Comparison of hhCG With hCG+ß in the Early Prediction of Ongoing Pregnancy.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of hhCG With hCG+ß in the Early Prediction of Ongoing Pregnancy. (NCT03184519), a na na study. The primary outcome is Number of Participants With Early Detection of Pregnancy.

2. Clinical Question

In practical statistical terms, the question suggested by the title is whether hhCG can support early prediction in the setting of IVF and fresh embryo transfer, in relation to hCG+ß. The registered design information does not establish that the two tests were evaluated as distinct comparison groups. It is therefore important to distinguish the intended scientific question from the comparison that can be confirmed from the registry entries.

The record labels the study a proof-of-concept investigation. Such work can examine whether a proposed measurement is suitable for further evaluation, but a proof-of-concept label alone does not specify diagnostic accuracy, prediction performance, or clinical usefulness. Those conclusions require clearly defined measurements, outcome criteria, and reported results. The registry record does not provide enough information to assess those features.

3. Trial Design

The registry identifies this as a completed, single-group study with enrollment of 156. The allocation field is listed as NA, masking is none, and the phase is listed as NA. The sponsor is Instituto Valenciano de Infertilidad, IVI VALENCIA. The study dates recorded are 2017-06-19 for the start and 2018-08-10 for primary completion.

The study summary describes a proof-of-concept investigation into prediction of ongoing pregnancy among women undergoing IVF, using hhCG early after IVF and fresh embryo transfer. The intervention entry is called a pregnancy test. The arm description says all patients undergo 3 blood samples after IVF-ET to determine pregnancy. Taken together, these descriptions indicate a cohort with repeated blood sampling, rather than a randomized allocation to distinct treatment arms.

The title refers to comparison of hhCG with hCG+ß. However, the record identifies a single-group model and does not describe separate arms, assignment procedures, or a control group. It does not report whether the two tests were measured in the same samples, in different samples, or according to another comparison procedure. Consequently, the title alone cannot establish the structure of the analysis.

The primary outcome is described as the number of participants with early detection of pregnancy, with a timeframe of one month. Its description specifies detection before day-11 after embryo transfer. The outcome population text says that, from 155 patients, 13 were excluded from analysis for several issues. This differs from the enrollment figure of 156, and the record does not explain the discrepancy or enumerate the exclusion reasons.

The registry lists one outcome measure and one analysis. It does not report the analysis population definition, a detailed statistical analysis plan, or a sample-size justification for the study itself. The planning assumptions associated with illustrative sample-size calculations are not the trial’s own design rationale. Because no separate comparison arms are described, the posted design should not be read as a randomized comparison of the named tests.

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: From the 155 patients, 13 were excluded from analysis for several issues.

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 Participants With Early Detection of Pregnancy, measured over One month.

The primary endpoint is named as the number of participants with early detection of pregnancy. It is a binary-type outcome summarized as a count: each participant would be classified according to whether early detection occurred under the outcome definition. The description sets the timing as before day-11 after embryo transfer, and the timeframe field gives one month.

Early detection is relevant to the stated study objective because the summary concerns prediction of ongoing pregnancy after IVF and fresh embryo transfer. A measure taken earlier than a later pregnancy assessment could be investigated as a predictor. To interpret such an endpoint, however, readers need to know how pregnancy was defined, how an early test result was classified, and how ongoing pregnancy was established. Those operational definitions and validation details are not reported in the registry record.

The outcome title and study summary do not use exactly the same framing: the title refers to early detection of pregnancy, while the summary describes prediction of ongoing pregnancy. The record does not explain how these concepts were linked in the endpoint analysis. It also does not provide the observed count of participants meeting the endpoint, an estimate of predictive performance, or uncertainty around such an estimate. Therefore, the endpoint definition can be described, but its observed result and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

For this study, the outcome is expressed as a count of participants with an event: early detection of pregnancy. For a binary outcome, each participant is classified into one of two categories under a stated definition, such as whether the event occurred. A count is interpretable only alongside a clear analysis denominator. The registry record gives an enrollment figure and a separate population description, but does not report the analyzed denominator or the observed endpoint count.

What an early-detection endpoint can describe

In general, an early-detection endpoint records whether a target condition is detected by a defined time. Its meaning depends on the target condition, the test procedure, the timing rule, and how the condition is confirmed. Here, the endpoint description specifies detection before day-11 after embryo transfer, while the study summary refers to prediction of ongoing pregnancy. The record does not explain the confirmation standard or the relationship between the early measurement and ongoing pregnancy.

Prediction and detection are related but distinct statistical tasks. In general, detection asks whether a condition is identified at a measurement time; prediction asks whether an earlier measurement identifies a later outcome. A predictive evaluation commonly needs a defined later outcome and an assessment of how the early test classifications correspond to it. The registry entry does not provide the detailed outcome-validation procedure or reported measures of predictive performance.

Why the design description matters

The record identifies a single-group model, no masking, and an allocation entry of NA. It also describes blood sampling for all patients after IVF-ET. In general, a single-group design can characterize measurements and outcomes among enrolled participants, but it does not automatically create a valid comparison between two tests. A comparison requires information about how tests were administered and how their results were analyzed. The title names hhCG and hCG+ß, but those implementation details are not reported in the registry record.

Masking refers generally to whether people involved in a study are kept unaware of assigned interventions or measurements. The record lists masking as none. It does not explain whether outcome assessment was independent of test results or whether the absence of masking could affect classification. No further inference about bias can be made from the masking entry alone.

Estimates and uncertainty

For a binary outcome, an analysis might report a count, a proportion, or a contrast between groups, depending on the design and question. This registry record identifies the outcome as a participant count, but does not post the observed count or an inferential estimate. A confidence interval is a general way to represent uncertainty around an estimate; narrower intervals generally indicate greater precision under the model assumptions. No interval is reported for this endpoint, so its precision cannot be evaluated.

A p-value, in general, describes how compatible observed data are with a specified null model, under the assumptions of the statistical test. It does not measure the size or practical importance of an effect. The registry record does not report a p-value or identify a null hypothesis or test. It is therefore not possible to describe statistical significance for the primary endpoint.

Planning illustrations and study size

The posted planning illustration is based on the observed effect and is not the trial’s own design justification. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is expressed as a stated fraction of the observed effect. In general, sample-size calculations estimate the number of observations needed under selected assumptions about effect size, variability, error rates, and design. A planning illustration is conditional on those assumptions and does not show that the study had a particular probability of detecting an effect after data collection.

For count-based outcomes, event totals and participant totals are not interchangeable. A sample-size method may refer to participants per arm or, for time-to-event methods, to a total number of events. Those conventions describe planning outputs, not observed outcomes. The record’s assumptions specify the relevant convention for the illustrative calculations, but they do not establish that this study used two allocated arms. The listed single-group design makes that distinction especially important. These calculations should not be interpreted as observed power, which is not a useful substitute for reported estimates and their uncertainty.

Over-dispersion and model choice

In general, over-dispersion occurs when outcome variability is greater than a chosen statistical model expects. If count data are more variable than assumed, standard errors may be understated and intervals or tests may be misleading. Whether over-dispersion is relevant depends on the actual outcome structure and model. The registry describes the primary endpoint as a count of participants with an event, but does not report a model, dispersion estimate, or diagnostic assessment. No claim about over-dispersion can therefore be made for this analysis.

Model choice should follow the study design and endpoint. A single-group binary endpoint may be analyzed differently from paired test results or outcomes compared across independent groups. The record does not specify whether the named tests were evaluated on matched samples, nor does it provide an analysis plan. Consequently, no particular statistical model or adjustment procedure can be attributed to the study.

Overall, general statistical principles help explain what would be needed to evaluate early detection: a defined analysis population, a reproducible test procedure, a clear later outcome, an appropriate analysis for the design, and an estimate with uncertainty. The registry record does not report enough of those elements to assess the numerical performance of the primary endpoint.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and one analysis. It does not report a detailed statistical analysis plan, a hierarchy of endpoints, or a multiplicity adjustment. Multiplicity arises in general when several hypotheses or outcomes are tested, because repeated testing can increase the chance of at least one apparently positive result under a null model. The record does not establish whether additional analyses were conducted beyond the listed entry, so no conclusion about multiplicity handling is possible.

The endpoint population text says that, from 155 patients, 13 were excluded from analysis for several issues. The enrollment field reports 156. The record does not reconcile these figures, list the reasons for exclusion, identify when exclusions occurred, or state how missing measurements were handled. It also does not report the number of participants with incomplete blood sampling or unavailable outcome assessment.

In general, missing-data methods depend on why data are missing and on the assumptions made about the missing outcomes. Excluding participants can affect the composition of the analysis population, while imputation or other methods require explicit specification. The registry record does not say whether exclusions were planned, whether any imputation was used, or whether sensitivity analyses were performed.

The analysis population is therefore not sufficiently defined for a full appraisal. The record does not report whether all enrolled participants were included in any analysis, how exclusions related to test results or pregnancy outcomes, or whether the reported endpoint used an intention-to-diagnose or other population definition. These details matter when interpreting any diagnostic or predictive estimate, but no such estimate is posted in the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The serious adverse-event figures list 156 patients at risk, 0 affected, and 0 deaths in the all-patients group. The record also lists 156 at risk and 0 affected in its other adverse-event category. No serious adverse-event terms are listed among the most frequent terms.

These figures should be read as the events recorded in the registry fields, not as proof that no adverse experiences of any kind occurred. The entry does not provide narrative detail about safety monitoring, the definitions used for reportable events, or the period of observation for these counts. The primary study question concerns pregnancy detection, and the record describes blood sampling after IVF-ET; the safety figures do not provide information about test accuracy or pregnancy outcomes.

Zero affected participants in the reported categories means that no events were recorded in those categories for the listed group. It does not establish the absence of unreported events or quantify risk beyond the registry’s reporting. The record does not list additional safety analyses or subgroup results.

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

The registry record identifies the topic and broad design of a completed proof-of-concept study: early pregnancy detection after IVF and fresh embryo transfer, with hhCG and hCG+ß named in the title. It reports that all patients were to undergo 3 blood samples after IVF-ET and defines the primary endpoint in terms of early detection before day-11 after embryo transfer.

Those details do not establish how well either test predicted ongoing pregnancy. The record does not report the observed number meeting the endpoint, test-specific results, a comparison estimate, or uncertainty around an estimate. The title cannot replace those results, and the single-group model does not, by itself, demonstrate a direct comparison between tests.

The record also does not clarify the discrepancy between enrollment of 156 and the endpoint description’s reference to 155 patients, from whom 13 were excluded. Without the final analysis denominator and reasons for exclusion, the population contributing to the endpoint cannot be fully characterized. Definitions of ongoing pregnancy and assay procedures are also not reported in the registry record.

In general, a completed study status indicates that the study is recorded as completed; it does not establish that a particular hypothesis was confirmed. A proof-of-concept objective can motivate further research, but it does not alone establish accuracy, generalizability, or usefulness outside the studied setting. Those judgments require transparent methods and numerical results.

The most defensible interpretation is therefore limited: the registry documents an investigation of early pregnancy detection after IVF-ET, but it does not provide the results needed to judge predictive performance or a difference between hhCG and hCG+ß. No conclusion about either test’s performance can be drawn from the recorded information.

13. Why This Trial Matters Statistically

This study raises a statistically important distinction between an intended comparison and a design that the registry actually describes. The title names hhCG and hCG+ß, whereas the design is listed as single-group and the intervention is described as a pregnancy test. For statistical interpretation, knowing whether tests were compared within the same participants or across distinct groups is essential. The record does not provide that detail.

The endpoint also illustrates why definitions matter. Early detection before day-11 after embryo transfer is a timing rule, while ongoing pregnancy is a later outcome described in the study summary. A clear link between the early test and that later outcome is necessary to interpret predictive performance. The registry record does not report the operational details or the numerical results needed to evaluate that link.

Population accounting is another central issue. The enrollment field reports 156, while the endpoint description refers to 155 patients and 13 exclusions. Without an explained participant flow and analysis denominator, estimates cannot be placed in context or assessed for possible selection effects.

These issues are common in diagnostic and prediction research: conclusions depend not only on a test result, but also on the reference outcome, timing, participant selection, and analysis method. The registry entry shows why a study title and a completed status are not sufficient evidence of comparative performance. Transparent reporting of methods and results is needed to distinguish a promising study question from a supported statistical conclusion.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record does not report the observed primary endpoint count or an estimate of performance. It also does not provide a confidence interval, p-value, or other measure of uncertainty. As a result, neither the magnitude nor precision of the primary result can be assessed.

The title suggests a comparison of hhCG with hCG+ß, but the registered model is single-group and the intervention is described as a pregnancy test. The record does not explain whether both tests were assessed in the same participants, how their results were paired, or whether any comparator group existed. This limits interpretation of the comparison implied by the title.

The record describes the endpoint as early detection before day-11 after embryo transfer, while the study summary emphasizes prediction of ongoing pregnancy. It does not report the definition or confirmation method for ongoing pregnancy, the detailed assay procedures, or the relationship between the early test result and the later outcome.

Participant accounting is unclear: enrollment is 156, while the endpoint population text refers to 155 patients and 13 exclusions. The reasons for exclusion, the final analyzed population, and the handling of missing samples or outcomes are not reported in the registry record. The analysis plan, including any adjustment, sensitivity analysis, or handling of multiple analyses, is also not described in detail.

Finally, the study is identified as proof of concept, but the registry does not provide the study’s own sample-size justification or evidence that the illustrative planning assumptions were used in its design. These limitations prevent a full assessment of validity, precision, and generalizability from the registry information alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of hhCG With hCG+ß in the Early Prediction of Ongoing Pregnancy. — NCT03184519.
• Registry record last updated 2020-08-13; status last verified 2020-07.
• Results first posted 2020-03-04.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record identifies NCT03184519 as a completed, single-group study sponsored by Instituto Valenciano de Infertilidad, IVI VALENCIA. Enrollment is listed as 156, the phase as NA, masking as none, and allocation as NA. The recorded start is 2017-06-19 and primary completion is 2018-08-10.

The study concerns early pregnancy detection after IVF and fresh embryo transfer. Its title names hhCG and hCG+ß, while the registered intervention is a pregnancy test and the arm description states that all patients undergo 3 blood samples after IVF-ET. The primary outcome is the number of participants with early detection of pregnancy, described as detection before day-11 after embryo transfer, with a timeframe of one month.

The endpoint population text refers to 155 patients and says 13 were excluded from analysis, while enrollment is 156. The registry record does not explain this discrepancy or report the observed endpoint result. It also does not report comparative estimates or sufficient detail to assess prediction performance.