This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Optimizing Risk Messages for Waterpipe Tobacco Cessation in Young Adults (NCT03595280), a randomized na study. The primary outcome is Perceived Harm.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03595280 |
| Phase | NA |
| Condition | Hookah Smoking |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 349 |
| Arms in the primary outcome | 3 |
| Lead sponsor | Georgetown University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns young adults ages 18 to 30 years in the context of hookah tobacco use. The registry record identifies hookah smoking as the condition, but the specific eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
Participants assigned to either message group received mobile multimedia service messages about hookah tobacco risks. In the tailored group, message content was personalized to hookah tobacco use behavior and beliefs. The messages addressed harms and addictiveness.
Comparator
The control group received no study messages. A separate group received risk messages that were not tailored. Thus, the registry record describes a no-message control and two message approaches, although the posted primary results are arm-specific rather than inferential comparisons.
Primary question
At six-month follow-up, what perceived-harm scores were reported in each group? The endpoint is a self-reported perception of how likely harms are to occur from hookah tobacco use. Greater perceived likelihood is considered a better outcome. The study objective also refers to promoting cessation, but the posted primary endpoint is perceived harm, not a direct measure of quitting.
3. Trial Design
The registry record describes a randomized, parallel-group trial with no masking. It lists three groups: a control group receiving no study messages, an untailored-message group receiving hookah-risk messages by mobile multimedia service, and a tailored-message group receiving messages personalized to participants’ hookah tobacco use behavior and beliefs. The listed intervention is behavioral. The record does not describe the randomization sequence, allocation concealment, or additional steps used to deliver or monitor the messages; those details are not reported in the registry record.
Enrollment is listed as 349. The primary outcome results at six-month follow-up include 113 participants in the control group, 108 in the untailored-message group, and 98 in the tailored-message group. These are the group counts attached to the posted outcome values; the registry record does not explain how those counts relate to enrollment or identify the analysis population.
The study is marked completed. Its listed start date is 2018-08-28, and its primary completion date is 2020-08-01. The phase is recorded as NA. These design details establish the broad structure of the experiment, but do not specify the statistical analysis plan or how participants were followed between the intervention and the six-month assessment. Such details are not reported in the registry record.
The three-group structure permits separate descriptive reporting for the no-message control and each message approach. However, the posted record gives no analyses for comparisons between groups. It therefore supports a description of the reported arm-level scores and their confidence intervals, not a claim about the statistical significance of differences between the groups.
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
| Stage | Control | Untailored Messages | Tailored Messages |
|---|---|---|---|
| STARTED | 119 | 117 | 113 |
| COMPLETED | 113 | 108 | 98 |
| NOT COMPLETED | 6 | 9 | 15 |
Reasons for not completing this period:
| Reason | Control | Untailored Messages | Tailored Messages |
|---|---|---|---|
| Lost to Follow-up | 6 | 9 | 15 |
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.
| Characteristic | Unit | Control | Untailored Messages | Tailored Messages | Total |
|---|---|---|---|---|---|
| Participants analysed | 119 | 117 | 113 | 349 | |
| Age, Continuous | years | 23.9 (SD 3.4) | 23.7 (SD 3.5) | 24.6 (SD 3.5) | 24.0 (SD 3.4) |
| Sex: Female, Male: Female | Participants | 71 | 57 | 59 | 187 |
| Sex: Female, Male: Male | Participants | 48 | 60 | 54 | 162 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 15 | 14 | 11 | 40 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 104 | 103 | 101 | 308 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 1 | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 | 1 | 2 | 4 |
| Race (NIH/OMB): Asian | Participants | 8 | 14 | 9 | 31 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 2 | 2 | 1 | 5 |
| Race (NIH/OMB): Black or African American | Participants | 27 | 26 | 27 | 80 |
| Race (NIH/OMB): White | Participants | 51 | 43 | 53 | 147 |
| Race (NIH/OMB): More than one race | Participants | 30 | 31 | 21 | 82 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 |
| Education: Less Than College Education | Participants | 16 | 24 | 16 | 56 |
| Education: Some College or Higher | Participants | 103 | 93 | 97 | 293 |
6. Primary Endpoint
The registry lists the primary outcome as Perceived Harm, measured over 6-months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is perceived harm of hookah tobacco at six-month follow-up. It is measured with a valid self-report item asking how likely harms are to occur from hookah tobacco use. Responses range from 1, meaning “no chance,” to 7, meaning “certain to happen.” A higher score represents a greater perceived likelihood of harm, which the registry record defines as a better outcome for this measure.
The registry record says the assessment was administered immediately after the intervention and at three-month and six-month follow-ups, and that six-month data are reported. The reported statistic is the mean score for each group, accompanied by a 95% confidence interval. The mean describes the group’s average response; it does not show the full range of individual responses or how responses are distributed within the group.
Perceived harm is a measure of beliefs about risk, not a direct measure of hookah tobacco use or cessation. Although the study objective concerns promoting cessation, the posted primary endpoint addresses whether participants perceive harm as likely. These outcomes can answer different questions, so a change in perceived-harm scores alone would not establish a change in tobacco-use behavior.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
At six-month follow-up, the control group had a reported mean perceived-harm score of 4.1, with a 95% confidence interval from 3.9 to 4.4. The untailored-message group had a mean of 4.2, with a 95% confidence interval from 4.0 to 4.5. The tailored-message group had a mean of 4.5, with a 95% confidence interval from 4.2 to 4.8. These are descriptive summaries on the stated response scale, where higher scores indicate a greater perceived likelihood of harm.
The listed means place the tailored-message group highest, the untailored-message group between the other two, and the control group lowest. This ordering describes the reported group averages; it does not establish that the groups differ statistically. The intervals for the groups overlap. More importantly, the registry record posts no inferential analyses for the primary endpoint, so it gives no test result or estimated between-group contrast with uncertainty. The arm-level confidence intervals should not be treated as substitutes for such a comparison.
A confidence interval communicates uncertainty around an estimate under the method used to construct it. In general, a 95% confidence interval is not a range containing 95% of individual participants’ scores, nor is it a guarantee that the true value lies within the interval. Here, the intervals describe uncertainty around each group’s reported mean. The method used to calculate them is not reported in the registry record.
The outcome counts attached to the means are 113 for control, 108 for untailored messages, and 98 for tailored messages. The registry record does not explain whether these counts represent all randomized participants, participants with observed six-month data, or another analysis population. It also does not state how missing responses were handled. Consequently, the extent to which the reported means represent all enrolled participants cannot be determined from the posted result.
The endpoint concerns perceived risk, not cessation itself. No secondary results are posted, and the registry record lists zero analyses. The study objective describes cessation as the broader goal, but the available primary result cannot establish whether participants stopped using hookah tobacco or changed their use. Nor does the arm-level ordering show that tailored messages caused higher perceived-harm scores. Such conclusions would require an appropriate comparative analysis and information about the analysis population and missing data, which are not reported in the registry record.
9. Statistical Methods Explained
What does the mean describe?
The reported primary statistic is a mean, or average, of the self-reported perceived-harm scores within each group at six-month follow-up. The underlying response scale runs from 1 (“no chance”) to 7 (“certain to happen”). A mean condenses a group’s responses into one summary. It is useful for comparing the general level of responses across groups, but it does not reveal whether most participants answered near the mean or whether responses were widely spread. The registry record gives no standard deviations or other measure of participant-to-participant spread.
What does a confidence interval add?
Each mean is accompanied by a 95% confidence interval. In general, a confidence interval describes the precision of an estimated quantity under a specified statistical method. A narrower interval indicates greater precision for that estimate than a wider interval would, all else equal. It does not describe the range of scores among participants, and it is not a test of whether two groups differ. The registry record does not state the method used to calculate the intervals or provide a confidence interval for a between-group contrast.
Why are arm-level summaries not a group comparison?
The means and confidence intervals characterize the groups separately. To evaluate a difference between groups, an analysis would ordinarily estimate a contrast and its uncertainty, or report an appropriate statistical test. Such a result would directly address the comparative question while accounting for the design and chosen analysis method. The registry record lists no analyses, so no inferential comparison is posted. It is not appropriate to infer statistical significance from the relative positions of the means or from overlap between separate confidence intervals.
General statistical principle: randomization can support comparisons between assigned groups when the analysis is conducted appropriately, but the fact that a study is randomized does not itself supply a result of a treatment comparison. Interpretation also depends on how participants were included in the analysis, how missing outcomes were handled, and what model or test was prespecified. Those details are not reported in the registry record.
What can the three-group design show descriptively?
The registry record lists a no-message control, untailored risk messages, and messages tailored to behavior and beliefs. The arm-specific results let readers describe perceived-harm scores in each group. They do not by themselves isolate the effect of receiving messages, the effect of tailoring, or the effect of either approach relative to control. Those questions require specified contrasts and comparative analyses. No such analyses are posted for this endpoint.
How should planning illustrations be understood?
General statistical principle: sample-size planning asks how many participants may be needed under a set of assumptions to detect a specified effect with a chosen error rate and power. A planning illustration based on an observed effect is not a report of the trial’s original design rationale and is not “observed power.” The registry record describes an illustration using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects expressed as stated fractions of an observed effect. It also distinguishes participants per arm for outcomes other than time-to-event outcomes. The illustration is not evidence that the trial was planned with those assumptions, and it does not replace a reported analysis. The trial’s own sample-size justification is not reported in the registry record.
General statistical principle: when outcomes are over-dispersed, a model that assumes less variability than the data contain can understate uncertainty. That concern applies only when relevant to the outcome and analysis; the posted primary result is a continuous mean with confidence intervals, and the registry record does not report an analysis model or an over-dispersion assessment. No conclusion about whether over-dispersion was present or addressed can be drawn from the posted information.
What analysis details remain unknown?
The record does not report the confidence-interval construction method, an adjusted or unadjusted comparative model, covariates, a prespecified statistical analysis plan, or an interim-analysis plan. The listed analysis count is zero. These omissions limit what can be said about inferential methods. General explanations of statistical concepts describe how methods work in principle; they should not be read as claims about methods used in this trial.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists seven outcome measures overall, but it posts no secondary results. It lists zero analyses, and no inferential analysis of the primary endpoint is posted. The statistical plan for handling multiple outcomes or multiple comparisons is not reported in the registry record. As a result, it is not possible to determine whether a multiplicity adjustment was planned or used. General statistical principle: when several hypotheses are tested, the chance of at least one false-positive finding can increase, and prespecified methods may be used to address that issue. That general concern does not establish what happened in this trial.
The record gives six-month primary outcome counts and results for the three groups, but it does not specify the analysis population. It does not state whether the reported counts include all randomized participants, only participants who completed the assessment, or participants meeting another criterion. The handling of missing responses, withdrawals, and incomplete follow-up is not reported in the registry record. There is therefore no basis to characterize the posted results as intention-to-treat, per-protocol, or another analysis population.
General statistical principle: missing outcome data can affect an estimate when the participants with observed results differ from those without observed results. Statistical methods for missing data rely on assumptions, and different assumptions can lead to different interpretations. Because the registry record does not describe missingness or its handling, the potential impact on the arm-level means cannot be evaluated from the posted information.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Control | 0 | 113 | 0.0% |
| Untailored Messages | 0 | 108 | 0.0% |
| Tailored Messages | 0 | 98 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Control | 0 of 113 |
| Untailored Messages | 0 of 108 |
| Tailored Messages | 0 of 98 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Control | 0 of 113 |
| Untailored Messages | 0 of 108 |
| Tailored Messages | 0 of 98 |
The registry record lists serious adverse events for each group and reports zero affected participants in the control group, zero in the untailored-message group, and zero in the tailored-message group. The corresponding at-risk counts are 113, 108, and 98. It also lists zero participants affected by other adverse events in each group and zero deaths in each group.
These entries describe the adverse-event figures posted in the registry record. They do not establish that no adverse events of any kind occurred, that every possible event was collected, or that the groups had equivalent safety experience. The record’s reporting definitions, collection procedures, observation period, and attribution of events are not reported in the registry record. The listed at-risk counts should not be taken as proof that all enrolled participants contributed safety information across the same period.
Zero reported affected participants is a count, not a demonstration that risk is absent. Safety interpretation depends on the scope and completeness of monitoring as well as the event counts. The posted figures allow a direct account of what was recorded, but do not support broader conclusions about safety beyond those entries.
12. What the Result Does, and Does Not, Mean
The posted primary outcome gives a descriptive picture of perceived harm at six-month follow-up in three groups. The mean score was 4.1 in control, 4.2 with untailored messages, and 4.5 with tailored messages, with a 95% confidence interval reported for each mean. Because higher scores indicate a greater perceived likelihood of harm, the arm-level summaries show the highest average score in the tailored-message group. They do not establish that any group difference is statistically significant or attributable to the messages.
The endpoint measures perception, not hookah tobacco cessation. The study objective concerns cessation, but the primary result posted in the registry record is a self-reported risk-perception score. It cannot, by itself, show whether participants stopped using hookah tobacco, reduced use, or changed use in another way. No secondary results are posted, so other outcome measures cannot be used to answer those questions.
The results also do not show how durable any change in perceived harm might be beyond the reported six-month assessment. The registry record says assessments occurred immediately after the intervention and at three-month and six-month follow-ups, but only six-month data are reported. Earlier outcome values are not reported in the registry record.
More broadly, the available information does not report comparative analyses, missing-data methods, or the analysis population. Those limitations restrict interpretation of the means and their precision. The statistics describe what was posted for the three groups; they do not establish a causal effect, a cessation benefit, or a difference in clinical outcomes.
13. Why This Trial Matters Statistically
This trial raises a useful statistical distinction between an intervention’s intended goal and the endpoint reported as primary. The stated objective concerns promoting hookah tobacco cessation, while the posted primary outcome is perceived harm. Perceptions can be relevant to understanding message response, but a score about perceived likelihood of harm is not the same measurement as tobacco-use behavior. Keeping those outcomes distinct prevents an interpretation of the risk-perception result from drifting into a claim about quitting.
The three-arm design also makes the choice of comparison important. A no-message control and two message approaches allow several potentially relevant questions, including whether messages differ from no messages and whether tailoring matters. Arm-level means alone do not answer those comparative questions. A direct contrast with an uncertainty estimate would be needed to assess them statistically, and no such analysis is posted in the registry record.
The example illustrates why estimates and precision should be read together, while also recognizing that arm-specific confidence intervals are not a substitute for a contrast. The record gives mean scores and intervals, but omits the interval method and analysis population. Those details matter for evaluating what the estimates represent and how strongly they support a comparison.
Finally, the posted safety counts and the lack of secondary results show why a registry record is best read as a bounded account of reported outcomes. Counts, outcome definitions, timepoints, and analysis methods each shape what can be concluded. Here, the most defensible statistical reading stays with the descriptive six-month perceived-harm results and avoids extending them to unreported comparative or behavioral findings.
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 registry record provides limited information about the primary analysis. It lists means and 95% confidence intervals, but does not report the method used to calculate the intervals or a statistical test or contrast between groups. It also lists zero analyses. Therefore, the arm-level results do not quantify the uncertainty around between-group differences.
The analysis population and handling of missing six-month outcomes are not reported in the registry record. Although counts are listed with each group’s result, the record does not explain how those counts were determined or how they relate to total enrollment. The completeness of follow-up and potential effects of missing responses cannot be assessed from the posted information.
The endpoint is a self-reported perceived-harm item, and its response range is stated, but further details about scoring beyond the item, assessment procedures, or the distribution of individual responses are not reported in the registry record. The result is specific to perceived harm at six-month follow-up; only that follow-up data are reported despite assessments also being described immediately post intervention and at three-month follow-up.
The intervention descriptions distinguish tailored from untailored messages, but details such as message frequency, duration, and delivery fidelity are not reported in the registry record. Eligibility criteria and participant characteristics beyond the study’s stated focus on young adults ages 18 to 30 years are also not reported. These omissions constrain assessment of how the findings might apply to other settings or populations.
Finally, no secondary results or inferential analyses are posted. The registry record does not report the statistical plan, multiplicity approach, sample-size justification, or interim analyses. These limits prevent assessment of how the posted primary endpoint fits into the complete outcome and analysis plan.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Optimizing Risk Messages for Waterpipe Tobacco Cessation in Young Adults — NCT03595280.
- Registry record last updated 2021-10-20; status last verified 2021-10.
- Results first posted 2021-10-20.
- 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.
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18. Record Summary
The registry record identifies NCT03595280 as a completed, randomized, parallel-group study sponsored by Georgetown University. It lists no masking and records the phase as NA. Enrollment is 349. The listed study start date is 2018-08-28, and the primary completion date is 2020-08-01.
The study concerns hookah smoking among young adults and evaluates mobile multimedia messages about hookah tobacco risks. The three groups are control, untailored messages, and tailored messages. The primary endpoint is perceived harm at six-month follow-up, reported as a mean and 95% confidence interval for each group. No inferential analyses or secondary results are posted. The registry record also lists zero serious adverse events, zero other adverse events, and zero deaths in each group.