Contraceptive Counseling Following an Abortion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Contraceptive Counseling Following an Abortion (NCT00756314), a randomized na study. The primary outcome is Contraceptive Acceptability and Use of Contraceptives During the 6-month Follow-up.

2. Clinical Question

The trial was designed to examine whether contraceptive counseling was effective on acceptance and use of methods among women following an abortion. The comparison is between two counseling approaches: individualized, face-to-face counseling with a method chosen for free, and the standard educational group counseling available at IMIP. It is not a comparison between counseling and no counseling, because both groups received a counseling intervention.

The primary endpoint combines the concepts of acceptability and contraceptive use in its title. The registry describes a yes-or-no measure during follow-up, but does not report further operational details about how a yes response was determined or whether acceptability and use were assessed separately. The primary question should therefore be read in the terms used by the registry rather than as a more detailed measure of consistent use, method continuation, or another unreported construct.

3. Trial Design

This was a completed, randomized, parallel-group intervention study. The registry identifies the masking as double, but does not report which people involved in the trial were masked or how masking was maintained. The enrollment was 246, with 123 women allocated to personalized contraceptive counseling and 123 to control. The control group received standard care at IMIP.

The study record lists the start as 2008-07 and primary completion as 2009-09. The intervention was behavioral: personalized, face-to-face counseling, with the method chosen by the woman made available for free by a specialized doctor trained in family planning. The control condition was also active care. It consisted of educational group counseling from specialized nursing staff in family planning, including discussion of contraceptive methods and side effects.

The primary outcome was assessed after counseling and during the 6-month follow-up. The primary analysis population is described as intention to treat, retaining women in the groups to which they were originally assigned. The secondary outcomes listed in the registry were pregnancies among all women and satisfaction with the used contraceptive method; both are reported for the 6-month period.

The registry gives the allocation and arm sizes but does not describe the randomization sequence, allocation concealment, recruitment procedures, eligibility criteria, or the specific roles of masked staff. The original sample-size justification and the trial's prespecified statistical analysis plan are not reported in the registry record. The planning figures elsewhere are illustrations based on observed effects, not evidence of the assumptions used to design this trial.

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: Of the 403 women invited, 310 attended the service. However 39 women were excluded because they did not agree to participate and 25 women did not fill the inclusion criteria, as for gestational trophoblastic disease, benign and malignant tumors of the uterus and uterine malformation.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The analysis was by "intention to treat" in both groups. All the women were retained in their original assigned group.

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 Contraceptive Acceptability and Use of Contraceptives During the 6-month Follow-up, measured over after the contraceptive counseling and during the 6-month follow.

The primary endpoint is titled contraceptive acceptability and use of contraceptives during the 6-month follow-up. It is recorded as a number of participants, with the registry describing each participant's outcome as yes or no. The analysis is stated to be intention to treat, so participants were retained in their original assigned groups for the reported comparison.

A binary endpoint is useful when the trial question concerns whether a defined condition or response occurred for each participant. It allows the groups to be compared through the number meeting the endpoint and the number assigned to each group. Here, the recorded counts are 121 of 123 in the personalized counseling group and 86 of 123 in the control group. The registry's outcome title connects acceptability with use, while its description does not provide a more detailed definition of the criteria for a yes response.

This distinction matters for interpretation. The endpoint can describe the proportion recorded as meeting the registry's yes-or-no definition, but does not by itself describe which contraceptive method was chosen, how consistently it was used, or whether use continued throughout follow-up. Those details are not reported in the registry record. The endpoint is therefore most directly informative about the recorded binary outcome, not every dimension of contraceptive experience or use.

7. Results Posted in the Registry

• Personalized Contraceptive Counseling: 98.4% (121/123) versus 69.9% (86/123) on control; risk difference 28.5 percentage points (95% CI 20.0 to 36.9), risk ratio 1.41 (1.25–1.58); unadjusted two-proportion z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Pregnancies Among All Women

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Personalized Contraceptive Counseling: 1.6% (2/123) versus 9.8% (12/123) on control; risk difference -8.1 percentage points (95% CI -13.8 to -2.4), risk ratio 0.17 (0.04–0.73); unadjusted two-proportion z-test p = 0.006.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically lower for Personalized Contraceptive Counseling than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Satisfaction With the Used Contraceptive Method

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Personalized Contraceptive Counseling: 80.5% (99/123) versus 33.3% (41/123) on control; risk difference 47.2 percentage points (95% CI 36.3 to 58.0), risk ratio 2.41 (1.85–3.15); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Personalized Contraceptive Counseling than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The two secondary outcomes broadly point in different outcome directions while describing aspects related to the primary question. The pregnancy outcome concerns an event during the follow-up period; satisfaction concerns participants' assessment of the contraceptive method used. Together, they add context about outcomes beyond the primary yes-or-no measure of acceptability and use. They do not measure exactly the same construct, and their counts should not be treated as interchangeable with the primary endpoint.

The secondary results are directionally consistent with a pattern in which the personalized counseling group had a more favorable recorded outcome for satisfaction and fewer recorded pregnancies than the control group. This pattern is relevant context for the primary result, but it does not establish a single overall effect across outcomes. Each outcome has its own definition, measurement process, and uncertainty.

The registry reports unadjusted comparisons for these endpoints and does not list reported analyses or describe a prespecified multiplicity strategy. When several outcomes are examined, the chance of finding at least one apparently notable result can increase. Adjustment or a prespecified hierarchy can help control how conclusions are drawn across multiple tests. Because such procedures are not reported, the secondary p-values should carry less confirmatory weight than a prespecified primary result and should be interpreted as exploratory or supportive evidence.

The record does not describe whether these outcomes were designated in advance as confirmatory, how they were assessed, or whether missing responses affected their counts. Nor does it report an analysis connecting pregnancy or satisfaction to individual participants' primary endpoint status. The secondary findings can therefore provide a broader descriptive picture, but cannot explain the mechanism behind the primary comparison or establish that all outcomes changed through the same process.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Pregnancies Among All Women
• Satisfaction With the Used Contraceptive Method

9. Statistical Interpretation

10. Statistical Methods Explained

The primary result is a comparison of a binary outcome between two randomized groups. Each participant was classified as a yes or no for the registry-defined measure of contraceptive acceptability and use during follow-up. For such an outcome, a group proportion describes the share of participants in that group recorded as having the outcome. The posted proportions are 0.984 for personalized counseling and 0.699 for control.

What does the risk difference express?

The risk difference is the intervention-group proportion minus the control-group proportion. It is an absolute contrast, so its scale directly reflects the change in outcome probability between groups rather than a relative multiplication of one group's probability. The posted estimate for the primary endpoint is 0.285. A positive value indicates that the recorded outcome was more frequent in the personalized counseling group. Its confidence interval, 0.201 to 0.369, gives a range of values compatible with the data under the assumptions of the interval calculation.

Relative measures answer a different question. A risk ratio compares the two proportions by division, while an odds ratio compares the odds of the outcome in each group. The posted primary risk ratio is 1.407, with interval limits 1.25 and 1.583; the posted odds ratio is 26.03, with interval limits 6.109 and 110.9. These relative estimates can appear large when the outcome is common, and the odds ratio is not an absolute probability difference. The risk difference is often the most direct measure for understanding an absolute group contrast, while relative measures can offer complementary descriptions.

How should the p-value be read?

The primary unadjusted p-value is <0.001. In general, a p-value describes how incompatible the observed data are with a specified null model, assuming that model and the analysis assumptions are appropriate. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of the effect. The registry does not report a complete statistical analysis plan or more details about the test used for the posted p-value, so the p-value should be interpreted alongside the estimate and interval rather than in isolation.

The term unadjusted means that the reported comparison is not described as adjusted for covariates or for testing multiple outcomes. The record lists no reported analyses. That absence does not establish what methods were used outside the posted record; detailed analytic procedures are not reported in the registry record.

Why does intention to treat matter?

The registry says the primary analysis retained all women in their original assigned group. This intention-to-treat approach preserves the randomized comparison and estimates the contrast associated with assignment to the intervention strategy, rather than reassigning participants according to what they later received. It can help avoid bias that would arise if post-randomization decisions determined group membership. The record does not give further detail about adherence or whether participants received additional services.

Intention to treat does not by itself resolve missing outcome information. If responses are unavailable, the analysis still needs a rule for handling them. The record does not describe missingness, imputation, exclusions from endpoint assessment, or sensitivity analyses. The displayed counts use 123 participants as the group size, but the record does not give a separate account of outcome availability or explain whether every participant posted endpoint data.

Why can over-dispersion matter?

Over-dispersion is a general issue in analyses of counts or clustered observations: the observed variability can exceed what a simple model assumes. When that happens, standard errors and confidence intervals from the simpler model may be too narrow. The posted endpoints are participant counts for binary outcomes, not an over-dispersed count-rate analysis. The registry does not report a model specification or a statistical assessment of dispersion, so no such adjustment should be inferred.

Randomization supports a causal comparison when assignment, follow-up, outcome measurement, and analysis are handled appropriately. The registry identifies the trial as randomized but does not report the sequence-generation method or allocation concealment. It also labels the study double masked without describing who was masked. These missing procedural details limit assessment of how well randomization and masking protected the comparison.

Finally, a confidence interval describes statistical uncertainty conditional on the analysis and data; it does not account for every possible source of bias. It cannot correct an ambiguous endpoint definition, unmeasured differences in care, incomplete follow-up, or limitations in external validity. The primary estimate should therefore be read together with the trial design and the details that are absent from the registry record.

11. Confidence Intervals and Precision

The primary risk difference is 0.285, with a 95% confidence interval from 0.201 to 0.369. A confidence interval describes a range of effect estimates that are reasonably compatible with the observed data under the calculation's assumptions. The interval lies above zero, which is consistent with the posted positive difference. Its width also shows that the exact size of the difference is not pinned down to a single value.

Precision is not the same as validity. A narrow interval would not rule out systematic bias, and an interval does not compensate for uncertainty about outcome definitions or missing follow-up. The registry does not provide the interval method, a detailed analysis plan, or information about missing-data handling. The estimate and interval should therefore be read as summaries of the posted comparison, not as a complete account of all uncertainty.

The secondary endpoints also have confidence intervals in the posted results. For pregnancies, the risk difference is -0.081, with an interval from -0.138 to -0.024. For satisfaction, it is 0.471, with an interval from 0.363 to 0.580. These intervals express the statistical precision of their respective unadjusted comparisons, but do not address the additional uncertainty from evaluating multiple outcomes without a reported adjustment or hierarchy.

For binary outcomes, absolute and relative effect measures can convey precision differently. The risk difference describes an absolute contrast, while risk ratios and odds ratios describe relative contrasts. The primary relative estimates are also posted, but the absolute risk difference is directly tied to the observed group proportions. None of these measures establishes that the results will be reproduced in other settings.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations based on the observed effects, not the trial's original design justification. The original sample-size assumptions are not reported in the registry record. These planning calculations use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. They show participants per arm for the binary outcomes, not total events.

The 80% power column gives the number of participants per arm indicated by the stated planning assumptions to have an 80% chance of detecting the specified effect if that effect were present. The 90% power column uses a higher target chance of detection, and therefore generally calls for more participants per arm under otherwise similar assumptions. Power is a feature of a planned study calculation, not a measure of how likely the trial's result is true.

The rows use the full observed effect and smaller fractions of that observed effect. Smaller effects are harder to distinguish from random variation, so the planning illustrations require more participants per arm to detect them at the stated power targets. The figures are sensitive to the observed effect used as their starting point; they should not be treated as a universal sample-size recommendation or as evidence that the original trial was designed around these calculations.

This is not observed power. The registry's original design assumptions, including any planned effect size or sample-size justification, are not reported in the registry record. The displayed figures are useful for understanding how sample size changes under the listed assumptions, but they do not retrospectively establish the probability that the completed study detected an effect.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.699; treatment proportion p₁ = 0.984; average p̄ = 0.841.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5165 = 1.0124.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.4757 = 0.4004.
4. n = (1.0124 + 0.4004)² / (0.2846)² = 24.7, rounded up to 25 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.699186991869919                          # control proportion
p1 <- 0.983739837398374                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(756314)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 25 (80% power), 33 (90% power)
 75% of observed effect: n per arm = 53 (80% power), 71 (90% power)
 50% of observed effect: n per arm = 137 (80% power), 182 (90% power)
power.prop.test: 24.7 
Simulated power at n = 25 per arm: 0.893 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary endpoint and lists two secondary outcomes. It does not describe a multiplicity adjustment, a testing hierarchy, or a statistical analysis plan specifying how conclusions across outcomes should be controlled. The posted p-values are unadjusted. When multiple outcomes are tested, the overall chance of a chance-positive finding can be higher than for a single prespecified test. For that reason, secondary findings generally warrant more caution unless their role and adjustment strategy were planned in advance. Those details are not reported in the registry record.

The primary endpoint is described as analyzed by intention to treat, with all women retained in their original assigned group. However, the registry does not explain how missing outcome data were handled, whether all participants completed follow-up, or whether any endpoint assessments were unavailable. The reported group sizes are 123 in each arm, but the record does not provide a participant-flow account that clarifies outcome completion at each follow-up assessment.

There is no reported description of imputation, complete-case analysis, assumptions about missingness, or sensitivity analyses. Without such information, readers cannot assess whether incomplete outcome information might have influenced the estimates. Retaining participants in their assigned groups is important, but it does not itself resolve missing data or guarantee that all assigned participants contributed observed endpoint values.

The registry lists no reported analyses. This means the record does not document adjusted models, subgroup analyses, or additional sensitivity work; it does not establish that none were conducted outside the registry. The endpoint definitions, analysis populations for secondary outcomes, and any corrections for multiple comparisons are also not detailed. These reporting gaps limit the strength of conclusions that can be drawn from the posted results, especially for secondary outcomes.

15. 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 lists zero serious adverse events among 37 participants at risk in the personalized counseling group and zero among 48 participants at risk in the control group. These are the reported serious-event figures; the at-risk counts are not the full randomized group sizes. The record does not explain why the serious-event denominators differ from the allocated group sizes or how the at-risk populations were defined.

For other adverse events, the registry entries show zero participants at risk and zero affected in each group. With no participants listed as at risk for those entries, the figures do not establish that no other adverse events occurred. Death counts are not reported in the registry record. No serious adverse-event terms are listed.

These safety entries should be read as registry reporting, not as a complete safety evaluation. The record does not describe the adverse-event collection period, event ascertainment procedures, seriousness criteria, or missing safety information. The zero serious-event counts are a factual description of the posted figures, but do not by themselves demonstrate the absence of risk.

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

The primary result describes a difference between the randomized groups in the registry-defined binary measure of contraceptive acceptability and use during follow-up. The posted counts and risk difference indicate that the recorded yes outcome was more frequent in the personalized counseling group than in the standard-care group. The interval conveys uncertainty about the magnitude of that contrast. These findings concern assignment to the two counseling approaches as recorded in this trial.

The result does not compare counseling with no counseling. Both groups received care that included family-planning counseling, although the delivery and staff differed. It also does not identify which part of the intervention account for the group contrast. The record does not report a component analysis that could separate the effect of individualized discussion, method choice, free provision, or other differences between the arms.

The primary endpoint is not a complete measure of contraceptive behavior or experience. The registry describes it as a yes-or-no outcome but does not provide detailed criteria, and the title combines acceptability with use. The result does not establish consistent use, long-term continuation, or use of any particular method. Those outcomes are not reported in the registry record.

The secondary findings add information about pregnancies and satisfaction during follow-up, but they are unadjusted and the registry does not describe a multiplicity plan. They should not be treated as independent confirmation of every possible benefit or as proof of a causal pathway. The findings also do not establish effects beyond the follow-up period or in populations and care settings not represented in the record.

Randomization supports a comparative interpretation, but details about sequence generation, allocation concealment, masking, and missing outcomes are not reported. These limitations affect how confidently the estimates can be generalized or protected against bias. The statistical results describe the posted data; they do not, on their own, resolve these design and reporting uncertainties.

17. Why This Trial Matters Statistically

This trial illustrates the importance of distinguishing an active comparison from a treatment-versus-no-treatment comparison. Both groups received counseling, but in different formats and from different staff. The estimated contrast therefore concerns the complete intervention strategies as implemented and recorded, not counseling in the abstract or any single component of the personalized approach.

The primary endpoint is binary and its absolute contrast is reported as a risk difference, alongside relative measures. Reading the risk difference together with the group counts and confidence interval helps keep the interpretation anchored to the observed participant outcomes. A p-value alone would not describe the size or precision of the group contrast.

The result also highlights how outcome definitions shape interpretation. A yes-or-no measure described as acceptability and use can be informative, but the registry does not explain the criteria for a yes response. Statistical precision cannot compensate for ambiguity about what was measured. A clearly specified endpoint is essential for determining what a reported group difference means.

Finally, the distinction between planning calculations and the original design is important. The registry includes sample-size illustrations based on observed effects, while the trial's original design assumptions are not reported. Those illustrations cannot be used as observed power or as proof that the trial was adequately designed. The posted findings are best understood by considering the randomized comparison, endpoint definition, interval estimates, secondary-outcome multiplicity, and the information missing from the record together.

18. 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 provides limited detail about trial conduct and analysis. It identifies the study as randomized and double masked, but does not report the randomization sequence, allocation concealment, or who was masked. The exact procedures used to deliver counseling and assess outcomes are not described beyond the arm summaries.

The primary outcome is described as a yes-or-no measure of acceptability and contraceptive use, but the criteria for classifying a participant as yes are not reported. The record does not clarify whether acceptability and use were assessed separately or how the combined endpoint was constructed. This limits the specificity of interpretation.

Although the primary analysis is described as intention to treat, the handling of missing outcome data is not reported. There is no participant-flow account or description of follow-up completion in the registry record. The serious adverse-event entries also use at-risk counts that differ from the randomized group sizes, without an explanation of those denominators. Other adverse-event entries and death information are incomplete for evaluating safety.

The registry does not report the original sample-size justification, statistical analysis plan, adjustment for multiple outcomes, or analyses beyond the posted comparisons. The results are unadjusted, and there are no reported analyses in the record. The absence of these details makes it difficult to assess whether the posted analyses were prespecified or how secondary outcomes were prioritized.

Finally, the setting is described as IMIP in Recife, Brazil, and the record does not provide details supporting generalization to other settings or populations. The follow-up outcomes are reported for the 6-month period; later outcomes are not reported in the registry record.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Contraceptive Counseling Following an Abortion — NCT00756314.
• Registry record last updated 2010-10-13; status last verified 2010-03.
• Results first posted 2010-09-30.
• 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.

22. Record Summary

The registry record describes a completed, randomized, double-masked, parallel-group behavioral intervention study with enrollment of 246 women following an abortion. It compared personalized face-to-face contraceptive counseling with standard group counseling at IMIP in Recife, Brazil. Each group included 123 allocated participants.

The primary binary endpoint was contraceptive acceptability and use during the 6-month follow-up. The registry states that the primary analysis was intention to treat. The posted primary comparison favors the personalized counseling group for the recorded yes-or-no outcome, with a risk difference of 0.285 and a confidence interval from 0.201 to 0.369.

Pregnancies and satisfaction were listed as secondary outcomes. The record also contains serious adverse-event figures, but safety reporting details are limited. The original sample-size assumptions, detailed analysis plan, missing-data procedures, and multiplicity strategy are not reported in the registry record.