Use of High Cost Monitoring During Letrozole Ovulation Induction: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Use of High Cost Monitoring During Letrozole Ovulation Induction (NCT01279200), a randomized phase 4 study. The primary outcome is Pregnancy Success Rate.

2. Clinical Question

The clinical question is about the monitoring strategy used during letrozole cycles, rather than a comparison of letrozole with another medication. Both arms concern ovulation monitoring during treatment. The distinction is that one relies on home urinary testing, while the other uses office-based ultrasound and may include an hCG injection when a mature-size follicle is seen.

The registry identifies infertility as the condition and labels the study a pilot study. The posted primary outcome is pregnancy success rate, expressed as a percentage of participants. A secondary outcome is time to conception, measured in cycles, but a result for that outcome is not reported in the registry record. Eligibility criteria, baseline characteristics, and details needed to determine how broadly the results apply are not reported in the registry record.

3. Trial Design

The registry describes a randomized, parallel-group, unmasked phase 4 pilot study sponsored by the University of Michigan. The study status is completed. The listed enrollment is 21. The start is recorded as 2011-01 and primary completion as 2013-03.

Participants were assigned to one of two monitoring approaches. The Urinary LH Kits arm used home-based kits to monitor ovulation. The Midcycle Ultrasound + hCG Injection arm used midcycle ultrasound and included an hCG injection if evidence of a mature-size follicle was found. The record does not describe the sequence or method used to generate the random allocation, how assignments were concealed, or whether allocation was balanced during recruitment. Those details are not reported in the registry record.

Parallel-group means that the arms are described as separate groups receiving different monitoring approaches. Unmasked means that the study is recorded as having no masking. The registry does not specify which people involved in care, outcome assessment, or analysis knew the assigned monitoring approach. The details of the study setting, recruitment process, eligibility criteria, and treatment procedures beyond the arm descriptions are not reported in the registry record.

The primary outcome was pregnancy success rate within 3 menstrual/treatment cycles, approximately 28-33 days each. The posted percentages use different arm denominators: n=8.0 for Urinary LH Kits and n=4.0 for Midcycle Ultrasound + hCG Injection. The overall enrollment is listed as 21, and the registry does not explain why the outcome denominators differ from that total or from each other. The secondary outcome is time to conception, measured in cycles, but no result is reported in the registry record.

The study is labelled a pilot, but its intended feasibility goals and the way they informed its design are not reported in the registry record. A sample-size justification, planned interim analyses, and a detailed statistical analysis plan are also 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

Reasons for not completing this period:

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 Pregnancy Success Rate, measured over 3 menstrual/treatment cycles (approximately 28-33 days each).

The primary endpoint is pregnancy success rate: the percentage of women in each arm who became pregnant within the stated study time frame of 3 menstrual/treatment cycles, approximately 28-33 days each. This is a binary outcome at the participant level: each participant either met the pregnancy outcome within that period or did not. Reporting a percentage gives a direct description of how often the outcome occurred in each monitoring group.

This endpoint is relevant to the study question because the registry’s stated purpose is to investigate monitoring methods during letrozole ovulation induction and their relationship to pregnancy rates. It captures pregnancy within a defined period, rather than time to pregnancy across a longer or unspecified period. The listed secondary outcome, time to conception measured in cycles, addresses timing in a different way; its result is not reported in the registry record.

The registry posts a pregnancy success rate of 75.0% for Urinary LH Kits, with n=8.0, and 25.0% for Midcycle Ultrasound + hCG Injection, with n=4.0. These are descriptive percentages based on the listed arm denominators. The record does not provide confidence intervals or an inferential comparison for this endpoint, so the precision of each percentage and the uncertainty around the between-arm contrast cannot be assessed from the posted results. The reason the outcome denominators differ from the listed enrollment is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary measure is a binary outcome summarized as a percentage of participants with the event. In this study, the event is becoming pregnant within the specified study period. A percentage is a descriptive statistic: it states the proportion of the listed group recorded as having the outcome. The registry gives 75.0% for Urinary LH Kits (n=8.0) and 25.0% for Midcycle Ultrasound + hCG Injection (n=4.0).

What does a confidence interval add?

In general, a confidence interval expresses the uncertainty in an estimate arising from sampling variability. A narrow interval indicates greater precision, while a wide interval indicates less precision. For a binary percentage, the amount of information depends in part on the number of participants and the balance of outcome statuses. Small groups generally yield less precise estimates. No confidence intervals are reported for the primary outcome in the registry, so readers cannot assess precision using intervals or compare the range of plausible values across arms.

What does randomization contribute?

In general, random assignment is intended to make treatment groups comparable with respect to measured and unmeasured characteristics on average. It does not guarantee balance in every small trial. The registry labels this study randomized but does not report the allocation sequence, concealment procedures, or baseline characteristics. It is therefore possible to identify the design label, but not to assess how randomization was implemented or whether the groups appeared similar at the start.

How should the arm denominators be read?

The primary outcome is reported with n=8.0 in the urinary-kit arm and n=4.0 in the ultrasound-plus-injection arm. Enrollment is listed as 21. A denominator specifies the group count associated with the reported outcome; it does not, on its own, explain how participants were selected for that outcome summary. The registry does not say why the denominators are smaller than the enrollment figure or why they differ between arms. The analysis population and handling of missing outcome data are not reported in the registry record.

The safety outcome counts have separate denominators: 10 participants at risk for the listed serious and other adverse-event summaries in the urinary-kit arm and 11 in the ultrasound-plus-injection arm. These are safety denominators, not the primary-endpoint denominators. The registry does not explain the relationship among these different counts and the overall enrollment.

What is available for the between-arm comparison?

The registry does not report an inferential comparison for the binary primary endpoint; it notes that values are missing or not estimable for a two-arm comparison. No p-value, confidence interval, or model-based estimate is listed. General statistical practice distinguishes a descriptive difference between observed group percentages from an inferential estimate that quantifies uncertainty and supports a formal comparison. The registry results support the descriptive statement of each arm’s percentage, but not a claim about statistical significance.

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not evidence about the study’s observed statistical power, and the sample-size justification for the trial itself is not reported in the registry record. The illustration is not the trial’s own design calculation.

What can be learned from a pilot study?

In general, pilot studies can help characterize procedures and generate preliminary estimates, but small groups often leave treatment-effect estimates imprecise. The registry calls this a pilot study, yet does not report specific feasibility outcomes or a rationale for the enrollment target. The primary results should therefore be treated as limited descriptive evidence rather than as a definitive estimate of comparative performance.

The listed secondary outcome is time to conception measured in cycles. Time-to-event methods can account for the timing of an event and, when relevant, participants who have not yet experienced it by the end of observation. The registry does not provide a result, event count, censoring information, or analysis method for this outcome. Those features cannot be evaluated from the posted record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Urinary LH Kits", "Midcycle Ultrasound + hCG Injection")
n      <- c(8, 4)
events <- c(6, 1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Urinary LH Kits  8  6  75.0  34.9  96.8  40.9  92.9  40.0  92.5
ARM  Midcycle Ultrasound + hCG Injection  4  1  25.0  0.6  80.6  4.6  69.9  5.3  71.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome, pregnancy success rate, and one secondary outcome, time to conception measured in cycles. It reports no analyses. A plan for handling multiple outcomes or multiple statistical tests is not reported in the registry record. Without that information, it is not possible to determine whether the primary outcome was the sole confirmatory analysis or how any secondary findings were intended to be interpreted.

Missing-data procedures are not reported in the registry record. The primary outcome lists n=8.0 for Urinary LH Kits and n=4.0 for Midcycle Ultrasound + hCG Injection, while overall enrollment is 21. The registry does not explain the difference or state whether participants without a recorded pregnancy outcome were excluded, treated as not pregnant, or handled another way. These possibilities should not be assumed.

The analysis population is not reported in the registry record. The record does not say whether the reported primary percentages include all randomized participants, only participants with observed outcomes, or another defined group. It also does not describe withdrawals, losses to follow-up, or protocol deviations. The posted results therefore cannot be used to reconstruct the analysis population or evaluate the consequences of missing outcomes.

The registry’s lack of reported analyses and missing-data methods does not establish that no such methods were used; it means the registry record does not document them. The same distinction applies to multiplicity: no adjustment strategy or testing hierarchy is reported. The secondary outcome has no posted result, so its relationship to the primary outcome cannot be assessed.

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.

Most frequent non-serious adverse event terms

The registry reports no serious adverse events among the 10 participants at risk in the Urinary LH Kits arm and none among the 11 participants at risk in the Midcycle Ultrasound + hCG Injection arm. For other adverse events, it reports 1 affected participant among 10 at risk in the urinary-kit arm and 0 among 11 at risk in the ultrasound-plus-injection arm. These are separate safety summaries, not the denominators used for the primary pregnancy outcome.

Zero reported serious events means that none were recorded in these groups during the registry’s safety reporting. It does not establish that the risk is absent; small groups can provide limited information about uncommon events. The registry does not provide serious adverse-event terms, and deaths are not reported in the registry record. The duration and completeness of safety follow-up and the criteria used to classify events are not reported in the registry record.

These figures should be read as counts within the stated at-risk groups. They do not provide a formal comparison of safety between arms, and the registry does not report an inferential analysis of adverse events. The counts alone cannot establish whether one monitoring approach has a different safety profile.

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

The registry records different pregnancy percentages in the two arms: 75.0% for Urinary LH Kits and 25.0% for Midcycle Ultrasound + hCG Injection. These are observed descriptive results among the listed primary-outcome denominators, n=8.0 and n=4.0, respectively. They describe the participants included in those summaries and the study’s stated period of 3 menstrual/treatment cycles, approximately 28-33 days each.

The results do not establish the size or precision of a reliable comparative effect. No confidence intervals or inferential comparison are reported, and the registry notes that values were missing or not estimable for a two-arm comparison of the binary endpoint. The outcome denominators are small, and the reason for their difference from each other and from the listed enrollment of 21 is not reported in the registry record. Those features limit what can be inferred from the percentages.

The results also do not answer every question posed by the study description. Time to conception, measured in cycles, is listed as a secondary outcome, but a result is not reported in the registry record. There is no reported analysis of how pregnancy timing differed between monitoring approaches.

These registry results do not show whether the monitoring approaches are equivalent, nor do they establish that either is superior. They also do not establish that ultrasound monitoring adds or does not add cost, because cost results are not reported in the registry record. The posted values are preliminary descriptive findings from a pilot study, not a complete account of comparative effectiveness, cost, or safety.

14. Why This Trial Matters Statistically

This study raises a useful statistical question about how monitoring strategies are compared when the outcome is a participant-level event such as pregnancy within a defined period. The binary endpoint is easy to describe as a percentage, but interpreting a difference between percentages depends on the amount of information behind each estimate. Here, the registry lists n=8.0 and n=4.0 for the primary outcome, so the percentages are based on small groups.

The study also illustrates why the denominator is essential to interpretation. A percentage without its group count can suggest more precision than the data support. Even with the counts posted, the relationship between the primary-outcome denominators and the overall enrollment of 21 is unexplained. Readers cannot determine from the record whether this reflects missing outcomes, an analysis-population decision, or another circumstance.

Another important statistical distinction is between an observed contrast and a reported inferential comparison. The registry gives arm-specific percentages, but no confidence intervals or hypothesis-test results and records the two-arm comparison as not estimable. The values can be described, but their comparative uncertainty is not quantified in the posted results.

Finally, the registry lists time to conception as a secondary outcome without a result. This matters because pregnancy within a fixed period and time to conception answer related but distinct questions. Reporting both outcomes with clear denominators and methods would allow readers to understand whether the evidence concerns the chance of pregnancy within the specified window, the timing of conception, or both. The record demonstrates the importance of transparent outcome reporting in small randomized studies.

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 primary outcome denominators are n=8.0 and n=4.0, while enrollment is listed as 21. The registry does not explain this difference. Without an account of participant flow, missing outcomes, or the analysis population, it is not possible to establish how the posted percentages relate to all randomized participants.

No confidence intervals or inferential comparison are reported for pregnancy success rate. The registry states that values were missing or not estimable for the two-arm comparison. Consequently, the precision of the arm-specific percentages and the uncertainty around their contrast are not quantified in the record.

Important design and analysis details are absent. The randomization method and concealment procedures, eligibility criteria, baseline characteristics, missing-data approach, multiplicity plan, and statistical analysis plan are not reported in the registry record. The details of outcome ascertainment and follow-up are also not reported, so completeness and consistency of pregnancy assessment cannot be evaluated.

The secondary outcome, time to conception measured in cycles, has no posted result. The registry does not provide participant-level timing, event or censoring information, or an analysis method for that outcome. Cost outcomes are not reported, despite the study description raising cost as a motivation. The safety record provides event counts but does not report follow-up duration or detailed event terms; deaths are not reported in the registry record.

Finally, the registry calls the study a pilot but does not report the objectives behind that designation or a sample-size justification for the trial. The posted planning assumptions are described as an illustration based on the observed effect, not the trial’s design. These limitations restrict conclusions to the descriptive results and the information explicitly recorded.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Use of High Cost Monitoring During Letrozole Ovulation Induction — NCT01279200.
• Registry record last updated 2015-01-06; status last verified 2015-01.
• Results first posted 2015-01-06.
• 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

NCT01279200 is a completed, randomized, parallel, unmasked phase 4 pilot study sponsored by the University of Michigan. The registry lists enrollment of 21, a start of 2011-01, and primary completion of 2013-03. The study concerns monitoring during letrozole ovulation induction for infertility.

The two arms used home urinary LH kits or midcycle ultrasound with hCG injection if a mature-size follicle was identified. The primary outcome was pregnancy success rate within 3 menstrual/treatment cycles, approximately 28-33 days each. The posted percentages are 75.0% for Urinary LH Kits (n=8.0) and 25.0% for Midcycle Ultrasound + hCG Injection (n=4.0).

No inferential comparison or confidence intervals are reported for the primary outcome. The registry lists time to conception measured in cycles as a secondary outcome but provides no result. The reasons for the primary-outcome denominators and their difference from total enrollment are not reported in the registry record.