This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Compare Two Copper IUDs: Mona Lisa NT Cu380 Mini and ParaGard (NCT03124160), a randomized phase 3 study. The primary outcome is Pregnancy Rate of Mona Lisa Copper IUD Over 3 Years.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03124160 |
| Phase | Phase 3 |
| Condition | Healthy Women, Female Contraception |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 1105 |
| Arms in the primary outcome | n/a |
| Lead sponsor | FHI 360 |
| Results posted | Yes |
2. Clinical Question
Population
Eligible participants were healthy women seeking female contraception. The primary outcome description limits the efficacy population to participants with an evaluable cycle for estimating efficacy. Eligibility details beyond the registry’s brief description are not reported in the registry record.
Intervention
Mona Lisa® NT Cu380 Mini, described as containing 380mm2 of copper surface and inserted into the uterine cavity.
Comparator
ParaGard® TCu380A, also described as containing 380mm2 of copper surface and inserted into the uterine cavity.
Primary question
The named primary question concerns the pregnancy rate for Mona Lisa over 3 years, expressed as a Pearl Index. Although the trial compares two IUDs, a comparative primary outcome estimate is not reported in the registry record.
The record describes a randomized, multi-center clinical trial and lists pregnancy rate as its primary outcome. The Pearl Index is defined as the number of method failures per 100 person-years. This is an exposure-based rate rather than a simple count of pregnancies: the amount of time participants contribute to the efficacy assessment matters to its interpretation.
The record also lists secondary outcomes concerning IUD continuation, failed insertion, uterine perforation, complete and partial expulsion, vaginal bleeding patterns, pelvic pain recorded in subject diaries, dysmenorrhea, and insertion-related pain recorded by study subjects. These outcomes reflect additional aspects of use and safety, but their results are not reported in the registry record. The posted information therefore identifies what the trial set out to examine without establishing how the devices compared on pregnancy or those secondary outcomes.
3. Trial Design
The trial is identified as a phase 3, randomized, parallel-group, multi-center clinical trial. Its masking classification is single, and the brief summary describes it as participant-blinded. The record does not specify whether anyone besides participants was masked, or provide further details about how masking was maintained.
The brief summary describes planned randomization in a 4:1 ratio: 800 participants to Mona Lisa® NT Cu380 Mini and 200 to ParaGard® TCu380A. The registry lists enrollment as 1105. It does not report the actual number assigned to each arm or explain the difference between the planned allocation described in the summary and the enrollment figure. Those values should not be treated as the observed group sizes.
Both devices are described as copper IUDs containing 380mm2 of copper surface and inserted into the uterine cavity. The primary outcome is the pregnancy rate of Mona Lisa over 3 years, measured as a Pearl Index. The record specifies that the efficacy population includes only participants with an evaluable cycle for estimating efficacy. It does not explain the criteria for an evaluable cycle or give the number of participants included in that population.
The registry lists a start date of 2017-05-26, primary completion on 2022-06-06, and a completed status. FHI 360 is listed as sponsor. The record does not report the allocation concealment procedure, the detailed schedule of follow-up, or the statistical plan. These omissions limit what can be inferred about conduct and analysis from the registration information alone.
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
| Stage | Mona Lisa® NT Cu380 Mini | ParaGard® TCu380A |
|---|---|---|
| STARTED | 887 | 218 |
| COMPLETED | 426 | 91 |
| NOT COMPLETED | 461 | 127 |
Analysis population for the primary outcome, as defined in the registry: includes only participants with an evaluable cycle for estimating efficacy
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: Females aged 17-40 interested in using a contraceptive method
| Characteristic | Unit | Mona Lisa® NT Cu380 Mini | ParaGard® TCu380A | Total |
|---|---|---|---|---|
| Participants analysed | 887 | 218 | 1105 | |
| Age, Continuous | years | 26.3 (SD 5.23) | 26.3 (SD 4.96) | 26.3 (SD 5.19) |
| Sex: Female, Male: Female | Participants | 887 | 218 | 1105 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 117 | 31 | 148 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 765 | 187 | 952 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 5 | 0 | 5 |
| Number of Participants | Participants | 887 | 218 | 1105 |
6. Primary Endpoint
The registry lists the primary outcome as Pregnancy Rate of Mona Lisa Copper IUD Over 3 Years, measured over 3 years.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Pearl Index = Num preg per 100 person yr |
| Endpoint classification | Event-Rate Endpoint |
The primary outcome is titled pregnancy rate of Mona Lisa copper IUD over 3 years. It is measured with the Pearl Index, defined in the registry record as the number of method failures per 100 person-years. This measure relates the number of pregnancies classified as method failures to the time participants contribute while being evaluated for efficacy. It therefore accounts for exposure time rather than reporting a pregnancy count without a time basis.
The record says the Pearl Index is a measure of contraceptive efficacy used by the FDA. Rates can be useful when participants contribute different amounts of observation time, although interpreting a rate still depends on how follow-up and eligible exposure time are defined. In this trial, the described efficacy population includes participants with an evaluable cycle for estimating efficacy. The registry does not define that criterion further or report the amount of evaluable exposure.
The title names Mona Lisa’s rate, while the trial design describes a randomized comparison with ParaGard. A direct comparison would require outcome information for both groups and an analysis specifying how the rates are compared. Such estimates, their uncertainty, and the underlying pregnancy counts or exposure times are not reported in the registry record. The endpoint definition alone describes what was intended to be measured; it does not establish the observed rate or a difference between devices.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies pregnancy rate over 3 years as the primary outcome and gives the Pearl Index as its measure. However, the posted results do not include a primary outcome estimate, confidence interval, pregnancy count, or exposure-time total. The registry record lists no analyses, and it indicates that the primary outcome cannot be displayed because there are fewer than two arms in that outcome. Consequently, the posted information does not support a numerical assessment of either the Mona Lisa pregnancy rate or its comparison with ParaGard.
This absence matters because the outcome title alone is not a result. The trial’s randomized design describes how a comparison was intended to be made; it does not supply evidence about the direction, magnitude, or precision of an observed difference. Nor does enrollment establish how many participants contributed to the efficacy analysis. The record’s planned allocation and overall enrollment cannot be substituted for the missing arm-specific analysis population or person-time.
A confidence interval, if reported, would describe the precision of an estimated rate or comparison under the analysis used. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. No interval is reported for the primary outcome, so the precision of the pregnancy-rate estimate cannot be evaluated. A p-value is also not reported. Even if a p-value were available, it would address compatibility with a specified statistical model and null hypothesis, not the clinical importance of a difference.
The listed secondary outcomes indicate that the study also sought information on continuation, insertion, expulsion, bleeding, and pain. Their names do not show whether events occurred, how frequently they occurred, or how groups compared. Results for these outcomes are not reported in the registry record, so they cannot fill the primary outcome gap.
Safety counts are posted separately. They describe reported serious and other adverse events in the registry’s group entries, but they are not a substitute for a pregnancy-rate analysis. The counts do not by themselves establish causation, comparative risk, or the completeness of follow-up. In particular, no uncertainty estimates or statistical comparisons for the safety figures are reported. Overall, the registry supports a description of the trial question and design, but not a conclusion about comparative contraceptive efficacy or the magnitude of any safety difference.
9. Statistical Methods Explained
The registry identifies a randomized, parallel-group comparison. In general, random assignment is intended to make treatment groups comparable in expectation with respect to measured and unmeasured characteristics. It does not guarantee that groups are identical in a particular trial, and it does not remove the need to describe who was analyzed, how outcomes were measured, and how missing information was handled. The registry record does not provide those analysis details for the primary outcome.
The primary measure is an event rate per unit of exposure: the Pearl Index is defined as method failures per 100 person-years. In general, a rate uses an event count in relation to accumulated time at risk or under observation. Participants may contribute different exposure times, so the denominator is not necessarily equivalent to the number enrolled. The record says the efficacy population includes only participants with an evaluable cycle, but does not report each group’s event count, evaluable exposure, or the rules used to determine eligibility for that denominator.
A confidence interval expresses uncertainty around an estimated quantity under the statistical method used. Its interpretation depends on the model, assumptions, and data included in the analysis. The primary outcome description specifies a 95% confidence interval as the dispersion measure, but no primary estimate or interval is reported. Therefore, readers cannot assess the outcome’s precision or whether the available data would distinguish among a range of plausible rates. The registry also does not state the exact method used to calculate the interval.
For a rate analysis, modeling may need to account for variation in event counts beyond what a simple model assumes. In general, over-dispersion means that observed variation exceeds the model’s expected variation; ignoring it can make uncertainty estimates too small. The registry does not report whether over-dispersion was assessed or how the rate was modeled. This is a general consideration, not a claim about the analysis used in this trial.
The registry’s sample-size assumptions describe a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The stated target effect is a fraction of the observed effect. These assumptions describe how an illustrative planning calculation is framed; they do not establish the trial’s original design rationale, the size of any observed effect, or the operating characteristics of the trial as conducted. The registry does not report the trial’s own sample-size justification. An illustration based on an observed effect is not observed power and should not be interpreted as a finding about the probability that the trial detected an effect.
The record describes a planned 4:1 assignment, whereas the planning illustration assumes equal allocation. These are different purposes: the former is the ratio described in the brief trial summary, while the latter is an assumption for the stated illustration. The registry does not explain the rationale for either choice or provide the actual allocation counts. It is therefore not possible to use the planned ratio as a substitute for analyzed group sizes.
Multiplicity concerns the increased chance of finding at least one apparently notable result when many outcomes or comparisons are examined. The registry lists multiple secondary outcomes, but does not report an adjustment strategy, a hierarchy of hypotheses, or which outcomes were formally tested. No conclusion about multiplicity control can be drawn. The record also does not report an interim-analysis plan, stopping boundaries, or a detailed statistical analysis plan.
Analysis populations determine which participants contribute to an estimate. In general, an intention-to-treat analysis retains participants according to assigned group, while an efficacy or per-protocol analysis can apply additional criteria. The registry’s primary outcome description names an evaluable-cycle population, but does not define it fully or say whether other analysis populations were used. Without group-specific populations, event counts, exposure, and missing-data handling, the primary effect and its uncertainty cannot be independently evaluated. These are general statistical considerations; the registry record does not specify the methods actually used for the unreported primary analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary pregnancy-rate outcome and multiple secondary outcomes, including continuation, insertion failure, uterine perforation, expulsion, bleeding, pelvic pain, dysmenorrhea, and insertion-related pain. When a trial examines several outcomes, the interpretation of individual statistical tests can depend on whether a testing hierarchy or multiplicity adjustment was planned. The record does not report a hierarchy, adjustment method, or statistical analysis plan. It is therefore not possible to determine how the family of outcomes was handled or which comparisons, if any, were designated as confirmatory.
The registry record lists no analyses and does not report results for the primary or secondary outcomes. It also does not provide numbers analyzed by outcome, reasons for exclusion, or missing-data procedures. The primary outcome description restricts the efficacy population to participants with an evaluable cycle, but the criteria and consequences of that restriction are not stated. Without these details, the potential effects of incomplete follow-up or outcome availability cannot be assessed.
General statistical practice distinguishes missing outcomes from outcomes that did not occur; an unreported event count cannot be interpreted as zero events. Likewise, enrollment is not the same as the number contributing outcome information. The registry’s planned allocation is not a report of actual analysis populations. Since the primary outcome is not available for both arms in the posted analysis, no comparative estimate or uncertainty measure can be interpreted.
Interim analyses and any adjustment for repeated looks at the data are not reported in the registry record. No inference should be made about whether such analyses occurred. The reported information leaves the analysis population, missing-data handling, multiplicity approach, and interim-monitoring procedures unresolved.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Mona Lisa® NT Cu380 Mini | 32 | 887 | 3.6% |
| ParaGard® TCu380A | 3 | 218 | 1.4% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Mona Lisa® NT Cu380 Mini | 0 of 887 |
| ParaGard® TCu380A | 0 of 218 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Mona Lisa® NT Cu380 Mini | 742 of 875 |
| ParaGard® TCu380A | 183 of 213 |
Most frequent serious adverse event terms
| Event term | Organ system | Mona Lisa® NT Cu380 Mini | ParaGard® TCu380A |
|---|---|---|---|
| appendicitis | Infections and infestations | 8 of 887 | 0 of 218 |
| pyelonephritis | Infections and infestations | 4 of 887 | 0 of 218 |
| suicidal ideation | Psychiatric disorders | 2 of 887 | 0 of 218 |
| suicidal attempt | Psychiatric disorders | 2 of 887 | 0 of 218 |
| anaphylactic reaction | Immune system disorders | 2 of 887 | 0 of 218 |
| infected bite | Infections and infestations | 1 of 887 | 0 of 218 |
| tubo-ovarian abscess | Infections and infestations | 1 of 887 | 0 of 218 |
| enteritis | Gastrointestinal disorders | 1 of 887 | 0 of 218 |
| food poisoning | Gastrointestinal disorders | 1 of 887 | 0 of 218 |
| gastrointestinal pain | Gastrointestinal disorders | 1 of 887 | 0 of 218 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Mona Lisa® NT Cu380 Mini | ParaGard® TCu380A |
|---|---|---|---|
| procedural pain | Injury, poisoning and procedural complications | 511 of 875 | 135 of 213 |
| dysmenorrhoea | Reproductive system and breast disorders | 390 of 875 | 100 of 213 |
| menorrhagia | Reproductive system and breast disorders | 315 of 875 | 82 of 213 |
| metrorrhagia | Reproductive system and breast disorders | 250 of 875 | 54 of 213 |
| pelvic pain | Reproductive system and breast disorders | 186 of 875 | 46 of 213 |
| uterine spasm | Reproductive system and breast disorders | 71 of 875 | 22 of 213 |
| abdominal pain | Gastrointestinal disorders | 61 of 875 | 16 of 213 |
| dyspareunia | Reproductive system and breast disorders | 61 of 875 | 8 of 213 |
| bacterial vaginosis | Infections and infestations | 48 of 875 | 11 of 213 |
Serious events with the highest arm-level rate: appendicitis (0.9%), limb injury (0.5%), ovarian mass (0.5%), rash (0.5%), pyelonephritis (0.5%).
The registry reports serious adverse event figures separately for Mona Lisa® NT Cu380 Mini and ParaGard® TCu380A. For Mona Lisa, the group entry lists 887 at risk and 32 affected by serious adverse events; for ParaGard, it lists 218 at risk and 3 affected. The record also lists other adverse event figures: 875 at risk and 742 affected for Mona Lisa, and 213 at risk and 183 affected for ParaGard. No deaths are listed for either group.
These are counts as recorded in the registry, not comparative estimates adjusted for follow-up or exposure. The registry does not explain whether affected refers to participants with at least one event, how recurrent events were handled, or whether exposure duration differed by group. The counts should therefore not be converted into a risk comparison without additional information. No uncertainty intervals or formal tests for these figures are reported.
The record lists appendicitis at 0.9%, and limb injury, ovarian mass, rash, and pyelonephritis at 0.5% each, followed by suicidal ideation at 0.2%, among its top serious terms. The denominator and group attribution for these percentages are not reported in the registry record. These terms describe recorded events; they do not establish that an IUD caused them. The registry’s safety figures do not provide a complete comparative safety analysis or indicate how the event counts relate to the trial’s follow-up time.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized trial was conducted to compare two copper IUDs and that pregnancy rate over 3 years was named as the primary outcome. It identifies the Pearl Index as the planned measure and describes an efficacy population based on an evaluable cycle. It also records secondary outcomes and adverse event counts. Those details help define the research question and some of the information collected.
The record does not report the primary pregnancy-rate results. It therefore cannot show the observed Pearl Index for Mona Lisa, the corresponding ParaGard rate, or a comparative estimate. There is no primary confidence interval or p-value with which to assess statistical precision or evidence of a between-group difference. The missing result is not evidence that the rates were the same, and it is not evidence that one device had a higher rate.
Likewise, the secondary outcome list does not establish whether continuation, insertion, expulsion, bleeding, or pain differed between groups. The adverse event counts are descriptive registry entries and cannot, on their own, establish a causal relationship or quantify a comparative safety effect. The record does not provide enough detail to assess differences in follow-up, event ascertainment, or exposure time.
Statistically, the principal limitation is not an unusual numerical result but the absence of reported primary outcome analysis. Randomization describes the intended design, not the result. The planned assignment ratio and enrollment figure do not substitute for analyzed group sizes, event counts, or exposure. Any interpretation of efficacy or comparative safety would require outcome results and sufficient analysis details, including the population analyzed and the handling of missing data.
The appropriate reading is therefore bounded: the registry documents a completed randomized comparison and its stated objectives, but the posted results do not permit conclusions about how the devices compared on pregnancy rate or the listed secondary outcomes. No medical recommendation follows from the registry information alone.
13. Why This Trial Matters Statistically
This trial is statistically notable as a randomized comparison with a rate-based primary outcome. A Pearl Index expresses method failures relative to person-time, so interpretation depends on both the events counted and the amount of eligible exposure. The registry explicitly limits the efficacy population to participants with an evaluable cycle, making the definition and reporting of that population important to understanding any estimate.
The design summary describes unequal planned allocation, while the planning illustration uses equal allocation. This distinction matters because design choices and planning assumptions serve different purposes. Neither the planned allocation nor the total enrollment gives the actual analyzed group sizes. The registry does not report those sizes or the primary outcome data needed to evaluate precision.
The record also illustrates why a trial’s registration details and its results are not interchangeable. The phase, randomization, masking classification, outcomes, and completion status describe the study, but they do not disclose its effect estimates. Without the primary rate and its uncertainty, readers cannot judge how precise an estimate was or how compatible it is with different possible effects.
Finally, the breadth of listed secondary outcomes raises general questions about outcome hierarchy, multiplicity, and missing data. These issues matter for interpreting a set of analyses, but the record does not document the relevant analysis plan or results. The statistical value of the record is therefore mainly in clarifying the intended comparison and the limits of what the posted results establish.
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 gives limited information for evaluating the trial’s conduct and analysis. It identifies the study as randomized and single-blind, while the brief summary specifies participant blinding; the masking of other people involved in the trial is not reported. The allocation concealment method and detailed randomization procedures are also not reported in the registry record.
The brief summary describes a 4:1 planned allocation and lists planned group counts of 800 and 200, while the registry enrollment is 1105. Actual arm sizes and an explanation of the difference between planned allocation and enrollment are not reported. Enrollment cannot be used to infer the number included in the efficacy analysis.
The primary endpoint’s evaluable-cycle criterion is not defined in detail. The registry does not report group-specific pregnancy counts, person-time, effect estimates, confidence intervals, or p-values. It also does not report the secondary outcome analyses. As a result, neither efficacy estimates nor their precision can be assessed from the posted results.
Important statistical details are absent: the trial’s own sample-size justification, a full analysis plan, the missing-data approach, the multiplicity strategy, and any interim-analysis procedures are not reported in the registry record. Follow-up completeness and the handling of participants who did not contribute evaluable cycles are likewise not described.
The serious and other adverse event entries lack detail on event definitions, recurrent events, exposure time, and the denominator behind the listed serious-event percentages. The registry does not establish causation for the event terms. These limitations constrain interpretation of safety counts as well as efficacy results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Compare Two Copper IUDs: Mona Lisa NT Cu380 Mini and ParaGard — NCT03124160.
- Registry record last updated 2024-09-25; status last verified 2024-09.
- Results first posted 2024-09-25.
- 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.
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18. Record Summary
NCT03124160 is a completed phase 3, randomized, parallel-group, multi-center clinical trial sponsored by FHI 360. The record describes a participant-blinded comparison of Mona Lisa® NT Cu380 Mini and ParaGard® TCu380A, with a 4:1 allocation ratio in the brief summary and enrollment listed as 1105.
The primary outcome is pregnancy rate of Mona Lisa over 3 years, measured by the Pearl Index as method failures per 100 person-years among participants with an evaluable cycle. The registry lists secondary outcomes on continuation, insertion, expulsion, bleeding, and pain. It also reports serious and other adverse event counts and selected serious-event terms.
Primary and secondary outcome analyses are not reported in the registry record. Actual arm-specific analysis populations and primary rate estimates are not available, so the posted information does not establish a comparative efficacy result.