The Effects of Menstrual Cycle Phase on Exercise Treadmill Test Results in Premenopausal Women: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effects of Menstrual Cycle Phase on Exercise Treadmill Test Results in Premenopausal Women (NCT05985980), a registered phase not stated study. The primary outcome is ST/HR Index (μV/Bpm).

2. Clinical Question

The registry frames the question around whether menstrual-cycle phase is associated with exercise treadmill test results in premenopausal women. Its primary endpoint is the ST/HR index, a continuous measure automatically generated at the end of the exercise treadmill test. The stated comparison is between measurements from tests at the two follicular phases. The intended setting was routine clinical workup for women with chest pain who had been ordered an exercise treadmill test.

The registry summary offers a biological rationale: estrogen levels are described as low in the early follicular phase and increasing to higher levels in the late follicular phase; it also notes estrogen's direct vasodilatory effects on coronary arteries. These statements motivate the research question, but do not establish that a phase-related difference in the endpoint occurred. The registry record does not report numerical results for the primary comparison, so the direction, magnitude and precision of any difference cannot be assessed.

3. Trial Design

The registry describes a study of exercise treadmill test results in premenopausal women, with testing planned separately during the early and late follicular phases of the menstrual cycle. Participants were women aged 20-55 years who presented with chest pain to cardiology outpatient clinics and had an exercise treadmill test ordered. The tests were planned as part of routine clinical workup. The registry lists Istanbul Medeniyet University as the sponsor and records the study status as completed.

This is not described as a randomized comparison: allocation is not stated, and the phase-based groups are not a like-for-like control comparison. The registry's stated question is a comparison of tests performed at different phases, not a comparison of exercise treadmill testing against no testing or another treatment. The description implies repeated testing across phases, but the analysis plan for relating those measurements is not reported in the registry record. In particular, it does not specify whether the primary statistical analysis treated the measurements as paired, or how it handled any participant without measurements at both phases.

The registry records enrollment of 47. Its safety listing reports 43 at risk in each of the phase-based groups; the basis for the difference between these enrollment and safety figures is not reported in the registry record. The study dates recorded are 2023-03-01 for start and 2023-09-11 for primary completion. These details describe the registered study, but do not supply its outcome estimates or establish how many complete paired outcome records were analyzed.

The primary outcome is the ST/HR index, and the registry identifies five secondary outcomes: high-sensitive cardiac troponin T after testing, maximal exercise capacity, ST/HR slope, maximal horizontal or down-slope ST segment depression during testing, and estrogen levels before testing. The statistical analysis methods, missing-data handling and analysis populations are not reported in the registry record. Completion status indicates an administrative study status, not that results were reported or that a particular finding was obtained.

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: ST/HR index (μV/bpm) are compared between the ETTs performed at the early and late follicular phases of menstrual cycle.

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 ST/HR Index (μV/Bpm), measured over approximately 15 minutes each during the exercise treadmill tests performed at the early and late follicular phases of the menstrual cycle.

The primary endpoint is the ST/HR index, measured in μV/Bpm and reported as a mean with standard deviation. The registry says the index is automatically generated by the General Electronic GE Healthcare T2100-ST Treadmill & CASE 6.73 Stress Test System at the end of an exercise treadmill test. The stated comparison is between tests performed during the early and late follicular phases; each test is described as lasting approximately 15 minutes.

The registry summary identifies ST segment deviation from baseline as a major finding of an exercise treadmill test and says ST segments are evaluated 60-80 ms after the J point. That context helps explain the endpoint's relation to the test's ECG findings. It does not establish that the ST/HR index itself diagnoses a condition, nor does the record report a threshold or a clinical interpretation for a particular index value.

As a continuous measure, the endpoint can describe both the average index and variation among the measurements, if those results are reported. Comparing the phases may address whether the measured index differs with menstrual-cycle timing in this study population. However, without the phase-specific means, a between-phase estimate and its uncertainty, the registry record does not show the size, direction or precision of any difference. The choice of this endpoint identifies the study's primary measurement; it is not evidence that a difference was found or that such a difference has a particular clinical meaning.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome summarized as a mean and standard deviation. These summaries address different features of the measurements. The mean describes the central value of a set of observations, while the standard deviation describes how spread out individual observations are around that mean. Neither summary alone gives the estimated difference between the early and late follicular phases or the precision of that difference. Those comparison results are not reported in the registry record.

What does a confidence interval add?

As a general statistical concept, a confidence interval expresses the uncertainty around an estimate under a specified analysis. For a phase comparison, an interval around the estimated difference would help readers assess which differences remain compatible with the data and how precisely the effect was estimated. It would not by itself prove a biological mechanism or establish clinical importance. No confidence interval for the primary comparison is reported in the registry record, so the precision of the result cannot be judged.

Why does the repeated-measure structure matter?

The registry describes exercise treadmill tests at both the early and late follicular phases. If the same participant contributes a result at each phase, the two values are related within that person. In general, a paired analysis uses the within-person changes and accounts for this relationship; an independent-groups analysis treats observations as unrelated. The choice can affect the standard error and the resulting uncertainty. The record does not state how the analysis handled the relationship between phase measurements, whether all analyzed participants had both tests, or how incomplete pairs were treated. It is therefore not possible to attribute a particular statistical method to this study.

How should the planning assumptions be read?

The registry describes sample-size planning as an illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is the stated fraction of the observed effect. These are planning assumptions, not a report of the trial's original design rationale. The registry record does not report the sample-size justification or its underlying protocol assumptions. Any planning figures derived from an observed effect are illustrations of how a future study might be sized under those assumptions; they are not observed power and do not measure the probability that this completed study found an effect.

The equal-allocation assumption should also be read in light of the described phase comparison. The record does not describe randomized arms; it describes testing at two phases. An assumption used for a planning calculation does not establish how participants were actually allocated, whether the measurements were paired, or whether the analyzed data had equal numbers at each phase. Those design and analysis details are not reported in the registry record.

What do the outcome summaries establish?

A mean and standard deviation can describe the distribution of a continuous outcome in each group or phase, if the relevant summaries are reported. To evaluate a comparison, readers also need the estimated contrast and its uncertainty. Statistical significance, if reported, would address compatibility with a null hypothesis under the analysis assumptions; it would not on its own establish the size, relevance or cause of a difference. Here, the primary outcome estimates and inferential results are not reported in the registry record.

For repeated measurements, the phase contrast can be described as a within-participant change, but only if the data and analysis support that interpretation. The registry's wording identifies the two test phases and comparison, but does not specify whether a change score, paired model or another method was used. Nor does it explain how the analysis accounted for possible differences in test conditions or timing. These are general considerations for interpreting repeated measurements, not claims that such problems occurred in this study.

What is known about the analysis plan?

The record lists six outcome measures and six analyses, but does not report the statistical methods for those analyses, the prespecified testing order, or whether any adjustment for multiple comparisons was planned. It does not specify how missing outcome values were handled or define the analysis population for the primary outcome. These omissions make it difficult to judge how the reported analysis, if any, relates to the registered outcomes and how robust its uncertainty estimates would be. No numerical primary-outcome result is reported in the registry record, so these method considerations cannot be resolved by interpreting an estimate.

For time-to-event outcomes, some planning approaches express required sample size as a total number of events; the registry's planning note says that its time-to-event illustrations use total events and that other illustrations use participants per arm. The primary endpoint in this study is continuous, not described as time-to-event. This distinction is general guidance for interpreting the planning convention, not evidence that a time-to-event analysis was used for the primary outcome.

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("Early Follicular Phase", "Late Follicular Phase ETT")
n   <- c(43, 43)
m   <- c(1.2, 1.3)
sp  <- c(0.82, 0.59)
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  Early Follicular Phase  43  1.200  0.820  0.948  1.452
CARM  Late Follicular Phase ETT  43  1.300  0.590  1.118  1.482

11. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and six analyses. It identifies the ST/HR index as the primary outcome and lists other measures concerning cardiac troponin T, exercise capacity, ST/HR slope, ST segment depression and estrogen levels. The registry record does not report whether the analyses followed a prespecified hierarchy, whether secondary outcomes were considered exploratory, or whether an adjustment for multiple comparisons was used.

As a general statistical issue, examining multiple outcomes can increase the chance that at least one result appears noteworthy by chance if each is tested separately. Adjustment methods or a clearly stated testing hierarchy can address this issue, but neither should be assumed without a reported plan. Since the outcome results and multiplicity strategy are not reported in the registry record, the extent to which multiple testing affected interpretation cannot be assessed.

The missing-data plan is also not reported in the registry record. It does not state whether participants missing a phase measurement were excluded, whether an imputation method was used, or what assumptions were made about missingness. The analysis population is not defined, and the record does not say how many participants contributed to each outcome analysis. The enrollment figure and the safety listing's at-risk figures do not establish the primary-outcome denominator or the completeness of paired phase measurements.

These omissions matter because the estimated comparison and its precision depend on which measurements were available and how incomplete records were handled. They do not establish that missing data or multiplicity changed a result; rather, the record does not provide enough detail to evaluate either issue.

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 safety listing reports 43 at risk in each of the two phase-based groups, zero serious adverse events in each, zero other adverse events in each, and zero deaths. The group is titled as exercise test results grouped based on the menstrual cycle. These are the safety figures recorded for the listed groups; the registry record does not explain the basis of the at-risk denominators or how they relate to enrollment of 47.

A recorded zero means no event was entered for that category in the registry listing. It does not establish that the risk of an event is zero, and it does not show how intensively events were collected or what follow-up period was used. The registry record does not report further detail about adverse-event definitions, collection procedures or the safety analysis population.

These safety counts should be interpreted separately from the primary endpoint. They do not provide evidence about whether the ST/HR index differed by phase, and they do not establish that every participant completed both tests. The record's zero counts are a limited registry report, not a complete characterization of safety or tolerability.

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

The registry defines a question about whether the ST/HR index differs between exercise treadmill tests conducted at the early and late follicular phases in premenopausal women. It also gives a rationale connected to estrogen levels and the possibility of phase-related variation in treadmill-test results. These details explain the question the study was designed to address; they do not state what the observed comparison found.

Numerical primary-outcome results are not reported in the registry record. There is no reported phase-specific mean, estimated difference, uncertainty interval or statistical test result. As a result, the evidence in this record cannot establish the direction or size of a phase-related difference, nor how precisely it was estimated. The study's completed status does not fill this reporting gap.

Even if a numerical association were available, a comparison across menstrual-cycle phases would not by itself establish that hormone changes caused a change in the test measure. The registry record does not report an analysis that separates the phase comparison from other possible influences, and it does not provide enough methodological detail to evaluate that question. A statistical difference would also not automatically tell readers whether a change is clinically important.

The study population is described as premenopausal women with chest pain who attended cardiology outpatient clinics and were ordered an exercise treadmill test. Findings from such a population, even if reported, would not automatically apply to people outside that description. The posted record does not provide outcome results that could support a broader or narrower inference.

The registry's safety listing records no serious adverse events, other adverse events or deaths in its phase-based groups. Those entries are limited to the registry safety report and do not constitute a complete account of risk. Overall, the record establishes the planned comparison and the outcomes of interest, but it does not provide the numerical findings needed to judge whether the primary endpoint varied by phase.

14. Why This Trial Matters Statistically

This study addresses a statistical question that is easy to misread if the comparison structure is overlooked. The registry describes tests at two phases of the menstrual cycle, rather than a randomized treatment and control. If the same women contributed measurements at both phases, the natural analysis would need to account for the relationship between those measurements. The registry record does not report whether that was done, making the analysis structure important to interpretation.

The primary endpoint is continuous and summarized by a mean and standard deviation. Those summaries can characterize measured values, but the central quantity for the research question is the phase contrast and its uncertainty. Without the estimate and an interval or other precision measure, a reader cannot tell whether the data are compatible with a small or large difference. The registry record does not report those results.

The record also illustrates the difference between an enrollment figure, safety denominators and an outcome-analysis population. Enrollment is recorded as 47, while the safety listing gives 43 at risk in each phase-based group. The basis for those figures and the number analyzed for the primary endpoint are not reported. These counts should not be treated as interchangeable measures of the same analytic population.

Finally, the registry lists multiple outcomes and analyses but does not report a multiplicity strategy, missing-data approach or detailed statistical plan. Those details are important for evaluating how robust an analysis is and how much weight to give findings across several measures. Without the results and methods, the scientifically useful conclusion is about what was asked, not what was found: the record registers a phase-based comparison but does not supply its inferential evidence.

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 most important limitation for interpreting this record is that it does not report numerical results for the primary ST/HR index comparison. Phase-specific means, standard deviations, an estimated contrast and a measure of precision are absent. The record therefore cannot support a conclusion about the observed direction or magnitude of a difference.

The description indicates tests during both menstrual-cycle phases, but does not specify the statistical model or whether the comparison accounted for within-participant measurements. The analysis population, number with complete measurements at both phases and handling of incomplete records are not reported in the registry record. The relationship between the enrollment figure and the safety listing's at-risk figures is also not explained.

The registry lists several outcome measures and analyses without reporting a multiplicity plan or a method for handling missing data. It does not provide enough detail to assess whether the analysis methods matched the intended comparison, whether any adjustments were prespecified, or how the uncertainty was calculated. The sample-size note describes a planning illustration based on the observed effect, not the study's own design rationale; the protocol's sample-size justification is not reported in the registry record.

The population description is limited to premenopausal women aged 20-55 years with chest pain who attended cardiology outpatient clinics and were ordered an exercise treadmill test. Results, if available, would need to be interpreted in that context. In this registry record, however, outcome results are not reported, so neither study-specific findings nor their generalizability can be evaluated.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Effects of Menstrual Cycle Phase on Exercise Treadmill Test Results in Premenopausal Women — NCT05985980.
• Registry record last updated 2026-04-15; status last verified 2026-03.
• Results first posted 2024-11-12.
• 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 study of exercise treadmill test results at the early and late follicular phases in premenopausal women with chest pain who had been ordered testing. Its primary outcome is the ST/HR index, a continuous measure automatically generated at the end of each test and summarized as a mean with standard deviation. The registry records enrollment of 47 and lists five secondary outcomes in addition to the primary measure.

Numerical primary-outcome results, detailed statistical methods, the analysis population and missing-data handling are not reported in the registry record. The record also does not report a multiplicity plan. Its safety listing records zero serious adverse events, zero other adverse events and zero deaths in each of the phase-based groups, with 43 at risk in each group. These safety figures do not establish the primary-outcome results or resolve the difference from the enrollment figure.

The record defines the research question but does not provide the results needed to assess the observed phase comparison.