The Pharmacokinetics of 12 Week Continuous Patch Use: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Pharmacokinetics of 12 Week Continuous Patch Use (NCT02585999), a na na study. The primary outcome is Change in Serum EE2 Levels Over 12 Weeks of Continuous Contraceptive Patch Use.

2. Clinical Question

In practical statistical terms, the question is about the pattern of measured hormone concentrations over time within a group using the patch. The primary endpoint is described as change in EE2, but the first blood draw occurred at the end of the first patch week, not before patch use. Thus the listed measurements do not include a pre-use baseline value. The record describes repeated blood collection during the weeks of use and after removal of the final patch, but does not provide the observed concentrations, an estimated change, or a summary of the time pattern.

Without a comparator, measurements cannot establish how the observed course would differ from a course without the patch or under another regimen. The study can be understood as a descriptive pharmacokinetic investigation, as stated in the record; the posted information does not allow readers to assess the size or precision of any observed hormone changes.

3. Trial Design

This completed study is registered as a single-group, descriptive pharmacokinetic study of continuous contraceptive patch use. The planned enrollment was 30, and the intervention was the Xulane contraceptive patch used for 12 continuous weeks. The record lists no allocation method and no masking. Its phase is recorded as not applicable. The sponsor is Boston Medical Center. The recorded start was 2015-10 and primary completion was 2016-05.

The study was not designed as a randomized comparison: all participants in the described group used the patch, and there is no separate control arm. Accordingly, its central statistical purpose is to characterize serum hormone measurements across a schedule of repeated blood draws, not to estimate a treatment difference between groups. The registry lists pharmacokinetics as the condition and identifies two outcome measures: the primary EE2 outcome and the secondary NGMN outcome.

The primary outcome description specifies 18 blood draws in total: once at the end of each patch week, with two draws during weeks four, eight and twelve, the additional draw occurring mid-week, and further draws for three continuous days after the final patch was removed. The first draw was at the end of the first patch week; there was no pre-use baseline draw. The record says liquid chromatography-tandem triple quadrupole mass spectrometry was used to assess EE2.

Although enrollment was 30, the primary outcome description says samples from 28 participants were analyzed. It includes samples from one participant who began the study and withdrew early. The record does not clarify the disposition of every enrolled participant or provide a participant flow account beyond this statement.

The registry status is completed, but completion status does not itself provide outcome findings. Numerical hormone measurements, estimates of change, uncertainty intervals, and statistical tests are not reported in the registry record. The analysis model and detailed statistical plan are also not reported in the registry record. Therefore, design features can be described, but the particular approach used to summarize or compare the repeated measurements cannot be established from this 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.

Before assignment: 30 participants completed the baseline questionnaire, but 2 withdrew prior to starting the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis was performed on all samples. Thus samples for 28 participants were analyzed, including the one participant who began the study but withdrew early \[lost to follow up\]. The first blood draw occurred at the end of the first patch week; there was no baseline draw prior to patch use.

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.

Population: 30 participants completed the baseline questionnaire, but 2 withdrew prior to starting the study.

6. Primary Endpoint

The registry lists the primary outcome as Change in Serum EE2 Levels Over 12 Weeks of Continuous Contraceptive Patch Use, measured over Total of 18 blood draws - once at the end of each patch week and two times during weeks four, eight and twelve (with the additional blood draw occurring mid-week); and blood draws performed for three continuous days after the final patch was removed.

The primary endpoint concerns change in serum ethinyl estradiol (EE2) levels during 12 weeks of continuous contraceptive patch use. EE2 is one of the hormones the investigators planned to monitor as part of the study’s pharmacokinetic description. The outcome is continuous: each blood sample yields a concentration measurement, expressed in pg/ml, and the registry identifies the intended summary parameter as a mean with standard deviation.

Repeated concentration measurements can describe how a measured level varies across the study’s sampling schedule. In general, tracking a continuous measure over time can help characterize its pattern and variability during an exposure period. The listed schedule includes weekly sampling, additional mid-week draws in specified weeks, and draws after the final patch was removed. The record says the first sample was collected at the end of the first patch week, so the measurements do not include a pre-use baseline. That distinction matters when interpreting the word “change”: the registry title states a change outcome, but a pre-use value is not among the described samples.

The endpoint description names the laboratory method used to assess EE2, but the record does not provide assay results, an estimated mean at any time point, a change estimate, standard deviations, or confidence intervals. It also does not report the statistical model used to handle the repeated measurements. Consequently, the endpoint’s intended subject and measurement schedule are clear, while the magnitude, direction, and precision of any observed pattern are not reported in the registry record.

NGMN levels form the secondary outcome. Their results are likewise not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous outcome, a mean summary, and standard deviation as the measure of dispersion. It also gives a detailed schedule of repeated blood draws. These details identify the type of data planned, but they do not state the exact statistical model or inferential procedure used. The method of analysis is not reported in the registry record.

What does a mean summarize?

In general, a mean is the arithmetic average of measured values. For a concentration outcome, it gives a central summary of the readings included in the calculation. A mean can be useful for describing a group’s measurements, but it does not show whether each participant followed the same pattern. Different underlying distributions and participant-level trajectories can yield similar averages. The record does not provide the EE2 means at particular sampling times, so no observed mean pattern can be described.

What does a standard deviation describe?

In general, a standard deviation describes the spread of measurements around their mean. It is not the same as a confidence interval. A standard deviation describes variability among observations, whereas a confidence interval expresses uncertainty about an estimated quantity under the assumptions of the analysis. The registry names standard deviation as the intended dispersion measure but does not report its values. It also does not report confidence intervals for the primary or secondary outcomes.

Why do repeated measurements matter?

The sampling plan includes multiple blood draws over time, and measurements from the same participant are usually related. In general, repeated readings from one person tend to share participant-specific features, so treating every reading as if it came from a different person can misrepresent the amount of independent information. Analyses of longitudinal data commonly account for within-person association, but the registry does not identify whether a repeated-measures model, another longitudinal method, or only descriptive summaries were used. It is not possible to infer the analysis from the endpoint wording alone.

The schedule itself is not uniform in the sense of one sample at every listed occasion: it specifies weekly draws, extra mid-week draws in weeks four, eight and twelve, and post-removal draws on three continuous days. In general, measurements taken at different intervals can contribute different information about a time course. An analysis would need to respect the actual sampling times and the relationship among a participant’s observations. The record supplies no model specification, handling of timing, or rule for summarizing these repeated readings.

What can a confidence interval tell a reader?

In general, a confidence interval gives a range of values compatible with an estimate under a specified statistical procedure and its assumptions. A narrower interval indicates greater precision for that estimate, while a wider interval indicates greater uncertainty. It does not mean that the true value has a specified probability of lying in the particular interval after it has been calculated. No confidence interval is reported for either hormone outcome, so the precision of the findings cannot be judged from the registry record.

What do p-values and significance levels mean?

In general, a p-value measures how unusual data at least as extreme as the observed data would be under a specified null model and its assumptions. It does not measure the size or clinical importance of an effect, nor does it establish that an effect is absent when the result is not statistically significant. The registry record does not report outcome p-values or a planned hypothesis test. Its sample-size assumptions mention a two-sided significance level of 0.05 for a planning illustration; that is not evidence that this study used a particular test or significance threshold in its outcome analysis.

How should the planning illustration be understood?

The registry describes a planning illustration based on an observed effect, with a normal approximation, equal allocation between two arms, and a two-sided significance level of 0.05. It considers an effect to detect expressed as a fraction of the observed effect. Those assumptions describe an illustrative two-arm planning exercise, not the actual design of this single-group study. The study has no randomized two-arm comparison, and the registry does not report the numerical planning results in the information available for interpretation. Such sample-size illustrations are hypothetical planning quantities, not observed power and not evidence about the precision achieved in the completed study.

The record does not state how the observed effect used in that illustration was obtained, and readers should not substitute an assumed value. Nor should a planning calculation be read as a trial’s original sample-size justification: the record explicitly characterizes it as an illustration rather than the trial’s own design. The trial’s protocol-level sample-size justification is not reported in the registry record.

Finally, the laboratory method is named for EE2, but statistical analysis and measurement are distinct. A laboratory assay produces concentration readings; statistical methods summarize or compare those readings. Naming the assay does not reveal how values were transformed, how repeat measurements were modeled, how missing readings were treated, or how uncertainty was calculated. Those details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary outcome, change in EE2 levels over 12 weeks, and a secondary outcome, NGMN levels over the same period. It does not report how many statistical hypotheses were tested, whether particular time points were designated for formal testing, or whether any multiplicity adjustment was planned. A multiplicity strategy is not reported in the registry record. When multiple outcomes or comparisons are considered, general statistical practice recognizes that the chance of at least one false-positive result can rise; methods to address that depend on the intended inferential questions. The record does not establish whether such methods were used.

The record lists no analyses. This does not establish that no analysis occurred; it means that no specific analysis results or methods are presented in the registry information. The endpoint specifies mean and standard deviation, but that alone does not identify a complete analysis plan, including tests, models, confidence intervals, or rules for interpreting results.

For the primary outcome, the description says analysis was performed on all samples and that samples from 28 participants were analyzed. It explicitly includes the one participant who began the study and withdrew early. Enrollment was 30. The record does not account for every enrolled participant or state why every other enrolled participant’s samples are not included. It does not say whether all planned samples were available from each analyzed participant.

In general, missing measurements can affect a repeated-measures analysis, particularly if missingness is related to participant characteristics or outcomes. The record does not report how missing blood draws were handled, whether missingness was assessed, or whether any imputation or sensitivity analysis was used. A formal intention-to-treat or per-protocol population is not identified in the registry record. Therefore, the stated analysis of all samples should not be expanded into assumptions about participant-level inclusion or missing-data methods.

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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: any adverse event (0.0%).

The registry’s serious adverse event figures list 28 participants at risk in the Xulane group and zero serious adverse events. It also lists zero other adverse events and zero deaths for that group. The record gives “Any Adverse Event” as 0.0% among the top serious terms. These are the posted counts and percentage; they do not provide the underlying collection procedures or a description of event surveillance.

In general, an observed count of zero means no event of the listed type was recorded in the stated group during the registry’s reporting period. It does not prove that the true event risk is zero, and it does not establish that an event could not occur in another setting or population. The amount of information in a safety count depends on the number of participants observed, the duration and completeness of follow-up, and how events were collected and classified. Details on those matters are not reported in the registry record beyond the stated at-risk count and study schedule.

The figures should be read separately from the pharmacokinetic endpoints. They do not supply EE2 or NGMN concentrations and do not indicate the direction or precision of any hormone measurements. The single-group design also provides no randomized control group for a comparative safety estimate. No broader safety conclusion can be drawn from the posted zero counts alone.

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

This study asks a focused descriptive question: how serum EE2 and NGMN levels were assessed during 12 weeks of continuous Xulane patch use. It documents repeated sampling, including draws during patch use and after removal of the final patch, and identifies the assay method for EE2. The registry record also reports that samples from 28 participants were analyzed and that one participant who withdrew early was included in the sample analysis.

What the posted information does not show is the result of those measurements. No hormone concentrations, means, standard deviations, estimates of change, confidence intervals, or p-values are reported. It is therefore not possible to say from this record whether concentrations rose, fell, remained similar, or varied in some other pattern, or how precisely any such pattern was estimated. The outcome results are not reported in the registry record.

The lack of a pre-use baseline is another limit on what can be interpreted. Since the first draw occurred at the end of the first patch week, the described measurements do not directly compare a pre-use value with subsequent values. The single-group design also has no concurrent comparator, so it cannot provide a randomized contrast against another treatment or no patch use.

In general, a pharmacokinetic description can inform understanding of measured concentrations over time, but a registry description of study aims is not itself evidence about the observed trajectory. The named laboratory assay and sampling plan explain how the intended data were collected; they do not replace numerical results or an account of statistical analysis. The record’s completed status means the trial is marked completed, not that its primary question has been answered in the posted results.

Accordingly, the statistical meaning of this record is chiefly about design, measurement, and the limits of available reporting. It supports describing the intended longitudinal assessment, but not estimating the magnitude or precision of either hormone outcome or drawing comparative conclusions.

13. Why This Trial Matters Statistically

This trial is statistically notable for the distinction between a longitudinal measurement question and a comparative treatment question. It follows one group and schedules repeated blood draws during continuous patch use. Such data can describe within-group patterns over time, but they do not create a control comparison. Keeping those questions separate prevents a descriptive trajectory from being interpreted as a treatment contrast.

The repeated-measures structure also matters. A participant may contribute multiple observations, and those readings are generally related. In general, analyses that ignore within-person association can misstate uncertainty. The registry gives enough detail to recognize repeated sampling, but it does not identify the model or other analysis method used. That makes the absence of reported analysis results particularly consequential: even a list of means would not by itself explain how dependence among repeated readings was handled.

The sampling plan has a further interpretive feature: the first blood draw occurred at the end of the first patch week, with no pre-use baseline. The stated primary objective concerns change, yet a direct pre-use-to-follow-up comparison is not available from the described schedule. This is a useful reminder that an endpoint label and the data actually collected must be considered together.

Finally, the registry’s planning illustration uses a hypothetical equal-allocation, two-arm framework, whereas the study itself is single group. That distinction is important when interpreting any sample-size planning figures: a planning scenario does not describe the observed design and does not establish observed power. Since numerical outcome estimates and the analysis are not reported, the central statistical lesson is one of careful boundaries—what the design can describe, what it cannot compare, and what cannot be evaluated without results.

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 main trial-specific limitation in interpreting the registry record is the absence of numerical outcome results. The primary and secondary hormone measurements are named, but observed values, summaries, estimates, and uncertainty measures are not reported in the registry record. It is therefore not possible to assess the direction, size, variability, or precision of the measured hormone patterns.

The design is single group, with no randomized comparator. As a result, the record describes measurements during patch use but does not provide a direct comparative estimate against another regimen or a control group. The absence of a pre-use blood draw also limits interpretation of “change”: the first listed draw was at the end of the first patch week, rather than before patch use.

The analysis details are sparse. The record identifies mean and standard deviation for the primary continuous outcome and names the EE2 assay, but the statistical model, uncertainty method, handling of repeated observations, and any analysis of missing measurements are not reported in the registry record. The registry lists no analyses, so inferential conclusions cannot be checked against a stated model or reported result.

Enrollment was 30, while samples from 28 participants were analyzed. The outcome description includes one participant who withdrew early, but the record does not account for every enrolled participant or explain all missing participant-level data. It also does not say how many planned draws were available from each participant or how any absent readings were treated.

Finally, the safety figures report zero listed adverse events among 28 at risk, but the registry does not provide detailed event-collection methods or a comparator. Those counts should not be treated as a complete assessment of safety. Together, these reporting and design limits constrain what can be concluded from the registry record, independently of the study’s completed status.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Pharmacokinetics of 12 Week Continuous Patch Use — NCT02585999.
• Registry record last updated 2017-05-30; status last verified 2017-04.
• Results first posted 2017-05-30.
• 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.

18. Record Summary

NCT02585999 is a completed, single-group descriptive pharmacokinetic study sponsored by Boston Medical Center. The record lists planned enrollment of 30 and continuous use of the Xulane contraceptive patch for 12 weeks. Its primary objective was to assess change in serum EE2; its secondary objective was to assess NGMN levels. The primary outcome description specifies repeated blood draws during patch use and after final patch removal, with no pre-use baseline draw. EE2 was assessed using liquid chromatography-tandem triple quadrupole mass spectrometry.

The record states that samples from 28 participants were analyzed, including one participant who withdrew early. It lists zero serious adverse events, zero other adverse events, and zero deaths among 28 at risk. Numerical hormone results, statistical analyses, and detailed missing-data methods are not reported in the registry record. Thus the study’s design and measurement plan are described, but the outcome magnitude and precision cannot be evaluated from the posted information.