SmokefreeSGM, A Text-based Smoking Cessation Intervention for Sexual and Gender Minority Groups: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for SmokefreeSGM, A Text-based Smoking Cessation Intervention for Sexual and Gender Minority Groups (NCT05029362), a na na study. The primary outcome is Perceived Usability as Assessed by the System Usability Scale (SUS).

2. Clinical Question

3. Trial Design

SmokefreeSGM was a completed, single-group behavioral study sponsored by The University of Texas Health Science Center, Houston. The registry lists enrollment of 18 and identifies the group as Beta testing group. Its stated purpose was to pretest the design of a text-based smoking cessation program tailored to sexual minority individuals. The registry title and intervention description refer to sexual and gender minority groups, while the brief purpose specifically refers to sexual minority individuals.

The study began on 2022-01-05, had a primary completion date of 2022-10-05, and is listed as completed. Phase and allocation are recorded as NA, and masking is listed as none. These entries do not indicate a randomized comparison: the model is single group, and no control arm is described. The registry record does not report a protocol-level explanation for the phase or allocation entries.

The primary outcome was perceived usability measured by the System Usability Scale at 1 month after the quit date. A secondary outcome concerned engagement, assessed by the number of text messages sent and received by study participants after enrollment. The registry lists 2 outcome measures and 0 analyses. It does not report numerical results for the primary usability measure or the engagement outcome.

This design is suited to describing participants’ experience with the intervention during beta testing, but it does not provide a like-for-like control comparison. Without a comparator, any change or score cannot be attributed to the program by contrasting it with another condition. The registry record does not report further details about recruitment, eligibility, intervention delivery, or the analysis plan.

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 Perceived Usability as Assessed by the System Usability Scale (SUS), measured over 1 month after quit date.

The primary endpoint is perceived usability, assessed with the 10-item System Usability Scale (SUS). The registry describes the outcome as a mean score on a scale, with standard deviation as its dispersion measure. The assessment time is 1 month after the quit date. The SUS is used to capture users’ overall assessment of a system’s usability; in this study, it provides a way to describe how participants experienced the text messaging program rather than a direct measure of smoking cessation.

The registry defines a total score ranging from 0 to 100. Higher scores indicate greater acceptability, and a score above 75 is described as indicating that the program is perceived as acceptable. This threshold gives the score a stated interpretive reference, but it does not substitute for the actual observed result. The registry record does not report the mean SUS score or its standard deviation, so the recorded endpoint cannot be compared with the stated threshold from the available result information.

Usability is relevant to a pretest because a text-based program depends on participants being able to engage with and use its messages. However, a usability score alone does not establish whether smoking behavior changed, whether the intervention caused a change, or how the program compares with another approach. Those questions are not answered by this endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

In general, a mean represents the average of the recorded scores, while a standard deviation describes how dispersed individual scores are around that average. Together, these summaries can describe the central tendency and variability of a continuous measure. They do not show the full distribution, and they do not by themselves indicate how precisely the mean has been estimated. The registry specifies a mean and standard deviation for the SUS outcome, but does not report their numerical values.

For this endpoint, the SUS total score ranges from 0 to 100, with higher scores representing greater acceptability. The registry also states that scores above 75 indicate that the program is perceived as acceptable. A mean could be considered in relation to that stated threshold, while the standard deviation would provide information about variation in participant scores. Without the observed mean and standard deviation, neither the average rating nor the spread of ratings can be described. A mean alone, even if reported, would not establish that every participant gave a similar rating.

What would an uncertainty interval add?

In general, a confidence interval conveys the uncertainty associated with an estimated quantity. It is different from a standard deviation: the standard deviation describes variation among observations, while a confidence interval describes uncertainty in an estimate under the assumptions of the method used. An interval’s width can help readers judge how precisely a mean or effect has been estimated. The registry record does not report a confidence interval for the primary endpoint, and it does not give a numerical mean from which to interpret one.

Statistical significance and practical interpretation are also distinct. A significance test, when used, evaluates compatibility between data and a specified null hypothesis under its assumptions. It does not by itself show that a result is important or that an intervention caused an outcome. No primary-outcome test result is reported in the registry record. With no comparator and no reported estimate, there is no recorded between-group effect to assess.

What can the single-group design estimate?

In general, a single-group study can describe measured outcomes among participants who took part. It cannot directly estimate a contrast with a control condition that was not included. Because the SmokefreeSGM record lists a single-group model, the usability measure is appropriately read as a planned description of participants’ perceptions, not as a comparative effect. The design does not separate possible intervention effects from other explanations for participants’ responses.

The secondary engagement measure counts text messages sent and received after enrollment. In general, engagement measures can describe interaction with an intervention, but message counts do not necessarily establish usability, acceptability, or behavioral change. The registry does not report the engagement result or specify additional analyses of message activity.

How should the planning assumptions be read?

The registry describes a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These assumptions describe a planning illustration, not the design actually used in this single-group study. The registry record does not report the numerical observed effect or planning counts, so those quantities cannot be interpreted from the available record. Planning sample sizes are not observed power, and they do not provide evidence about the results of this completed study.

In general, power calculations depend on assumptions about the effect to detect, variability, allocation, significance level, and analysis method. If an assumed effect is smaller, a design generally requires more information to detect it under otherwise comparable assumptions. Such calculations are planning tools rather than a retrospective measure of whether a completed study succeeded. Here, the listed two-arm assumptions should not be confused with the actual single-group beta-testing design.

Why does dispersion matter?

In general, over-dispersion means that observed variation is greater than a model assumes. When that occurs, standard errors based on the narrower variation assumption can be too small, making uncertainty appear less than it is. The registry identifies standard deviation as the dispersion measure for the continuous SUS outcome, but does not report a model, an over-dispersion assessment, or an inferential analysis. This general concept therefore does not imply that over-dispersion was present or relevant to the reported study.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Beta Testing Group")
n   <- c(9)
m   <- c(81.67)
sp  <- c(15.46)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Beta Testing Group  9  81.670  15.460  69.786  93.554

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures: the primary SUS usability outcome and a secondary engagement outcome based on the number of text messages sent and received after enrollment. Considering multiple outcomes can raise a multiplicity issue when several statistical tests are conducted, because repeated testing can increase the chance of at least one apparently notable result under a null hypothesis. In general, methods such as prespecifying a primary outcome or adjusting for multiple tests can address particular multiplicity concerns. The registry record does not report a multiplicity strategy, and it lists 0 analyses. It is therefore not possible to determine whether any adjustment was planned or applied.

The numerical results for the primary usability measure and secondary engagement measure are not reported in the registry record. No analysis-specific confidence intervals, test statistics, or p-values are reported. The record also does not describe a statistical analysis population, such as which participants contributed to each outcome. Enrollment of 18 should not be treated as proof that every enrolled participant contributed an outcome measurement.

Missing-data handling is not reported in the registry record. There is no description of the amount or pattern of missing outcome data, any imputation method, or a sensitivity analysis. In general, missingness can affect interpretation if participants with unrecorded outcomes differ systematically from those with recorded outcomes. Without information about missingness and analysis populations, the extent of that concern cannot be assessed for this study.

The registry record also does not report an interim-analysis plan or a detailed statistical analysis plan. No assumptions about such procedures should be inferred from the study’s design or from the absence of analysis results.

12. 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’s safety record lists the Beta Testing Group with 18 participants at risk for serious adverse events and 0 affected. It also lists 18 at risk for other adverse events and 0 affected, with 0 deaths. No top serious adverse-event terms are listed.

These entries describe the counts recorded in the registry; they are not a comparison with another group. They should not be read as proof that no adverse events could occur, or as evidence about safety outside the participants and observation captured in this record. The registry does not provide further detail about event definitions, the observation period for safety, or completeness of event reporting. Those details are not reported in the registry record.

The safety counts are separate from the primary SUS endpoint, which measures perceived usability. They do not establish whether the program was acceptable or effective for smoking cessation. They indicate only that the listed adverse-event and death counts for the beta testing group were recorded as zero.

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

The study was designed to pretest the design of SmokefreeSGM, a text-based smoking cessation program tailored to sexual minority individuals. Its primary outcome was perceived usability measured with the SUS 1 month after the quit date, and its secondary outcome concerned engagement through text-message activity. The registry also records enrollment of 18 in a single beta testing group and reports zero serious adverse events, zero other adverse events, and zero deaths in that group.

The registry record does not report the numerical SUS result or the engagement result. It therefore does not show what participants’ average usability rating was, how ratings varied, or how much they engaged with the messaging program. Although the registry defines scores above 75 as indicating perceived acceptability, the missing score means the result cannot be classified relative to that threshold.

The study does not include a comparator. Its results, as recorded, cannot establish a difference between SmokefreeSGM and another program or usual care. A usability measure is also not a direct measure of smoking cessation, so it cannot answer whether participants stopped smoking or whether the intervention changed smoking behavior. Such conclusions are not reported in the registry record.

These limits do not make the study’s purpose irrelevant: beta testing can address questions about users’ experience and program design. But the available registry results do not provide the outcome values needed to judge that experience quantitatively. The most defensible interpretation is limited to the recorded design and outcome definitions, alongside the safety counts. Claims about acceptability, engagement, cessation, comparative benefit, or precision would require results or methods that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why design and endpoint must be considered together. SmokefreeSGM was a single-group beta test intended to pretest a text-based program’s design. Its primary endpoint measures perceived usability, not smoking cessation. The endpoint is relevant to evaluating how participants experience an intervention, but it does not answer every question that may be important about a cessation program.

The distinction between a descriptive study and a comparative trial is important for biostatistical interpretation. With no comparator, the study cannot estimate an intervention-versus-control contrast. That is a design limitation for causal comparison, not evidence that the intervention did or did not change an outcome. The registry also does not report numerical results for the usability or engagement outcomes, so even the descriptive outcome findings cannot be evaluated quantitatively from the record.

The record gives a SUS scale range and an acceptability reference above 75. Those definitions help explain how the outcome was intended to be interpreted, but a threshold is useful only when the observed score is available. This makes clear why outcome definitions and outcome results need to be read separately.

Finally, the planning assumptions described in the record refer to equal allocation between two arms, while the actual study model is single group. Recognizing that distinction prevents a planning illustration from being mistaken for the design used or for observed evidence. Overall, the study raises useful statistical questions about what a beta test can describe, how missing outcome reporting constrains interpretation, and why a usability measure should not be treated as a comparative or cessation result.

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 principal trial-specific limitation is the single-group design. The registry does not describe a control condition, so the study cannot make a direct comparison with another intervention or usual care. This limits causal interpretation and means the record cannot support a comparative effect estimate.

The registry describes enrollment of 18, but does not report how many participants contributed to the primary or secondary outcome analyses. It lists 0 analyses and does not provide the numerical SUS or engagement results. Consequently, the record does not allow assessment of the size, variability, or precision of either outcome. The SUS threshold is defined, but the outcome value needed to apply that threshold is not reported in the registry record.

Further details that would help interpret a beta test are not reported in the registry record, including eligibility criteria, participant characteristics, program delivery details, and the statistical analysis plan. Missing-data methods and analysis populations are also not reported. The available information therefore does not show whether all enrolled participants completed the usability measure or how unrecorded observations, if any, were handled.

The registry lists a sample-size planning approach with two-arm assumptions, while the completed study is identified as single group. The planning illustration should not be taken as a description of the trial’s actual design or as evidence of observed power. Numerical planning outputs and the underlying observed effect are not reported in the registry record. These limitations restrict interpretation to the stated purpose, design, outcome definitions, and recorded safety counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: SmokefreeSGM, A Text-based Smoking Cessation Intervention for Sexual and Gender Minority Groups — NCT05029362.
• Registry record last updated 2025-07-20; status last verified 2025-07.
• Results first posted 2024-05-01.
• 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

SmokefreeSGM was a completed, single-group behavioral study sponsored by The University of Texas Health Science Center, Houston. Its stated purpose was to pretest a text-based smoking cessation program tailored to sexual minority individuals. Enrollment was 18 in the beta testing group. The study began on 2022-01-05 and had a primary completion date of 2022-10-05.

The primary outcome was perceived usability measured by the System Usability Scale at 1 month after the quit date. The secondary outcome concerned engagement measured through text messages sent and received after enrollment. The registry lists 2 outcome measures and 0 analyses; numerical results for these outcomes are not reported in the registry record. The safety record lists 0 serious adverse events, 0 other adverse events, and 0 deaths in the beta testing group.