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 Study to Assess the Long-term Safety and Efficacy of Erenumab (AMG 334) in Chronic Migraine Prevention. (NCT02174861), a na phase 2 study. The primary outcome is CHU Substudy: Number of Participants Able to Administer a Full Dose of Erenumab in Home-use.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02174861 |
| Phase | Phase 2 |
| Condition | Treatment for Prevention of Chronic Migraine |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 609 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Amgen |
| Results posted | Yes |
2. Clinical Question
Population
Participants with chronic migraine who entered the study’s home-use substudy and had received at least 1 dose of erenumab in that substudy. The registry describes the primary endpoint population as all randomized participants meeting that condition; it does not report the number in this endpoint population.
Intervention
Erenumab, administered by participants at home as a 140 mg dose posted by the study site. The main study also included erenumab 70 mg once a month or 140 mg once a month by subcutaneous injection for up to 52 weeks.
Comparator
There was no control group listed for this single-group, open-label extension. The registry lists allocation as not applicable, so the study does not provide a like-for-like comparison between erenumab and another treatment or placebo.
Primary question
At the substudy assessments, how many participants reported administering the entire dose of erenumab at home? A full dose meant injecting the entire volume of both prefilled syringes or the autoinjector/pens. The registry record does not report the number able to administer a full dose.
The clinical question is about the practical administration of a dose at home, not a comparison of migraine outcomes between treatment groups. At the day 28 and day 56 substudy visits, the study site posted erenumab 140 mg for self-administration on the following day. Study staff then called participants and asked whether they had administered a full, partial, or no dose.
This endpoint can describe whether participants reported completing the intended home administration under the substudy’s procedures. It does not, by itself, establish how accurately participants administered the medicine, whether home use was preferred, or whether migraine symptoms changed. Those questions require other measurements. Although the record lists several secondary migraine-related outcomes, their results are not included in the registry record.
3. Trial Design
This was a phase 2, open-label extension study of erenumab, with a single-group design and no masking. The study was titled as an assessment of long-term safety and efficacy in chronic migraine prevention. Its stated brief purpose was to assess long-term safety and efficacy. The registry lists an enrollment of 609 and a completed status.
Participants received erenumab 70 mg once a month or 140 mg once a month by subcutaneous injection for up to 52 weeks. The registry does not describe how participants came to receive one dose rather than the other, so this page cannot characterize that process as randomized or infer a comparison between the dose groups. Allocation is listed as not applicable, and the record does not provide a like-for-like control group.
The primary endpoint addressed a home-use substudy. At the day 28 and day 56 substudy visits, the site provided participants with erenumab 140 mg to inject at home the following day. Staff subsequently called and asked whether the participant administered a full, partial, or no dose. The endpoint timeframe is listed as day 29 (week 4) and day 57 (week 8) of the substudy. The registry defines a full dose as the entire volume of both prefilled syringes or the autoinjector/pens being injected.
The registry lists a start date of 2014-06-30 and a primary completion date of 2017-05-26. It also lists secondary outcomes concerning monthly migraine days, acute migraine-specific medication treatment days, cumulative monthly headache hours, and adverse events. These listed outcomes describe what was assessed, not the results. The record does not report the protocol details needed to explain the study’s enrollment rationale, the selection of participants for the substudy, or how dose groups were handled analytically.
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 at sites in the United States, Sweden, and Germany had the option of enrolling in the Clinical Home Use (CHU) Substudy to assess their ability to self-administer 140 mg erenumab for in-home use. Participants in the substudy were randomized 1:1 to self-administer erenumab using either a prefilled syringe or autoinjector/pen.
Overall Study
| Stage | Erenumab |
|---|---|
| STARTED | 609 |
| Enrolled in CHU Substudy | 53 |
| COMPLETED | 451 |
| NOT COMPLETED | 158 |
Reasons for not completing this period:
| Reason | Erenumab |
|---|---|
| Decision by sponsor | 8 |
| Withdrawal by Subject | 124 |
| Lost to Follow-up | 26 |
Analysis population for the primary outcome, as defined in the registry: All enrolled participants who received at least 1 dose of erenumab
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.
| Characteristic | Unit | Erenumab |
|---|---|---|
| Participants analysed | 609 | |
| Age, Continuous | years | 42.5 (SD 11.3) |
| Age, Customized: 18 - 64 years | Participants | 608 |
| Age, Customized: 65 - 74 years | Participants | 1 |
| Sex: Female, Male: Female | Participants | 509 |
| Sex: Female, Male: Male | Participants | 100 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 25 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 584 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race/Ethnicity, Customized: American Indian or Alaska Native | Participants | 0 |
| Race/Ethnicity, Customized: Asian | Participants | 7 |
| Race/Ethnicity, Customized: Black or African American | Participants | 25 |
| Race/Ethnicity, Customized: Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race/Ethnicity, Customized: White | Participants | 574 |
| Race/Ethnicity, Customized: Other | Participants | 3 |
6. Primary Endpoint
The registry lists the primary outcome as CHU Substudy: Number of Participants Able to Administer a Full Dose of Erenumab in Home-use, measured over Day 29 (week 4) and day 57 (week 8) of the substudy.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants able to administer a full dose of erenumab at home in the CHU substudy. It is assessed at day 29 (week 4) and day 57 (week 8) of the substudy. At the preceding day 28 and day 56 visits, the site gave participants erenumab 140 mg to self-administer on the following day. A study staff member then called to ask whether the participant had administered a full, partial, or no dose.
The registry’s definition of a full dose is procedural: the participant must inject the entire volume of both prefilled syringes or the autoinjector/pens. Thus, the endpoint records a reported administration category against a defined criterion. It is not a direct measure of drug exposure, migraine prevention, or clinical benefit. Nor does the record indicate that staff observed the injection; it describes a follow-up call and participant report.
General statistical context: a participant count is useful for expressing how many people meet a stated criterion in the population assessed. To interpret such a count fully, readers also need the denominator, the handling of participants without an assessment, and a clear indication of whether the endpoint is reported separately at each assessment. These details matter because a count alone does not convey the proportion of the assessed population or the precision of that estimate.
The registry record does not report the primary endpoint counts or the endpoint denominator. It therefore does not show how many participants were able to administer a full dose at either assessment, or how precisely that quantity was estimated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary endpoint is a count of participants who reported administering the full erenumab dose at home. The posted the registry entries explain how the endpoint was defined and assessed, but do not include the observed counts. The result therefore cannot be described as showing a particular level of successful home administration. The endpoint denominator is also not reported, so neither a proportion nor its precision can be interpreted.
The registry lists enrollment of 609 for the study as a whole. That number should not be treated as the number assessed for the primary endpoint: the endpoint population is described specifically as participants in the CHU substudy who had received at least 1 dose in that substudy, and its size is not reported in the registry record. The study-wide enrollment does not fill that gap.
The design also limits what the study can establish comparatively. It is an open-label, single-group extension with allocation listed as not applicable. There is no like-for-like control group in the registry record. The primary endpoint is therefore descriptive of reported home administration in the assessed substudy population; it is not a treatment-versus-control estimate. The record does not describe a randomized comparison of the 70 mg and 140 mg monthly regimens, so the listed dosing options cannot be used to infer a dose effect.
The record lists adverse-event counts for the erenumab group: 24 participants with serious adverse events among 609 at risk, 162 with other adverse events among 609 at risk, and 0 deaths. These are safety summaries for the recorded group. They do not establish that events were caused by treatment, nor do they compare risk with an untreated or alternative-treatment group. The listed serious adverse-event terms and their posted percentages provide additional descriptive detail, but do not establish comparative risk.
Secondary outcomes include changes in monthly migraine days, acute migraine-specific medication treatment days, and cumulative monthly headache hours, as well as a measure of participants with at least a 50% reduction in monthly migraine days. Their inclusion in the registry indicates planned or listed assessments, not particular findings. Their results are not reported in the registry record.
General statistical context: estimates are easier to assess when the result, denominator, uncertainty interval, and analysis population are all available. Without the primary endpoint count and denominator, readers cannot assess either the magnitude or precision of the home-use result. The absence of those details is a reporting limitation, not evidence that the result was favorable or unfavorable.
9. Statistical Methods Explained
The primary endpoint is a count: the number of participants classified as able to administer a full dose at home. The registry defines the classification through a participant’s report after the home-use attempt. A full dose means the entire volume of both prefilled syringes or the autoinjector/pens was injected. The call also allowed a partial-dose or no-dose response. The listed endpoint timeframe is day 29 (week 4) and day 57 (week 8) of the substudy.
What a count can show
General statistical explanation: a count gives the number of participants meeting a criterion in an assessed group. It is most interpretable alongside the group’s denominator. A count without its denominator cannot show the share of participants meeting the criterion. If observations are available at more than one assessment, readers also need to know whether results are presented separately by assessment and how participants without a response are treated. The registry record does not report the primary endpoint counts, denominator, or missing-response handling.
What uncertainty means
General statistical explanation: a confidence interval describes uncertainty around an estimate under a specified statistical method. It helps readers distinguish a precise estimate from one that remains compatible with a broader range of values. For a participant count or proportion, interpretation depends on the underlying observations and denominator. Since neither the primary endpoint result nor its denominator is reported in the registry record, this page cannot explain an endpoint-specific confidence interval or its width.
Open-label, single-group evidence
The record describes an open-label study with no masking and a single-group model. General statistical explanation: open-label assessments can be influenced by participants’ knowledge of the treatment, particularly when an endpoint depends on self-report. A single-group design can describe what happened in the participants assessed, but it cannot separate changes associated with treatment from other explanations as a controlled comparison can. Here, the endpoint records reported administration; the registry does not describe an observed injection or a blinded assessment.
The record lists allocation as not applicable and does not identify a control group. The page therefore should not frame the home-use count as a contrast against placebo, usual care, or another treatment. Although the study description lists 70 mg and 140 mg monthly dosing, the record does not say how those regimens were assigned or provide a comparative analysis for the primary endpoint. No dose comparison can be inferred from the dosing description alone.
Safety summaries and interpretation
The registry reports participants at risk and participants affected for serious and other adverse events. General statistical explanation: these figures are descriptive summaries of recorded events in the listed group. Without a concurrent comparison group and sufficient information about event ascertainment and follow-up, they do not estimate a treatment-attributable effect. They should not be read as proof that treatment caused or prevented an event.
The posted sample-size section is a planning illustration based on an observed effect, not the study’s own design justification. General statistical explanation: such illustrations show how sample size can vary under chosen assumptions about the effect to detect, significance level, allocation, and statistical approximation. They are planning scenarios, not evidence that a study had a particular probability of detecting an effect, and not a measure of observed power. In this record, no study-specific sample-size justification or statistical plan is reported. The illustration should not be used to fill in the missing primary endpoint result.
What the methods record leaves unclear
The registry record does not report the analysis method for the primary endpoint, whether counts were analyzed separately at each timepoint, or how repeated observations were handled. It also does not report the number of participants assessed at either timepoint, the number who did not respond to the follow-up call, or the analysis population used for posted endpoint results. The stated endpoint population is all randomized participants who received at least 1 dose in the CHU substudy, but the record does not provide its size or explain the underlying selection and analysis procedures.
General statistical explanation: these details help readers judge whether an analysis matches the question, whether observations are complete, and how much uncertainty remains. They are especially relevant when the endpoint involves participant report at separate follow-up times. Without the result and analysis details, the registry description supports an explanation of what was measured, but not a quantitative conclusion about the endpoint.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 7 outcome measures and includes several secondary migraine-related measures as well as an adverse-event measure. It reports 0 analyses in the record. The primary endpoint is the count of participants able to administer a full dose at home, but its result is not reported in the registry record.
Multiplicity concerns arise when a study assesses several outcomes or makes several statistical comparisons. General statistical explanation: the more results examined, the greater the chance that at least one result may appear notable by chance if all are interpreted without an appropriate plan. Researchers may address this through a prespecified testing sequence, adjustment procedures, or careful emphasis on estimation rather than isolated significance tests. The registry record does not report a multiplicity strategy, a hierarchy of statistical tests, or which outcomes were treated as confirmatory.
Missing data also cannot be evaluated from the endpoint description alone. The primary endpoint population is described as all randomized participants who received at least 1 dose in the CHU substudy, but the registry does not report how many participants were assessed at each timepoint, whether any responses were missing, or how missing responses were handled. These details are not reported in the registry record.
Likewise, the record does not report a statistical analysis plan, the exact analysis populations for the secondary outcomes, or whether interim analyses were conducted. The study is described as an open-label extension, but that description does not supply those methodological details. Consequently, the listed outcomes should be read as measures the registry identifies, not as a complete account of the testing strategy or evidence that all listed results were analyzed in the same way.
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 |
|---|---|---|---|
| Erenumab | 24 | 609 | 3.9% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Erenumab | 0 of 609 |
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 |
|---|---|
| Erenumab | 162 of 609 |
Most frequent serious adverse event terms
| Event term | Organ system | Erenumab |
|---|---|---|
| Migraine | Nervous system disorders | 4 of 609 |
| Intervertebral disc protrusion | Musculoskeletal and connective tissue disorders | 3 of 609 |
| Depression | Psychiatric disorders | 2 of 609 |
| Myocardial bridging | Congenital, familial and genetic disorders | 1 of 609 |
| Abdominal pain | Gastrointestinal disorders | 1 of 609 |
| Oesophagitis | Gastrointestinal disorders | 1 of 609 |
| Volvulus | Gastrointestinal disorders | 1 of 609 |
| Alcoholic liver disease | Hepatobiliary disorders | 1 of 609 |
| Appendicitis | Infections and infestations | 1 of 609 |
| Gastroenteritis viral | Infections and infestations | 1 of 609 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Erenumab |
|---|---|---|
| Viral upper respiratory tract infection | Infections and infestations | 96 of 609 |
| Upper respiratory tract infection | Infections and infestations | 45 of 609 |
| Sinusitis | Infections and infestations | 44 of 609 |
Serious events with the highest arm-level rate: migraine (0.7%), intervertebral disc protrusion (0.5%), depression (0.3%), myocardial bridging (0.2%), abdominal pain (0.2%).
The registry lists 609 participants at risk for serious adverse events in the erenumab group, with 24 participants affected. For other adverse events, it lists 609 at risk and 162 affected. The record reports 0 deaths. These are participant counts for the group listed in the registry; they are not comparative effects.
The registry also identifies serious adverse-event terms with posted percentages: Migraine, 0.7%; Intervertebral disc protrusion, 0.5%; Depression, 0.3%; Myocardial bridging, 0.2%; Abdominal pain, 0.2%; and Oesophagitis, 0.2%. These percentages should be read as the registry’s descriptions, not recalculated estimates. The record does not provide further event-level detail here, such as timing, duration, or whether individual participants experienced more than one event.
General statistical explanation: “at risk” denotes the group used as the denominator for the displayed event summary, while “affected” counts participants with the event category. A participant count does not necessarily equal an event count, since one person may have more than one event. The registry record does not describe event adjudication or establish whether events were caused by treatment.
Because this was a single-group, open-label study without a listed control group, these numbers do not show how event frequency compares with another treatment or with no treatment. They are descriptive safety information, not proof of causation or comparative safety.
12. What the Result Does, and Does Not, Mean
This record describes a study of erenumab that included a home-use substudy. Its primary endpoint asks whether participants reported administering the entire dose at home at the specified follow-up assessments. The registry explains the procedure and the definition of a full dose, but the primary result is not reported in the registry record. Accordingly, the page cannot state how many participants met the criterion or how precisely that number was estimated.
The record also lists an overall enrollment of 609, monthly dosing options of 70 mg or 140 mg, and treatment for up to 52 weeks. Those details describe the study, not the primary endpoint result. The home-use endpoint population is limited to participants who received at least 1 dose in the substudy, and its size is not reported. Study-wide enrollment is not a substitute for the endpoint denominator.
What the study design can describe is the experience recorded in its participants. As an open-label, single-group extension, it does not provide a like-for-like control comparison. The registry does not describe a randomized dose comparison for the primary endpoint. It therefore cannot, on the information, establish that erenumab caused a particular home-use result or that one dose regimen performed differently from another.
The adverse-event figures offer descriptive information for the listed erenumab group, including serious events, other events, and deaths. Without a control group and further event details, these figures do not establish comparative safety or causation. Similarly, listing secondary migraine outcomes does not show what those outcomes were.
General statistical explanation: a result is most informative when readers can see the estimate, its denominator, an uncertainty measure, and the analysis population. Those elements allow assessment of both magnitude and precision. In this record, the primary endpoint result and key analysis details are absent. The appropriate conclusion is therefore limited: the registry describes what the study intended to assess, but does not report the primary home-use finding.
13. Why This Trial Matters Statistically
This study raises a statistical question that differs from a conventional treatment-versus-control efficacy question: can participants report administering a full dose at home under the study’s procedures? The endpoint is operationally defined, with a specified dose, a follow-up call, and categories for full, partial, or no administration. Such detail makes clear what the count is intended to represent.
It also illustrates why a clearly defined outcome is only one part of an interpretable result. A count needs its denominator, and readers need to know who was assessed and how missing responses were handled. The registry record does not report the primary endpoint count or denominator. As a result, the endpoint definition can be understood, but its observed frequency and precision cannot be assessed.
The design is equally important to interpretation. This is an open-label, single-group extension, with no control comparison listed. The home-use result, if reported, would describe participants in the substudy rather than provide a randomized comparison of administration strategies. The record also lists two monthly dose regimens but does not report how participants were assigned to them or a primary endpoint comparison between them.
The study’s safety figures are also best understood descriptively. The registry gives participant counts for serious and other adverse events and reports 0 deaths, but the absence of a control group limits comparative interpretation. These values do not establish whether an event was attributable to treatment.
General statistical explanation: this case shows how design, endpoint definition, denominator, analysis population, and uncertainty work together. Reporting only a study’s purpose and measurement procedure is not enough to assess an observed result. Here, the registry record provides useful design and endpoint descriptions, while leaving the primary endpoint result and several analysis details unreported.
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 principal limitation for interpreting the primary endpoint is that its result is not reported in the registry record. Neither the number able to administer a full dose nor the endpoint denominator is available. Without those, the endpoint’s observed frequency and precision cannot be assessed.
The endpoint depends on participant report after a telephone call. The registry explains that staff asked whether the participant administered a full, partial, or no dose, and defines what counts as full. It does not describe direct observation of administration or another method to verify the report. It also does not say how unanswered calls or incomplete responses were handled.
The reported endpoint population is limited to participants who were randomized and received at least 1 dose in the CHU substudy. The record does not report how many people were in that population, how substudy participation was determined, or the number assessed at either timepoint. The study’s enrollment of 609 does not resolve these endpoint-specific gaps.
The open-label, single-group design offers no like-for-like control comparison. Allocation is listed as not applicable, and the record does not describe how the 70 mg and 140 mg monthly regimens were assigned. The results therefore cannot be used to compare those regimens or separate treatment-associated outcomes from other explanations.
For safety, the record provides participant counts and selected serious adverse-event terms, but does not provide further detail about event timing, duration, participant overlap, or causality. The registry also does not report the statistical plan, multiplicity approach, missing-data methods, or study-specific sample-size justification. These omissions constrain interpretation of the listed outcomes and the completeness of the analysis description.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Assess the Long-term Safety and Efficacy of Erenumab (AMG 334) in Chronic Migraine Prevention. — NCT02174861.
- Registry record last updated 2022-10-12; status last verified 2022-10.
- Results first posted 2018-06-19.
- 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
NCT02174861 is a completed phase 2, open-label extension study of erenumab for chronic migraine prevention. The registry lists a single-group design, enrollment of 609, a start date of 2014-06-30, and a primary completion date of 2017-05-26. Participants received erenumab 70 mg once a month or 140 mg once a month by subcutaneous injection for up to 52 weeks.
The primary endpoint concerns participants able to administer a full dose of erenumab at home in the CHU substudy, assessed at day 29 (week 4) and day 57 (week 8). The registry defines a full dose by the entire volume of the syringes or autoinjector/pens being injected. The primary endpoint result and its denominator are not reported in the registry record.
The record lists 24 participants with serious adverse events among 609 at risk, 162 with other adverse events among 609 at risk, and 0 deaths. These are descriptive figures without a listed control group. The registry does not report the primary endpoint analysis method, missing-data handling, multiplicity strategy, or study-specific sample-size justification.