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 A Clinical Study to Evaluate the Safety and Efficacy of Elagolix in Participants With Moderate to Severe Endometriosis-Associated Pain (NCT03213457), a randomized phase 3 study. The primary outcome is Co-Primary Endpoint: Percentage of Participants With a Response for Dysmenorrhea (DYS) at Months 6 and 12 Based on Daily Assessment.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03213457 |
| Phase | Phase 3 |
| Condition | Endometriosis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 681 |
| Arms in the primary outcome | n/a |
| Lead sponsor | AbbVie |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled adult premenopausal female participants with moderate to severe endometriosis-associated pain. The condition listed in the registry record is endometriosis. The trial enrolled 681 participants overall. Its primary analysis population is described as randomized participants who received at least 1 dose of study drug and had an assessment at the relevant time point.
Intervention
The active regimens used elagolix 200 mg twice daily, either alone during an initial period or with estradiol/norethindrone acetate (E2/NETA) 1 mg/0.5 mg once daily. One group received the combination during the 12-month placebo-controlled treatment period. Another began with elagolix alone and then changed to the combination.
Comparator
The placebo group received placebo for elagolix twice daily and placebo for E2/NETA once daily during the 12-month placebo-controlled treatment period. The arm description then states that participants received elagolix with E2/NETA for the remaining 36 months of the treatment period. The listed primary comparison is between the combination regimen and placebo.
Primary question
The co-primary endpoint asks what percentage of participants met the registered dysmenorrhea response definition at month 6 and month 12. A response required the specified reduction in dysmenorrhea score and no increase in rescue analgesic use according to the endpoint definition. The primary response percentages and their confidence intervals are not reported in the registry record, so the size and precision of the treatment contrast cannot be assessed.
3. Trial Design
This was a randomized, quadruple-masked, parallel Phase 3 study sponsored by AbbVie. The registry record lists 681 participants and describes the study as completed. The study start date is 2017-07-07, and the primary completion date is 2020-03-27. These dates describe the record's study timeline; they do not by themselves establish when particular participants entered or completed treatment.
The arm descriptions identify three initial regimens. Participants assigned to placebo received placebo for elagolix and placebo for E2/NETA during the 12-month placebo-controlled treatment period. Participants in the elagolix-alone sequence received elagolix 200 mg twice daily for the first 6 months, then elagolix with E2/NETA for the second 6 months. The combination group received elagolix 200 mg twice daily plus E2/NETA 1 mg/0.5 mg once daily during the 12-month placebo-controlled period. The descriptions then specify combination treatment for the remaining 36 months.
Randomization is intended to distribute participant characteristics across assigned groups, while masking is intended to limit the influence of treatment knowledge on care, reporting, or assessment. Those are general design purposes, not evidence that bias was eliminated in this study. The registry record does not identify which roles were masked or describe allocation procedures. It also does not report the exact methods used to generate or conceal the random sequence. The posted study has a parallel-group structure, rather than describing each participant as crossing through all assigned regimens during the initial comparison.
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: Participants were randomly assigned on Study Day 1 in a 4:1:2 ratio as follows: * elagolix 200 mg twice daily (BID) plus estradiol/norethindrone acetate (E2/NETA) 1 mg/0.5 mg once daily (QD) * elagolix 200 mg BID * placebo Data are presented for the 12-month Placebo-Controlled Treatment Period.
Screening Period
| Stage | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| STARTED | 194 | 98 | 389 |
| COMPLETED | 193 | 97 | 389 |
| NOT COMPLETED | 1 | 1 | 0 |
Reasons for not completing this period:
| Reason | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| Withdrawal by Subject | 0 | 1 | 0 |
| Other | 1 | 0 | 0 |
Double-Blind Period
| Stage | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| STARTED | 193 | 97 | 389 |
| COMPLETED | 157 | 85 | 337 |
| NOT COMPLETED | 36 | 12 | 52 |
Reasons for not completing this period:
| Reason | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| Adverse Event | 3 | 2 | 7 |
| Withdrawal by Subject | 14 | 2 | 14 |
| Lost to Follow-up | 2 | 3 | 9 |
| Requires surgery or invasive intervention for treatment of endometriosis | 2 | 0 | 1 |
| Non-compliance with study procedures | 0 | 2 | 4 |
| Pregnancy | 5 | 0 | 0 |
| Other | 10 | 3 | 17 |
Open-Label Period
| Stage | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| STARTED | 106 | 59 | 215 |
| COMPLETED | 90 | 48 | 170 |
| NOT COMPLETED | 16 | 11 | 45 |
Reasons for not completing this period:
| Reason | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| Adverse Event | 1 | 2 | 2 |
| Withdrawal by Subject | 12 | 5 | 24 |
| Lost to Follow-up | 1 | 2 | 8 |
| Requires surgery or invasive intervention for treatment of endometriosis | 0 | 0 | 2 |
| Non-compliance with study procedures | 1 | 1 | 2 |
| Exclusionary medications | 0 | 0 | 1 |
| Other | 1 | 1 | 6 |
Follow-Up Period
| Stage | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| STARTED | 194 | 98 | 389 |
| COMPLETED | 102 | 51 | 185 |
| NOT COMPLETED | 92 | 47 | 204 |
Reasons for not completing this period:
| Reason | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA |
|---|---|---|---|
| Adverse Event | 16 | 8 | 37 |
| Withdrawal by Subject | 18 | 11 | 55 |
| Lost to Follow-up | 28 | 15 | 50 |
| Requires surgery or invasive intervention for treatment of endometriosis | 3 | 1 | 2 |
| Non-compliance with study procedures | 4 | 1 | 6 |
| Pregnancy | 7 | 0 | 18 |
| Exclusionary medications | 1 | 1 | 5 |
| COVID-19 logistical restrictions | 1 | 0 | 0 |
| Other | 14 | 10 | 31 |
Analysis population for the primary outcome, as defined in the registry: Full Analysis Set: all randomized participants who received at least 1 dose of study drug. Participants with an assessment at given time point. Last observation carried forward. Per protocol, the primary comparison for the co-primary endpoints was between the elagolix plus E2/NETA and placebo arms only.
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: Full Analysis Set: all randomized participants who received at least 1 dose of study drug.
| Characteristic | Unit | Placebo | Elagolix / Elagolix + E2/NETA | Elagolix + E2/NETA | Total |
|---|---|---|---|---|---|
| Participants analysed | 193 | 97 | 389 | 679 | |
| Age, Continuous | years | 33.1 (SD 6.72) | 32.5 (SD 6.44) | 32.3 (SD 6.74) | 32.5 (SD 6.69) |
| Sex/Gender, Customized: Female | Participants | 193 | 97 | 389 | 679 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 37 | 11 | 58 | 106 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 156 | 86 | 331 | 573 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 | 0 | 1 | 2 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 4 | 4 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 1 | 1 |
| Race (NIH/OMB): Black or African American | Participants | 31 | 19 | 49 | 99 |
| Race (NIH/OMB): White | Participants | 159 | 74 | 328 | 561 |
| Race (NIH/OMB): More than one race | Participants | 2 | 4 | 6 | 12 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Co-Primary Endpoint: Percentage of Participants With a Response for Dysmenorrhea (DYS) at Months 6 and 12 Based on Daily Assessment, measured over Month 6, Month 12.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The co-primary endpoint is the percentage of participants who met the response definition for dysmenorrhea (DYS) at month 6 and month 12. Participants recorded menstrual pain and its impact on daily activities in an electronic diary. The four-point scale ranged from 0, no discomfort, to 3, severe pain that made usual activities difficult. Pain scores and rescue analgesic use were averaged over 35 days before each visit.
Response required a reduction of -0.92 or more from baseline in DYS, together with no increase in rescue analgesic use for endometriosis-associated pain. The record defines no increase as a < 15% increase in average rescue analgesic pill count and no additional analgesic. Thus, response incorporates both a symptom measure and a constraint on rescue medication use. It is not simply a change in pain score.
Using a binary responder endpoint can make the result easier to describe as the proportion meeting a prespecified threshold. In general, this is useful when a study seeks to summarize how many participants achieved a particular level of improvement, rather than only reporting an average score change. However, the threshold separates responders from nonresponders and does not show the range of score changes within either group. The response percentages and confidence intervals for the two time points are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted information defines the primary endpoint and the planned comparison, but it does not include the primary response percentages or confidence intervals. The registry record therefore does not allow readers to determine the observed responder proportion in each primary arm, the size of the difference between arms, or how precisely that difference was estimated. No conclusion about the direction or magnitude of the primary treatment contrast can be drawn from the endpoint definition alone.
The endpoint has two components: a reduction in daily-assessment dysmenorrhea score and a limit on increased rescue analgesic use. This means a participant could meet the score-change condition but fail the combined response definition because of analgesic use, or meet the response definition only when both conditions are satisfied. The definition makes the result clinically interpretable as a composite response, but it also means the percentage cannot be understood as a pain-score result in isolation. The registry record does not report separate primary results for the score and analgesic components.
Two assessment times are named: month 6 and month 12. Results at different times answer different questions about the treatment period, and they should not be treated as interchangeable. The posted information also gives secondary outcomes at several time points, including dysmenorrhea, non-menstrual pelvic pain, fatigue, and dyspareunia. Their presence shows that the study recorded more than the co-primary endpoint, but does not supply the results or establish which findings were statistically persuasive.
The primary analysis population is described as the Full Analysis Set: randomized participants who received at least 1 dose of study drug and had an assessment at the given time point. The registry description also says last observation carried forward. This tells readers something about the recorded analysis population and missing-data handling, but it does not provide the number included at each time point or explain how many observations were carried forward.
For an estimate of a responder percentage, a confidence interval communicates uncertainty around the estimated proportion. In general, a narrower interval indicates greater precision, while a wider interval indicates less precision. Here, the endpoint specifies a 95% confidence interval, but the interval limits are not reported in the registry record. Statistical significance, practical importance, and the robustness of the result therefore cannot be evaluated from the posted primary endpoint description. The outcome values and analysis details needed for that interpretation are not reported in the registry record.
9. Statistical Methods Explained
The registry describes a binary endpoint: each participant is classified according to whether the dysmenorrhea response definition was met. The reported measure is a percentage of participants, with a 95% confidence interval. The endpoint is assessed at month 6 and month 12. The registry record does not report the primary response estimates, confidence interval limits, or a p-value for these assessments.
What does a responder percentage represent?
A binary response converts an underlying measure into two categories: meeting the specified response rule or not meeting it. In this study, the rule combines a reduction in DYS from baseline with a condition on rescue analgesic use. The resulting percentage summarizes how many participants in an analysis group fulfilled both parts of the rule. It does not describe the average amount of pain-score change, the distribution of individual changes, or results for participants who nearly met the threshold. Those require separate summaries.
Because the endpoint is binary, the denominator matters. A responder percentage describes the participants counted in its analysis population, not necessarily every randomized participant. The record describes the Full Analysis Set as all randomized participants who received at least 1 dose of study drug, with participants having an assessment at the given time point. It does not state the analyzed group size for each primary assessment. Those counts are not reported in the registry record.
What does a confidence interval add?
In general, a confidence interval expresses the uncertainty associated with an estimate under the statistical procedure used. For a percentage, it gives a range of values compatible with the observed data and method, rather than a guarantee that the true value lies within that particular interval. When comparing groups, estimates and intervals help readers judge both the apparent difference and its precision. An interval alone does not establish whether a difference matters in practice, and a p-value alone would not describe the size or precision of an effect.
The endpoint specifies a 95% confidence interval. The interval values are not reported in the registry record, so its precision cannot be evaluated. The registry record also does not describe the interval calculation method or state whether the primary comparison was adjusted for other variables. Those details are not reported in the registry record.
How should the two assessment times be understood?
Month 6 and month 12 are separate assessment times for the co-primary endpoint. A result at one time point would describe response at that assessment, while a result at the other would describe response at the later assessment. In general, a study that evaluates multiple primary endpoints or times needs a statistical plan for interpreting the set of tests, because repeated testing can increase the chance of at least one false-positive finding. The registry record names co-primary endpoints and times but does not report whether or how multiplicity was controlled.
The record lists 16 outcome measures and 18 analyses. These counts indicate that the posted study includes multiple outcomes and analyses; they do not reveal the statistical hierarchy, which results were confirmatory, or how testing across outcomes was handled. Such details are not reported in the registry record.
What does last observation carried forward mean?
The Full Analysis Set description states that last observation carried forward was used. In general, this method substitutes a participant's last recorded measurement for a later missing measurement, allowing some participants with incomplete follow-up to contribute to an analysis. It relies on an assumption that the carried-forward value is an appropriate stand-in for the unobserved value. When symptoms may change over time, that assumption can be questionable; the method can understate or overstate uncertainty depending on the data and circumstances. This general limitation does not establish the direction or size of any bias in this study.
The registry record does not report how many observations were missing, the reasons for missing assessments, or sensitivity analyses using alternative missing-data assumptions. It also does not report an imputation model beyond the stated carry-forward approach. Readers therefore cannot judge from the posted description how sensitive the primary findings were to missing data.
What is not documented about the analysis?
The posted description identifies the primary comparison as elagolix with E2/NETA versus placebo and gives the endpoint definition, analysis population, and carry-forward approach. It does not report the sample-size justification, detailed statistical model, interim analyses, covariate adjustment, or full multiplicity strategy. Those items are not reported in the registry record. Their absence from the posted description should not be filled by assuming common practice. Without primary results and analysis details, this page can explain the registered design and statistical concepts, but cannot reconstruct or validate the trial's full inferential analysis.
10. Multiplicity, Missing Data and Analysis Populations
The study identifies co-primary endpoint assessments for dysmenorrhea at month 6 and month 12, and the registry lists 16 outcome measures and 18 analyses. Considering multiple endpoints or assessment times raises a general statistical issue: if many hypotheses are tested, the chance of at least one apparently positive result can increase. A prespecified multiplicity strategy can address that issue, for example by defining which tests must succeed or by adjusting how evidence is evaluated. The registry record does not report whether such a strategy was used or describe its details.
The Full Analysis Set is described as randomized participants who received at least 1 dose of study drug and had an assessment at the given time point. The record says last observation carried forward was used. It does not report the number of participants analyzed at each time point, the amount or pattern of missing data, or the reasons assessments were missing. It also does not report sensitivity analyses or another method for assessing how missing observations might affect the results. Those details are not reported in the registry record.
These omissions limit independent interpretation. The named population and carry-forward approach give some information, but they do not establish whether missingness differed between groups or how robust results were to alternative assumptions. Because the primary response estimates themselves are also not reported in the registry record, readers cannot assess either the treatment comparison or the impact of the analysis choices.
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 |
|---|---|---|---|
| SCR_Placebo | 0 | 194 | 0.0% |
| SCR_Elagolix | 0 | 98 | 0.0% |
| SCR_Elagolix_and_E2-NETA | 1 | 389 | 0.3% |
| DB_Placebo | 8 | 194 | 4.1% |
| DB_Elagolix | 2 | 98 | 2.0% |
| DB_Elagolix_and_E2-NETA | 14 | 389 | 3.6% |
| OL_Placebo_to_ELA_and_E2-NETA | 7 | 106 | 6.6% |
| OL_ELA_to_ELA_and_E2-NETA | 2 | 59 | 3.4% |
| OL_ELA_and_E2-NETA_to_ELA_and_E2-NETA | 10 | 215 | 4.7% |
| FU_Placebo_to_ELA_and_E2-NETA | 2 | 194 | 1.0% |
| FU_ELA_to_ELA_and_E2-NETA | 0 | 98 | 0.0% |
| FU_ELA_and_E2-NETA_to_ELA_and_E2-NETA | 1 | 389 | 0.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| SCR_Placebo | 0 of 194 |
| SCR_Elagolix | 0 of 98 |
| SCR_Elagolix_and_E2-NETA | 0 of 389 |
| DB_Placebo | 0 of 194 |
| DB_Elagolix | 0 of 98 |
| DB_Elagolix_and_E2-NETA | 0 of 389 |
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 |
|---|---|
| SCR_Placebo | 1 of 194 |
| SCR_Elagolix | 0 of 98 |
| SCR_Elagolix_and_E2-NETA | 1 of 389 |
| DB_Placebo | 89 of 194 |
| DB_Elagolix | 74 of 98 |
| DB_Elagolix_and_E2-NETA | 236 of 389 |
Most frequent serious adverse event terms
| Event term | Organ system | SCR_Placebo | SCR_Elagolix | SCR_Elagolix_and_E2-NETA | DB_Placebo | DB_Elagolix | DB_Elagolix_and_E2-NETA |
|---|---|---|---|---|---|---|---|
| ENDOMETRIOSIS | Reproductive system and breast disorders | 0 of 194 | 0 of 98 | 0 of 389 | 2 of 194 | 1 of 98 | 0 of 389 |
| ABORTION SPONTANEOUS | Pregnancy, puerperium and perinatal conditions | 0 of 194 | 0 of 98 | 0 of 389 | 1 of 194 | 0 of 98 | 1 of 389 |
| ABORTION INDUCED | Surgical and medical procedures | 0 of 194 | 0 of 98 | 0 of 389 | 1 of 194 | 0 of 98 | 1 of 389 |
| SINUS NODE DYSFUNCTION | Cardiac disorders | 0 of 194 | 0 of 98 | 0 of 389 | 0 of 194 | 0 of 98 | 1 of 389 |
| VESTIBULAR DISORDER | Ear and labyrinth disorders | 0 of 194 | 0 of 98 | 0 of 389 | 0 of 194 | 0 of 98 | 1 of 389 |
| PITUITARY APOPLEXY | Endocrine disorders | 0 of 194 | 0 of 98 | 0 of 389 | 0 of 194 | 0 of 98 | 1 of 389 |
| INTESTINAL PERFORATION | Gastrointestinal disorders | 0 of 194 | 0 of 98 | 0 of 389 | 0 of 194 | 1 of 98 | 0 of 389 |
| PANCREATITIS | Gastrointestinal disorders | 0 of 194 | 0 of 98 | 0 of 389 | 1 of 194 | 0 of 98 | 0 of 389 |
| UMBILICAL HERNIA | Gastrointestinal disorders | 0 of 194 | 0 of 98 | 0 of 389 | 1 of 194 | 0 of 98 | 0 of 389 |
| BILIARY COLIC | Hepatobiliary disorders | 0 of 194 | 0 of 98 | 0 of 389 | 1 of 194 | 0 of 98 | 0 of 389 |
Most frequent non-serious adverse event terms
| Event term | Organ system | SCR_Placebo | SCR_Elagolix | SCR_Elagolix_and_E2-NETA | DB_Placebo | DB_Elagolix | DB_Elagolix_and_E2-NETA |
|---|---|---|---|---|---|---|---|
| HOT FLUSH | Vascular disorders | 0 of 194 | 0 of 98 | 0 of 389 | 14 of 194 | 43 of 98 | 69 of 389 |
| NAUSEA | Gastrointestinal disorders | 1 of 194 | 0 of 98 | 0 of 389 | 12 of 194 | 16 of 98 | 51 of 389 |
| HEADACHE | Nervous system disorders | 1 of 194 | 0 of 98 | 0 of 389 | 10 of 194 | 13 of 98 | 46 of 389 |
| SINUSITIS | Infections and infestations | 0 of 194 | 0 of 98 | 0 of 389 | 13 of 194 | 10 of 98 | 32 of 389 |
| NIGHT SWEATS | Skin and subcutaneous tissue disorders | 0 of 194 | 0 of 98 | 0 of 389 | 6 of 194 | 13 of 98 | 24 of 389 |
| URINARY TRACT INFECTION | Infections and infestations | 0 of 194 | 0 of 98 | 0 of 389 | 9 of 194 | 9 of 98 | 15 of 389 |
| NASOPHARYNGITIS | Infections and infestations | 0 of 194 | 0 of 98 | 0 of 389 | 6 of 194 | 5 of 98 | 21 of 389 |
| UPPER RESPIRATORY TRACT INFECTION | Infections and infestations | 0 of 194 | 0 of 98 | 0 of 389 | 7 of 194 | 7 of 98 | 17 of 389 |
| FATIGUE | General disorders | 0 of 194 | 0 of 98 | 0 of 389 | 7 of 194 | 5 of 98 | 17 of 389 |
| ACNE | Skin and subcutaneous tissue disorders | 0 of 194 | 0 of 98 | 0 of 389 | 7 of 194 | 5 of 98 | 17 of 389 |
Serious events with the highest arm-level rate: abdominal pain lower (1.7%), nausea (1.7%), ovarian cyst ruptured (1.7%), endometriosis (1.0%), intestinal perforation (1.0%).
The safety listing separates serious adverse events, other adverse events, and deaths, and reports participants at risk and affected within each listed group. During the groups labelled SCR, serious adverse events were recorded for 0 participants in placebo, 0 in elagolix, and 1 in elagolix and E2/NETA. During the groups labelled DB, the corresponding counts were 8, 2, and 14. The listing records 0 deaths in every displayed group.
The other adverse-event counts also differ by group and phase: the DB groups list 89, 74, and 236 affected participants for placebo, elagolix, and elagolix with E2/NETA, respectively. Other listed phases include OL and FU groups. Their denominators and affected counts are shown in the posted safety table, which should be read by group rather than combined across phases. The registry record does not explain the SCR, DB, OL, and FU labels.
The serious-term listing includes abdominal pain lower, nausea, ovarian cyst ruptured, endometriosis, intestinal perforation, and abscess intestinal, with the displayed percentages ranging from 1.0% to 1.7%. These figures are descriptive safety summaries. Group sizes, treatment duration, and phase labels should be considered when reading them; the listing alone does not establish that a treatment caused an event or permit a causal comparison. The registry record does not provide further context for these terms in the posted safety summary.
12. What the Result Does, and Does Not, Mean
This record establishes that a randomized, quadruple-masked, parallel Phase 3 study was conducted to evaluate elagolix regimens, including combination treatment with E2/NETA, in participants with moderate to severe endometriosis-associated pain. It also defines a co-primary responder endpoint at month 6 and month 12 and describes a placebo-controlled treatment period followed by continued combination treatment in the arm descriptions. These are features of the study design, not evidence of the direction or size of an outcome.
The record does not report the primary response percentages or confidence intervals. Accordingly, this page cannot state how many participants responded in each group, estimate a treatment difference, or describe its precision. It also cannot say whether the primary result met a statistical threshold. The endpoint definition alone does not establish a favorable or unfavorable result.
Safety counts are available for several listed groups and phases, including serious adverse events and deaths. They are useful as a description of the posted safety record, but they do not by themselves identify the cause of an event or provide a complete comparative safety analysis. The group labels span phases with different treatment sequences, so combining their counts would obscure the distinctions in the registry listing.
In general, a trial result is interpreted by considering the estimated effect, its uncertainty, the analysis population, missing data, multiplicity, and the design. The registry record does not report several of those elements in enough detail to support a complete statistical assessment. The absence of a result in the posted record is not evidence that no effect occurred; it means the result cannot be assessed from this record. No treatment recommendation follows from this statistical description.
13. Why This Trial Matters Statistically
This trial is statistically notable for a responder endpoint that combines a symptom threshold with a rescue-medication condition. That design makes the outcome more specific than a pain score alone, but also means interpretation depends on both components. A response percentage would summarize the proportion meeting the full rule; it would not reveal how much each participant's score changed or how rescue-analgesic use varied within the group.
The co-primary assessments at month 6 and month 12 also illustrate why time points should be interpreted distinctly. A study can ask whether a response is present at more than one stage of treatment, but a statistical plan is needed to clarify how evidence across those assessments is judged. The registry record does not report that plan. The posted counts of 16 outcome measures and 18 analyses further make the treatment of multiple analyses relevant, without revealing the testing hierarchy.
The analysis description offers some information: it names the Full Analysis Set, says participants needed an assessment at the given time point, and reports last observation carried forward. These details make clear that the primary analysis is not described simply as including every randomized participant at every time. Yet the record does not report time-specific analysis counts or missing-data sensitivity analyses, so the implications for precision and robustness cannot be assessed.
Most importantly, the primary response values and confidence intervals are absent from the registry record. Statistical education can explain how these results should be read, but it cannot substitute for the results themselves. This record therefore demonstrates the distinction between a defined endpoint and an interpretable result: knowing what would count as response does not tell readers how often response occurred or how precisely groups differed.
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 limitation for interpretation is that the primary response estimates and 95% confidence intervals are not reported in the registry record. The record defines the co-primary outcome and its assessment times, but without the observed values readers cannot assess the treatment contrast or its precision. A full primary-results table is not available in the record.
The analysis description is also incomplete for independent statistical review. It identifies the Full Analysis Set and last observation carried forward, but does not report the number analyzed at each time point, the amount and pattern of missingness, or sensitivity analyses. The statistical model, any covariate adjustment, and the detailed method for calculating confidence intervals are not reported in the registry record.
Multiplicity is another unresolved issue. There are co-primary endpoint assessments at month 6 and month 12, alongside 16 outcome measures and 18 analyses. The registry record does not report a testing hierarchy or whether adjustments were applied across outcomes and time points. The sample-size justification and any interim-analysis plan are also not reported in the registry record.
The safety listing presents data across several phase-labelled groups, but the registry record does not explain all group abbreviations or provide enough context to combine phase-specific counts. The listed counts should therefore be read as posted for each group, not as a single pooled comparison. These limitations arise from the information available in the registry record and do not establish that unreported analyses were or were not conducted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Clinical Study to Evaluate the Safety and Efficacy of Elagolix in Participants With Moderate to Severe Endometriosis-Associated Pain — NCT03213457.
- Registry record last updated 2024-12-20; status last verified 2024-11.
- Results first posted 2021-04-20.
- 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
NCT03213457 is a completed randomized, quadruple-masked, parallel Phase 3 study sponsored by AbbVie. The registry lists 681 participants with endometriosis-associated pain. The study evaluated elagolix alone and with estradiol/norethindrone acetate, with placebo used during the 12-month placebo-controlled treatment period and further treatment described for the remaining 36 months.
The co-primary endpoint was the percentage of participants meeting a dysmenorrhea response definition at month 6 and month 12. Response required a specified reduction from baseline and no increase in rescue analgesic use under the registered criterion. The primary response results and confidence intervals are not reported in the registry record.
The record describes the Full Analysis Set and last observation carried forward, and lists serious and other adverse events across multiple groups. It does not report detailed multiplicity handling, missing-data sensitivity analyses, or the sample-size justification. The posted information supports a description of the design and registered methods, but not an assessment of the primary treatment effect.