Computer-Assisted Self-Interviews and Health Screening in the Pediatric Emergency Department: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Computer-Assisted Self-Interviews and Health Screening in the Pediatric Emergency Department (NCT01708317), a na na study. The primary outcome is Gonorrhea and Chlamydia Testing in the Pediatric ED.

2. Clinical Question

The study’s stated purpose was to determine whether an audio-enhanced computer-assisted self-interview would lead to increased testing for sexually transmitted infections among youth visiting a pediatric emergency department. The outcome focuses on testing during the visit, rather than on whether a test was positive or whether an infection was treated.

The registry describes staff education as beginning before ACASI enrollment and continuing after enrollment ended. Its outcome description says eligible patients were considered across all four periods to help distinguish changes associated with ACASI from changes associated with education alone. That is the stated rationale for the period-based analysis; the registry does not report results that establish whether testing changed or what caused any change.

3. Trial Design

This is a completed, single-group behavioral study, with enrollment of 801. The intervention was an audio-enhanced computer-assisted self-interview. The registry lists allocation as NA and masking as none. It does not describe a randomized assignment or a concurrent, like-for-like control group.

The primary outcome concerns the proportion of eligible adolescent patients who received chlamydia and gonorrhea testing during an emergency department visit. The registry describes four periods: 2010 as a historical control; January 2011, when staff education about infection risks and the need for increased testing began; April 18, 2011 through December 20, 2011, when education continued and ACASI enrollment took place; and a period after ACASI enrollment ended, with education continuing through March 2012. The outcome’s stated timeframe is 27 months.

The analysis population described for this outcome is every patient during the relevant period who met the ACASI inclusion and exclusion criteria. This is broader than, and should not automatically be equated with, the 801 people enrolled in the ACASI group. The registry does not report the number of eligible patients in each period or clarify the denominators used for the period-specific testing rates.

The period structure matters for interpretation. Testing rates could change over time alongside staff education, ACASI availability, or other changes in emergency department practice. The registry’s stated analysis aim was to separate the effect of ACASI from education alone, but the design information does not describe randomization or another control strategy that would ensure those influences were separated. Protocol details, the statistical analysis plan, and the method used to compare periods 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.

Before assignment: There was an education lead in before introducing the ACASI, to see if education alone would increase the amount of patients receiving gonorrhea/chlamydia testing. The education started in Jan, 2011 and continued the remainder of the study period.

2010 Control Period

Initial Education Period

ACASI + Education Period

Final Education Period

Analysis population for the primary outcome, as defined in the registry: We analyzed every patient in this time period that met our ACASI inclusion/exclusion criteria

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.

6. Primary Endpoint

The registry lists the primary outcome as Gonorrhea and Chlamydia Testing in the Pediatric ED, measured over 27 months.

The primary endpoint is the change in the proportion of adolescent patients receiving chlamydia and gonorrhea testing during an emergency department visit across four time periods. It is expressed as a percentage of participants. The registry describes the target population as patients in each period who met the study’s ACASI inclusion and exclusion criteria.

A testing proportion is a process measure: it describes how often testing occurred among the eligible patients being counted. It does not, by itself, describe infection prevalence, test accuracy, positive results, treatment, or later health outcomes. The registry’s stated reason for measuring this outcome is to assess whether testing rates changed in relation to ACASI, while accounting for the period when staff education was introduced and the later period when education continued without ACASI enrollment.

General: A proportion can be useful for comparing how frequently an action occurs across groups or periods, particularly when the number of people considered differs. Interpretation depends on clear definitions of eligibility, the outcome, and the denominator. Those details are important because the registry describes an eligible emergency department population but does not report the period-specific counts or testing percentages.

The endpoint’s actual values, the estimated changes between periods, and measures of statistical uncertainty are not reported in the registry record. Consequently, the size and precision of any change cannot be assessed from the registry information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a percentage-based primary outcome and a comparison across four time periods. It does not report the statistical method used to estimate or compare the testing proportions. The explanations below are general statistical context, not a description of an analysis method confirmed by the registry.

What does a testing proportion describe?

General: A proportion is the count of people with a specified event divided by the number of people eligible for that measure. Here, the event is receiving chlamydia and gonorrhea testing during the emergency department visit, and the intended denominator is eligible patients in the relevant time period. A proportion is only interpretable when the event definition and denominator are clear and applied consistently.

The registry says every patient meeting the ACASI inclusion and exclusion criteria was analyzed across the relevant periods. It does not give the number meeting those criteria in each period, the number tested, or the resulting percentages. The 801 enrolled participants are reported for the ACASI group, but the outcome population is described in terms of eligible patients across periods. Those descriptions do not establish that the outcome denominator in each period was 801 or that it consisted only of enrolled participants.

Why compare periods?

General: A period-based analysis can describe whether an outcome differs over time as a service, policy, or intervention is introduced. It can be informative for monitoring changes in practice, but time itself can be associated with other changes. Historical periods are not necessarily comparable to later periods in patient mix, staffing, workflow, or other circumstances.

In this study, the registry describes a historical period in 2010, staff education beginning in January 2011, ACASI enrollment from April 18, 2011 through December 20, 2011 while education continued, and a later period when education continued after enrollment ended. This sequence means ACASI and education are not described as independently assigned interventions. The registry says eligible patients were examined across the periods to isolate the effects of ACASI versus education alone, but the statistical approach used to do so is not reported.

What can a confidence interval contribute?

General: A confidence interval presents a range of values compatible with an estimate under a specified statistical procedure and its assumptions. It helps readers judge the precision of an estimated difference: a narrower interval indicates greater precision, while a wider interval indicates greater uncertainty. It does not address every source of bias, and it cannot by itself show that an intervention caused an observed difference.

No confidence interval or other uncertainty interval for the testing outcome is reported in the registry record. The precision of the period-specific proportions and of any change between periods therefore cannot be assessed from the registry information.

What does a p-value address?

General: A p-value describes how unusual data at least as incompatible with a null hypothesis would be under a specified model, if that hypothesis and the model assumptions were correct. It is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of an effect. Its interpretation depends on the analysis plan and the way the data were collected.

The registry record does not report a p-value or the hypothesis test, if any, used for the primary outcome. It also does not report whether comparisons were adjusted for differences between periods or for other characteristics.

Why can the analysis model matter?

General: Statistical methods for proportions must reflect how observations are organized and what question is being estimated. For example, analyses may need to account for clustering when observations are grouped, or for covariates when adjustment is planned. The appropriate approach depends on the design and data structure. The registry does not report whether observations were modeled as independent, whether any grouping was considered, or whether adjustment was performed.

The outcome description labels the parameter as NUMBER, but does not specify a model or the form of the statistical comparison. The exact estimation method, standard errors, and assumptions are not reported in the registry record. It is therefore not possible to determine from the record whether the method accounted for relevant features of the data.

How should planning illustrations be understood?

General: A sample-size calculation is a planning exercise based on assumptions about the effect to detect, the significance level, allocation, and statistical method. It is not evidence that an effect was observed, and it is not a substitute for a confidence interval around an actual estimate. A calculation based on an observed effect uses that effect as an input for illustration; it does not mean the study was originally designed to detect it or that the study had a particular probability of finding a result.

The planning assumptions described for this record use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and a stated fraction of an observed effect. Those are labeled as a planning illustration rather than the trial’s own design. The observed effect and the resulting participant requirements are not reported in the registry information available for this analysis. Such planning numbers should not be read as observed enrollment comparisons or as observed power.

Overall, the record identifies the outcome, the intended eligible population, and the timing of education and ACASI enrollment. It does not provide the numerical outcome results or the statistical analysis details needed to reproduce or evaluate the primary comparison. General statistical concepts can clarify what those details would mean, but they cannot fill in results that are not reported.

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("Historical Control", "Initial Education Period", "ACASI + Education", "Final Education Period")
n      <- c(3929, 982, 2601, 909)
events <- c(381, 91, 463, 113)
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  Historical Control  3929  381  9.7  8.8  10.7  8.8  10.7  8.8  10.7
ARM  Initial Education Period  982  91  9.3  7.5  11.3  7.6  11.2  7.6  11.2
ARM  ACASI + Education  2601  463  17.8  16.3  19.3  16.4  19.3  16.4  19.3
ARM  Final Education Period  909  113  12.4  10.4  14.8  10.4  14.7  10.4  14.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and one analysis. It does not report whether the analysis plan included additional outcomes, subgroup comparisons, multiple pairwise comparisons between periods, or any adjustment for multiplicity. The four-period outcome description identifies a series of periods but does not specify which contrasts were tested or how any collection of tests was handled. A multiplicity strategy is therefore not reported in the registry record.

Missing-data methods are also not reported. The registry does not state whether outcome data were complete for all eligible patients, how records with unknown testing status were treated, or whether any imputation or sensitivity analysis was used. It does not provide period-specific counts that would allow readers to assess the extent of missing outcome information.

The analysis population is described as every patient in the relevant time period who met the ACASI inclusion and exclusion criteria. The record does not report a detailed accounting of how patients were identified, excluded, or retained in each period, or how the population used in the analysis relates to the 801 ACASI participants enrolled. No intention-to-treat or other formal analysis-population label is reported.

General: Multiplicity can increase the chance of finding an apparently notable result when many hypotheses are tested, while missing data can affect both the estimate and its uncertainty if the reasons for missingness are related to the outcome. These issues require information about the planned analyses and the observed data. The registry record does not provide enough detail to assess either issue for this outcome.

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.

The registry’s serious adverse event summary lists the ACASI group with 801 participants at risk and 0 serious adverse events. No serious adverse event terms are listed. The record also lists 801 at risk and 0 for the other adverse-event count shown. Deaths are not reported as a count.

These figures describe the safety information recorded for the ACASI group; they do not establish that every possible adverse event was assessed or that no events of any kind occurred. The registry does not provide additional details about how adverse events were collected, the observation period for safety, or the definitions used for the event categories. A zero recorded count should therefore be read as the reported count in this registry entry, not as proof of absence of risk.

There is no randomized comparison group in the record, so these figures do not provide a comparative estimate of safety. They also do not address whether testing rates changed. The serious adverse event summary and the primary testing outcome answer different questions.

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

The study addresses a relevant service-delivery question: whether offering an audio-enhanced computer-assisted self-interview in a pediatric emergency department was associated with changes in testing for chlamydia and gonorrhea among eligible adolescent patients. The registry describes an outcome intended to track testing proportions across four periods that include staff education, ACASI enrollment, and a later period after enrollment ended.

The actual testing proportions and the statistical results are not reported in the registry record. As a result, the posted information does not establish whether testing changed, how large any change was, or how precise an estimate would be. It cannot support a conclusion that ACASI increased or did not increase testing.

Even if period-specific differences were available, a period-based, single-group design would require cautious interpretation. The record describes education beginning before ACASI enrollment and continuing afterward, so changes in testing could be related to education, ACASI, other changes over time, or a combination. No randomized assignment or like-for-like control comparison is described. The stated aim of separating ACASI from education alone is not enough, without the analysis details and results, to determine whether that distinction was achieved.

General: An association between an intervention period and an outcome does not alone show that the intervention caused the outcome to change. Causal interpretation depends on the study design, the comparability of groups or periods, measurement quality, and analytic assumptions. Statistical precision and causal validity are separate concerns: a precise estimate can still be biased, and an imprecise estimate can leave a wide range of effects compatible with the data.

The enrollment count of 801 describes the ACASI group, while the primary outcome population is defined as eligible patients across the time periods. Without period-specific denominators and a clear account of the analysis population, the enrollment count cannot be used to infer the size or composition of the endpoint population. The record is informative about the question and the timeline, but it does not provide enough results to judge the magnitude, direction, precision, or cause of a testing-rate change.

14. Why This Trial Matters Statistically

Statistically, this study illustrates the distinction between an intervention enrollment count and the population used to assess a service outcome. The registry reports 801 people enrolled in the ACASI group, but describes the primary outcome as testing among every patient in the relevant periods who met the ACASI eligibility criteria. The counts and denominators for those periods are not reported. Keeping those populations distinct is necessary to interpret what a percentage represents.

The study also illustrates the challenges of evaluating changes in clinical practice over time. The registry describes staff education beginning before ACASI enrollment, continuing during enrollment, and continuing after enrollment ended. A period comparison can describe changes in testing, but attributing a change specifically to ACASI requires a credible way to separate its influence from education and other time-related influences. The registry states that this separation was the analysis aim, while allocation is listed as NA and no randomized comparison is described.

A further statistical lesson is that a clearly stated research question is not the same as a reported result. The registry identifies a primary outcome and an analysis, but the numerical testing rates, estimated changes, and uncertainty measures are not reported. Without these, readers cannot assess the size or precision of the observed pattern or determine whether the data are compatible with a range of different effects.

General: Transparent reporting of denominators, estimates, uncertainty, analysis methods, and missing-data handling helps readers distinguish descriptive patterns from inferential conclusions. Those elements are particularly important for nonrandomized comparisons across periods, where both statistical uncertainty and potential confounding affect interpretation. This record makes the intended question and intervention timeline clear, but leaves these key statistical details unreported.

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 interpreting the outcome is that its values are not reported in the registry record. There are no period-specific testing proportions, estimated differences, confidence intervals, or p-values available to assess the direction, size, or precision of a change.

The comparison is across time periods in a single-group study, not between randomized groups. Staff education began before ACASI enrollment and continued during and after it. The registry’s stated goal was to distinguish ACASI from education alone, but it does not describe the analysis method used to address that challenge. Other influences that may vary over time are not characterized in the record.

The primary outcome population is described as all eligible patients across the relevant periods, whereas 801 is the number enrolled in the ACASI group. Period-specific denominators, numbers tested, and the relationship between enrollment and outcome inclusion are not reported. This makes it difficult to assess the size and composition of the populations underlying the intended percentages.

Other analytic details are also absent: the statistical model, the exact contrasts between periods, covariate adjustment, missing-data handling, and any approach to multiple comparisons are not reported in the registry record. The method for identifying eligible patients and the consistency of outcome measurement across periods are not described in the available information.

Finally, masking is listed as none, and the registry does not provide additional details about outcome ascertainment or safety-event collection. These limitations do not establish that bias occurred, but they constrain assessment of possible bias and of how broadly the findings might apply. Most importantly, without the reported outcome estimates and their uncertainty, no quantitative conclusion about testing changes can be drawn.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Computer-Assisted Self-Interviews and Health Screening in the Pediatric Emergency Department — NCT01708317.
• Registry record last updated 2013-01-08; status last verified 2012-12.
• Results first posted 2013-01-08.
• 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

This completed, single-group behavioral study evaluated an audio-enhanced computer-assisted self-interview in a pediatric emergency department. Enrollment was 801, allocation is listed as NA, and masking as none. The primary outcome concerns the proportion of eligible adolescent patients receiving chlamydia and gonorrhea testing during their visit across four periods, including periods before, during, and after ACASI enrollment, with staff education described as continuing across several periods.

The registry record does not report the period-specific testing rates, estimated changes, uncertainty intervals, or inferential results. It also does not report the statistical method, missing-data approach, or multiplicity handling. The serious adverse event summary lists 0 events among 801 at risk in the ACASI group. The record describes the research question and timeline, but does not provide the outcome results needed to determine whether testing changed or how precisely any change was estimated.