Pain Control for Intrauterine Device Placement: A Trial of Ketorolac Prior to Intrauterine Device Placement: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pain Control for Intrauterine Device Placement: A Trial of Ketorolac Prior to Intrauterine Device Placement (NCT01664559), a randomized na study. The primary outcome is VAS (Visual Analogue Scale) Measurement of Pain.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group, quadruple-masked trial, with an enrollment of 67. The status is completed. The record identifies the sponsor as Lynn Ngo and lists the study as phase NA. It describes the condition as pain control with IUD insertion.

Participants were assigned to intramuscular ketorolac or intramuscular normal saline. The active arm is described as 30mg of Toradol in a 1cc volume; the placebo arm received 1cc of normal saline. The summary states that the study hypothesis concerned ketorolac given at least 30 minutes before insertion. The arm descriptions themselves specify treatment and route, without additional timing details.

The primary outcome was pain with IUD placement, measured immediately after placement. The record says patients marked pain on a visual analogue scale running from 0 to 10cm, where 0 cm represents no pain and 10 cm the worst pain ever. The outcome is reported as a median with an inter-quartile range.

Four secondary outcomes are named: pain scores at other time points during and after placement, a nulliparous-patient subgroup analysis, a post-insertion patient questionnaire, and a post-insertion provider questionnaire. The registry lists 5 outcome measures and 30 analyses. It does not report further design details such as eligibility criteria, concealment procedures, or the statistical analysis plan. The start and primary-completion dates are recorded in the registry, but additional explanation of the trial timeline is 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

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 VAS (Visual Analogue Scale) Measurement of Pain, measured over Pain with IUD placement, measured immediately after placement.

The primary endpoint is the patient-marked pain score immediately after IUD placement. The registry describes a visual analogue scale from 0 to 10cm: 0 cm is no pain, and 10 cm is the worst pain ever. The endpoint therefore records a patient's rating of pain at a specified point in the procedure, rather than an observer's rating or a later assessment.

The registry summarizes scores using the median and inter-quartile range. The median is the middle value in an ordered set of scores. The inter-quartile range describes the spread between the lower and upper quartiles, showing how scores vary around the center without requiring a symmetric distribution. These summaries can be useful when outcome values are not well represented by a mean and standard deviation.

Pain scores are used to make the subjective experience of pain measurable for comparison between randomized groups. They do not capture every aspect of discomfort, experience, or satisfaction. The study also lists other pain time points and patient and provider questionnaires as secondary outcomes, but the primary result pertains specifically to the immediate post-placement score.

The registry states a study hypothesis of a reduction of at least 20mm on the visual analogue scale at various time points. That is the stated hypothesis, not an observed result. The primary endpoint description reports a scale in centimeters, while the hypothesis is expressed in millimeters; the registry record does not explain this wording further.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a pain score measured on a visual analogue scale immediately after IUD placement. The registry reports a median and inter-quartile range for each arm, and identifies the between-arm method as the Wilcoxon (Mann-Whitney) test. These summaries and the test answer related but different questions: the arm summaries describe score distributions, while the test evaluates a comparison between groups.

Why report medians and inter-quartile ranges?

A median is the central observation after scores are ordered. It is less influenced by unusually high or low observations than a mean. The inter-quartile range gives the span from the lower quartile to the upper quartile, conveying how dispersed the central portion of the observed scores is. In general, this can be a useful way to describe outcomes that are skewed or otherwise not well summarized by a mean and standard deviation. The posted summaries are 5.2 with an inter-quartile range of 1.2 to 7.4 for normal saline, and 3.6 with an inter-quartile range of 1.5 to 6.3 for ketorolac.

What does the Wilcoxon test assess?

The Wilcoxon rank-sum test, also called the Mann-Whitney test, compares the relative ordering of observations between two independent groups. It uses ranks rather than requiring the comparison to be based directly on group means. General explanations sometimes describe this test as a test of medians, but that interpretation requires conditions on the shapes of the group distributions. More generally, it assesses whether observations in one group tend to rank differently from observations in the other. The registry reports p = 0.99 for this test, but does not provide the test statistic, a treatment-effect estimate, or a confidence interval.

What can the p-value say?

In general, a p-value is calculated under a null hypothesis and a statistical model. It describes how unusual a result at least as extreme as the observed test result would be under that model. It is not the probability that the null hypothesis is true, and it does not state the probability that a treatment has no effect. The registry's p = 0.99 should therefore be read as the reported test result, not as proof that the arm outcomes are identical. A formal equivalence conclusion would require an appropriate design and a prespecified margin; those details are not reported in the registry record.

How does masking fit the design?

The study is identified as randomized, parallel, and quadruple masked. Randomization is intended, in general, to support a fair comparison by assigning treatment independently of participant characteristics. A parallel design assigns participants to one of the treatment groups rather than having each participant receive both treatments. Masking is intended to limit the influence of knowledge of assignment on care, reporting, or assessment. The registry does not describe who was included in the masking designation, how masking was maintained, or whether it was assessed.

What is not available from the posted analysis?

The primary result contains arm-level medians and inter-quartile ranges, plus the reported test and p-value. It does not report a confidence interval for a between-arm effect. A confidence interval is a range of effect values compatible with the data under a specified method; it conveys precision in a way that a p-value alone does not. The record also does not report the analysis population definition, a missing-data method, or a detailed statistical plan. These omissions limit assessment of the analysis choices and the robustness of the result.

The registry lists 5 outcome measures and 30 analyses, with four secondary outcomes described by name. When multiple outcomes or analyses are considered, multiplicity can increase the chance of finding an apparently notable result by chance. General approaches include prespecifying a primary outcome, adjusting inference for multiple comparisons, or treating secondary analyses as exploratory. Which approach was used is not reported in the registry record. The record also notes that values are missing or not estimable for a two-arm comparison for another endpoint; it does not explain the reason or the handling of those data.

10. Analyses Reported by the Sponsor

The registry reports the sponsor's primary comparison as a Wilcoxon (Mann-Whitney) test with p = 0.99. The posted arm summaries are medians and inter-quartile ranges. No separate recalculated treatment-effect estimate or confidence interval is available for this endpoint, so there is no additional unadjusted estimate to compare with the registry's test result.

The registry record does not identify a discrepancy between a sponsor-reported result and a recalculation. The sponsor's reported test should therefore be read as the available inferential analysis, alongside the posted arm summaries. The p-value does not supply an effect size, and the inter-quartile ranges do not function as uncertainty intervals for the between-arm contrast.

The record does not provide additional detail about the test statistic, missing observations, or the analysis population. It also does not report a confidence interval or an equivalence margin. Those absences matter when judging how precisely the comparison estimates a treatment effect and whether the result can support a claim of equivalence. The reported analysis is informative as a registry result, but its interpretation remains limited to the endpoint, summaries, and test that are posted.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 5 outcome measures and 30 analyses. The primary endpoint is the immediate post-placement pain score. Four secondary outcomes are named: pain scores at other time points during and after placement, a nulliparous-patient subgroup analysis, a post-insertion patient questionnaire, and a post-insertion provider questionnaire. The record does not provide a full mapping of the listed analyses to outcomes or identify which analyses were prespecified.

When researchers evaluate multiple outcomes, time points, subgroups, or comparisons, the chance of at least one apparently notable result can increase. General statistical approaches include adjusting significance thresholds, controlling a measure of overall error, or treating secondary analyses as exploratory. The registry record does not report whether any multiplicity procedure was planned or used. The primary p-value should therefore be understood as the reported test result, without assuming that it was or was not adjusted for other analyses.

Details about missing data are also limited. The record does not report the amount or pattern of missing primary outcome data, the method used to address missingness, or whether all randomized participants were included in the primary analysis. An analysis population definition, such as whether analysis followed assigned treatment, is not reported in the registry record. These details can affect how a randomized comparison is interpreted, particularly when outcome data are unavailable.

The registry notes that values are missing or not estimable for a two-arm comparison for another endpoint. It does not state why those values are unavailable or how that endpoint was handled in the broader set of analyses. This note does not change the posted primary result, but it illustrates that not every analysis has a reported two-arm comparison. Readers should distinguish the available primary comparison from the less fully documented secondary analysis record.

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.

The registry reports zero serious adverse events among the 34 participants at risk in the normal-saline arm and zero among the 33 participants at risk in the ketorolac arm. It also reports zero other adverse events in each arm, using the same at-risk counts. These are the adverse-event figures posted in the record; they should not be interpreted as proof that no adverse events could occur.

The death counts are not reported in the registry record. The record does not give further information about adverse-event definitions, how events were collected, the observation period, or how completely safety outcomes were ascertained. Without those details, the zero reported counts cannot establish that the treatments have identical safety profiles or rule out uncommon events. They describe only the adverse-event results recorded for this trial.

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

The posted result describes pain ratings immediately after IUD placement in a randomized comparison of intramuscular ketorolac and normal saline. The registry gives arm-specific medians and inter-quartile ranges and reports a Wilcoxon (Mann-Whitney) test with p = 0.99. These registry entries allow readers to identify the endpoint, the summaries, and the test used for the reported comparison.

The result does not establish that the treatments are equivalent. A failure to show a statistically notable difference is not the same as evidence that any difference is sufficiently small to be unimportant. An equivalence interpretation would require an appropriate design, a prespecified margin, and an analysis that evaluates the treatment contrast against that margin; these are not reported in the registry record. The posted result also does not include a between-arm confidence interval, so it does not show the range of effects compatible with the data.

The primary endpoint is a patient-reported score at a defined time point. It does not represent every aspect of pain during and after placement. The registry names other time points and questionnaires as secondary outcomes, but their presence does not supply results or settle questions that the primary endpoint does not measure. The listed nulliparous-patient subgroup analysis also cannot be interpreted without its result and analysis details.

The trial summary states a hypothesis about a reduction of at least 20mm at various time points. The posted primary summaries are not themselves a reported estimate of that hypothesized reduction. A reader should not infer that the target was met or not met from the arm medians alone.

Overall, the record supports a limited statistical description of the primary outcome and reported test. It does not, on its own, justify a general claim about all patients, all IUD types, all pain-management approaches, or treatment effects at other time points.

14. Why This Trial Matters Statistically

This trial raises a practical measurement question: how to compare patient-reported pain following a procedure when the outcome is a rating on a bounded visual analogue scale. The registry's use of medians and inter-quartile ranges describes the center and spread of the observed ratings, while the Wilcoxon (Mann-Whitney) test provides a rank-based comparison between randomized groups. Understanding that the summaries and test answer different questions helps prevent over-reading the p-value.

The record also illustrates why a result needs more than a p-value for full interpretation. A reported p-value does not convey the size or precision of a treatment contrast. A confidence interval or another effect estimate would help readers understand which values are compatible with the data. The registry does not report such an interval for the primary comparison, and does not give an equivalence margin. Those omissions limit conclusions about both magnitude and practical importance.

Multiplicity is relevant because the registry lists numerous analyses and several secondary outcomes, including other pain time points and a subgroup analysis. Without a reported analysis plan, readers cannot tell whether these were prespecified, how results were prioritized, or whether any adjustment was used. This is a general concern in studies with multiple outcomes, not a claim that any particular analysis was conducted improperly.

Finally, this record demonstrates the value of distinguishing observed summaries from inferential conclusions. The arm medians and their inter-quartile ranges describe scores in the analyzed groups; they do not establish equivalence or determine how patients will experience pain in other settings. Clear reporting of analysis populations, missing-data handling, effect estimates, and uncertainty would make the statistical evidence easier to assess.

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 registry record gives the primary endpoint summaries and a p-value, but does not report a between-arm effect estimate or confidence interval. As a result, the precision of the comparison and the range of effects compatible with the data cannot be assessed directly from the posted primary result. The within-arm inter-quartile ranges describe score dispersion, not uncertainty around the treatment contrast.

The record does not report eligibility criteria, a detailed analysis population, missing-data amounts or methods, or a full statistical analysis plan. It does not describe the randomization or allocation-concealment procedures, how quadruple masking was implemented, or whether masking was evaluated. These details would help readers assess the conduct and analysis of the trial.

The registry lists 5 outcome measures and 30 analyses, but does not explain the analysis hierarchy or any approach to multiplicity. It names four secondary outcomes without providing a full account of their results or methods. It also notes that a two-arm comparison is missing or not estimable for another endpoint, without explaining why. These reporting gaps make it difficult to evaluate secondary evidence alongside the primary result.

The summary's hypothesis refers to a reduction of at least 20mm at various time points, whereas the primary endpoint is reported as an immediate post-placement score on a scale described in centimeters. The record does not explain the relationship between that stated hypothesis and the reported primary analysis. Finally, the registry's adverse-event information lacks details about definitions and ascertainment, and death counts are not reported. These are limits of the information in the record, not proof that any specific trial procedure or analysis was inadequate.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Pain Control for Intrauterine Device Placement: A Trial of Ketorolac Prior to Intrauterine Device Placement — NCT01664559.
• Registry record last updated 2015-12-23; status last verified 2015-11.
• Results first posted 2015-12-23.
• 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

This completed randomized, parallel-group, quadruple-masked trial compared intramuscular ketorolac with intramuscular normal saline before IUD placement. The registry records an enrollment of 67. The primary endpoint was patient-reported pain immediately after placement, marked on a visual analogue scale and summarized as a median with an inter-quartile range.

The normal-saline arm had a reported median of 5.2 and inter-quartile range of 1.2 to 7.4; the ketorolac arm had a median of 3.6 and inter-quartile range of 1.5 to 6.3. The registry reports a Wilcoxon (Mann-Whitney) test with p = 0.99. It does not report a confidence interval or treatment-effect estimate for the primary comparison.

Other pain time points, a nulliparous-patient subgroup analysis, and patient and provider questionnaires are listed as secondary outcomes. The record does not report a multiplicity approach, detailed missing-data handling, or an analysis population definition. Its results support a description of the posted primary summaries and test, rather than an equivalence conclusion.