Engagement With an Adaptive Mobile Health Smoking Cessation Intervention: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Engagement With an Adaptive Mobile Health Smoking Cessation Intervention (NCT04020718), a randomized phase 4 study. The primary outcome is Number of Participants With Self-reported 7-day Abstinence From Smoking at 12 Weeks.

2. Clinical Question

This is a feasibility-focused pilot sequential multiple assignment trial (SMART), rather than a simple comparison of one fixed treatment with another. Its stated aims are to examine when to assess response to the text-message intervention and how adding medication alone compares with adding medication and telephone coaching for non-responders. The registry record identifies the study as randomized and sequential, but does not report enough detail to reconstruct every randomization step or define one primary contrast. As a result, the clinical question is best understood as a set of pathway questions, not as a single head-to-head test with a reported answer.

3. Trial Design

The registry record describes a randomized, sequential pilot study and gives the study title as Engagement With an Adaptive Mobile Health Smoking Cessation Intervention. The phase is listed as PHASE4. Enrollment is 35, and the record marks the study completed. The listed start date is 2020-01-31 and the primary completion date is 2020-11-30. These are registry dates, not a description of how long each participant was followed.

The study is organized around response to brief telephone advice plus a tailored text-message program. One pathway assesses response at 4 weeks post-randomization; the other assesses it at 8 weeks post-randomization. Response is based on self-reported 7-day point prevalence abstinence. For non-responders, the study description refers to randomization to mailed nicotine patches and/or lozenges, or to NRT with proactive telephone coaching. The arm descriptions in the registry record are incomplete, so details beyond the stated pathway components are not reported in the registry record.

The record lists three intervention types: brief telephone advice plus tailored text messages, mailed NRT, and proactive telephone coaching. It also lists five outcome measures. Secondary measures include 7-day abstinence at 8 weeks, exhaled carbon monoxide less than 8 parts per million, reported days of nicotine lozenge and/or patch use, and change in average cigarettes smoked per day. The posted endpoint list does not give results for these measures.

Masking is listed as none. The registry record does not report the allocation sequence, allocation concealment, randomization probabilities at each stage, or the exact decision rules used to assign later treatment. Those omissions limit reconstruction of the trial pathways from the record alone.

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.

Only the first 6 of 8 groups are shown.

Pre-assessment and Adaptation

Post-assessment and Adaptation

Analysis population for the primary outcome, as defined in the registry: Excluding n=2 withdrawn, n=3 LTFU

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 Participants With Self-reported 7-day Abstinence From Smoking at 12 Weeks, measured over 12 weeks post-randomization.

The primary endpoint is the number of participants reporting 7-day abstinence from smoking at 12 weeks post-randomization. The registry defines the measure through the question, Have you smoked cigarettes, even a puff, in the past seven days? The recorded coding is 0 for abstinent and 1 for smoking. This is a self-reported point-prevalence measure: it concerns smoking status over the specified recent period, rather than continuous abstinence across the full study.

A binary endpoint is useful when the research question concerns whether participants meet a defined status at a particular assessment. It makes the outcome easy to describe as a count of participants in each category, but it does not capture every possible pattern of smoking between assessments. Self-report also means the endpoint depends on participants’ reports. The study lists exhaled carbon monoxide less than 8 parts per million as a secondary measure, but the registry record does not describe how that measure was used to confirm or interpret the primary endpoint.

The primary endpoint population is described as excluding n=2 withdrawn and n=3 LTFU. The registry record does not report the resulting abstinence counts, the number classified as smoking, or an estimated contrast between pathways. Therefore, the endpoint definition is available, but its observed result and precision cannot be evaluated from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a sequential multiple assignment trial, often abbreviated SMART. In general, this design can study treatment strategies in which later care depends on an earlier response. Rather than treating the whole study as one unchanging intervention assignment, a SMART may include an initial decision point and a later decision point for participants meeting a response criterion. Here, the stated decision structure concerns assessment at 4 weeks or 8 weeks and additional support for non-responders. The registry record does not report the complete randomization procedures or all decision rules, so the pathway structure cannot be reconstructed in full.

What randomization contributes

In general, randomization helps make groups comparable at the point of assignment, reducing the risk that observed differences are driven by systematic selection. In a sequential design, randomization may occur at more than one decision point, but the precise stages and assignment probabilities matter for interpreting results. The record labels the study randomized and sequential, but the allocation sequence, concealment procedures, and probabilities at each stage are not reported in the registry record. No claims about those details can be made from the description available.

What the endpoint represents

The primary outcome is binary: participants are classified according to self-reported abstinence during the past seven days at 12 weeks post-randomization. A count-based summary would report how many participants fall into each status within the relevant pathway. For a comparative analysis, the contrast must be clearly defined: for example, which treatment strategies are being compared and which participants contribute to each strategy. Because the registry record does not provide a single comparison or the observed outcome counts, neither a treatment contrast nor its uncertainty can be described.

In general, a confidence interval expresses the range of effect values that are reasonably compatible with the observed data under the analysis assumptions. A narrow interval indicates greater precision than a wide interval, though neither one alone determines whether a result is clinically important. No primary endpoint confidence interval or other precision estimate is reported in the registry record.

Why staged designs need careful analysis

In general, analysis of a SMART needs to reflect the way treatment assignment and response status shape later pathways. A comparison that ignores the staged assignments can misrepresent the strategy being evaluated. Researchers may estimate outcomes for complete treatment strategies or compare specified components, but the choice depends on the trial’s randomization and prespecified analysis plan. The statistical plan, estimand, handling of the staged assignments, and any adjustment for the design are not reported in the registry record. The record also does not report an interim analysis plan.

The binary nature of the primary outcome does not by itself specify an analysis method. Counts could be summarized descriptively, while a model-based analysis might estimate a contrast with an uncertainty interval. The choice would depend on the question, design, and analysis plan. No such model or inferential analysis is reported in the registry record. The registry lists zero analyses, so the posted information does not include a reported treatment-effect test for the primary endpoint.

Missing outcomes and analysis populations

The primary endpoint population is described as excluding n=2 withdrawn and n=3 LTFU. This tells readers that those participants are not included in the stated endpoint population, but it does not describe how missing status was handled in the analysis or whether the exclusions were specified before results were examined. In general, complete-case analysis can be biased if the participants with observed outcomes differ systematically from those without observed outcomes. Other approaches may use assumptions about missingness, but no method is specified in the registry record.

For any trial with staged response assessments, missing information at an earlier decision point could also affect later pathway classification. This is a general methodological issue, not a claim about what occurred in this study. The registry record does not report missingness by arm, reasons for loss to follow-up, or sensitivity analyses. It also does not explain whether all randomized participants were included in any analysis population.

Planning illustrations are not observed power

In general, a sample-size illustration describes how many participants might be needed under specified assumptions about the effect, significance level, allocation, and statistical approximation. It is a planning calculation, not evidence that the completed study had a particular probability of detecting an effect. The assumptions listed for the illustration use a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and effects defined as fractions of an observed effect. These calculations are not the trial’s own design justification, and the sample-size illustration is not observed power. The registry record does not report the trial’s sample-size justification.

The listed planning approach is framed around two arms, whereas the trial itself is described as sequential and includes multiple pathways. In general, planning for a multi-stage design may depend on pathway probabilities and the estimand of interest. No design-specific planning rationale is reported in the registry record. The planning section should therefore be read as an illustration under its stated assumptions, not as a substitute for the trial’s own statistical plan or as a result of the trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary endpoint and lists several secondary outcomes, but it does not report how many hypotheses were tested or how any tests were organized. The record lists five outcome measures in total, including the primary endpoint and secondary measures of 8-week abstinence, exhaled carbon monoxide, medication-use days, and change in average cigarettes per day. Because no analyses are posted, there are no reported tests or estimates to interpret across these outcomes.

Multiplicity is the general issue that arises when several outcomes, time points, treatment contrasts, or subgroup questions are examined. Testing many questions can increase the chance of apparently notable results arising by chance. In general, a prespecified hierarchy or adjustment can help address that issue, but whether either approach was used is not reported in the registry record. The statistical plan for multiplicity is not reported in the registry record.

Missingness is also relevant. The primary endpoint population excludes n=2 withdrawn and n=3 LTFU, but the record does not give reasons for loss to follow-up, missingness by treatment pathway, or the method used to handle unavailable outcomes. In general, excluding participants with missing outcomes can affect a comparison if outcome availability is related to prognosis or treatment assignment. That possibility cannot be assessed. Imputation methods, sensitivity analyses, and the assumptions underlying any missing-data analysis are not reported in the registry record.

The record does not report the analysis population beyond the stated primary endpoint exclusions. It is therefore unclear whether any analysis was based on all randomized participants, participants with observed outcomes, or another defined population. The interim-analysis approach and any stopping rules are not reported in the registry record.

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 record lists serious adverse event figures for five groups: Early Assessment Non-responder NRT, Early Assessment Non-responder NRT Plus Coaching, Early Assessment Responder, Late Assessment Non-responder NRT, and Late Assessment Non-responder NRT Plus Coaching. It records 0 serious adverse events in each listed group. It also records 0 deaths in each group. No serious adverse event terms are listed.

The record separately reports other adverse events: 0 in Early Assessment Non-responder NRT, 2 in Early Assessment Non-responder NRT Plus Coaching, 0 in Early Assessment Responder, 1 in Late Assessment Non-responder NRT, and 1 in Late Assessment Non-responder NRT Plus Coaching. These figures should be read alongside the corresponding at-risk counts in the registry, rather than as comparative rates calculated. No overall comparison or statistical test is reported.

These entries do not describe event type, severity beyond the serious-event classification, timing, duration, or relationship to study interventions. The registry record also does not give a narrative explaining how events were collected or adjudicated. A zero count in the listed groups means no event was recorded in that category in the posted figures; it does not establish that the interventions are free of risk. The safety information is limited to the categories and counts shown in the record.

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

The study asks a useful methodological question about adaptive care: when response is assessed, and what additional support is offered to people who do not respond to an initial text-message program. The randomized sequential design is intended to examine early assessment at 4 weeks versus late assessment at 8 weeks, with later options that include mailed NRT and telephone coaching. The registry record also defines a 12-week self-reported abstinence endpoint.

What the posted record does not show is the primary endpoint result. There are no reported abstinence counts by pathway, no estimated treatment effects, and no confidence intervals or inferential tests. The trial therefore cannot be used from this record to quantify whether one pathway was associated with more abstinence than another, or how precise such a comparison might be. The absence of a reported result is not evidence that the pathways had identical outcomes.

The endpoint itself has a defined but limited meaning: a participant’s report of whether they smoked, even a puff, in the seven days before the 12-week assessment. It does not, on its own, describe smoking behavior throughout the full follow-up period. The listed secondary measures might add context, but their results are not reported in the registry record.

The enrollment of 35 and the pilot designation situate the study as a feasibility-oriented project, but the record does not report which feasibility criteria were used or whether they were met. Nor does it report a sample-size justification or the statistical analysis plan. These gaps prevent a reader from assessing the intended precision, the prespecified comparisons, or how the design was analyzed.

Accordingly, the defensible conclusion is about the evidence available in the registry: it describes a completed randomized pilot and its intended questions, but it does not supply the outcome analysis needed to answer those questions. This is not a conclusion about whether smoking-cessation support is beneficial; it is a boundary on what can be inferred from the posted record.

13. Why This Trial Matters Statistically

This trial matters statistically because it frames smoking-cessation support as a sequence of decisions rather than a single, fixed assignment. In practice, adaptive strategies raise questions about when response should be assessed and whether later treatment should depend on that response. A sequential trial can be structured to study such questions while preserving randomized comparisons at defined decision points. The registry record identifies this kind of design, making the trial a useful example of why the pathway and analysis plan matter as much as the intervention labels.

The contrast between assessment at 4 weeks and 8 weeks is not merely a comparison of calendar timings. It is part of a treatment strategy that may lead to different later decisions for non-responders. As a general statistical principle, the comparison must be stated in terms of the full strategy or a clearly defined component. Without the randomization details, outcome counts, and analysis plan, readers cannot tell which estimand was intended or how the evidence should be summarized.

The trial also illustrates the difference between a defined endpoint and an analyzed endpoint. The record clearly specifies self-reported 7-day abstinence at 12 weeks, but a definition alone cannot establish a result. Counts, contrasts, and measures of precision are needed to judge what the observed data show. The absence of those analyses makes restraint essential: the design can be described, but comparative conclusions cannot be drawn.

Finally, its pilot setting highlights the distinction between feasibility work and definitive treatment-effect evidence. General planning illustrations may help readers understand assumptions, but they are not observed power and do not replace a prespecified rationale matched to a sequential design. This record demonstrates why trial registration and posted results need enough detail about randomization, missing data, multiplicity, and analysis populations for the statistical conclusions to be independently interpreted.

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 the primary endpoint counts or any treatment-effect analysis. It names the outcome and gives its definition, but does not show how many participants reported abstinence in each pathway. Precision estimates, such as confidence intervals, are also not reported in the registry record. The central comparison therefore cannot be evaluated from the posted results.

The design description is incomplete. Although the study is identified as randomized and sequential, the registry record does not report the allocation sequence, concealment, assignment probabilities, or complete decision rules. The arm descriptions end before all pathway details are given. These omissions limit a reader’s ability to reconstruct exactly which treatments and populations should be compared.

The endpoint relies on self-report and represents 7-day point prevalence at 12 weeks, rather than an account of smoking status across the whole follow-up period. The record lists exhaled carbon monoxide as a secondary measure, but does not report its results or explain its relation to the self-reported endpoint. Results for other secondary outcomes are also not reported in the registry record.

The primary endpoint population excludes n=2 withdrawn and n=3 LTFU. Reasons for these exclusions, outcome availability by pathway, and methods for handling missing data are not reported in the registry record. There is also no reported statistical analysis plan, multiplicity approach, interim analysis plan, or sample-size justification. These gaps prevent assessment of whether the analysis matched the sequential design and the intended questions.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Engagement With an Adaptive Mobile Health Smoking Cessation Intervention — NCT04020718.
• Registry record last updated 2022-03-10; status last verified 2022-02.
• Results first posted 2022-03-10.
• 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 record describes NCT04020718, Engagement With an Adaptive Mobile Health Smoking Cessation Intervention, as a completed randomized PHASE4 sequential pilot. Enrollment is 35. The listed study start date is 2020-01-31 and primary completion date is 2020-11-30. Masking is listed as none.

The study aims to compare response assessment at 4 weeks with assessment at 8 weeks for brief telephone advice plus tailored text messages, and to examine additional NRT and telephone-coaching options for non-responders. The primary endpoint is the number reporting 7-day abstinence at 12 weeks post-randomization. The record excludes n=2 withdrawn and n=3 LTFU from that endpoint population.

Although the endpoint and study aims are described, primary outcome results and analysis estimates are not reported in the registry record. The listed safety figures include 0 serious adverse events and 0 deaths in each of the five groups, with other adverse-event counts also recorded. Interpretation of treatment differences is not possible from the posted record.