FAST as a Treatment for Obstructive Sleep Apnea: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for FAST as a Treatment for Obstructive Sleep Apnea (NCT01611779), a na phase 4 study. The primary outcome is Place the Implant and Stabilize the Tongue.

2. Clinical Question

In practical terms, the question is whether the device procedure could be carried out with the intended placement and stabilization, alongside the study’s broader feasibility and safety objective. This is not a randomized comparison of the device against another intervention or a control. Several secondary outcomes are named: Apnea Hypopnea Index, Functional Outcomes and Sleep Questionnaire (FOSQ), Snoring Scale (VAS), and Epworth Sleeping Scale (ESS). Their names identify areas measured, but do not establish what the results were. The registry record does not report numerical results for these measures or explain how they were analyzed.

3. Trial Design

This was a phase 4, single-group study of the Encore Tongue Suspension System for obstructive sleep apnea. The registry record lists an enrollment of 5 participants and describes the arm as tongue suspension. Allocation is recorded as not applicable, and masking is listed as none. There is no separate comparison arm in the recorded design, so the study cannot provide a randomized estimate of how outcomes differ between the device and a control intervention.

The stated objective was to assess feasibility and safety. The primary outcome was the ability to place the implant and stabilize the tongue, expressed as a participant count, with a timeframe of up to 7 weeks after the procedure. The record also names secondary measures covering apnea and hypopnea, sleep-related functioning, snoring, and sleepiness. It lists 6 outcome measures overall, but the registry record does not give results for these measures in the information available for interpretation.

The study start is recorded as 2012-05, and primary completion as 2013-06. Its status is terminated. The reason for termination is not reported in the registry record, and the status alone does not establish why the study ended or what happened to planned follow-up. The registry record does not report further details about the protocol, recruitment, participant characteristics, procedure delivery, or follow-up beyond the primary endpoint timeframe. It also does not report a statistical analysis plan or analysis results; the recorded number of analyses is 0.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Patients with obstructive sleep apnea were enrolled in the trial. Subjects meeting the inclusion and exclusion criteria were invited to participate in the trial. Subjects were treated with the the Encore System, and followed at 1 week, and then at 1, 3, and 12 months.

6. Primary Endpoint

The registry lists the primary outcome as Place the Implant and Stabilize the Tongue, measured over Up to 7 weeks after the procedure.

The primary endpoint is titled “Place the Implant and Stabilize the Tongue.” It measures the ability to place the implant and stabilize the tongue, with the result expressed as a count of participants. Its stated timeframe is up to 7 weeks after the procedure. The registry record does not report the observed participant count or provide a more detailed operational definition of how successful placement and stabilization were determined.

This endpoint fits the stated feasibility objective because it focuses on whether the device procedure could achieve its intended placement and stabilization task. A participant count is a binary-outcome format: each participant would be classified according to whether the specified event occurred, then summarized as a count. That general description does not fill in any unreported criteria for classifying the outcome in this study.

For interpretation, the count would need to be read alongside its denominator and the endpoint definition. The enrollment is recorded as 5, but the primary result itself is not reported in the registry record, and the record does not state whether all enrolled participants contributed an endpoint assessment. Thus, neither the number meeting the endpoint nor the completeness of endpoint ascertainment can be established from the registry information. The record also does not give a precision estimate, such as a confidence interval, for this outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What a participant count means. The primary endpoint is a binary outcome summarized as a count of participants. In general, a binary endpoint classifies each participant into one of two categories, such as whether a defined event occurred. A count states how many participants fall into one category. To interpret such a count fully, readers need the outcome definition, the number assessed, and the number meeting the endpoint. Here, the registry record gives the endpoint description and enrollment, but not the primary result or the number with an available assessment.

What a single-group design can estimate. In general, a single-group study can describe outcomes observed among participants who received the intervention. Without a comparator, it cannot directly estimate a between-group treatment contrast. Changes over time, the course of the condition, participant selection, and other factors cannot be distinguished from intervention-associated effects through a randomized comparison in this design. This study is recorded as single-group, with allocation not applicable and no masking. No control arm is listed.

Precision and uncertainty. A point estimate is a single summary of the observed data. A confidence interval is a range calculated by a statistical method to represent uncertainty around an estimate under that method’s assumptions. In general, estimates based on fewer observations tend to carry greater uncertainty, though the actual precision depends on the data and method. The registry record does not report a confidence interval or other precision estimate for the primary endpoint, nor does it report the endpoint count needed to interpret an estimate. No precision value should therefore be inferred from the enrollment alone.

Analyses are not the same as outcomes. Listing an outcome measure indicates that it is part of the registry record; it does not establish that a result was collected or analyzed. The registry lists 6 outcome measures and 0 analyses. The record names the primary placement and stabilization measure and four secondary measures, but does not report their observed values or analysis procedures. The registry record also does not report whether analyses were descriptive, adjusted, or based on a particular analysis population.

Planning calculations and observed power. General sample-size planning uses assumptions about the target effect, variability, significance threshold, allocation, and analysis method. The planning assumptions associated with this record describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of the observed effect. They are described as planning illustrations, not as the trial’s own design. Since the study is single-group and the primary outcome result is not reported, those illustrations do not represent the trial’s planned enrollment or observed power. A planning sample size is not evidence that a study had a particular probability of detecting an effect after the data were collected.

Why a two-arm planning assumption does not describe this trial. Equal allocation between two arms is an assumption used in the planning illustration. It does not change the recorded study design: this trial has one group and no like-for-like control. General planning calculations can explore hypothetical designs, but they should not be read as describing participants actually enrolled in this study or as a comparison performed in the registry record. The assumed normal approximation is likewise a planning choice, not evidence of the method used to analyze the trial outcome.

Multiplicity and secondary measures. When several outcomes are tested, the chance of at least one apparently notable result can increase if each is assessed separately without accounting for the collection of tests. General methods for addressing this include prespecifying a primary outcome, adjusting inference, or treating secondary results as exploratory. The registry record identifies a primary outcome and names secondary measures, but does not report a multiplicity strategy, statistical testing plan, or analyses. It is therefore not possible to determine how any multiple-outcome issue was handled.

Missing data and model assumptions. General analysis depends on knowing which participants contributed data and how missing outcomes were handled. The registry record does not report missing-data methods, the number assessed for each outcome, or an analysis population. Over-dispersion is a general concern when count data vary more than a chosen model expects; it is not a reported finding in this record, and the primary endpoint is described as a participant event count rather than a repeated count process. No model or variance assumption for the primary analysis is reported. These distinctions matter because a model cannot be inferred solely from the outcome label.

Overall, the registry record identifies a design, endpoint, and outcome list, but does not describe an analysis method or give results for the primary or secondary outcomes. Statistical interpretation must therefore remain descriptive about the record’s contents rather than inferential about an unreported effect.

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("Tongue Suspension")
n      <- c(5)
events <- c(5)
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  Tongue Suspension  5  5  100.0  47.8  100.0  56.6  100.0  54.1  99.6

11. Multiplicity, Missing Data and Analysis Populations

The registry record names one primary outcome and lists secondary outcomes of Apnea Hypopnea Index, Functional Outcomes and Sleep Questionnaire (FOSQ), Snoring Scale (VAS), and Epworth Sleeping Scale (ESS). It also records 6 outcome measures overall. The presence of several measures raises a general multiplicity question: when multiple outcomes are analyzed, the interpretation of individual findings depends partly on whether a testing hierarchy or adjustment strategy was planned. The registry record does not report a multiplicity plan, so it is not possible to establish how the outcomes were prioritized or how any repeated testing was addressed.

The record lists 0 analyses and does not report numerical results for the primary or secondary outcomes. It also does not report an analysis population, whether all enrolled participants were included in each outcome summary, or how any missing measurements were handled. These details are important because results can depend on which participants have outcome data and on the rules used to include or exclude observations. The registry record does not report the number assessed for each measure or reasons for any missing data.

General statistical practice distinguishes the population targeted by a study from the participants included in a particular analysis. For example, a protocol may define an intention-to-treat or another analysis population, but no such population is reported in the registry record. The record also does not report imputation, complete-case analysis, sensitivity analyses, or other missing-data procedures. None should be assumed. Consequently, the available registry information is insufficient to evaluate missing-data bias, multiplicity handling, or the relationship between the listed outcomes and any analysis population.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

For the Tongue Suspension group, the registry record lists 5 participants at risk for serious adverse events and 0 participants affected. It separately lists 5 participants at risk for other adverse events and 1 participant affected. The death count is not reported in the registry record. These are aggregate counts; they do not provide event-level detail or a time-to-event analysis.

The serious adverse-event count should not be interpreted as a complete account of all safety outcomes. The registry record does not report the nature, severity, timing, duration, or relatedness of the other adverse event. It also does not describe the duration or completeness of safety follow-up, or whether all participants had the same observation period. The list of top serious event terms is empty, so the record does not identify a specific serious event term.

General interpretation: zero serious adverse events recorded in a small study does not establish that serious events cannot occur, nor does an aggregate count alone characterize the overall safety profile. The reported figures describe only the counts recorded for this group. They should be kept distinct from the unreported primary feasibility result and from unreported secondary outcomes.

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

The registry record describes a phase 4, single-group study intended to assess the feasibility and safety of tongue suspension using the Encore Tongue Suspension System for obstructive sleep apnea. Its primary endpoint concerns the ability to place the implant and stabilize the tongue within a timeframe of up to 7 weeks after the procedure. The record does not report the observed primary endpoint result, so it cannot establish how many participants met that measure or how precisely it was estimated.

The study enrolled 5 participants and records no comparator group. General statistical interpretation therefore distinguishes a description of outcomes in one group from evidence based on a randomized comparison. Without a comparator, differences attributable to the intervention cannot be isolated through a between-group contrast. In this case, the registry record also lacks numerical outcome results, so even descriptive conclusions about the primary and secondary measures are not available.

The recorded adverse-event summary reports 0 participants affected by serious adverse events among 5 at risk and 1 participant affected by other adverse events among 5 at risk. The death count and further event details are not reported in the registry record. These counts are limited safety summaries; they do not supply a complete account of event characteristics or follow-up.

The terminated status is a study-status entry, not an explanation of why the study ended and not a result. The reason for termination is not reported in the registry record. Nor does the stated feasibility and safety objective itself demonstrate an outcome. The information supports describing the study’s design, objectives, and limited safety counts, but not a conclusion about whether the device achieved the primary endpoint or how the secondary measures changed.

14. Why This Trial Matters Statistically

This study illustrates why the distinction between a registered outcome and a reported result matters. The primary endpoint is clearly named and tied to a procedure-related feasibility question, but its observed count is not reported in the registry record. Without that result, readers cannot assess the endpoint’s occurrence or precision. An outcome label and a stated timeframe are not substitutes for outcome data.

The design also shapes what a result could mean. A single-group study can describe outcomes among the participants enrolled, but it does not create a randomized control comparison. The registry record lists 5 participants, so any observed pattern would also need to be interpreted in light of the limited amount of information available from a small group. General statistical principles caution that estimates from small samples are often uncertain; the actual uncertainty cannot be quantified because the primary result and a precision estimate are not reported.

The record also demonstrates the importance of transparent analysis reporting. It lists 6 outcome measures and 0 analyses, while not reporting an analysis plan, analysis population, multiplicity strategy, or missing-data approach. These omissions prevent readers from assessing how outcome selection, incomplete measurements, or multiple comparisons might affect interpretation.

Finally, the aggregate safety counts are informative only within their limits. They identify counts for serious and other adverse events, but not event details or the observation process. Statistical importance lies not in stretching these sparse records into a treatment conclusion, but in recognizing exactly what the registry can document and where the evidence remains unavailable.

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 limitation for statistical interpretation is that the registry record does not report the primary endpoint result. It gives the endpoint description and timeframe, but not the number of participants who met the endpoint, the number assessed, or a precision estimate. This prevents even a complete descriptive summary of the primary feasibility outcome.

The study is recorded as single-group, with no comparator, and enrollment of 5 participants. Consequently, the design cannot provide a randomized comparison, and the small enrollment limits the amount of information any observed pattern could supply. Masking is listed as none. The registry record does not report participant characteristics or detailed eligibility criteria, so the enrolled population cannot be characterized or compared with other populations.

Although secondary outcomes are named, their results and analysis methods are not reported. The record lists 6 outcome measures and 0 analyses, without explaining analysis populations, multiplicity handling, missing-data methods, or which participants contributed data to each measure. These gaps make it impossible to assess completeness, potential selection effects in the analyzed data, or the precision of secondary findings.

Safety reporting is also limited to aggregate counts. The record does not report the type or timing of the other adverse event, detailed follow-up, or the death count. The reason for the terminated status is not reported in the registry record. No conclusion about the reason for termination or its effect on data collection can be drawn from the status entry alone.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: FAST as a Treatment for Obstructive Sleep Apnea — NCT01611779.
• Registry record last updated 2017-02-24; status last verified 2017-01.
• Results first posted 2017-01-06.
• 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

NCT01611779 is titled “FAST as a Treatment for Obstructive Sleep Apnea”; its official title describes Functional Advancement and Suspension of the Tongue (FAST) as a treatment for obstructive sleep apnea. Siesta Medical, Inc. is listed as sponsor. The study is recorded as phase 4, single-group, with no masking and allocation not applicable.

The intervention was the Encore Tongue Suspension System, described as tongue-based suspension. Enrollment is listed as 5, the study start as 2012-05, primary completion as 2013-06, and status as terminated. The stated objective was to assess feasibility and safety. The primary endpoint concerns implant placement and tongue stabilization, measured as a participant count up to 7 weeks after the procedure.

The record names secondary outcomes and reports aggregate adverse-event counts, but does not report the primary result, secondary outcome results, analysis methods, or reason for termination. It records 0 analyses.