Self-Administered Lidocaine Gel for Pain Management With IUD Insertion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Self-Administered Lidocaine Gel for Pain Management With IUD Insertion (NCT02738203), a randomized phase 3 study. The primary outcome is (IUD Insertion): Pain Perceived by Visual Analogue Scale (0-100 mm) Immediately Following Procedure Completion.

2. Clinical Question

The trial was described as a superiority, blinded, randomized controlled trial. Its central question concerns pain perceived immediately after the procedure, not the secondary outcomes of anticipated pain, baseline pain, or pain after speculum or tenaculum placement. Those secondary outcomes are listed separately in the registry record.

The comparison is between two vaginally administered gels before insertion. It is not a comparison of lidocaine with an untreated control in the posted arm descriptions: the recorded control is surgical lubricant jelly. That distinction matters when interpreting what the trial directly evaluates. The registry record does not report further detail about the clinical setting, eligibility criteria, or the experience of participants undergoing insertion.

3. Trial Design

The registry record describes a randomized, double-masked, parallel-group Phase 3 trial, marked completed. Enrollment is listed as 220. The start date is 2016-06-01, and the primary completion date is 2017-10-19. The sponsor is Stanford University. These record details describe the trial's registered design and administrative status; they do not, by themselves, establish how the intervention affected pain.

Participants were assigned to an experimental group receiving vaginal 2% lidocaine or a control group receiving surgical lubricant jelly. Each arm description specifies a pre-filled vaginal inserter containing 10 ml of gel, to be inserted 20-30 minutes before the procedure. The record says participants would not know which gel they received, but the arm-description text is incomplete. The exact masking procedures for clinicians, outcome assessors, or other personnel are not reported in the registry record.

Random allocation is generally used to reduce systematic differences between groups at assignment. In a parallel-group design, participants remain in their assigned study group rather than crossing between interventions. These are general features of the design; they do not guarantee balanced groups or remove bias in every aspect of trial conduct. The registry record does not report the randomization sequence, allocation concealment procedures, or the methods used to preserve masking.

The registry summary describes the study as testing lidocaine in place of standard-care pain management, described there as no intervention. However, the listed control arm and intervention are surgical lubricant jelly. The record therefore identifies the active comparison as lidocaine gel versus surgical lubricant, and the difference in wording should be kept in view. Further protocol detail explaining that wording is not reported in the registry record.

The posted primary outcome uses a per-protocol population. The registry record does not provide a corresponding intention-to-treat analysis, a participant flow account, or details of exclusions from the per-protocol population. Those omissions limit assessment of how the analyzed participants relate to everyone enrolled.

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: Per protocol analysis

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: Per protocol analysis

6. Primary Endpoint

The registry lists the primary outcome as (IUD Insertion): Pain Perceived by Visual Analogue Scale (0-100 mm) Immediately Following Procedure Completion, measured over 0-3 minutes after procedure completed.

The primary endpoint is pain perceived immediately after IUD insertion, measured by a visual analogue scale. The registry title describes the measure as pain following procedure completion; its description specifies pain immediately after speculum removal. The recorded timeframe is 0-3 minutes after the procedure was completed. The score ranges from 0-100 mm, anchored by no pain at 0 and worst pain imaginable at 100. A higher score indicates higher pain.

The reported summary measure is the median, accompanied by the full range. The median describes the middle of the observed scores when they are ordered; it is a useful general summary when scores may be unevenly distributed or affected by extreme values. The full range gives the lowest and highest observed scores, but does not show how scores are distributed between those endpoints. The registry record does not report an interquartile range or another measure of spread.

A patient-reported pain score is relevant to the question because it records the participant's perception of pain rather than relying only on an observer's assessment. That is a general reason to use a self-report measure for a subjective experience. The score should nevertheless be interpreted as a measure at the stated time, not as a complete account of pain before, during, or after the procedure.

The endpoint is reported for a per-protocol analysis. The registry record does not explain the criteria used to define that population. It also does not provide a formal estimate of the between-group difference or its uncertainty, so the posted medians and ranges alone do not quantify the precision of a treatment contrast.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the primary outcome as a median pain score with full range, analyzed in a per-protocol population. It does not identify a formal statistical test or provide a model-based estimate of the treatment contrast. The following concepts explain how such results are generally read; they are not claims about unreported methods used by the trial.

What does a median describe?

In general, the median is the central value after observations are ordered. Unlike a mean, it is not calculated by adding every score and dividing by the number of observations. This makes it less sensitive to extreme scores, although it does not show the shape of the score distribution. For the trial, the reported medians are 65.0 for lidocaine and 59.0 for surgical lubricant. The registry record does not report another location measure, such as a mean, or a measure such as the interquartile range.

What does the full range add?

In general, the range runs from the smallest to the largest observed value. It gives a direct account of the endpoints of the observed data but says little about the scores between them. The lidocaine group's range is 1.0 to 99.0; the control group's range is 5.0 to 100.0. The endpoints do not reveal whether extreme scores were unusual or common, and they do not give a confidence interval for the median or the difference between groups.

Why is a comparative estimate useful?

A randomized trial is usually interpreted through a contrast between groups, accompanied by an assessment of uncertainty. In general, an estimate states the size and direction of the contrast under a chosen analysis, while a confidence interval indicates the precision of that estimate. A p-value, if reported, addresses compatibility with a specified null hypothesis under the test's assumptions; it does not measure the probability that the null hypothesis is true or the clinical importance of an effect. The registry record does not report a comparative estimate, confidence interval, or p-value for the primary outcome. None should be inferred from the medians alone.

Why can medians and ranges be insufficient?

Group summaries compress participant-level data. Different distributions can have the same median and range, so the summaries cannot show the full pattern of scores. General methods for comparing medians or ordinal-like outcomes may use different assumptions and answer different questions. The registry record does not report which method, if any, was used for a formal comparison. It would not be appropriate to select a test after seeing these summaries and present its result as the trial's analysis.

What does randomization contribute?

In general, random assignment aims to make treatment groups comparable with respect to measured and unmeasured characteristics at the point of assignment, on average over repeated randomizations. It does not ensure that every individual characteristic is balanced in one trial. It also does not correct issues that can arise after assignment, such as missing outcomes, non-adherence, or analysis choices. The registry describes random allocation, but the sequence-generation and concealment methods are not reported in the registry record.

How should the analysis population be read?

The primary outcome is labeled per protocol. In general, a per-protocol analysis focuses on participants who meet criteria for adherence or protocol completion, but the exact definition varies by trial. Here, the criteria are not reported in the registry record, so the label cannot be used to determine who was included or excluded. An intention-to-treat analysis generally retains participants in their randomized groups regardless of adherence. Whether such an analysis was conducted is not reported in the registry record.

What is over-dispersion, and does it apply?

In general, over-dispersion occurs when observed variability is greater than a model expects under its assumptions. It can matter for count outcomes when a model assumes a particular variance structure. The primary endpoint is a pain score summarized by a median and range, not a posted count outcome with a variance model. The registry record does not report a model or an over-dispersion assessment for the primary endpoint; no such assessment can be attributed to the trial.

What do planning illustrations mean?

In general, sample-size planning asks how many participants per arm would be needed to detect a chosen effect under specified assumptions. The record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the target effect is a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the trial was designed with those assumptions. The registry record does not report the trial's own sample-size justification.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists four secondary outcomes: anticipated pain, baseline pain, pain after speculum placement, and pain after tenaculum placement, each measured by a visual analogue scale. The primary outcome is pain immediately after the procedure. The presence of several outcomes raises a general multiplicity issue: when many hypotheses are tested, the chance of at least one apparently notable result can increase. Adjustment strategies and a prespecified hierarchy can address this, depending on the scientific question and analysis plan.

Whether any multiplicity adjustment was planned or applied is not reported in the registry record. No secondary outcome results or formal analyses are included in the record. The registry lists no analysis entries. It is therefore not possible to determine which outcomes were formally tested, whether tests were prespecified, or how multiple comparisons were handled.

The primary outcome is labeled per protocol. The registry record does not report the criteria for inclusion in that population, the number excluded from it, or whether participants with missing pain scores were excluded or handled by another method. It does not describe imputation, sensitivity analyses, or reasons for missing outcome data. The posted outcome counts are 108.0 for the experimental group and 107.0 for the control group, but these figures alone do not explain missingness or establish how many randomized participants contributed to other analyses.

In general, missing-data methods rely on assumptions about why measurements are absent. Different assumptions can yield different estimates, so reporting the amount, pattern, reasons, and handling of missing data is important. Those details are not reported in the registry record. The record also does not report an intention-to-treat analysis. Consequently, the posted per-protocol summaries should not be treated as a complete account of the analysis populations or as proof that missing data had no effect.

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 adverse-event record reports zero serious adverse events in the experimental group, with 108 at risk, and zero in the control group, with 107 at risk. It also reports zero other adverse events in the experimental group, with 108 at risk, and zero in the control group, with 107 at risk. Deaths are recorded as zero in each group. No top serious-event terms are listed.

These entries describe what is recorded in the registry for the listed groups; they do not establish that no adverse events occurred outside the recorded categories or reporting process. The registry record does not provide definitions of serious or other adverse events, details of ascertainment, follow-up duration for safety, or an account of event-reporting completeness. Zero reported events should therefore be read as a registry result, not as proof of zero risk.

General interpretation of safety comparisons also depends on the number of participants observed, the duration and completeness of follow-up, and how events were defined and collected. The available figures do not include a comparative statistical analysis or an uncertainty estimate. They should not be used to conclude that the groups have identical safety profiles or to make clinical decisions.

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

The posted primary results show the median pain score and full range for each randomized group, measured on a scale where higher scores indicate higher pain. The lidocaine group median is 65.0, with a range of 1.0 to 99.0; the surgical-lubricant group median is 59.0, with a range of 5.0 to 100.0. The endpoint refers to pain immediately after speculum removal, within the recorded timeframe of 0-3 minutes after procedure completion.

Those summaries describe the observed scores in the per-protocol analysis population. They do not provide a formal estimate of the difference between groups, the uncertainty around a difference, or a test of statistical significance. The registry record does not report a p-value or confidence interval for the primary outcome. The direction and size of a treatment effect cannot be judged reliably from the medians and ranges alone, and the summaries do not establish whether a difference is clinically important.

The results also do not answer every question about pain management. The posted primary endpoint concerns a particular point immediately after the procedure, while the record lists anticipated pain, baseline pain, and pain after speculum and tenaculum placement as secondary outcomes. Results for those secondary measures are not reported in the registry record. Nor does the record explain whether the control condition was intended to represent no treatment: its listed intervention is surgical lubricant jelly, although the summary describes standard care as no intervention.

More broadly, these registry entries should not be interpreted as proof that lidocaine works or does not work. They are descriptive posted results with important inferential and reporting details absent. The trial record does not provide enough information to assess the comparative effect with precision, evaluate the robustness of findings to missing data, or determine how multiple outcomes were handled. No medical advice follows from these results.

13. Why This Trial Matters Statistically

This trial illustrates the distinction between a randomized design and a fully reported statistical comparison. Random allocation and masking are relevant design features, but readers still need an effect estimate and a measure of its uncertainty to assess how the groups compare. Here, the registry record posts group medians and ranges for the primary pain outcome but does not include a formal comparative analysis, confidence interval, or p-value.

It also shows why the outcome definition and analysis population matter. Pain is measured at a specific point after IUD insertion, using a scale with clearly stated anchors, and the primary result is labeled per protocol. Those details help define what the posted summaries represent. At the same time, absent criteria for the per-protocol population and absent missing-data information limit interpretation of who contributed to the result.

The record's wording about the comparator is another statistical and reporting concern. The summary refers to standard care as no intervention, while the registered control intervention is surgical lubricant jelly. A clear account of the comparator is necessary to understand the causal question the trial addresses and to interpret its results in context.

Finally, the trial lists multiple secondary pain outcomes, but multiplicity procedures and secondary results are not reported. This matters because conclusions can depend on which outcomes were selected for emphasis and how multiple comparisons were handled. The record therefore offers a useful example of why interpreting trial evidence requires more than reading a group summary: the analysis plan, uncertainty, population definitions, missingness, and comparator all shape what can be concluded.

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 a formal comparative analysis for the primary outcome. Without an estimate of the between-group effect and its uncertainty, the reported medians and ranges cannot establish the precision or statistical significance of a comparison. The record also does not explain why no analysis entry is posted.

The primary population is described as per protocol, but the criteria defining that population are not reported. There is no participant-flow account or explanation of how participants with missing pain scores were handled. This limits assessment of potential selection effects and of how the analyzed participants relate to those randomized.

Details of the randomization process and allocation concealment are not reported in the registry record. Although the trial is described as double-masked and the participant is described as unaware of the gel received, the masking procedures for other trial personnel are not specified in the available arm descriptions. The descriptions themselves are incomplete.

The record's summary describes no intervention as standard care, but its listed control is surgical lubricant jelly. This difference in wording leaves the comparator's intended role unclear. The record also lists secondary outcomes without posting their results or reporting how multiplicity was addressed. Sample-size planning assumptions for illustrations are described, but the trial's own sample-size justification is not reported in the registry record.

Safety entries record no serious or other adverse events and no deaths, but definitions, ascertainment methods, completeness of reporting, and safety follow-up details are not reported. These limitations concern the detail available in the registry record; they do not establish that the trial lacked procedures that were not recorded there.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Self-Administered Lidocaine Gel for Pain Management With IUD Insertion — NCT02738203.
• Registry record last updated 2019-06-06; status last verified 2019-06.
• Results first posted 2018-09-18.
• 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 describes a completed Phase 3 randomized, double-masked, parallel-group trial sponsored by Stanford University. Enrollment is listed as 220. The experimental intervention was self-administered vaginal 2% lidocaine gel; the listed control was surgical lubricant jelly. Both arm descriptions specify 10 ml administered with a pre-filled vaginal inserter 20-30 minutes before IUD insertion.

The primary outcome was pain measured on a 0-100 mm visual analogue scale immediately after the procedure, with higher scores indicating higher pain. The outcome is reported as a median and full range in a per-protocol population: 65.0, range 1.0 to 99.0, for lidocaine and 59.0, range 5.0 to 100.0, for control. The registry record does not report a formal comparative analysis, confidence interval, or p-value.

Four secondary outcomes are listed, but their results are not reported in the registry record. The record also does not report multiplicity procedures, missing-data handling, or the criteria for the per-protocol population. Serious adverse events, other adverse events, and deaths are recorded as zero in both groups.