Improving the Delivery of Smoking Cessation Guidelines in Hospitalized Veterans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving the Delivery of Smoking Cessation Guidelines in Hospitalized Veterans (NCT00816036), a non-randomized na study. The primary outcome is 7-day Point-prevalence Smoking Abstinence (6-month).

2. Clinical Question

3. Trial Design

The registry record identifies NCT00816036 as a completed study titled Improving the Delivery of Smoking Cessation Guidelines in Hospitalized Veterans. The sponsor is the US Department of Veterans Affairs. The recorded start is 2009-05, and the primary completion is 2013-06. The study is listed as non-randomized, unmasked, and parallel, with an enrollment of 898. Its phase is recorded as NA.

The arms are labeled Baseline Period and Intervention Period. The intervention is behavioral and concerns implementation of smoking cessation guidelines. The study objective describes a nurse-initiated intervention that couples brief counseling during hospitalization with proactive telephone counseling from a centralized tobacco quitline. The registry record does not provide further details about implementation, the order or duration of the periods, or whether there were differences in care beyond the stated intervention.

Non-randomized status matters when interpreting an arm comparison. Random assignment is not described, and the registry record specifically cautions that these arms are not a like-for-like control comparison. Differences between periods, if reported, could not automatically be attributed solely to the intervention: the groups may differ in ways not described, and other changes associated with the periods may also matter. The record does not report methods to address such concerns.

The listed secondary outcomes concern referrals to the quitline and prescription of recommended pharmacotherapy for smoking cessation. The record lists three outcome measures, but it does not provide results for the primary or secondary outcomes. It also records no analyses. Details of the statistical analysis plan, allocation procedures beyond non-randomization, and any adjustment for differences between groups 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: This is the total number of subjects who completed 6 month follow-up (complete case 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 7-day Point-prevalence Smoking Abstinence (6-month), measured over 6 months post enrollment.

The primary endpoint is 7-day Point-prevalence Smoking Abstinence at six months post enrollment. It is measured as the number of participants who reported not having smoked cigarettes during the seven days before the six-month follow-up interview. The endpoint description specifies a complete-case population: subjects who completed the six-month follow-up.

Point-prevalence abstinence asks about smoking status during a defined recent period. As a general statistical concept, this differs from an outcome that requires continuous abstinence throughout the whole follow-up period. A participant’s report for the seven days before the interview does not, by itself, describe smoking behavior during all earlier months. The endpoint is therefore a time-specific measure of reported abstinence, not a complete account of every participant’s smoking history.

The registry record describes the outcome as a participant count and specifies self-report at follow-up. It does not report the observed counts, the number completing follow-up in each arm, or any confirmation procedure beyond the interview. The purpose of using an endpoint is to make the primary question measurable, but interpreting it depends on knowing both the recorded outcome and the population included in its analysis. Those results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the endpoint count?

The primary outcome is a count of participants reporting no cigarette smoking during the seven days before the six-month follow-up interview. It is a binary outcome at the participant level: each person either meets the stated abstinence definition or does not, while the registered summary measure is the number meeting it. A count is not itself a comparison. To assess the study question, readers would need the relevant outcome counts and denominators for the periods, along with an estimate of their contrast and its uncertainty. Those results are not reported in the registry record.

As a general statistical concept, binary outcomes can be summarized as counts, proportions, or contrasts between groups. A count depends on how many people were assessed, so it should be interpreted alongside its denominator. For this endpoint, the record says the population is participants who completed the six-month follow-up, but it does not state the completion counts by arm. The enrollment figure alone does not identify the denominator used for the primary analysis.

What does a confidence interval express?

In general, a confidence interval describes the uncertainty around an estimated quantity under the assumptions of the statistical method used. A narrow interval indicates greater precision than a wide interval, while the interval’s location indicates which values remain compatible with the data and method. It is not a guarantee that the true value lies within the particular interval. The registry record does not report a confidence interval for the primary outcome, so the precision of any comparison cannot be evaluated.

A p-value, in general, measures how incompatible the observed data are with a specified null model, assuming that model and the analysis assumptions hold. It does not measure the probability that the null hypothesis is true, and it does not convey the size or practical importance of an effect. No primary-outcome p-value is reported in the registry record. Thus, there is no reported test result to interpret, and a significance conclusion cannot be drawn from the study objective or completion status.

Why does the allocation method matter?

The study is registered as non-randomized, with arms labeled Baseline Period and Intervention Period. Randomization, as a general design method, aims to balance measured and unmeasured participant characteristics across comparison groups on average. Without randomized assignment, an observed difference may reflect the intervention, group composition, changes over time, or other factors. This does not mean that a non-randomized study cannot be informative; it means that causal interpretation requires care and depends on design and analysis details.

The record expressly says the arms are not a like-for-like control comparison. It does not report participant characteristics by period, adjusted estimates, or a method for accounting for possible period differences. It is therefore not possible to determine from the registry record whether such differences were present or how they were addressed. The posted design labels alone do not resolve these questions.

What does complete-case analysis imply?

The primary endpoint population is described as participants who completed the six-month follow-up, characterized as a complete case analysis. As a general statistical concept, complete-case analysis uses participants with the information needed for the outcome and excludes those without it. Its interpretation depends in part on why information is missing. If the likelihood of completing follow-up is related to smoking status or other participant characteristics, the analyzed group may differ from the group initially enrolled. The record does not report follow-up completion counts, reasons for missingness, or sensitivity analyses.

Missing outcome data are not automatically equivalent to abstinence or to smoking. The registry record does not say that missing responses were classified in either way; it describes the primary population as those completing follow-up. Without the number and characteristics of participants not included in that complete-case population, the potential effect of missingness cannot be assessed.

What can be inferred from the analysis information?

The record lists zero analyses and does not provide a statistical analysis plan. It does not report the model used for the primary comparison, covariate adjustment, handling of repeated or clustered observations, or a method for deriving uncertainty estimates. These details are important because analysis choices determine the estimate being reported and the assumptions behind its precision. Their absence means that a reader cannot reconstruct or evaluate a primary comparison from the registry information.

The registry record also describes planning assumptions for sample-size illustrations as using a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects defined as fractions of an observed effect. These are planning assumptions, not a description of the trial’s own design justification, and the record does not report a trial-specific sample-size justification. Any such illustration should be understood as a planning exercise rather than evidence about the observed outcome or observed power. The record does not report an interim analysis plan.

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("Arm 1", "Arm 2")
n      <- c(498, 394)
events <- c(69, 53)
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  Arm 1  498  69  13.9  10.9  17.2  11.1  17.2  11.1  17.2
ARM  Arm 2  394  53  13.5  10.2  17.2  10.4  17.2  10.4  17.2

11. Multiplicity, Missing Data and Analysis Populations

The registered outcomes include the primary six-month point-prevalence abstinence measure and secondary outcomes concerning referrals to the quitline and prescription of recommended pharmacotherapy. Considering multiple outcomes can raise a multiplicity question: when several hypotheses are tested, the chance of at least one apparently unusual result may change. As a general statistical concept, a study may prespecify a primary outcome, adjust inference across tests, or treat secondary results as exploratory. The registry record does not report a multiplicity strategy or the statistical analysis plan, so the approach to multiple outcomes is not known.

The primary endpoint population is defined as participants who completed the six-month follow-up, which the record calls a complete case analysis. The number completing follow-up in each period, the amount of missing outcome information, and the reasons for missingness are not reported in the registry record. The record also does not report imputation, sensitivity analyses, or another method for evaluating how missing observations might affect the result. Therefore, the extent and potential influence of missing data cannot be assessed.

The record lists zero analyses. It does not report whether analyses were planned at interim time points, whether any subgroup analyses were prespecified, or how the listed outcomes were modeled. Such information is not reported in the registry record; it should not be inferred from the outcome list or from the study’s completed status. The registry description does identify the primary population and outcome definition, but it does not provide the analytic detail needed to evaluate the handling of multiplicity or missingness.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event figures list 503 participants at risk in the Baseline Period and 395 in the Intervention Period. For serious adverse events, the recorded number affected is 0 in each period. The figures also list 503 and 395 participants at risk, respectively, for other adverse events, with 0 affected in each period. These are the counts recorded in the registry; they do not provide additional detail about event definitions, surveillance, or ascertainment.

A recorded zero means that the registry reports no affected participants for that category in the listed data. It should not be interpreted as proof that no events occurred outside the data collection or reporting captured in the record. The record does not list serious adverse-event terms. Death counts are null, so deaths are not reported in the registry record; null should not be read as a count of zero.

These safety counts are separate from the primary smoking abstinence endpoint. They do not supply evidence about cessation outcomes, and the registry record does not describe an analysis comparing safety risks between periods. The non-randomized design also means that these groups should not be treated as randomized safety comparators.

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

The registry record establishes that a study was conducted to examine nurse-initiated smoking cessation guideline implementation among hospitalized veterans. It identifies the comparison as a Baseline Period versus an Intervention Period and defines the primary outcome as reported abstinence during the seven days before a six-month follow-up interview. It also identifies quitline referrals and recommended pharmacotherapy prescriptions as secondary outcomes. These details describe the research question and planned measurement, not the study’s observed effect.

The record does not report primary or secondary outcome results. It therefore does not support a conclusion about whether abstinence was more or less frequent in the Intervention Period, how large any difference was, or how precise an estimate might be. No statistical significance claim can be made from the information recorded. The study’s stated objective is not a substitute for outcome data.

Even if a period comparison were reported, the non-randomized design would call for caution in interpreting it as an effect caused by the intervention. The registry record itself warns that the arms are not a like-for-like control comparison. As a general principle, differences in participants or circumstances across periods can complicate attribution, and the available record does not describe adjustment methods.

The endpoint has a defined, limited scope: self-reported smoking status during a seven-day window at six months, among people completing follow-up. It does not establish whether participants remained abstinent throughout the interval before the interview. Follow-up completion counts and missing-data handling beyond the complete-case description are not reported. Accordingly, neither the representativeness of the analyzed participants nor the sensitivity of results to missing information can be judged.

The record also does not provide evidence that the intervention succeeded or failed. It documents a completed study and records adverse-event counts, but neither status nor safety counts answer the primary cessation question. Interpretation of that question requires outcome results and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why identifying an outcome is not the same as having evidence about its result. The registry record gives a specific primary endpoint, a six-month assessment time, and a clear seven-day recall window. Those features help readers understand what the study intended to measure. However, without the observed counts, denominators, and comparison estimate, the endpoint definition alone cannot tell readers whether outcomes differed between periods.

It also highlights the importance of design when interpreting comparisons. The record labels the study non-randomized and explicitly cautions that its arms are not a like-for-like control comparison. A statistical contrast is most useful when readers can understand not only its magnitude and uncertainty, but also the basis for comparing the groups. The registry does not report participant characteristics or analytic adjustments that would clarify comparability.

The complete-case definition makes follow-up information part of the interpretation. Knowing which participants completed the six-month interview, and what happened to those without outcome data, would help readers assess the population represented by the primary analysis. Those details are not reported in the registry record. The record’s analysis count is zero, and it does not describe the analysis plan or multiplicity handling for the primary and secondary outcomes.

Finally, the adverse-event counts illustrate the distinction between a recorded zero and a fully characterized safety assessment. The registry lists zero affected participants in the displayed categories, but deaths are not reported and event ascertainment details are absent. Statistical reading requires attending to what each field does and does not establish, rather than treating missing results or details as reassuring findings.

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 interpreting this study from the registry record is the absence of reported outcome results. The six-month abstinence endpoint is defined, but its counts, denominators, comparison estimate, and uncertainty are not reported. The secondary outcomes are named without results. Consequently, the magnitude and precision of any difference between the periods cannot be assessed from the record.

The comparison is non-randomized, and the record cautions that the arms are not a like-for-like control comparison. It does not report baseline characteristics by period, the details needed to judge comparability, or adjusted analyses. Potential differences between periods therefore cannot be evaluated from the registry information.

The primary outcome uses participant reports about the seven days before the six-month interview and is limited to people who completed follow-up. The record does not report how many completed follow-up in each period, how missing responses were handled beyond the complete-case definition, or whether sensitivity analyses were performed. It also does not describe confirmation of reported abstinence.

The statistical analysis plan, multiplicity approach, and interim analysis information are not reported in the registry record. Nor does the record provide the operational detail needed to assess the consistency of intervention delivery. These omissions limit evaluation of both the analysis and implementation. The adverse-event data list zero affected participants for serious and other events, but deaths are not reported and ascertainment detail is absent. These limits describe gaps in the registry record and do not establish what may have been available elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Improving the Delivery of Smoking Cessation Guidelines in Hospitalized Veterans — NCT00816036.
• Registry record last updated 2015-04-27; status last verified 2014-04.
• Results first posted 2014-08-06.
• 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

NCT00816036 is a completed, non-randomized study sponsored by the US Department of Veterans Affairs, with an enrollment of 898. The record lists a Baseline Period and an Intervention Period and describes a nurse-initiated smoking cessation guideline intervention involving brief inpatient counseling and proactive quitline telephone counseling. The primary endpoint is the number of participants reporting no cigarette smoking during the seven days before a six-month follow-up interview, among those who completed follow-up.

Quitline referrals and prescription of recommended smoking cessation pharmacotherapy are listed as secondary outcomes. The record does not report primary or secondary outcome results, a statistical analysis plan, or analyses. Serious and other adverse-event counts are recorded as 0 affected in both periods; death counts are not reported in the registry record. The non-randomized comparison should not be treated as a like-for-like control comparison.