Effectiveness of a Smoking Cessation Algorithm Integrated Into HIV Primary Care: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effectiveness of a Smoking Cessation Algorithm Integrated Into HIV Primary Care (NCT03670316), a randomized phase 4 study. The primary outcome is 7-day Point-prevalence Abstinence.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group clinical trial with no masking. The registry lists the study as completed and reports an enrollment of 371. The listed condition areas are HIV, AIDS, and smoking cessation. The sponsor was the University of Alabama at Birmingham. The registry dates are 2020-08-17 for study start and 2025-06-30 for primary completion. The study is identified as phase PHASE4.

The experimental approach was Algorithm Treatment plus referral to a quitline (AT). The registry describes an algorithm intended to recommend smoking-cessation pharmacotherapy options to primary care providers. Its arm description says participants would be assigned a recommended pharmacotherapy regimen. The comparator, Quitline (eTAU), was referral to telephone-based tobacco-cessation services. The record does not specify the particular medications, how providers applied recommendations, or what support participants received after referral.

Random allocation is intended to make the groups comparable on average at the time of assignment, including for characteristics that were not measured. It does not guarantee that the realized groups are alike, and the registry record does not provide baseline characteristics with which to assess their balance. With no masking, participants and care providers were not masked to assignment according to the registry’s masking field. The record does not describe whether outcome assessors were masked.

The parallel design means the assigned groups were followed as separate arms rather than participants switching between assigned approaches as part of the stated design. The record does not report the allocation sequence method, concealment procedures, treatment adherence, or departures from assigned care. Those details 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

Analysis population for the primary outcome, as defined in the registry: 118 missing

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: Region of Enrollment: Alabama, Massachusetts, and Washington state.

6. Primary Endpoint

The registry lists the primary outcome as 7-day Point-prevalence Abstinence, measured over 6 months.

The primary endpoint is 7-day Point-prevalence Abstinence at 6 months. It is defined as self-report of cigarette smoking in the last 7 days and expressed as a count of participants. It therefore concerns reported smoking status over a recent, bounded period at the follow-up assessment. It does not, by its stated definition, establish whether a participant remained abstinent throughout the period before that assessment.

As a general statistical concept, a point-prevalence measure can provide a practical snapshot of an outcome at a specified follow-up. It can be easier to interpret than a measure requiring continuous abstinence over a longer interval, but the two types of outcomes answer different questions. Self-report also means the endpoint depends on participants’ reports; the registry does not describe biochemical confirmation or another verification method.

The endpoint is relevant to the trial’s stated focus on smoking cessation, but the registry does not state why this particular definition was selected. It lists 118 missing for the primary outcome. Group-specific outcome counts, the handling of missing reports, and the primary statistical comparison are not reported in the registry record. Without those details, the outcome’s observed group contrast and its precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical interpretation of this trial depends on distinguishing the planned clinical question from the results actually reported. A randomized comparison aims to estimate how outcomes differ between assigned groups. For a binary endpoint such as whether a participant reports abstinence, the basic data would include the number meeting the endpoint and the number assessed in each group. The registry gives neither group’s primary-outcome count nor a corresponding comparison. No primary-outcome effect estimate or uncertainty interval is reported in the registry record.

What does a confidence interval communicate?

As a general statistical explanation, a confidence interval describes the uncertainty around an estimated effect under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, while either interval may include values that are compatible with different interpretations. A point estimate alone would not show how precisely an effect was estimated. In this case, neither the estimate nor its confidence interval is reported, so the precision of the primary comparison cannot be evaluated.

Why does the outcome definition matter?

The endpoint is a count of participants reporting no cigarette smoking in the last 7 days at the 6-month assessment. As a general concept, a binary endpoint reduces each participant’s status to whether the specified condition was met. The resulting group comparison depends on the outcome definition, the participants included in the analysis, and the way incomplete reports are treated. This point-prevalence definition should not be interpreted as evidence about smoking status on every day before the assessment. The record identifies self-report but does not describe validation procedures.

How should randomization be understood?

Random assignment is a design method for reducing systematic differences between groups at baseline. In expectation, assignment makes measured and unmeasured baseline characteristics comparable across groups. In any realized trial, chance imbalances can still occur. The registry does not provide baseline characteristics or the method used to generate and conceal allocation. It therefore allows the randomized, parallel design to be identified, but not a detailed appraisal of allocation procedures or group comparability.

Analysis choices also matter. An analysis based on assigned groups generally addresses the effect of being assigned to an approach, whereas an analysis based on treatment received can answer a different question and may be more vulnerable to differences arising after assignment. The record does not specify the analysis population, whether assignment was retained in the primary analysis, or whether adherence was assessed. These matters are not reported in the registry record.

What can be learned from the adverse-event counts?

The registry reports counts of participants affected in serious and other adverse-event categories, with at-risk counts for each category, and separate death counts. These are descriptive counts as posted. A comparison of such counts would require clarity about the event definitions, observation period, completeness of reporting, and whether events were assessed as related to treatment. Those details are not reported in the registry record. The posted counts alone do not establish that an intervention caused or prevented an event.

How should planning calculations be read?

As a general statistical concept, a sample-size calculation describes how many participants a future study might need under stated assumptions about the effect to detect, the significance level, allocation, and statistical method. It is a planning illustration, not an observed result and not a measure of the probability that this trial’s finding is correct. The described planning assumptions use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect expressed as a fraction of the observed effect. Such calculations depend on the effect estimate used; they do not replace the trial’s actual outcome analysis. Any planning figures should not be read as observed power.

The registry states that there are no analyses recorded. It also does not report a statistical analysis plan, a primary-outcome test, interim analyses, or adjustments for multiple outcomes. Their absence from the registry means readers cannot determine which model, test, or multiplicity strategy was used. Statistical methods can explain what would be needed to interpret a reported comparison, but they cannot reconstruct missing outcome data or establish an effect that the registry does not report.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and identifies 7-day Point-prevalence Abstinence as the primary outcome. The named secondary outcomes are cigarettes per day, the number of participants who attempt not to smoke for 24 hours at 6 months, and the number of prescriptions written by 6 months. Results for these outcomes are not reported in the registry record.

When a trial examines multiple outcomes or comparisons, the chance of at least one apparently unusual result can increase if each is assessed separately. As a general statistical principle, investigators may specify a hierarchy or adjustment to address this issue. The registry record does not report whether a multiplicity strategy was planned or applied, and it lists no analyses. It is therefore not possible to assess how the outcomes were analyzed or whether a reported result would account for multiple testing.

The primary outcome population field lists 118 missing. The record does not explain the reasons for missingness, how missing outcomes were handled, whether imputation was used, or whether sensitivity analyses were conducted. These choices can influence both the estimated outcome and its uncertainty. No analysis population, such as an intention-to-treat population, is identified in the registry record. The enrollment figure does not by itself establish how many participants contributed data to the primary analysis.

A protocol and statistical analysis plan could clarify prespecified outcomes, analysis populations, missing-data assumptions, and multiplicity handling, but these details are not reported in the registry record. Without them and without the outcome analysis, readers cannot judge whether the posted endpoint results reflect a prespecified analysis or assess the robustness of any comparison.

11. 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 registry reports serious adverse-event figures by group. For Enhanced Treatment as Usual (eTAU), 186 participants were listed at risk and 0 were affected. For Algorithm Treatment (AT), 184 were listed at risk and 0 were affected. For other adverse events, the corresponding at-risk counts were 186 and 184, with 0 affected in eTAU and 5 affected in AT. The registry separately lists deaths as 4 in eTAU and 3 in AT.

These are registry counts, not an explanation of the events. The record does not give the serious-event terms, event descriptions, severity details beyond the category, timing, or assessment of relatedness to treatment. It also does not clarify whether the death counts overlap with adverse-event categories or describe causes. The serious-event terms list is empty, so no specific serious-event types can be characterized from the record.

As a general statistical caution, counts should be interpreted with their definitions, follow-up, and ascertainment procedures in mind. The posted figures do not establish that an intervention caused an event, and they do not provide a complete basis for comparing safety. They should not be combined across categories or treated as a causal estimate.

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

The record establishes that a randomized, parallel-group trial compared an algorithm-guided pharmacotherapy approach plus quitline referral with quitline referral alone among smokers living with HIV/AIDS. It identifies self-reported 7-day point-prevalence abstinence at 6 months as the primary endpoint. It also lists secondary outcomes and adverse-event counts. These details describe the question and the intended measures.

The record does not report the primary-outcome counts by group, an estimated contrast, a confidence interval, or a statistical test. It therefore does not show whether the groups differed in the primary outcome, how large any difference was, or how precise an estimate might be. No conclusion about comparative effectiveness can be drawn from the primary-outcome information posted in the registry record.

The listing of 118 missing for the primary outcome adds a limitation to interpretation, but the record does not explain the missingness or the analysis used to address it. Without that information, the potential influence of missing reports cannot be evaluated. The registry’s adverse-event counts likewise do not establish causation or provide detailed information about event types and timing.

As a general principle, a statistically detectable difference would not automatically establish clinical importance, and an uncertain estimate would not establish absence of an effect. Interpretation requires the actual effect estimate, its uncertainty, the analysis population, outcome completeness, and appropriate context. Those elements are not reported for the primary comparison. The trial’s design and purpose are identifiable; its primary comparative result is not reported in the registry record.

13. Why This Trial Matters Statistically

This trial addresses a practical statistical question: how to evaluate an algorithm intended to guide smoking-cessation pharmacotherapy within HIV primary care, compared with quitline referral. The randomized design is relevant because it is intended to support a comparison between assigned approaches. The parallel structure and absence of masking are also important features for interpreting how treatment assignment and outcome reporting may operate in practice.

Its primary endpoint illustrates why precise outcome definitions matter. The measure is self-reported abstinence during the last 7 days at 6 months, rather than a measure explicitly defined as continuous abstinence across the entire follow-up period. Those definitions capture different aspects of smoking behavior. Readers need the endpoint definition and the accompanying analysis to know what the result does and does not represent.

The registry also highlights the importance of outcome completeness. It lists 118 missing for the primary outcome but does not describe the reasons or analytic handling. Missingness can affect estimates and their precision, so reporting how it was assessed and addressed is part of a transparent trial account. The absence of a reported primary analysis means the design alone cannot answer the clinical question.

Finally, the record separates outcome aims from outcome evidence. A registered objective and a randomized design do not substitute for group results, effect estimates, and uncertainty. The adverse-event counts are likewise most informative when event definitions and context accompany them. Statistically, the trial is useful as an example of why readers need complete reporting of the endpoint, missing data, analysis methods, and estimates before drawing conclusions from a clinical comparison.

14. 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 limitation for interpretation is that the registry record does not report a primary-outcome comparison. Group counts, an effect estimate, uncertainty intervals, and a statistical test are absent. The stated primary endpoint therefore cannot be evaluated as a comparative result using the registry information.

The record lists 118 missing for the primary outcome without describing the reasons, timing, group distribution, or handling of those missing reports. It also does not identify the analysis population or state whether sensitivity analyses were conducted. These omissions prevent an assessment of how incomplete outcome information may affect the result.

Although the trial is described as randomized, the registry does not report allocation-generation or concealment procedures, baseline characteristics, adherence, or departures from assigned treatment. Masking is listed as none, but the record does not clarify whether outcome assessment involved any masking. The self-reported endpoint is not described as having independent verification.

The record does not report a statistical analysis plan, model, interim analyses, multiplicity approach, or analyses for the primary outcome. Results for the listed secondary outcomes are also absent. The adverse-event section gives counts but no serious-event terms, event timing, relatedness assessment, or detailed definitions. These are limitations of the information in the registry record; they do not establish that the trial itself lacked procedures or analyses that were not recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effectiveness of a Smoking Cessation Algorithm Integrated Into HIV Primary Care — NCT03670316.
• Registry record last updated 2026-05-22; status last verified 2025-08.
• Results first posted 2026-04-15.
• 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.

18. Record Summary

The registry describes a completed, randomized, unmasked, parallel-group trial sponsored by the University of Alabama at Birmingham. Enrollment is listed as 371. The trial compared Algorithm Treatment plus quitline referral with quitline referral alone among smokers living with HIV/AIDS.

The primary endpoint was self-reported 7-day Point-prevalence Abstinence at 6 months. The registry lists 118 missing for this outcome but does not report group outcome counts or a primary statistical analysis. It names secondary outcomes concerning cigarettes per day, 24-hour quit attempts at 6 months, and prescriptions written by 6 months, without reporting their results.

Adverse-event counts are listed by group, but event descriptions and relatedness are not reported. The registry also does not state the analysis population, missing-data method, or multiplicity strategy. The trial’s design and intended outcomes are documented, while its comparative primary result is not reported in the registry record.