile. They are counts in the posted safety record and should be interpreted separately from the primary smoking outcome.

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

The primary endpoint records the number of patients classified as smoke-free at 6 months according to the registry’s stated measures. The posted counts are 0.0 in the intervention group and 3.0 in the control group. The unadjusted risk-difference estimate points in the direction of fewer smoke-free patients in the intervention group, but its confidence interval includes zero and extends in both directions.

The registry’s Chi-squared analysis reports p =.111, while the unadjusted recalculation reports p = 0.068. These results do not provide clear evidence of a group difference under the listed planning significance level, but they do not demonstrate that the interventions are equivalent. The limited number of smoke-free outcomes leaves the estimate imprecise.

The findings apply to the trial as recorded: inpatient alcohol-dependent smokers, a cognitive-behavioural smoking cessation program, autogenic training as the control, and the specified smoke-free assessment at 6 months. They do not establish what would occur in other populations, settings, or comparisons. The record does not provide enough detail to assess all aspects of outcome ascertainment or missing-data handling.

The listed secondary outcome concerns drinking in the last 7 days, but its result is not reported in the registry record. The posted safety counts record no serious or other adverse events in the stated at-risk groups, while deaths are not reported. Neither the secondary outcome nor the safety figures change the uncertainty surrounding the primary endpoint comparison.

These results should be understood as a description of the posted data and their statistical precision. They do not constitute medical advice or a general claim about the effectiveness of a smoking cessation approach.

15. Why This Trial Matters Statistically

This trial illustrates how a small number of binary outcome events can leave a comparison uncertain even when group counts and a test result are available. The primary endpoint is easy to state as a count of smoke-free patients, but the contrast between groups is less straightforward: its direction depends on which group is subtracted from which, and its precision depends on the observed information.

It also shows why a p-value should not be read alone. The registry-reported Chi-squared p-value and the unadjusted recalculation differ, and neither is a measure of the size or clinical importance of an effect. The confidence interval provides additional context by showing that the estimated contrast remains compatible with no difference and with effects on either side.

The outcome definition combines self-report with biochemical measures, while the registry does not describe how discordant or missing measurements were handled. That distinction matters for reproducibility: a reader needs both the endpoint definition and the rules used to turn measurements into a final classification. The intention-to-treat label is useful, but without further analysis-population details it cannot answer all questions about denominators and missing information.

Finally, the record distinguishes a sponsor-reported analysis from a recalculation based on posted summary statistics. Keeping those roles separate helps avoid treating a secondary check as though it were the prespecified analysis. It also makes visible which questions remain unresolved in the registry record, including the original design assumptions and the approach to multiple outcomes.

16. 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 several trial-specific details unresolved. Although it identifies the study as randomized and gives a parallel-group model, it does not report the randomization procedure or allocation concealment. Masking is listed as none. The record does not describe how the intervention was delivered, the duration or intensity of treatment, or adherence to either behavioral condition.

The primary outcome definition lists patient report, carbon monoxide measurement, and urine cotinine, but the record does not explain how these components were combined, how conflicting measurements were classified, or how missing measurements were handled. It labels the endpoint analysis intention-to-treat without detailing the analysis population. Outcome group sizes are 46.0 and 43.0, while enrollment is 103; the reason for this difference is not reported.

The registry reports a Chi-squared test but does not provide a full analysis plan or explain the difference from the unadjusted recalculation. It does not report whether analyses were adjusted, whether interim analyses occurred, or how multiple outcomes were handled. The listed secondary drinking outcome has no result reported in the available record.

The safety record lists no serious or other adverse events in the reported at-risk groups, but does not give a safety follow-up timeframe. Deaths are not reported. The original sample-size justification and the assumptions used in the trial’s design are also not reported in the registry record. These limitations restrict what can be concluded from the posted information; they do not establish that the unreported procedures or events were absent.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Smoking Cessation in Alcoholics — NCT00963482.
• Registry record last updated 2015-03-27; status last verified 2015-03.
• Results first posted 2012-04-13.
• 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.

20. Record Summary

NCT00963482, titled “Smoking Cessation in Alcoholics,” is recorded as a completed randomized, unmasked, parallel-group trial. It compared a cognitive-behavioural smoking cessation program with autogenic training in inpatient alcohol-dependent smokers. Enrollment was 103, and the primary outcome was the number of smoke-free patients at 6 months.

The posted primary counts were 0.0 in the intervention group and 3.0 in the control group. The registry reports a Chi-squared p-value of =.111; an unadjusted recalculation gives p = 0.068. The recalculated confidence interval includes zero, and the record does not provide enough detail to explain the difference between the two analyses.

The registry lists drinking in the last 7 days as a secondary outcome, but its result is not reported in the registry record. Safety figures record zero serious and zero other adverse events in the stated at-risk groups; deaths are not reported. Details about missing primary outcome data, the original sample-size justification, and the full statistical plan are not reported.