Efficacy of Corifollitropin Alfa in Obese Women in Terms of Clinical and Molecular Parameters of IVF Success: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy of Corifollitropin Alfa in Obese Women in Terms of Clinical and Molecular Parameters of IVF Success (NCT02606500), a non-randomized phase 4 study. The primary outcome is Number of Oocytes Retrieved Per Patient.

2. Clinical Question

3. Trial Design

This is a completed Phase 4, parallel-group, non-randomized study sponsored by University Medical Centre Ljubljana. The registry record gives a start date of 2016-03 and a primary completion date of 2017-01, with enrollment of 70. Masking is listed as none. These design features matter when interpreting comparisons: participants were not allocated randomly, and the record does not describe blinded assessment.

The arm descriptions identify 35 participants at risk in each group. The obese study group is listed as receiving Elonva 150 mcg intramuscular daily; the normal-weight control group is listed as receiving Elonva 100 mcg intramuscular daily. The brief summary describes an aim of assessing whether clinical efficacy of 150 mcg is the same in normal-weight and obese women. That description does not align with the 100 mcg dose in the normal-weight arm description. The registry record does not resolve this difference, so the recorded arm descriptions and the stated aim should not be silently treated as identical.

The comparison combines differences in weight category with a difference in recorded dose. It therefore cannot isolate the effect of weight category or dose from the other group differences. The registry record does not report a randomized allocation procedure, a masking procedure, or additional details about recruitment and treatment delivery. Further protocol details 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.

Overall Study

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 Number of Oocytes Retrieved Per Patient, measured over 1 month.

The primary endpoint is the number of oocytes retrieved per patient, expressed as a mean with standard deviation and assessed over 1 month. It is a continuous measure: each patient can have a count, and the group mean describes the average count in the group. The standard deviation describes the spread of individual counts around that mean. These summaries can help characterize both the typical level and the variation in oocyte retrieval.

Oocyte retrieval is used in the registry record as a clinical measure relevant to the study’s IVF question. The endpoint description says that the number obtained in the study group was compared with the number in the control group. It does not establish that this measure alone represents overall IVF success, nor does the record state how the endpoint relates to later clinical outcomes.

The registry record does not report the group means, standard deviations, a difference between groups, or a confidence interval for this endpoint. Consequently, the magnitude and precision of the observed comparison are not reported in the registry record. The timeframe is recorded as 1 month, but further detail about the timing of measurement is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record specifies a mean and standard deviation for the primary continuous outcome, but it does not report the outcome summaries or the methods used for an inferential comparison. The statistical concepts below are general explanations; they should not be taken as confirmation that a particular analysis was conducted in this study.

What does a mean describe?

For a continuous measure, the mean is the average across the observations included in an analysis. Here, the measure is the number of oocytes retrieved per patient. A group mean can describe the average retrieval count among the participants whose observations were analyzed. It does not show how values are distributed across individuals, and it can be influenced by unusually high or low observations.

The standard deviation is a measure of dispersion around the mean. A smaller standard deviation indicates that observations tend to lie closer to the mean; a larger one indicates greater spread. It is not the same as the uncertainty in the estimated mean. The registry record names standard deviation as the dispersion measure but does not report its value for either group.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with the observed data and the method used to calculate it. For a group difference, it would help readers assess the estimate's precision as well as its direction and size. A narrow interval would indicate greater precision than a wide interval, all else being equal. The primary endpoint's confidence interval is not reported in the registry record, so its precision cannot be evaluated.

A confidence interval is not a guarantee that the true value lies within the particular interval. Its interpretation depends on the statistical method and assumptions used. The registry record does not report an interval method or the details needed to assess such assumptions for the primary comparison.

What does a significance test answer?

In general, a significance test evaluates how compatible the observed data are with a specified null hypothesis under a chosen statistical model. A p-value does not measure the size or importance of an effect, and it does not establish equivalence. A non-significant result, if one were reported, would not by itself show that groups are sufficiently similar. This study's primary p-value and testing method are not reported in the registry record.

The record's planning assumptions mention a two-sided significance level of 0.05 for illustrations based on the observed effect. That is a planning assumption, not a reported primary analysis result and not evidence that the trial was designed with that threshold. The registry record does not report the trial's own sample-size justification or a prespecified analysis plan.

How should planning estimates be understood?

In general, a sample-size calculation estimates the number of participants or events that may be needed to detect a specified effect under chosen assumptions. The registry record describes planning illustrations based on the observed effect, with equal allocation and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. Such illustrations are conditional on their assumptions and should not be interpreted as observed power or as proof that an analysis was adequately powered.

The registry record does not provide the trial's original planning rationale, the effect assumed for its design, or a sample-size justification. It also does not report enough primary outcome information to assess the observed effect directly. The planning assumptions therefore cannot substitute for a reported result or a prespecified design calculation.

Why does non-random allocation matter?

In general, random allocation helps balance both measured and unmeasured participant characteristics across groups, on average. Without random allocation, observed group differences can reflect baseline differences as well as the intervention or exposure of interest. Here, the comparison is between obese and normal-weight groups, and the arm descriptions also give different doses. The registry record does not report adjustment methods or enough participant characteristics to assess how differences between the groups were handled.

The record lists six outcome measures and five analyses, but it does not identify their full relationship or report a multiplicity strategy. General statistical practice recognizes that examining multiple outcomes or analyses can increase the chance of a misleading positive finding if interpretation does not account for that multiplicity. Whether and how that issue was handled in this study is not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Study Group", "Control Group")
n   <- c(35, 35)
m   <- c(11.3, 12.4)
sp  <- c(7.5, 7.4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Study Group  35  11.300  7.500  8.724  13.876
CARM  Control Group  35  12.400  7.400  9.858  14.942

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists six outcome measures and five analyses. It identifies the number of oocytes retrieved per patient as the primary endpoint and lists real-time PCR analysis of genes proposed as biomarkers of oocyte quality as a secondary outcome. It does not give a complete account of all outcomes and analyses, their prespecified hierarchy, or how the five analyses correspond to the six outcome measures.

Multiplicity arises in general when several outcomes, comparisons, or analyses are examined. Without an adjustment or a clearly prespecified hierarchy, the chance of at least one apparently notable result can increase. The registry record does not report whether multiplicity was addressed, which outcomes were included in any adjustment, or whether any outcomes were designated exploratory.

Missing-data handling is also not reported in the registry record. The group descriptions list 35 participants at risk in each arm, but the record does not state the number with observed primary endpoint data, whether any observations were missing, or how missing values were handled. It does not report an intention-to-treat population, a per-protocol population, or another analysis-population definition. Enrollment and at-risk counts alone cannot establish which participants contributed to each analysis.

The registry record does not report sensitivity analyses for missing data or the assumptions underlying any such analyses. These omissions make it difficult to assess whether the analyzed participants represent the enrolled groups or whether the reported estimates, if available, might depend on particular missing-data assumptions.

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 record lists 35 participants at risk in the study group and 35 in the control group. It records zero serious adverse events and zero other adverse events for each group. These are the counts recorded in the adverse-event fields; they should be read as reported event counts rather than as a complete account of all possible safety outcomes.

The deaths field is null for both groups. A null entry does not establish that no deaths occurred; deaths are not reported in the registry record. The record also does not list serious adverse-event terms. Additional information about how adverse events were defined, collected, or followed is not reported in the registry record.

Counts alone do not describe the timing, duration, severity, or clinical context of events. The registry record does not provide those details. The recorded zero counts therefore support only the limited statement that the adverse-event fields contain zero for these categories, not a broader conclusion about safety.

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

The record describes a non-randomized comparison of obese and normal-weight women undergoing IVF, with the mean number of oocytes retrieved per patient as the primary endpoint. It also records a molecular objective involving real-time PCR analysis of proposed biomarkers of oocyte quality. These features establish the questions the study was intended to address, but the registry record does not provide the primary endpoint results or molecular findings.

Without group outcome values, an estimated difference, or a confidence interval, the direction and precision of the clinical comparison cannot be judged. The record does not establish whether the groups had similar or different mean retrieval counts. It also does not establish equivalence: demonstrating similarity requires appropriate design and analysis, not merely an absence of a reported difference.

The design places further limits on interpretation. Participants were not randomly allocated, and the arm descriptions distinguish the groups by both weight category and recorded dose. The study therefore cannot isolate a causal effect of dose or weight category from the information in the registry record. The discrepancy between the brief summary's 150 mcg framing and the 100 mcg dose recorded for the normal-weight arm adds uncertainty about the intended comparison.

The adverse-event fields record zero serious and other adverse events in each group, while deaths are not reported in the registry record. These limited fields do not provide a comprehensive safety assessment. Overall, the registry record conveys the study's purpose, structure, and selected event counts, but does not provide the outcome information needed to evaluate the main clinical or molecular questions.

14. Why This Trial Matters Statistically

This study illustrates why a clearly defined comparison is central to interpreting clinical research. The registry record frames a question about obese and normal-weight women, but the groups also have different doses in their arm descriptions. When group membership and treatment dose differ together, the comparison cannot distinguish which feature might explain an outcome difference. Non-random allocation adds further scope for differences between groups to affect the comparison.

It also highlights the distinction between a registered endpoint and a reported result. Naming the mean number of oocytes retrieved per patient specifies what the study intended to measure, but does not reveal the observed group means, variability, or uncertainty. Statistical interpretation depends on estimates and their precision, not on the endpoint title alone. In this record, those primary outcome details are not reported.

The difference between the brief summary and the arm descriptions is another important reporting issue. The summary describes 150 mcg in both weight groups, while the normal-weight arm description records 100 mcg. A transparent account of the treatment actually given in each group is necessary to understand what a comparison represents.

Finally, the listed outcome and analysis counts raise questions about multiplicity, while missing-data and analysis-population details are absent. These are not technical footnotes: they help readers assess how results were selected, how much information contributed to an estimate, and how robust an interpretation may be. The registry record offers too little outcome and methods detail to resolve these questions.

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.

Several limitations are specific to the information in this registry record. First, it does not report the primary endpoint values, standard deviations, a group difference, or a confidence interval. The main clinical comparison therefore cannot be characterized in magnitude or precision.

Second, the study is non-randomized and unmasked. The groups are defined by weight category and have different doses in the arm descriptions. This makes it difficult to attribute any possible group difference to one feature, even if outcome estimates were available. The registry record does not report adjustment methods or participant characteristics that would help assess comparability.

Third, the stated study aim and recorded dose descriptions do not align: the brief summary refers to 150 mcg in both weight groups, whereas the normal-weight arm is listed at 100 mcg. The registry record does not explain the discrepancy. Treatment details beyond the arm descriptions are not reported in the registry record.

Fourth, the record does not explain the relationship between six outcome measures and five analyses, or whether multiplicity was addressed. Missing-data methods, analysis populations, and the number contributing outcome data are also not reported in the registry record. The serious and other adverse-event fields record zero counts, but deaths are not reported and details of event collection are absent. These omissions limit interpretation of both efficacy-related outcomes and safety reporting.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Efficacy of Corifollitropin Alfa in Obese Women in Terms of Clinical and Molecular Parameters of IVF Success — NCT02606500.
• Registry record last updated 2018-11-26; status last verified 2018-05.
• Results first posted 2018-11-26.
• 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

NCT02606500 is a completed Phase 4, parallel-group, non-randomized study sponsored by University Medical Centre Ljubljana. The registry record lists 70 participants enrolled, with start in 2016-03 and primary completion in 2017-01. Masking is listed as none.

The primary endpoint is the mean number of oocytes retrieved per patient over 1 month, with standard deviation as the dispersion measure. The arm descriptions list Elonva 150 mcg intramuscular daily for obese women and Elonva 100 mcg intramuscular daily for normal-weight women. The stated summary aim refers to 150 mcg for both groups, and the registry record does not resolve the discrepancy.

Real-time PCR analysis of proposed oocyte-quality biomarkers is listed as a secondary outcome. Primary outcome results, analysis methods, missing-data handling, and deaths are not reported in the registry record. The adverse-event fields record zero serious and other adverse events in each group.