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 Effectiveness of SMS (Short Message Service) Text Messaging in Increasing Adherence to Gardasil (NCT01276184), a randomized na study. The primary outcome is Number of Participants That Adhered to Vaccine Schedule.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01276184 |
| Phase | NA |
| Condition | HPV Vaccines |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 22 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Maryland, Baltimore |
| Results posted | Yes |
2. Clinical Question
The registry’s central question is whether SMS text-message reminders increase adherence to the recommended 3 dose Gardasil schedule compared with usual care in an outpatient clinic. The primary outcome counts participants who adhered to the schedule. The record gives its assessment timeframe as at the end of the study: 30 days after the third vaccination or 360 days after the first vaccination, whichever comes first.
Population
Participants in an outpatient clinic study concerning HPV vaccines. The primary outcome’s population field contains no further description, so specific eligibility characteristics are not reported in the registry record.
Intervention
SMS text-message reminders. Participants in this arm also received standard clinic reminders. The arm description says women who rescheduled a vaccination visit would receive a text message.
Comparator
Usual care: participants followed clinic practices for arranging vaccination follow-up visits and received standard appointment reminders, such as a phone call or letter, as appropriate.
Primary question
How many participants in each arm adhered to the recommended 3 dose Gardasil schedule by the stated end-of-study assessment?
The registry also describes objectives concerning the feasibility of text-message reminders and satisfaction and acceptability compared with telephone reminders among women in this discussion-message arm. However, no secondary outcome results are posted. The record therefore supports a description of the primary outcome counts, but does not provide reported results for those additional objectives.
3. Trial Design
This was a randomized, controlled trial with a parallel-group model and single masking. The registry records an enrollment of 22. The Usual Care arm lists 13 participants, and the SMS Text Message arm lists 9. The record does not identify who was masked, nor does it report the randomization sequence or allocation concealment procedures.
The comparison was between standard clinic appointment reminders and standard reminders supplemented by SMS messages. Under usual care, participants followed the clinic’s usual practices for scheduling follow-up vaccination visits and received standard reminders by phone, letter, or another appropriate method. The SMS arm also received standard clinic reminders; its description refers to text messages for women who rescheduled vaccination visits.
The primary outcome was a count of participants who adhered to the recommended 3 dose Gardasil schedule. Assessment was specified for the end of the study, defined as 30 days after the third vaccination or 360 days after the first vaccination, whichever came first. The registry lists the trial status as terminated. Its start is recorded as 2011-01, and primary completion as 2016-06-15. The reason for termination and the circumstances surrounding study completion are not reported in the registry record.
The phase is recorded as NA. The record lists one primary outcome measure and no posted secondary outcome results. Although the study description sets out feasibility and acceptability objectives, the posted results do not include corresponding findings. Details such as the intended recruitment target, sample-size justification, masking procedures, and duration or conduct of follow-up beyond the endpoint definition are 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
| Stage | Usual Care | SMS Text Message |
|---|---|---|
| STARTED | 13 | 9 |
| COMPLETED | 13 | 9 |
| NOT COMPLETED | 0 | 0 |
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 | Usual Care | SMS Text Message | Total |
|---|---|---|---|---|
| Participants analysed | 13 | 9 | 22 | |
| Age, Categorical: <=18 years | Participants | 2 | 2 | 4 |
| Age, Categorical: Between 18 and 65 years | Participants | 11 | 7 | 18 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 19 (12 to 26) | 17 (12 to 26) | 18 (12 to 26) |
| Sex: Female, Male: Female | Participants | 13 | 9 | 22 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 13 | 9 | 22 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 12 | 8 | 20 |
| Race (NIH/OMB): White | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 13 | 9 | 22 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants That Adhered to Vaccine Schedule, measured over at the end of the study (30 days after the third vaccination or 360 days after the first vaccination, whichever comes first).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants who adhered to the recommended 3 dose Gardasil vaccine schedule. It is a binary outcome at the participant level: each participant either met the stated adherence criterion or did not. The registry reports the outcome as counts, not as a continuous measurement.
Adherence is relevant to the trial’s stated question because the intervention was intended to prompt participants to attend vaccination visits. Counting participants who completed the recommended schedule gives a direct summary of whether the schedule was followed within the study’s defined assessment period. That period ended 30 days after the third vaccination or 360 days after the first vaccination, whichever came first.
The endpoint is not a measure of vaccine efficacy, HPV infection, or a clinical health outcome. It records adherence to a vaccination schedule. The registry does not provide a more detailed operational definition of adherence, such as how missed visits or incomplete records were handled. That definition, along with details of how outcome status was ascertained, is not reported in the registry record.
The posted result gives the number adhering in each arm: 10 in Usual Care and 8 in SMS Text Message. These counts describe observed outcomes within the recorded arms. A count alone does not show the precision of the difference between groups, and the registry reports no estimable two-arm comparison for this binary endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary outcome counts are 10 participants adhering in Usual Care and 8 in SMS Text Message. The arm sizes recorded for those results are 13 and 9, respectively. These are descriptive results from the registry. They do not, by themselves, establish whether the reminder strategy changed adherence compared with usual care.
The registry explicitly indicates that values are missing or not estimable for a two-arm comparison of the binary endpoint. No analysis result, confidence interval, or p-value for the treatment comparison is posted. Consequently, the record does not quantify the size or precision of a between-arm effect. It also does not provide a statistical basis for deciding whether an apparent difference in raw counts is distinguishable from random variation.
For a binary outcome, the counts are only one part of the evidence. An interpretable comparison also depends on the denominators and on an analysis that estimates the contrast between arms, with uncertainty. The registry gives arm sizes, but does not report the comparison estimate or its uncertainty. A recalculated estimate should not be substituted for the absent registry analysis; the record marks the binary comparison as not estimable.
The trial is listed as terminated, but the reason is not reported in the registry record. Termination alone does not explain why the analysis is absent, and it should not be taken as evidence about the direction or size of an intervention effect. Likewise, the record’s enrollment and arm counts do not establish whether recruitment met a target or whether the study had a prespecified ability to detect an effect; those design details are not reported.
The registry records no posted secondary results, despite describing feasibility and acceptability as secondary objectives. The available findings therefore concern the primary adherence counts and safety counts only. They do not answer the additional questions about feasibility, satisfaction, or acceptability. Overall, the appropriate reading is descriptive: the registry records adherence counts in both arms, while the comparative statistical result and its precision are unavailable.
9. Statistical Methods Explained
The primary outcome is binary because it classifies each participant according to whether the recommended schedule was completed. The registry reports counts of participants meeting that criterion by arm. For a binary outcome, an arm-level count is commonly accompanied by a denominator and a between-arm estimate, such as a difference in proportions or a relative measure. The choice of measure and analysis should be prespecified and appropriate to the trial. The registry does not report which comparative measure or statistical test was planned.
What does an uncertainty interval contribute?
In general, a confidence interval describes the range of effect values compatible with the observed data under the assumptions of the analysis. It helps readers judge precision, rather than merely whether a point estimate is above or below a reference value. A narrower interval indicates greater precision than a wider interval. Here, the registry does not post a confidence interval for the binary comparison, and the comparison is identified as not estimable. Therefore, the precision of any between-arm effect cannot be assessed from a reported interval.
Why are the counts not enough for inference?
Counts show how many participants met the endpoint in each arm, but comparison requires accounting for the number assessed in each arm and for the method used to estimate uncertainty. Raw counts cannot be compared as if the arms necessarily had the same size. The registry reports arm sizes, but provides no estimable comparative result. It is therefore important not to infer a treatment effect from the count values alone or to construct a new comparison that the record does not report.
What does “not estimable” mean?
The registry’s note says values are missing or not estimable for a two-arm comparison of the binary endpoint. This indicates that the posted results do not include usable values for that comparison. It does not explain why the comparison could not be estimated. The reason, the analysis approach, and any data-handling steps are not reported in the registry record. No conclusion about the cause of the missing analysis can be drawn from the note.
How should the planning calculations be understood?
General sample-size calculations can illustrate how many participants per arm might be needed under specified assumptions to detect a chosen effect with a chosen statistical procedure. The planning assumptions associated with this record describe a two-sided significance level of 0.05, equal allocation, and a normal approximation; the target effect is framed as a stated fraction of the observed effect. Such calculations are illustrations for planning, not observed trial outcomes and not observed power. They do not replace a reported trial analysis, resolve the unavailable binary comparison, or show that the study was designed with those assumptions. The registry does not report the trial’s own sample-size justification or statistical plan.
The term “observed power” is not an appropriate substitute for an effect estimate and its confidence interval. In general, power is a design concept tied to assumptions about a target effect and a testing procedure. Calculations based on an observed effect are particularly dependent on the observed estimate and should not be read as evidence that the trial did or did not establish a difference. No planning values are needed to interpret the posted outcome counts, and no such calculation changes the fact that the registry’s two-arm endpoint analysis is not estimable.
What other analysis details matter?
Randomization can support a fair comparison when allocation and analysis are conducted as intended, but the registry does not describe the sequence generation, concealment, or analysis population. It records single masking without specifying who was masked. It also does not report whether the analysis followed an intention-to-treat approach, how missing outcome data were handled, or whether any adjustment for baseline characteristics was planned. These details matter because they clarify which participants contribute to the estimate and how potential bias or imprecision was addressed. Their absence limits methodological appraisal, but it does not justify assuming that any particular procedure was or was not used.
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.
| Arm | Participants | Events | Observed % | Clopper-Pearson 95% CI | Wilson 95% CI | Bayesian 95% credible interval |
|---|---|---|---|---|---|---|
| Usual Care | 13 | 10 | 76.9% | 46.2% to 95.0% | 49.7% to 91.8% | 49.2% to 91.6% |
| SMS Text Message | 9 | 8 | 88.9% | 51.8% to 99.7% | 56.5% to 98.0% | 55.5% to 97.5% |
R code and output
arm <- c("Usual Care", "SMS Text Message")
n <- c(13, 9)
events <- c(10, 8)
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 Usual Care 13 10 76.9 46.2 95.0 49.7 91.8 49.2 91.6
ARM SMS Text Message 9 8 88.9 51.8 99.7 56.5 98.0 55.5 97.511. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure, the count of participants adhering to the vaccine schedule. It also describes secondary objectives involving feasibility and satisfaction and acceptability, but no secondary results are posted. The number of secondary outcomes analyzed, any prespecified hierarchy among outcomes, and any adjustment for multiple testing are not reported in the registry record. With no posted secondary analyses, those objectives cannot be assessed from the results.
Missing data handling is also not described. The record does not explain whether every randomized participant had an endpoint status recorded, how participants with incomplete vaccination follow-up were classified, or whether any imputation or sensitivity analysis was used. The arm counts and adherence counts are reported, but they do not establish how missing observations were treated.
The registry does not identify the primary analysis population, such as whether analysis was intended to include all randomized participants or only participants with observed endpoint data. Nor does it state whether analyses were adjusted or unadjusted. The comparative binary result is explicitly missing or not estimable, and the reason is not reported in the registry record. These omissions leave uncertainty about the analysis population, missing-data assumptions, and multiplicity procedures. They should be kept separate from the descriptive counts that are posted.
12. 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 |
|---|---|---|---|
| Usual Care | 0 | 13 | 0.0% |
| SMS Text Message | 0 | 9 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Usual Care | 0 of 13 |
| SMS Text Message | 0 of 9 |
The registry reports serious adverse events for 0 participants in Usual Care and 0 participants in SMS Text Message. The corresponding numbers at risk are 13 and 9. It also reports 0 other adverse events in each arm, with the same numbers at risk. These are the adverse-event counts listed in the registry, not estimates of comparative safety.
Zero reported events means that no participants are recorded as affected for those specified categories in these results. It does not show that the interventions have no risk, and it does not establish that all possible harms were assessed or reported. The registry does not list serious adverse event terms. Death counts are not reported in the registry record.
Adverse-event counts can be interpreted only in light of how events were defined, collected, and followed. Those details are not reported in the registry record. The trial’s listed status is terminated, but the record does not state whether termination was related to safety. No such connection should be inferred from the status or from the zero counts.
13. What the Result Does, and Does Not, Mean
The result establishes that the registry records participants adhering to the recommended 3 dose Gardasil schedule in both trial arms: 10 in Usual Care and 8 in SMS Text Message. It also records the arm sizes and the endpoint’s assessment timeframe. These registry entries describe the posted observations, but they do not provide a comparative estimate of the intervention effect.
Because the two-arm binary comparison is marked as missing or not estimable, the registry does not show how large a difference in adherence might be, how uncertain such a difference would be, or whether the data are compatible with a range of possible effects. No conclusion that SMS reminders increased or did not increase adherence follows from the counts alone. The record likewise does not support a conclusion about the feasibility or acceptability objectives, because no corresponding secondary results are posted.
The outcome is schedule adherence, not a measure of HPV infection or a health benefit. The results do not establish the effects of reminders in settings beyond the outpatient clinic study described, and the registry does not provide enough information to characterize the participants’ eligibility or broader representativeness. The trial’s terminated status is recorded, but the reason is not reported and should not be used to interpret the direction of the result.
In general, a useful treatment-effect interpretation needs an estimate, an account of its uncertainty, and enough information about the analysis to understand what the estimate represents. Those elements are absent for the primary comparison in this registry record. The defensible conclusion is therefore limited to the posted arm-level counts and the fact that no comparative analysis is available.
14. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between describing outcomes and estimating a comparative effect. The registry reports adherence counts in each arm, but marks the binary two-arm comparison as not estimable. Without that comparison and its uncertainty, the counts cannot answer the central question about whether adherence differed between the reminder strategies.
The distinction is important in randomized studies. Random allocation is intended to support a comparison between groups, but readers still need the analysis result and information about which participants and data were included. A count in each arm is not a substitute for an effect estimate. Nor can the lack of an estimable result be interpreted as evidence that the groups were the same.
The record also illustrates how a study may describe secondary objectives without posting corresponding findings. Feasibility and acceptability may be relevant to an intervention, but they require outcome definitions and results to support interpretation. Those results are not posted for this trial.
Finally, trial status and statistical evidence are separate matters. The record lists the study as terminated, but does not report why. That status cannot resolve the missing comparison or explain the result. Clear reporting of the planned analysis, missing-data handling, outcome ascertainment, and reasons for termination would help readers evaluate the evidence. In their absence, a careful reading keeps the descriptive details distinct from conclusions that the registry cannot support.
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 primary limitation for interpretation is that no estimable two-arm analysis is posted for the binary adherence outcome. The arm-level counts are available, but the comparative estimate and its uncertainty are not. The record does not explain why those values are missing or not estimable.
The registry does not report the sample-size justification, detailed statistical plan, randomization procedures, masking roles, analysis population, or missing-data methods. It also lacks a more detailed definition of adherence and does not describe how outcome status was ascertained. These omissions make it difficult to assess the assumptions and procedures behind the posted counts.
The record states that the trial was terminated but does not report the reason. It also posts no results for the stated feasibility and acceptability objectives. Consequently, neither the circumstances of termination nor those secondary questions can be incorporated into an interpretation of the primary result.
The population description is limited: the primary outcome’s population field is blank, and the registry does not give further eligibility details in the information recorded for this analysis. The available results therefore provide little basis for judging how readily they apply to other settings or groups. These limitations do not alter the recorded counts, but they constrain what can be concluded from them.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Effectiveness of SMS (Short Message Service) Text Messaging in Increasing Adherence to Gardasil — NCT01276184.
- Registry record last updated 2021-07-14; status last verified 2021-07.
- Results first posted 2021-07-14.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
NCT01276184 is a randomized, controlled, parallel-group trial comparing SMS Text Message reminders with Usual Care for adherence to the recommended 3 dose Gardasil schedule. The registry records single masking, enrollment of 22, status as terminated, a start of 2011-01, and primary completion on 2016-06-15.
The primary endpoint counts participants adhering by the end-of-study assessment, defined as 30 days after the third vaccination or 360 days after the first vaccination, whichever came first. The posted counts are 10 in Usual Care and 8 in SMS Text Message. The registry identifies the binary two-arm comparison as missing or not estimable. No secondary results are posted. Serious and other adverse-event counts are 0 in each arm; death counts are not reported in the registry record. The reason for termination and key analysis details are also not reported in the registry record.