Automated Mobile Contingency Management for Smoking Cessation: A Pilot RCT (SCC PREVAILgo): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Automated Mobile Contingency Management for Smoking Cessation: A Pilot RCT (SCC PREVAILgo) (NCT03739437), a randomized na study. The primary outcome is Self-Reported Smoking Cessation.

2. Clinical Question

3. Trial Design

NCT03739437 is a randomized, parallel-group pilot trial of a mobile contingency-management approach to smoking cessation. The registry identifies the allocation as randomized and the masking as none. The listed enrollment is 20, and the study status is terminated. The record gives a start date of 2020-12-10 and a primary completion date of 2022-05-03. It does not report why the trial was terminated, so no reason for that status can be inferred from these details.

The project summary describes an intended randomized pilot of 40 participants, assigned either to telephone counseling plus nicotine replacement therapy, called Standard Care, or to Standard Care plus a 12-week mobile financial-incentive intervention. The registry's enrollment figure is 20, and its outcome results list 9 participants in the Mobile Contingency Management arm and 11 in Standard Care. The summary describes follow-up for 12 weeks after a scheduled quit attempt, while the primary endpoint timeframe is listed as 13 weeks post-enrollment. The relationship between these time references is not explained in the registry record.

The intervention was designed to automate contingency management using mobile technology. Carbon monoxide monitors connected with mobile phones were intended to remotely verify smoking abstinence; facial recognition was intended to verify participant identity during breath sampling; and incentives were intended to be delivered automatically after biochemical confirmation of self-reported abstinence. These descriptions explain the proposed intervention, but the registry record does not report how often participants used the devices, whether verification was successful, or how incentives were actually delivered.

The record lists four outcome measures and two secondary outcomes: loss of smartphones and loss of iCO sensors. Detailed results for these secondary outcomes are not included in the registry entries. The masking field is none; whether outcome assessment was otherwise blinded is not reported in the registry record. Details of randomization procedures, allocation concealment, recruitment, and the protocol are also 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:

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 Self-Reported Smoking Cessation, measured over 13 weeks post-enrollment.

The primary endpoint is titled Self-Reported Smoking Cessation. It counts participants who reported smoking abstinence during the past 7 days, with assessment listed at 13 weeks post-enrollment. The posted counts are 4 participants in Mobile Contingency Management and 2 in Standard Care. This is a binary outcome at the participant level: each participant is classified according to whether the specified abstinence outcome was reported, and the result is expressed as a count of participants.

Self-report is used to capture a participant’s reported smoking status during a specified recent period. In this trial, the planned intervention also involved biochemical verification for triggering incentives, but the primary endpoint itself is described as self-reported abstinence. The record does not state that the primary endpoint count required biochemical confirmation. It therefore should not be conflated with the verification procedure described for the intervention.

As a general statistical point, a binary endpoint can be summarized by the number of participants meeting the outcome and the number assessed in each arm. Interpretation depends on clear outcome definitions, consistent assessment, and knowledge of which participants contributed data. The record gives arm counts but does not report missing endpoint data, the handling of missing responses, or the analysis population. It also does not report further detail about how self-reported abstinence was assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

A randomized parallel-group design assigns participants to separate study arms and compares outcomes between them. Random allocation is intended, in general, to reduce systematic differences between groups at the point of assignment. The registry identifies this trial as randomized and parallel, but does not report the sequence-generation method or allocation-concealment procedures. Masking is listed as none. The record does not describe whether participants, intervention staff, or outcome assessors were masked in any other way.

What does a chi-squared test assess?

A chi-squared test is a method for assessing whether observed counts across categories are compatible with a specified comparison under the test's assumptions. For a binary outcome such as the recorded abstinence result, the data can be represented as participants who did and did not meet the endpoint in each arm. The registry reports a chi-squared test for the primary comparison and gives p = 0.384. The detailed contingency table and any test-specific adjustments are not reported in the registry record.

A p-value is calculated relative to a statistical model and a null hypothesis. It describes how compatible the observed data are with that null model, assuming the test conditions hold. It is not the probability that the null hypothesis is true, nor is it a direct measure of the size or importance of an effect. The p-value also cannot show how precisely the effect has been estimated. For that, an effect estimate and a confidence interval are useful, but neither is reported for this comparison.

Why does the endpoint format matter?

This endpoint is a count of participants meeting a binary outcome, not a continuous measure such as a score. For binary outcomes, a comparison may be described using counts, proportions, risk differences, risk ratios, odds ratios, or other measures, depending on the analysis plan. The registry lists the counts and a chi-squared test but does not report an effect estimate in those forms. No additional contrast should be inferred from the counts without an explicit calculation, and no such recalculated estimate is reported in the registry record.

General statistical guidance for small binary datasets is that asymptotic tests, including the usual chi-squared approach, can be sensitive to sparse cell counts. Alternative methods may be considered in some settings, but the record does not report an alternative test or a sensitivity analysis. That general issue does not establish that the sponsor's chosen test was invalid; it identifies a consideration when reading a test result based on a small pilot dataset.

What does a confidence interval add?

In general, a confidence interval is a range of values produced by a method intended to reflect uncertainty in an estimate. It helps readers judge the precision and compatibility of a set of effect sizes with the observed data. An interval is not a guarantee that the true effect lies within its limits, and its interpretation depends on the method and assumptions used. No confidence interval for the primary between-arm effect is reported in the registry record. The p-value alone cannot replace that information.

General statistical methods also distinguish statistical evidence from practical importance. A test result does not measure the value of an outcome to participants, establish whether an effect is large enough to matter, or determine how well a finding transports to another population. Those judgments require context beyond a single p-value. The record does not report a prespecified threshold for a meaningful difference.

How should planning calculations be understood?

Sample-size planning asks how many participants may be needed under stated assumptions to detect a chosen effect with specified operating characteristics. The planning assumptions associated with this record describe an illustrative calculation based on the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is specified as a fraction of the observed effect. Such illustrations are not the trial's design justification, and they are not observed power. The registry does not report the trial's original sample-size justification or the planned effect used to design recruitment.

General guidance is to treat post hoc planning estimates cautiously. Calculations based on an observed effect can be unstable, particularly when the trial has limited data, and they do not change what was observed. They do not show the probability that the study would replicate or establish that the trial was adequately or inadequately sized. The registry record does not report an original power calculation, assumptions used at design, or any interim analysis plan.

The reported analysis is described as a superiority comparison using a chi-squared method. The record does not report a full statistical analysis plan, covariate adjustment, subgroup analysis, or sensitivity analysis. The meaning and limitations of the reported test should therefore be read from the method actually named, without attributing unreported procedures to the investigators.

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("Mobile Contingency Management", "Standard Care")
n      <- c(9, 11)
events <- c(4, 2)
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  Mobile Contingency Management  9  4  44.4  13.7  78.8  18.9  73.3  18.7  73.8
ARM  Standard Care  11  2  18.2  2.3  51.8  5.1  47.7  5.5  48.4

11. Analyses Reported by the Sponsor

The registry reports the sponsor's primary comparison as a chi-squared test with p = 0.384. The corresponding arm counts are 4 of 9 for Mobile Contingency Management and 2 of 11 for Standard Care. No sponsor-reported effect estimate or confidence interval is listed. The result can therefore be described through the counts and the reported test, but its precision cannot be summarized with an interval from the registry data.

No separate recalculated estimate or p-value is included in the record, so there is no recalculation to compare with the sponsor's analysis. The posted data do not identify an inconsistency between a sponsor analysis and a recalculation. The sponsor's chi-squared result remains the reported inferential analysis; it should not be replaced by an unreported calculation based only on the displayed counts.

The p-value is not a measure of the magnitude of the contrast, and it should not be read as the probability that the observed pattern occurred by chance in an everyday sense. It is tied to the specified statistical test and its assumptions. Without an effect estimate and confidence interval, readers cannot use the sponsor's p-value alone to assess the range of plausible between-arm effects.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and two secondary outcomes, identified as Loss of Smartphones and Loss of iCO Sensors. The registry entries do not give results for those secondary outcomes. The registry lists one analysis, but does not report whether additional analyses were conducted or planned outside the posted results. No multiplicity adjustment or strategy for handling multiple outcomes or comparisons is reported in the registry record.

As a general statistical concept, multiplicity arises when several outcomes, comparisons, time points, or analyses are examined. If many tests are conducted, the chance of at least one apparently unusual result can increase unless the analysis plan accounts for that testing. Whether an adjustment is needed depends on the research question and prespecified analysis strategy. Because that strategy is not reported, the impact of multiplicity on the primary result cannot be determined from the registry information.

Missing-data handling is also not reported. The primary outcome counts list 9 participants in the Mobile Contingency Management arm and 11 in Standard Care, but the record does not state whether all randomized participants had an endpoint assessment, how unavailable responses were classified, or whether any imputation was used. The analysis population—such as whether the analysis followed all randomized participants—is not reported in the registry record. No assumptions about missing outcomes or exclusions should be inferred from the arm counts alone.

The record does not report an interim-analysis plan, stopping boundaries, or an analysis plan explaining how outcomes and missing data were to be handled. The terminated status is recorded, but the reason for termination and any connection to recruitment, data availability, or the statistical plan are not reported. These omissions limit assessment of whether the posted analysis reflects a prespecified approach, but they do not establish that any particular analysis decision occurred.

13. 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 zero serious adverse events in the Mobile Contingency Management arm, with 9 participants listed at risk, and zero in Standard Care, with 11 listed at risk. It also reports zero other adverse events in each arm and zero deaths in each arm. These figures describe the events recorded in the registry for the listed groups.

A zero count in a pilot dataset does not establish that an event cannot occur or that the interventions have no safety risks. It means that no events of the specified type were recorded in the listed participants in the posted results. The adverse-event reporting period, event-collection procedures, and definitions used for serious and other adverse events are not reported in the registry record. The degree to which the results capture events outside the recorded reporting process therefore cannot be assessed.

The registry does not list serious adverse-event terms. The counts also do not provide a comparative estimate with a confidence interval. They should be read as descriptive safety reporting, not as a definitive comparison of safety between arms. The small enrollment and the absence of further event detail limit how much can be concluded from these figures.

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

The primary endpoint records self-reported abstinence during the past 7 days at 13 weeks post-enrollment. The posted results list 4 participants in Mobile Contingency Management and 2 in Standard Care as meeting that outcome. The sponsor's reported comparison is a chi-squared test with p = 0.384. Together, these registry entries describe the observed endpoint counts and the statistical test reported by the sponsor.

These results do not by themselves establish the size or precision of the between-arm effect. No effect estimate or confidence interval is reported. A p-value is not a probability that an intervention works, and it does not say how likely the result is to recur in a different sample. The registry record does not provide a prespecified threshold for a meaningful effect, so the statistical test cannot be used to decide practical importance on its own.

The trial is identified as a pilot, and the registry records enrollment of 20; the project summary described an intended enrollment of 40. The study status is terminated, but the reason is not reported. These details indicate that the result comes from a limited pilot dataset, but they do not establish why the trial ended or what the results would have been with further recruitment.

The intervention description includes biochemical verification as part of the incentive process. However, the primary outcome is explicitly described as self-reported abstinence, and the registry does not state that biochemical confirmation was required for the primary endpoint count. The result should not be interpreted as a count of biochemically verified abstinence unless that definition is reported.

More broadly, the registry record does not report participant demographics, the analysis population, missing-data methods, the original sample-size justification, or a detailed statistical analysis plan. These omissions limit assessment of representativeness, precision, and analytical choices. The posted results describe this pilot's recorded outcome; they do not settle the effect of the intervention in other settings or populations.

15. Why This Trial Matters Statistically

This trial raises statistical questions that are common in pilot studies of behavioral interventions. The primary outcome is binary, the listed arm sizes are limited, and the reported result consists of counts alongside a chi-squared p-value. Readers must distinguish the observed data from the uncertainty around an estimated contrast. Because no effect estimate or confidence interval is reported, the reported p-value cannot convey the precision or range of plausible effects.

The intervention also combines several processes: mobile breath monitoring, identity verification, biochemical confirmation, and incentive delivery. These elements are relevant to understanding the proposed intervention, but they are not themselves the primary endpoint. Separating the intervention mechanism from the outcome definition prevents a self-reported outcome from being mistaken for a biochemically confirmed one.

The registry identifies the trial as a pilot and reports enrollment of 20, while the project summary describes a planned enrollment of 40. That contrast makes transparency about recruitment and study status important. The record reports termination but not the reason, so statistical interpretation should avoid attributing the enrollment or status to any particular cause.

Finally, the result illustrates why a test statistic should be considered alongside reporting quality. Information on analysis populations, missing outcomes, multiplicity, and the statistical plan would help readers understand how the comparison was formed. Those details are not reported in the registry record. Recognizing those limits allows the observed counts and p-value to be read accurately without turning a pilot result into a stronger conclusion than the available information supports.

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.

Several trial-specific details needed for fuller interpretation are not reported in the registry record. The primary endpoint is described as self-reported abstinence during the past 7 days, but the record does not give further assessment procedures or say whether the endpoint count required biochemical confirmation. The intervention summary describes biochemical verification for incentives, which is not sufficient to establish the outcome-assessment rule.

The registry lists 20 participants enrolled and outcome-arm sizes of 9 and 11. It does not report participant flow, the number with missing primary outcomes, exclusions after randomization, or the analysis population. The demographic composition of participants is not reported, even though the project summary describes a target population of socioeconomically disadvantaged males and females seeking cessation treatment. This limits assessment of how closely the enrolled group reflected the intended population.

The record reports the chi-squared method and p-value but no effect estimate or confidence interval. It does not report the test details, covariate adjustments, sensitivity analyses, or a complete statistical analysis plan. The original sample-size justification and any interim-analysis plan are also not reported. The planning assumptions described for illustrative calculations are not the trial's design justification.

The trial is marked terminated, but no reason is reported. The relationship between the intended enrollment of 40 in the project summary and the registry enrollment of 20 is not explained. The record also does not provide results for the listed secondary outcomes. These gaps constrain interpretation; they do not reveal why the study ended or imply that unreported procedures or results occurred.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Automated Mobile Contingency Management for Smoking Cessation: A Pilot RCT (SCC PREVAILgo) — NCT03739437.
• Registry record last updated 2023-04-04; status last verified 2023-04.
• Results first posted 2023-04-04.
• 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

NCT03739437 is a randomized, parallel-group pilot trial of mobile contingency management for smoking cessation. The registry lists enrollment of 20 and status as terminated. The project summary describes Mobile Contingency Management as an addition to telephone counseling and nicotine replacement therapy, using mobile monitoring and incentives, compared with Standard Care alone.

The primary endpoint is self-reported smoking abstinence during the past 7 days at 13 weeks post-enrollment. The registry reports 4 of 9 participants meeting the endpoint in Mobile Contingency Management and 2 of 11 in Standard Care. The sponsor's reported chi-squared comparison has p = 0.384. No effect estimate or confidence interval is reported. The reason for termination, missing-data handling, analysis population, and detailed statistical plan are not reported in the registry record.