Testing Financial Incentive Interventions in Dyadic-Smoker Couples: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Testing Financial Incentive Interventions in Dyadic-Smoker Couples (NCT04832360), a randomized na study. The primary outcome is Smoking Abstinence.

2. Clinical Question

3. Trial Design

NCT04832360 is a completed randomized, parallel-design study sponsored by the University of Georgia. The registry lists an enrollment of 190 and identifies nicotine dependence as the condition. The recorded start date is 2021-01-15, and primary completion is recorded as 2022-08-01. The study phase is listed as NA.

The study description presents a three-group design involving couples in which both partners smoked. Participants were assigned to control, single-target financial incentives, or dyadic-target financial incentives. Control participants did not receive the incentive intervention. In the single-target condition, one member of each couple received it; in the dyadic-target condition, both members received it. The registry does not specify the randomization unit, allocation procedure, or whether the assignment process accounted for the pairing of partners.

The registry labels masking as single, but does not identify who was masked or what information was concealed. It describes follow-up across 3 months and gives the primary endpoint timeframe as a study session 3 months after baseline. The intervention is classified as behavioral and is described as involving incentives for online psychoeducation completion and smoking abstinence at follow-up. Details such as incentive amounts, timing, and the content of the psychoeducation are not reported in the registry record.

The design description establishes the planned group structure and the endpoint timing, but does not document procedures for follow-up, adherence, or handling of couples in which one partner did not complete the study. Those details are not reported in the registry record. The randomized design defines the intended basis for comparing conditions; it does not, by itself, establish that any observed difference was caused by the intervention. Interpretation depends on the outcome data and analysis, which are not reported for the primary endpoint.

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

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 Smoking Abstinence, measured over Follow-up study session 3 months post-baseline session.

The primary endpoint is titled Smoking Abstinence. It is described as the percentage of targets who had quit smoking by the follow-up study session 3 months after baseline, with cessation verified biochemically. In this context, the endpoint focuses on smoking status at follow-up rather than on a change score or time until quitting. The registry labels the measurement unit as targets and the parameter as a number, while the description expresses the endpoint as a percentage. No numerical endpoint value is reported in the registry record.

Biochemical verification is a way to assess smoking status using a biological measure rather than relying only on a participant’s report. General statistical context: when an outcome is defined as a proportion, its interpretation depends on both the number meeting the outcome definition and the number assessed in the relevant group. The registry does not report those primary-endpoint counts, the number assessed at follow-up, or the biochemical verification procedure.

A point estimate would describe the observed abstinence outcome, while an uncertainty interval would convey how precisely that estimate is determined by the data. Neither a primary-endpoint estimate nor an interval is reported in the registry record. The registry also does not report an inferential comparison between the three conditions. As a result, the endpoint definition and timing can be described, but the posted registry information does not establish the observed abstinence level in any condition or the precision of a difference between conditions.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The design is described as randomized and parallel, with three conditions: control, single target, and dyadic target. Randomization is a method for assigning participants to conditions by chance. General statistical context: when implemented as intended, random assignment helps make groups comparable on average with respect to factors measured and unmeasured before intervention. It does not guarantee identical groups, and it does not replace reporting the allocation method, participant flow, and analysis. The registry does not describe the random sequence, concealment of assignments, or the unit randomized. Because the intervention is defined in relation to couples, the unit of assignment and the handling of within-couple dependence are important design details, but they are not reported in the registry record.

What does the endpoint represent?

The primary outcome is smoking abstinence at a follow-up study session 3 months after baseline, with cessation verified biochemically. The description gives the outcome as a percentage of targets who quit. General statistical context: a percentage is a proportion expressed on a percentage scale, and its estimate depends on defining both the outcome numerator and the population denominator. The registry labels the unit as targets and the parameter as a number, alongside a description using percentage. No observed numerator, denominator, or endpoint estimate is reported, so the operational calculation cannot be reconstructed from the record.

How should a group comparison be understood?

The three conditions distinguish whether incentives were absent, directed to one member of a couple, or directed to both members. A group comparison would estimate how the endpoint differs across these conditions. General statistical context: an effect estimate describes the direction and magnitude of a comparison; an uncertainty interval describes the range of values compatible with the data under the stated method. A p-value, when reported, addresses compatibility with a specified null hypothesis under an analysis model; it is not a measure of clinical importance or the probability that the null hypothesis is true. The registry does not report an estimate, interval, p-value, or other inferential result for the primary outcome.

The record labels the outcome type as count other, but gives no dispersion value or analysis details. General statistical context: count outcomes can vary more than a simple model assumes, a feature often called over-dispersion. If that occurs, a model that accounts for the extra variability can produce more appropriate uncertainty estimates than one that assumes less variability. This is a general consideration, not a claim about this study: the registry does not report a dispersion estimate or identify a model used for the endpoint.

What does the design imply for analysis?

Partners in a couple may have related outcomes because they share an environment and may influence one another. General statistical context: outcomes that are correlated within a group are not necessarily independent observations. An analysis that ignores such dependence can misstate uncertainty; methods can instead account for clustering or model the relationship directly. The registry does not report whether the primary analysis accounted for couples, whether the outcome was analyzed at the target or couple level, or how missing partner outcomes were handled.

The registry lists 3 outcome measures and 0 analyses. It does not identify a statistical test, regression model, covariate adjustment, analysis population, or handling of repeated measurements. The description mentions tracking participants across 3 months, but the primary endpoint is defined at the follow-up session. The record does not clarify whether intermediate measurements were collected or analyzed. No detailed statistical analysis plan is reported in the registry record.

How should planning illustrations be read?

Planning illustrations use assumptions to show the sample size that might be needed for a specified effect and statistical design. The registry description of the illustration states that it is based on the observed effect, uses a two-sided significance level of 0.05, assumes equal allocation between two arms and uses a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. These are planning assumptions, not observed findings. A planning illustration does not establish that the study had a particular probability of detecting an effect, and it is not observed power. The registry does not report a trial-specific sample-size justification or the design assumptions used when the study was planned.

Any interpretation of the primary endpoint would require reported group-specific outcome data and an analysis that makes its population, comparison, and uncertainty clear. Those results and methods are not reported in the registry record. The design information alone cannot supply them.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures but describes only the primary endpoint in the available outcome information. Details of the other outcome measures, their timing, and their status as primary or secondary are not reported in the registry record. The record lists 0 analyses and does not report a statistical analysis plan, prespecified contrasts, or a method for addressing multiple outcomes or multiple comparisons.

General statistical context: when several outcomes or comparisons are tested, the chance of at least one apparently notable result can increase if each is interpreted without regard to the others. Multiplicity procedures can control or describe that issue, but the appropriate approach depends on which outcomes and comparisons were planned. Since those details are not reported, it is not possible to determine how multiplicity was addressed in this study.

Missing-data procedures and the analysis population are also not reported in the registry record. The record does not state how many participants completed follow-up, whether all randomized participants were included in the primary analysis, how missing smoking-status assessments were treated, or how unverified cessation status was classified. General statistical context: exclusions or assumptions about missing outcomes can affect both an estimated group difference and its uncertainty. Without the analysis population and missing-data approach, readers cannot assess how the endpoint result would relate to all randomized participants—even if an estimate were available.

The registry record gives no primary endpoint analysis or numerical result. Consequently, neither the handling of missing data nor the control of multiplicity can be evaluated from the posted information.

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.

The registry reports serious adverse events for each condition. In control, 0 serious adverse events were reported among 58 participants at risk. In single target, 0 were reported among 68 participants at risk. In dyadic target, 0 were reported among 64 participants at risk. The registry also reports 0 other adverse events in each group, with the same group-specific numbers at risk, and 0 deaths in each group.

These are event counts within the registry’s stated groups. They do not establish that no events occurred outside the recorded categories or observation period. The registry record does not define the adverse-event collection window, event ascertainment procedures, or whether events were judged related to the intervention. It also does not provide details about event severity beyond the serious-versus-other categorization.

General statistical context: zero recorded events is not proof that the underlying event risk is zero. The interpretation depends on the number of participants observed, the length and completeness of observation, and how events were sought and classified. These figures should therefore be read as the registry’s reported counts, not as a guarantee of absence of harm. They are safety counts and do not provide evidence about the primary smoking-abstinence endpoint.

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

The registry record establishes that NCT04832360 was designed to compare a control condition with two approaches to financial incentives in couples in which both partners smoked. It specifies a primary endpoint of biochemically verified smoking abstinence at a follow-up session 3 months after baseline. It also records that the study is completed and gives an enrollment of 190.

What the record does not establish is whether abstinence was more common in any condition, how large a difference was observed, or how precisely any difference was estimated. The primary endpoint’s numerical results and statistical analysis are not reported in the registry record. Therefore, the intervention cannot be described as having increased or decreased abstinence on the basis of this entry. The study’s completed status is not itself a result.

General statistical context: an efficacy interpretation requires more than the intervention description and a defined outcome. It ordinarily depends on the observed outcomes, the comparison being estimated, uncertainty around that estimate, and an account of who was included in the analysis. The record does not provide those elements for the primary endpoint. Nor does it report enough detail to evaluate the analysis of partner-level outcomes, missing follow-up data, or any multiplicity considerations.

The safety record reports no serious adverse events, other adverse events, or deaths in the listed groups. These counts should be understood within the registry’s recorded group sizes and without assuming details about observation or event collection that are not reported. They do not answer the efficacy question.

The design is relevant to a question about offering incentives to one or both members of a smoking couple, but the posted registry information supports a description of that question rather than a conclusion about its answer. Numerical results and analysis details would be needed to characterize the observed effect and its precision.

13. Why This Trial Matters Statistically

This trial’s design makes the relationship between intervention assignment and the couple central to statistical interpretation. The three conditions distinguish no financial-incentive intervention, an intervention for one member, and an intervention for both members. That structure raises a clear comparative question about whether targeting one or both partners relates to the abstinence endpoint. The primary outcome is also defined with biochemical verification, rather than solely as self-reported quitting.

General statistical context: dyadic studies require care in defining the unit of assignment, measurement, and analysis. Partners may share exposures or influence one another, so their outcomes may be statistically related. If outcomes are related, treating every target as entirely independent can lead to uncertainty estimates that do not reflect the study structure. The registry does not report how this issue was handled, making the analysis approach especially important to interpretation.

The endpoint is timed at follow-up, with a stated 3-month interval after baseline. That timing gives the outcome a clear assessment point, but the registry does not report the observed abstinence results, follow-up completeness, or the method for comparing groups. Without those details, readers can identify the intended statistical question but cannot judge its empirical answer or precision.

The record also lists multiple outcome measures while providing no analyses. This makes clear reporting of planned comparisons, analysis populations, and missing-data handling relevant to any fuller assessment. These are general reporting considerations; the registry does not establish what procedures were used. The statistical importance of the trial lies in its couple-oriented comparison and verified endpoint, while the absence of reported efficacy analyses limits what can be concluded from the record.

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 consequential limitation of the registry information is that it does not report numerical results or an analysis for the primary endpoint. Group-specific abstinence counts and percentages, estimates of differences, uncertainty intervals, and inferential results are not reported in the registry record. The clinical question can be stated, but its observed answer cannot be assessed from the available results.

The intervention is described at a broad level. Financial incentives addressed online psychoeducation completion and smoking abstinence at follow-up, but amounts, timing, delivery procedures, and participant adherence are not reported in the registry record. The study description says that one member received incentives in the single-target condition and both members did so in the dyadic-target condition; it does not give further details on selecting the single target.

Several design and analysis details are also absent. Although the record labels the study randomized and single masked, it does not identify the randomization unit or the masked party. It does not report how dependence between partners was addressed, which participants were included in each analysis, how missing follow-up outcomes were handled, or which statistical model was used. The record lists 3 outcome measures but does not describe the other measures or report analyses.

The safety counts are reported, but event definitions, collection procedures, and observation details are not. These omissions limit interpretation of the counts. Finally, the planning assumptions described in the registry do not constitute a trial-specific sample-size justification, and the registry does not report such a justification. These limitations concern the information available in the registry record; they do not establish what procedures may have been used outside it.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Testing Financial Incentive Interventions in Dyadic-Smoker Couples — NCT04832360.
• Registry record last updated 2025-01-24; status last verified 2025-01.
• Results first posted 2025-01-24.
• 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

NCT04832360, titled Testing Financial Incentive Interventions in Dyadic-Smoker Couples, is recorded as a completed, randomized, parallel study sponsored by the University of Georgia. The registry lists nicotine dependence as the condition, enrollment of 190, a start date of 2021-01-15, and primary completion on 2022-08-01. Phase is listed as NA, and masking is labeled single.

The three conditions were control, single-target incentives, and dyadic-target incentives. The primary endpoint was smoking abstinence at a follow-up study session 3 months after baseline, described as a percentage of targets who quit with biochemical verification. Numerical primary-outcome results and analyses are not reported in the registry record.

The record lists 3 outcome measures and 0 analyses. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each group. Details of the statistical analysis, missing-data handling, and analysis populations are not reported in the registry record.