Computerized Alcohol Screening for Children and Adolescents (cASCA) in Primary Care: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Computerized Alcohol Screening for Children and Adolescents (cASCA) in Primary Care (NCT02233946), a randomized na study. The primary outcome is Time to First Post-visit Drinking Day.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group behavioral study listed as completed. The registry record gives enrollment as 871 and identifies Boston Children’s Hospital as the sponsor. It lists the start as 2015-01 and primary completion as 2018-05-31. The phase is recorded as NA. These registry entries describe the study’s administrative status and design; they do not establish what the outcome results were.

Participants were assigned to computerized screening with a provider brief intervention, identified as cSBI, or screening with Treatment as Usual, identified as TAU. The intervention description refers to a personalized, computer-facilitated brief intervention based on screening results, delivered on a tablet computer and by the provider. The registry record does not report allocation procedures beyond randomization, whether allocation was concealed, or the methods used to maintain treatment assignment.

Masking is listed as none. This indicates that the registry does not describe a masked design, but it does not specify which people knew each participant’s assignment or how outcome assessment was conducted. The record does not report the planned sample-size justification, interim analyses, or detailed statistical analysis plan.

The primary outcome was time to first post-visit drinking day during 12-months follow-up. It was described using the median and interquartile range, and the population description specifies stratification by baseline past-12-month alcohol or other drug use. The record also lists time to first post-visit cannabis use day and past-3-month riding risk as secondary outcomes, as well as four outcome measures and 11 analyses. Those counts do not, by themselves, explain which results were prespecified or how analyses were selected for reporting.

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.

Baseline

Reasons for not completing this period:

Immediate Post-visit Questionnaire

3-months Follow-up

Reasons for not completing this period:

6-months Follow-up

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Stratified: Participants who reported past-12-month use of alcohol or other drugs at baseline vs. Participants who reported no past-12-month use of alcohol or other drugs at baseline

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: 12- to 18-year-olds arriving for their annual well-visit at participating pediatric practices

6. Primary Endpoint

The registry lists the primary outcome as Time to First Post-visit Drinking Day, measured over 12-months follow-up.

The primary endpoint measures the elapsed time from the post-visit starting point to a participant’s first reported drinking day. It is a time-to-event outcome: the event is the first post-visit drinking day, rather than simply whether any drinking occurred at a single assessment. The registry record specifies a 12-month follow-up period and describes the outcome with a median and interquartile range for cSBI and TAU.

As a general statistical explanation, time-to-event outcomes can retain information about when an event occurs, not only whether it occurs by a fixed endpoint. The median is the time by which half of the relevant observations have experienced the event, when that quantity can be estimated. The interquartile range describes the span from the lower to the upper quartile and conveys the spread of observed event times. Neither statistic alone adjusts for other factors or conveys the uncertainty of a between-group comparison.

The registry record describes stratification according to baseline reports of past-12-month alcohol or other drug use. That distinction matters to interpretation because the groups begin from different reported-use categories. The record does not report the median times, interquartile ranges, subgroup results, or sponsor-reported hazard ratios. Therefore, the endpoint definition is available, but the posted information does not establish how the groups compared.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a median time describe?

The primary outcome is a time-to-event measure, with the event defined as a first post-visit drinking day. As a general statistical explanation, the median event time is the point at which half of the observations have had the event, if the median can be estimated. It provides a central description of timing, not a complete account of the distribution. The interquartile range gives the span of the middle half of observations and indicates how dispersed event times are.

The registry record says that medians and interquartile ranges were used to describe the cSBI and TAU groups. It does not report their values. These descriptive statistics would not, by themselves, establish the strength or uncertainty of a between-group association. A comparative estimate and its uncertainty are needed to assess that question.

Why use a time-to-event analysis?

Generally, time-to-event methods are useful when both whether an event occurred and when it occurred are relevant. They can also account for observations whose event time is not fully observed by the end of follow-up, through censoring. Censoring means that the event has not been observed during the available observation period; it does not establish that it will never occur.

The registry record identifies the outcome as time to first post-visit drinking day over 12-months follow-up. It does not report how censoring was handled, how follow-up ended for individual participants, or what time-to-event model was used. Those details are not reported in the registry record and should not be inferred from the endpoint label.

What does a hazard ratio mean?

As a general explanation, a hazard ratio compares the instantaneous event rates between groups among people who have not yet experienced the event. A value’s interpretation depends on the stated group ordering and model. It describes a relative rate, not an absolute probability, and it is not interchangeable with a difference between medians.

The registry record’s endpoint description refers to medians and interquartile ranges. The available record details do not include sponsor-reported hazard ratios, their confidence intervals, or the model specification. Thus, no numerical hazard-ratio interpretation is possible. The record does not report whether model assumptions were assessed or whether any adjusted estimates were used.

Why does over-dispersion matter?

In general, over-dispersion occurs when variation in data exceeds what a chosen statistical model assumes. If it is ignored, standard errors can be too small and confidence intervals too narrow, making estimates appear more precise than they are. The appropriate response depends on the outcome type and model, and can involve a different variance estimate or a different model.

The primary outcome is described as time to an event, and the registry record does not report an over-dispersion assessment or identify a model for which that issue was evaluated. Over-dispersion should therefore be understood as a general statistical consideration, not as a documented feature or problem in this study.

What can a planning sample-size illustration show?

As a general explanation, a sample-size calculation describes how many observations a design might require under stated assumptions to target a specified power and significance level. It is a planning exercise, not evidence that a trial had a particular probability of detecting an effect after the results are known. “Observed power” is not a substitute for interpreting the effect estimate and its uncertainty.

The record states that any planning illustration is based on the observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event outcomes, it specifies that totals of events are used in those illustrations, whereas other outcomes use participants per arm. The resulting planning estimates are not reported in the registry record. They cannot be reconstructed from the available outcome details.

More broadly, the registry identifies randomization, parallel groups, and no masking, but does not report the detailed statistical plan, model diagnostics, or treatment of missing outcome data. These omissions limit evaluation of how the planned analysis was carried out. General statistical concepts explain what methods can mean; they do not fill in methods or results absent from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists four outcome measures and 11 analyses, along with a primary outcome and secondary outcomes. Those counts indicate that several outcomes or analyses were registered, but they do not establish how many hypotheses were formally tested, which comparisons were prespecified, or how results were prioritized. The record does not report a multiplicity adjustment or a strategy for controlling the chance of false-positive findings across analyses. The protocol’s approach to multiplicity is not reported in the registry record.

As a general statistical explanation, testing multiple hypotheses can increase the chance that at least one result appears statistically persuasive by chance. Methods to address this include adjusting significance thresholds or defining a hierarchy of outcomes in advance. Whether any approach was appropriate depends on the study’s objectives and analysis plan; no such plan should be inferred.

The record does not report how missing primary outcome data were handled, the extent or pattern of missingness, or whether sensitivity analyses were conducted. In general, missing data can affect estimates when the probability of being missing is related to outcomes or participant characteristics. The effect depends on the missingness process and the analysis assumptions, which are not documented.

The primary outcome population is described by baseline past-12-month alcohol or other drug use, but the registry record does not report the analysis population definition, exclusions, or whether results used an intention-to-treat approach. It also does not report participant flow through follow-up. Without these details and the outcome estimates, the robustness and completeness of the primary comparison cannot be assessed from the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The serious adverse event entries list 626 as at risk in the cSBI group and 243 as at risk in the TAU group. The listed serious adverse events are 0 in each group. Other adverse events are also listed as 0 in each group, and deaths are listed as 0 in each group. These figures describe the registry’s adverse-event entries; they are not the primary outcome results.

As a general statistical explanation, a zero reported event count means that no event was recorded in the specified category in the posted data. It does not prove that the underlying risk is zero, and it does not establish that all possible events were captured. Interpretation also depends on the event definitions, observation period, reporting process, and completeness of follow-up.

The registry record does not report the adverse-event definitions, the period covered by these entries, or further details about monitoring and ascertainment. The at-risk figures are safety reporting denominators and should not be interpreted as the number analyzed for the primary endpoint. The entries alone do not support a comparative safety conclusion.

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

The record establishes that a randomized, parallel-group study compared computerized screening with a provider brief intervention against screening with Treatment as Usual. Its primary endpoint was time to first post-visit drinking day during 12-months follow-up, described by medians and interquartile ranges and stratified according to baseline past-12-month alcohol or other drug use.

Those design details do not reveal the result. The primary outcome values, sponsor-reported hazard ratios, and confidence intervals are not reported in the registry record. No direction, magnitude, or precision of the comparison can therefore be stated. The study’s completed status does not supply those missing estimates.

As a general statistical point, a result is best interpreted using both an effect estimate and its uncertainty, alongside the outcome definition, analysis population, and study limitations. A descriptive median can show the timing pattern within a group, while a comparative estimate addresses differences between groups. Neither should be treated as a statement about every participant.

The record also lists secondary outcomes and adverse-event counts. The secondary outcome results are not reported in the registry record. The adverse-event entries show zero recorded events in the stated categories, but the available information does not describe event definitions or monitoring sufficiently to infer that risk was absent.

Thus, the registry record supports a description of the research question and design, but not a conclusion about the intervention’s effect. It does not establish whether the intervention changed the timing of first drinking, nor whether any observed difference would be clinically important. Those judgments require outcome estimates and supporting methods that are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial’s statistical question concerns the timing of a first post-visit drinking day, rather than only a yes-or-no report at one time point. That makes the endpoint a time-to-event measure and places attention on both event occurrence and timing. Describing the outcome with a median and interquartile range offers information about central timing and spread, while a comparative analysis would be needed to quantify the contrast between groups.

The registry record also identifies baseline use strata. This is statistically important because participants with and without past-12-month alcohol or other drug use at baseline represent different starting categories for interpreting post-visit drinking. The record specifies that distinction but does not report stratum-specific outcomes, so it is not possible to assess whether the comparison was similar across categories.

The study illustrates why design information and outcome information must be read separately. Randomization and a parallel-group structure describe the intended comparison; they do not reveal its result. Likewise, a completed status and a listed primary endpoint do not substitute for the effect estimate, uncertainty interval, or analysis details. Those results are not reported in the registry record.

Finally, multiple registered outcomes and analyses make transparency about prespecification and multiplicity relevant. The registry record does not report how multiplicity was addressed or how missing outcomes were handled. These are important considerations when assessing the credibility and precision of an analysis, but their absence does not justify guessing what methods were used.

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 primary limitation for interpreting the result is that the registry record does not report the primary outcome values, sponsor-reported hazard ratios, or confidence intervals. Although the endpoint and follow-up period are specified, the magnitude, direction, and precision of the comparison cannot be assessed.

The endpoint description names baseline-use strata but does not report results within them or clarify how those strata were incorporated into the analysis. The record also does not define TAU, describe the details of the intervention, or report adherence and implementation. These omissions make it difficult to characterize the contrast participants actually experienced.

Masking is listed as none, but the record does not specify which individuals were aware of assignment or how outcomes were assessed. It also does not report methods for missing data, participant flow, the analysis population, or the detailed statistical plan. The consequences of these gaps cannot be quantified from the registry record.

The record lists four outcome measures and 11 analyses but does not explain multiplicity handling or identify a complete hierarchy of reported comparisons. Secondary outcome estimates are not reported in the registry record. Finally, adverse-event entries list zero events, but definitions, ascertainment, and the period covered are not reported. These limitations concern the completeness of the available record and should not be mistaken for evidence that particular methods were or were not used.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Computerized Alcohol Screening for Children and Adolescents (cASCA) in Primary Care — NCT02233946.
• Registry record last updated 2021-03-11; status last verified 2021-02.
• Results first posted 2021-03-11.
• 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.

18. Record Summary

NCT02233946 is a completed, randomized, parallel-group study sponsored by Boston Children’s Hospital. The registry lists enrollment as 871, a start of 2015-01, primary completion on 2018-05-31, and masking as none. The phase is listed as NA.

The study evaluated computerized alcohol screening and a computer-facilitated brief intervention delivered by tablet and provider, compared with screening and Treatment as Usual. The primary outcome was time to first post-visit drinking day over 12-months follow-up, described using medians and interquartile ranges and stratified by baseline past-12-month alcohol or other drug use.

The primary outcome estimates, sponsor-reported hazard ratios, confidence intervals, and secondary outcome results are not reported in the registry record. Safety entries list zero serious adverse events, other adverse events, and deaths in both groups. The record does not report detailed analysis methods, missing-data handling, or multiplicity procedures.