Reducing Adolescent Pregnancy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Reducing Adolescent Pregnancy (NCT04120376), a na na study. The primary outcome is Intention to Initiate Contraception.

2. Clinical Question

The study is framed around emergency department-based counseling and factors that may affect decision making, along with barriers and facilitators to beginning contraception in that setting. Its overarching goal, as stated in the registry record, is to reduce unintended pregnancy among females ages 15 to 18 who present to the emergency department. That goal is distinct from the registered primary endpoint: the endpoint counts participants whose survey responses indicated high intention to initiate contraception.

The clinical question is therefore about a reported intention, not a confirmed contraceptive start or a later pregnancy outcome. The registry record names contraceptive care referral completion and initiation of contraception as secondary outcomes, but their numerical findings are not reported in the registry record. A single-group study can describe outcomes among people receiving an intervention. Without a like-for-like control group, however, the results cannot by themselves isolate what would have happened without counseling or establish that counseling caused any observed outcome.

3. Trial Design

The registry record identifies the study as multi-site and describes it as an emergency department-based contraception counseling study. The sponsor is Children's Hospital of Philadelphia. The record lists the study status as completed, with a start date of 2019-11-13 and a primary completion date of 2021-02-17. Enrollment is 144. The phase is recorded as NA.

The model is single group, allocation is NA, and masking is none. The intervention is behavioral contraception counseling. The arm description says that all participants will receive contraception counseling from study Advanced Practice Providers. These design details describe an intervention cohort rather than a randomized, like-for-like comparison. The record explicitly notes that the listed arms are not a like-for-like control comparison, so differences between those entries should not be treated as comparative treatment effects.

The primary outcome is a participant count for reported high intention to initiate contraception, assessed at the emergency department or a follow-up visit from survey responses, up to 8 weeks. The record also lists contraceptive care referral completion and initiation of contraception as secondary outcomes. It lists 4 outcome measures and 0 analyses. Numerical outcome findings and an inferential analysis are not reported in the registry record.

The record does not report a statistical analysis plan, a sample-size justification for the study design, or details of how participants were recruited or followed beyond the primary outcome timeframe. Those omissions limit how fully the design and the intended interpretation can be assessed from the registry entry alone.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Those who reported "high intention" to initiate contraception

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: 96 participants were assessed at baseline, received the adolescent counseling intervention and completed outcome information. Please note, no baseline measures were collected for the APP participants.

6. Primary Endpoint

The registry lists the primary outcome as Intention to Initiate Contraception, measured over up to 8 weeks.

The primary endpoint is a count of participants whose survey responses indicated high intention to initiate contraception. The assessment could occur at the emergency department or at a follow-up visit, with the timeframe listed as up to 8 weeks. The endpoint is therefore a measure of stated intention during the registered assessment period, rather than a count of verified contraception initiation or pregnancy outcomes.

Intention is relevant to this study because the intervention aims to inform decision making and the study description focuses on factors that may affect contraception-related decisions in an emergency department setting. A reported intention can capture a participant's expressed readiness at the time of assessment. It may be useful for describing a proximal response to counseling, while remaining conceptually distinct from later behavior. The registry record does not report how high intention was defined, how survey responses were scored, or how responses at the emergency department and follow-up were combined.

For a count endpoint, the observed count needs a clear denominator to support interpretation. The primary outcome population is described as those who reported high intention, but the registry record does not report the numerical result or the number of participants with outcome data. It also does not report whether all enrolled participants were assessed within the timeframe. Consequently, the endpoint's observed frequency and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends first on matching the method to the endpoint and design. In this study, the primary endpoint is a count of participants meeting a stated survey-response criterion: high intention to initiate contraception. The record identifies a single-group model and provides no like-for-like control comparison. These features shape what analyses could describe, but the registry record does not report the analysis used or an inferential result.

What does a participant count represent?

Generally, a count is the number of people who meet a specified outcome definition. A count alone does not indicate how common the outcome is unless its denominator is known. For example, the denominator might be all enrolled participants, those who answered a survey, or a defined analysis population. Each choice answers a different descriptive question. The registry record identifies participants reporting high intention as the primary outcome population, but does not report the observed count, the denominator used, or the number with outcome data. The endpoint's observed frequency therefore cannot be reconstructed from the entry.

The outcome definition also matters. The record describes intention based on survey responses but does not report the survey instrument, scoring rule, or threshold for high intention. A reproducible analysis requires a clear rule for classifying responses. Without that detail, readers cannot assess how consistently the outcome could be measured or whether alternative definitions would change the count.

What can a confidence interval tell a reader?

Generally, a confidence interval describes the statistical uncertainty around an estimate under a specified method and assumptions. For a proportion or count-derived estimate, it can help show how much precision the observed data support. It does not correct for bias in who was enrolled, who responded, or how an outcome was classified. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record. Therefore, the precision of the primary result cannot be evaluated from this record.

A p-value, when appropriate, addresses compatibility between observed data and a specified null model; it does not measure the size or practical importance of an effect. In a single-group study, a test would also require a meaningful reference value or comparison model. The registry record does not report a primary-outcome test, null hypothesis, reference value, or p-value. No claim of statistical significance or lack of significance can be made from the recorded information.

Why does the design constrain causal interpretation?

Generally, a concurrent control group can help distinguish an intervention-associated outcome from changes that might have occurred without the intervention. In a single-group design, the observed outcome has no like-for-like control outcome for that contrast. Descriptive summaries can characterize participants and their outcomes, but they do not by themselves establish what caused those outcomes. This is especially important when the study goal refers to reducing unintended pregnancy while the primary endpoint is reported intention to initiate contraception. The outcome and the broader goal are related in topic but are not interchangeable measures.

The record lists no masking. In general, lack of masking can affect subjective measures if awareness of the intervention influences reporting or assessment. That is a methodological consideration, not evidence that responses in this study were biased. The registry record does not report procedures intended to limit such effects or an assessment of their presence.

How should planning illustrations be understood?

Generally, sample-size planning asks how much information a study would need to estimate an outcome or detect a prespecified effect under stated assumptions. A planning illustration based on an observed effect is not the study's original design justification, and it does not describe an observed result. The registry record describes a planning illustration using 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 an observed effect. It also distinguishes participant-per-arm results from total-event results for time-to-event methods. These are descriptions of planning assumptions, not evidence that the trial used those assumptions to choose its enrollment. The record does not report the study's own sample-size justification.

Because the design is identified as single group and the displayed groups are explicitly not a like-for-like comparison, a hypothetical two-arm planning illustration should not be mistaken for the actual trial design. Nor should an illustrative sample-size output be interpreted as observed power. Planning calculations are conditional on assumptions about the effect, variability, allocation, and test; they do not establish the probability that a finding is true.

Over-dispersion is a general issue for count outcomes when the observed variability exceeds what a chosen probability model expects. If present, a model that ignores it can produce uncertainty estimates that are too narrow. The registry record does not report an over-dispersion assessment or a count model, and the primary endpoint is defined as a count of participants rather than a repeated-event count. Thus, no conclusion about over-dispersion or a particular modeling choice is possible from this entry.

In short, the registry record identifies an outcome and design but does not report the calculations needed to evaluate its observed result. The available endpoint description supports a conceptual account of what was intended to be counted; it does not supply an outcome estimate, its precision, or a test of an intervention 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("Adolescent Counseling Intervention")
n      <- c(96)
events <- c(59)
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  Adolescent Counseling Intervention  96  59  61.5  51.0  71.2  51.5  70.6  51.4  70.6

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 4 outcome measures, including the primary outcome of intention to initiate contraception and secondary outcomes of contraceptive care referral completion and initiation of contraception. It lists 0 analyses. A statistical analysis plan describing how these outcomes were tested, prioritized, or interpreted is not reported in the registry record.

Multiplicity is a general concern when several outcomes or analyses are examined. The more opportunities there are to identify a result, the more important it is to distinguish prespecified primary questions from secondary or exploratory questions and to explain any adjustment or interpretation strategy. The record identifies a primary outcome, but does not report whether any multiplicity adjustment was planned or used. No adjustment should be presumed.

Missing data can affect both the count and its interpretation. For a survey-based outcome, nonresponse or incomplete responses may mean that some enrolled participants cannot be classified. An analysis should state how many participants were assessed, how missing responses were handled, and whether the denominator differs by outcome. These details are not reported in the registry record. Enrollment is 144, but enrollment alone does not show how many primary outcome responses were available.

Analysis populations also matter. A report may describe all enrolled participants, participants who received an intervention, or participants with outcome data, among other possibilities. The registry record does not report a defined analysis population or how participants were included in any analysis. Since no analyses are listed, there is no reported basis for assessing exclusions or deviations from an analysis plan.

12. 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 registry record lists safety counts for a group titled Counseling Intervention and a group titled APP Contraception Counseling Training. For the Counseling Intervention group, 99 are listed as at risk for serious events and 99 as at risk for other events; both event counts are 0, and deaths are 0. For the APP Contraception Counseling Training group, 27 are listed as at risk for serious events and 27 as at risk for other events; both event counts are 0, and deaths are 0.

These are recorded counts for the named groups, not a randomized safety comparison. The registry record identifies a single-group model and explicitly warns that the arms are not a like-for-like control comparison. The group labels and different at-risk counts do not establish that the groups are comparable or that a difference in risk can be estimated between them.

Zero recorded events means that no events are listed for these entries; it does not prove that an event could not occur or that the intervention has no safety risk. The record does not report additional detail about event collection, observation time for the safety outcomes, or the completeness of safety follow-up. The serious adverse event figures should therefore be read as descriptive registry counts with their stated at-risk group sizes, not as proof of comparative safety.

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

The registry record establishes that the study examined emergency department-based contraception counseling and defined a primary outcome involving reported intention to initiate contraception. It also documents a single-group design, enrollment of 144, and an outcome timeframe of up to 8 weeks. These details describe the study question and structure; they do not provide the primary outcome result.

The result itself—the count of participants who reported high intention—is not reported in the registry record. Neither a denominator nor a confidence interval, standard error, or inferential test is reported. The primary outcome's magnitude and precision therefore cannot be assessed. The registry record also lists initiation of contraception and referral completion as secondary outcomes, but their numerical results are not reported in the registry record.

Even if a high-intention count were available, it would indicate reported intention, not necessarily later initiation. A survey response can be informative about a participant's stated view at an assessment, but it does not establish what happened afterward. The record does not report a numerical result for initiation, and no conclusion about subsequent contraceptive behavior or pregnancy outcome should be drawn from the primary endpoint description alone.

The study's single-group design also limits causal claims. Without a like-for-like control comparison, an observed outcome among participants who received counseling would not by itself show what difference counseling made. The registry record states that the displayed arms are not a like-for-like control comparison, so they cannot be treated as randomized intervention and control groups.

Accordingly, the record supports a description of the intended intervention, target context, and endpoint, but not a conclusion about the size, precision, or cause of an outcome. It does not establish that counseling did or did not reduce unintended pregnancy. Such a claim would require outcome data directly addressing that question and an analysis appropriate to the study design.

14. Why This Trial Matters Statistically

This study raises a useful statistical distinction between an intervention's broad clinical goal and the outcome selected for measurement. The stated overarching goal is to reduce unintended pregnancy among females ages 15 to 18 presenting to an emergency department. The registered primary outcome instead counts participants reporting high intention to initiate contraception. Separating these concepts is important: an intention measure may describe an early decision-related outcome, while pregnancy reduction is a different endpoint.

The emergency department setting is also relevant to measurement. The study description focuses on counseling, decision making, and barriers or facilitators to beginning contraception in that setting. Statistically, such a study needs clearly specified definitions and timing so that readers can tell what was measured and when. The registry record gives a timeframe of up to 8 weeks and identifies survey responses, while the scoring definition for high intention is not reported.

The single-group design makes transparent reporting especially important. Descriptive results can characterize participants who receive counseling, but comparison is needed to distinguish an intervention-associated effect from other explanations. The registry record explicitly cautions that the listed arms are not a like-for-like control comparison. This prevents treating their counts as a controlled estimate of intervention impact.

The entry also illustrates how outcome counts require context. Enrollment is 144, but a reader would need the outcome denominator, response completeness, and an uncertainty estimate to judge the count's precision and representativeness. Those details and the numerical outcome results are not reported in the registry record. Without them, even the descriptive result cannot be fully evaluated.

These issues matter beyond this study: a clear outcome definition, a suitable comparison, and transparent reporting of missingness and uncertainty are central to interpreting behavioral interventions. In this record, the design and primary question are identifiable, but the absence of numerical findings and analysis details limits the statistical conclusions that can be drawn.

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 registry record does not report the primary outcome count, its denominator, or an uncertainty estimate. As a result, neither the frequency of high intention nor the precision of that estimate can be assessed. Although enrollment is 144, the number of participants with a completed survey or classifiable primary outcome is not reported. The record also does not describe how missing survey responses were handled.

The primary endpoint's measurement rule is incompletely described. The record states that high intention was based on survey responses but does not report the instrument, threshold, scoring procedure, or how assessments at the emergency department and follow-up were combined. It gives a timeframe of up to 8 weeks, but does not report the timing or completeness of individual assessments.

The single-group design does not provide a like-for-like control comparison. The registry record cautions that displayed arms are not a like-for-like control comparison, so those group entries cannot support a direct intervention-versus-control interpretation. No causal estimate can be derived from the design description alone.

Numerical results for the secondary outcomes of referral completion and initiation of contraception are not reported in the registry record. Nor does the record report an analysis plan, multiplicity approach, or defined analysis population. These gaps make it difficult to assess how outcomes were prioritized, how participants were included, and how uncertainty was evaluated.

Finally, the goal of reducing unintended pregnancy is broader than the registered primary outcome of reported intention. The registry record does not report a pregnancy outcome result. The safety entries are also descriptive counts, and the record does not give further detail on safety-event collection or follow-up. These limitations are specific to what is documented in the registry record and constrain interpretation of both benefit-related outcomes and safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Reducing Adolescent Pregnancy — NCT04120376.
• Registry record last updated 2023-02-03; status last verified 2023-01.
• Results first posted 2023-02-03.
• 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

The registry record describes a completed, multi-site, single-group behavioral study of emergency department contraception counseling, sponsored by Children's Hospital of Philadelphia. Enrollment is 144. The study start date is 2019-11-13, and the primary completion date is 2021-02-17. The phase and allocation are listed as NA, and masking is none.

The primary outcome is a count of participants reporting high intention to initiate contraception from survey responses at the emergency department or a follow-up visit, up to 8 weeks. Referral completion and initiation of contraception are listed as secondary outcomes. The record lists 4 outcome measures and 0 analyses.

The numerical primary and secondary outcome findings, analysis methods, and uncertainty estimates are not reported in the registry record. The displayed safety entries list zero serious events, zero other events, and zero deaths in each named group, with different at-risk counts. The registry record cautions that the listed groups are not a like-for-like control comparison.