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 Accuracy of Self-estimation of Blood Alcohol Concentration Compared to Object Values (NCT02722564), a na na study. The primary outcome is Change in Breath Alcohol Content Between the Estimated Level and the Actual Level as Measured by an Alco Sensor IV Device.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02722564 |
| Phase | NA |
| Condition | Alcohol Intoxication |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | Single |
| Enrollment | 55 |
| Arms in the primary outcome | n/a |
| Lead sponsor | St. Luke's Hospital and Health Network, Pennsylvania |
| Results posted | Yes |
2. Clinical Question
Population
Volunteers of legal drinking age took part in a prospective survey study. The registry lists 55 participants enrolled and identifies alcohol intoxication as the condition. It does not report additional eligibility details, participant characteristics, or the number contributing data to each part of the primary outcome.
Intervention
Participants drank beer one beverage at a time and verbally estimated their current breath alcohol content. They were also asked whether they felt able to drive. An Alco Sensor IV device measured their breath alcohol content after each beer. Participants were not told the objective reading. Monitoring continued during the rise in readings and, after the specified threshold, during the decline.
Comparator
There was no separate control group or randomized comparison. The relevant within-study reference was the objective breath alcohol reading from the device, compared with each participant’s verbal estimate. The device reading is a measurement reference in this design, not a randomized treatment arm.
Primary question
The primary outcome concerns the change between estimated and objectively measured breath alcohol content. The registry says this was assessed while readings were ascending to 0.1 and descending to 0.08. It does not report the numerical changes, the direction used to calculate them, or whether the reported change was signed or absolute. The study also asked about perceived ability to drive, but a primary outcome result for that question is not reported in the registry record.
3. Trial Design
This was a prospective, single-group survey study, listed as completed. The registry gives an enrollment of 55 and identifies St. Luke's Hospital and Health Network, Pennsylvania, as the sponsor. The listed study dates are 2015-08 for the start and 2015-12 for primary completion. The phase and allocation are recorded as NA. The record lists single masking, but which parties were masked is not reported in the registry record. Participants were not told their objective breath alcohol reading after each measurement.
All participants followed the same general measurement sequence rather than being assigned to separate study arms. After each beer, they estimated their current level verbally, and the Alco Sensor IV device recorded an objective reading. The process continued until participants reached a minimum reading of 0.10. They were then monitored as readings declined, with estimates and device readings taken hourly until reaching 0.08 and clinical sobriety. The primary outcome timeframe is listed as 1 day.
This design can describe agreement or differences between participant estimates and device readings in this study context. It cannot compare randomized treatments, because there was no randomized allocation or separate control group. The detailed protocol, including the procedures for recruiting volunteers and defining clinical sobriety, is not reported in the registry record. The numerical primary outcome results and details of the analysis are also not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | All Study Participants |
|---|---|
| STARTED | 55 |
| COMPLETED | 55 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The number analyzed for ascending BrAC readings and descending BrAC readings
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 | All Study Participants |
|---|---|---|
| Participants analysed | 55 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 55 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 22 |
| Sex: Female, Male: Male | Participants | 33 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 55 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Breath Alcohol Content Between the Estimated Level and the Actual Level as Measured by an Alco Sensor IV Device, measured over 1 day.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Standard Deviation |
| Unit | percent blood alcohol content |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is described as the change between estimated breath alcohol content and the level measured by an Alco Sensor IV device. Its stated unit is percent blood alcohol content. The registry says the change was assessed during both the ascending and descending portions of the readings: ascending to 0.1 and descending to 0.08. The number analyzed for each portion is identified as part of the outcome description, but those counts are not reported in the registry record.
Comparing an estimate with a device reading addresses how closely participants’ self-assessments corresponded to an objective measurement under the study’s conditions. Considering the ascending and descending portions separately may be relevant because the same reading can occur at different stages of the drinking and monitoring sequence. This endpoint does not, by itself, establish whether a participant could drive safely or whether a particular estimate was sufficiently accurate for a real-world decision.
The registry identifies the summary parameter as a median and the dispersion measure as a standard deviation. It does not state the subtraction order, whether the change was signed or absolute, how observations across repeated measurements were combined, or the numerical results. Those details matter for interpreting the size and direction of any reported difference, and are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes the question and the planned measurement process, but it does not report numerical primary outcome results. In particular, no median difference, standard deviation, confidence interval, or test result for the estimated-versus-measured change is reported in the registry record. Consequently, the direction, magnitude, and precision of the observed differences cannot be assessed from the record.
The primary outcome is divided between readings that were ascending and readings that were descending. These are distinct contexts in the monitoring sequence, and the record indicates that both were assessed. However, without results for either context, it is not possible to say whether estimates tended to be higher or lower than device readings, how variable the differences were, or whether patterns differed between the ascent and descent. The precise construction of the change score is also not specified: the record does not give the subtraction order or say whether it used signed or absolute differences.
The study was single-group and did not use randomized allocation. The device reading served as an objective reference for the self-estimate, not as a treatment comparison. Thus, even if outcome values were available, the design would primarily support a description of estimation relative to measurement in the enrolled volunteers and study conditions. It would not establish a causal effect of one intervention against another. The sample consisted of volunteers of legal drinking age, and the registry does not report further participant characteristics that could help assess how broadly the findings apply.
The enrollment was 55, but the record does not report how many participants contributed ascending readings or descending readings. Enrollment alone does not establish the number included in each endpoint analysis or show whether all participants completed every measurement. Analysis-population definitions and missing-data handling are not reported in the registry record.
The record notes 2 analyses, but their methods and results are not reported in the registry record. No conclusion about statistical significance, precision, or consistency can be drawn from the count of analyses alone. Any planning illustration based on an observed effect should also be kept separate from observed evidence: it is a hypothetical planning calculation, not an additional trial result or a measure of observed power.
Overall, the posted information establishes that participant estimates were compared with device readings during a defined sequence of alcohol consumption and monitoring. It does not establish how close those estimates were, whether they differed systematically, or how precisely any difference was estimated. The study’s question is clear, but its numerical answer is not reported in the registry record.
9. Statistical Methods Explained
The registry identifies a median as the summary parameter for the primary endpoint and a standard deviation as its dispersion measure. It also says the change was assessed during ascending and descending readings. These entries describe the intended summary, but do not give the actual estimates or enough detail to reconstruct the analysis.
What does a median describe?
General explanation: the median is the middle value when observations are ordered. It can describe the typical value while being less affected than a mean by a small number of unusually large or small observations. For an estimated-versus-measured change, the median would summarize the distribution of those changes, provided the change has been defined consistently. The registry does not specify whether each participant contributed a single summary value or how multiple readings from the same participant were combined.
What does a standard deviation describe?
General explanation: a standard deviation describes the spread of observations around their mean. It is not the same as a confidence interval and does not, by itself, describe the precision of a median estimate. Reporting a median with a standard deviation can communicate a central value and a measure of spread, but readers should know how the observations were constructed and how many contributed. The record does not report those details or the numerical standard deviations.
Why distinguish ascending and descending readings?
General explanation: measurements taken at different stages of a process can have different patterns, so separating them can make the summaries easier to interpret. Here, the registry specifies ascending readings up to 0.1 and descending readings to 0.08. The same participant could contribute repeated estimates and device readings over the monitoring sequence. Repeated observations from one person are generally related; they should not automatically be treated as independent observations. The registry does not report how that within-person relationship was handled statistically, or whether readings were reduced to participant-level summaries before analysis.
The study’s repeated measurement structure also raises questions about the unit of analysis. A count of readings is not necessarily the same as a count of participants, and the primary outcome description refers to the number analyzed separately for ascending and descending readings. Those counts are not reported in the registry record. It is not possible to determine from the record whether every participant contributed to both portions, how incomplete sequences were treated, or whether any observations were excluded.
The objective measurement was made with an Alco Sensor IV device, while participants gave verbal estimates and were not told the objective reading. This makes the device reading the reference for the comparison described in the primary endpoint. The registry does not report calibration procedures, repeatability information, or other measurement-quality details. It also does not define the calculation of the change score. A signed difference would retain whether an estimate was above or below the device reading; an absolute difference would describe distance without direction. The record does not identify which definition was used.
The registry lists 2 analyses, but does not report their statistical tests, models, covariates, or analysis results. It does not report p-values or confidence intervals. General explanation: a confidence interval expresses uncertainty around an estimate under the assumptions of the method used; without the interval and its method, the precision of an estimate cannot be evaluated. A p-value, if reported, would address compatibility with a specified null model and would not by itself describe the size or practical importance of a difference. Neither type of result is reported in the registry record.
General explanation: over-dispersion matters when observed variability exceeds what a statistical model expects. If a model assumes less variation than the data contain, its standard errors can be too small and its intervals too narrow. The registry does not identify a model or report evidence of over-dispersion, so this is a general consideration rather than a description of an analysis performed in this study.
The sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The calculations are described as targeting stated fractions of the observed effect. This hypothetical setup is distinct from the actual single-group design, which had no randomized arms. Such illustrations are for planning, not observed power, and do not establish that the study was adequately sized for its endpoint. The numerical planning outputs and the observed effect used for them are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 2 analyses, but does not report what they tested, whether they were prespecified, or how they related to the primary endpoint. It also does not report whether any multiplicity adjustment was used. Without that information, the possibility of multiple statistical tests affecting interpretation cannot be assessed. The distinction between ascending and descending readings is part of the endpoint description, but the record does not explain whether these were treated as separate tests, separate summaries, or components of another analysis.
The primary outcome description identifies the number analyzed for ascending readings and descending readings, but does not state those counts. Although 55 participants were enrolled, the registry does not report the number with complete measurements, the number included in each analysis, or reasons for any missing observations. It does not report how missing readings or incomplete monitoring sequences were handled, whether imputation was used, or whether sensitivity analyses were performed.
Analysis-population definitions are not reported in the registry record. It is therefore unclear whether analyses included all enrolled participants, only those with usable device and estimate pairs, or another defined group. The record also does not report whether participants were excluded after enrollment or how observations were handled if a participant did not reach a stated threshold.
These omissions limit assessment of how much data contributed to the endpoint and how robust the results might be to missingness or analytic choices. They do not show that data were missing or that multiplicity adjustments were required; they mean the relevant procedures and counts are not reported in the registry record.
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 |
|---|---|---|---|
| All Study Participants | 0 | 55 | 0.0% |
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 |
|---|---|
| All Study Participants | 8 of 55 |
Most frequent non-serious adverse event terms
| Event term | Organ system | All Study Participants |
|---|---|---|
| vomiting | Gastrointestinal disorders | 5 of 55 |
| vertigo | Ear and labyrinth disorders | 3 of 55 |
For all study participants, the registry lists 55 at risk for serious adverse events and 0 affected. It also lists 55 at risk for other adverse events and 8 affected. These are counts recorded for the study group, not a comparison between randomized treatments, because the study had no separate control group.
The record does not list any serious adverse event terms. The deaths entry is null, so deaths are not reported in the registry record; null should not be read as a reported count of zero. The adverse-event figures describe events recorded in this group. They do not, by themselves, establish whether an event was caused by study participation or by any particular study procedure. The record does not provide event descriptions, timing, severity details for the other events, or an assessment of relatedness.
These figures are limited safety reporting for the enrolled group. They should not be interpreted as a comparative estimate of risk, and the absence of reported serious events does not establish that no other harms occurred beyond what was recorded.
12. What the Result Does, and Does Not, Mean
The study addresses a specific measurement question: how participants’ verbal estimates of their current breath alcohol content compared with readings from an Alco Sensor IV device during a sequence of drinking and monitoring. It also asked participants whether they felt able to drive. The registry describes the process but does not report numerical outcome results, so it cannot show the size or direction of the estimation differences.
Even with numerical differences, the interpretation would depend on how the change was calculated, how repeated readings were handled, and how many participants contributed to each portion of the endpoint. Those details are not reported in the registry record. The record does say the primary outcome was summarized with a median and standard deviation, but no actual median or standard deviation is reported.
This single-group study does not compare randomized interventions. The device measurement provides a reference for the participant’s estimate; it does not create a control group. The design can inform a descriptive assessment within the enrolled volunteers and study conditions, but it cannot establish a causal contrast between treatments. The enrollment of 55 does not, by itself, show how precise an estimate would be, particularly because analysis counts and outcome values are not reported.
The study’s question about perceived ability to drive should also be distinguished from evidence about driving performance. The registry summary says participants were asked whether they felt able to drive, but the primary endpoint is the estimated-versus-measured alcohol-content change. No result for actual driving ability or driving performance is reported in the registry record.
Accordingly, the posted information establishes the measurement setup and the intended comparison, not the answer to whether participants’ estimates closely matched the device readings. It does not support a conclusion about the safety of driving, the accuracy of any individual participant, or the generalizability of an unreported result.
13. Why This Trial Matters Statistically
This study raises a useful statistical distinction between a subjective estimate and an instrument reading. The participant’s estimate and the device measurement refer to the same point in the monitoring sequence, allowing the study to examine their difference rather than comparing unrelated groups. That makes the definition of the difference and the treatment of repeated measurements central to interpretation.
The monitoring sequence includes both increasing and decreasing readings. Separating those phases can matter because estimates may vary with context, and a single overall summary could conceal differences between them. The registry identifies both phases in the primary endpoint description, but does not report their separate results or the number analyzed in each. The absence of those details prevents assessment of whether the two parts of the sequence showed similar patterns.
The record also illustrates why enrollment is not interchangeable with the analysis sample. Although 55 participants were enrolled, the number contributing outcome data is not reported. For repeated-measurement studies, readers need to know how many people and readings contributed, how observations from the same person were handled, and how incomplete data were addressed. These are not reported in the registry record.
Finally, the study’s single-group structure defines what it can answer. The device reading is a measurement reference, not a randomized comparator. The design is suited to describing self-estimates relative to that reference under the study conditions, but does not provide a randomized treatment contrast. Without the numerical endpoint results, the registry record states the statistical question and measurement approach but leaves the central empirical finding unreported.
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 central limitation for interpreting this record is that it does not report the numerical primary outcome results. The registry identifies a median and standard deviation, but gives neither values nor confidence intervals or test results. The direction and magnitude of the difference between estimates and device readings therefore cannot be judged.
The outcome is described as a change between the estimated and actual level, but the record does not define the subtraction order or say whether the change is signed or absolute. It also does not explain how multiple readings from each participant were summarized or analyzed. Since readings were collected repeatedly during both ascending and descending portions, the approach to within-participant dependence is important and is not reported.
The population consisted of volunteers of legal drinking age. The record does not report detailed participant characteristics, recruitment procedures, or additional eligibility criteria, limiting assessment of how representative the group may be. The study’s structured monitoring sequence and device-based measurement may also differ from settings outside the study; the registry does not report results that would establish how well findings generalize to other circumstances.
Enrollment was 55, but the numbers analyzed for the two portions of the endpoint are not reported. The registry also does not describe missing-data handling, exclusions, or analysis populations. The primary outcome timeframe is 1 day, and the protocol summary specifies monitoring to stated thresholds, but operational details such as the definition of clinical sobriety are not reported in the registry record.
There was no randomized comparison, and no outcome for actual driving performance is reported. The registry lists 2 analyses without describing their methods. These limitations leave both the statistical analysis and the scope of any conclusion difficult to evaluate.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Accuracy of Self-estimation of Blood Alcohol Concentration Compared to Object Values — NCT02722564.
- Registry record last updated 2017-05-15; status last verified 2017-05.
- Results first posted 2017-05-15.
- 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
NCT02722564 is a completed prospective, single-group survey study sponsored by St. Luke's Hospital and Health Network, Pennsylvania. The registry lists enrollment of 55 volunteers of legal drinking age and a primary outcome comparing estimated breath alcohol content with readings from an Alco Sensor IV device. Estimates and measurements were collected after beers during ascending readings and during monitoring as readings declined.
The primary endpoint is described as a median change with standard deviation, assessed during ascent to 0.1 and descent to 0.08. Numerical outcome values, analysis counts, statistical test details, and missing-data procedures are not reported in the registry record. The record lists 2 analyses but does not describe their methods or results. It reports 0 participants with serious adverse events and 8 with other adverse events among 55 at risk; deaths are not reported in the registry record.
The design supports a descriptive comparison of self-estimates with device readings in the enrolled group, not a randomized treatment comparison. The posted record does not report the numerical findings needed to judge the magnitude or precision of the primary outcome.