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 Open-Label Extension Treatment With Etanercept (TNFR:Fc) for Participating Patients in Etanercept (TNFR:Fc) Clinical Trials (NCT00357903), a non-randomized phase 3 study. The primary outcome is Total Exposure to Etanercept With Gaps.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00357903 |
| Phase | Phase 3 |
| Condition | Rheumatoid Arthritis |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 639 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Amgen |
| Results posted | Yes |
2. Clinical Question
Population
Adult and pediatric arthritis patients who had participated in clinical trials of etanercept were eligible for continued treatment in this extension. The primary outcome population is described as participants who received at least one dose of etanercept. Rheumatoid arthritis is the condition listed in the registry record.
Intervention
The intervention was etanercept, also identified in the record as TNFR:Fc. The study offered continued treatment to participating patients who had previously received placebo or etanercept in clinical trials. The extension is described as open-label.
Comparator
No randomized control group is described. The study is listed as non-randomized and single-group, so it does not make a like-for-like comparison between randomized treatment groups. Prior placebo or etanercept exposure does not establish a concurrent control group in this record.
Primary question
The primary objective was to examine safety parameters during continued etanercept treatment. The primary outcome is total exposure to etanercept with gaps, measured in participant-years over up to 10 years. The registry record does not report a numerical result for this exposure measure, so it does not quantify the total exposure achieved.
The study was designed to give adult and pediatric arthritis patients who had participated in etanercept clinical trials an opportunity to continue treatment. The clinical question is therefore about safety and treatment exposure during an open-label extension, rather than whether etanercept is superior to a control treatment. The registry record also lists secondary measures involving joint counts, disability assessments, C-reactive protein, and response criteria. Those outcomes do not change the central limitation of the design: without a randomized comparison, outcomes observed during the extension cannot by themselves separate treatment effects from other explanations, including the course of disease over time.
3. Trial Design
This is a Phase 3, completed, open-label extension study. The registry record describes a non-randomized allocation and a single-group model, with etanercept as the intervention. Enrollment is listed as 639. The study began in 1997-04, and primary completion is listed as 2008-12.
The study was designed to offer continued etanercept treatment to adult and pediatric arthritis patients who had participated in clinical trials of etanercept. The brief summary says that participants could have previously received placebo or etanercept. It does not describe a randomized allocation to treatment in the extension. The record therefore does not establish a concurrent, randomized control group, and prior treatment history should not be treated as though it were a randomized comparison within this study.
The primary objective was to examine safety parameters. The primary outcome is total exposure to etanercept with gaps, in participant-years, over up to 10 years. The outcome population is described as all participants who received at least one dose of etanercept. The record also lists secondary outcomes that include dosing period, tender and swollen joint counts, disability indices for adults and children, C-reactive protein, and response measures at Month 3.
The registry record lists 19 outcome measures and 2 analyses. It does not report the detailed analysis plan, the rationale for the enrollment target, or whether interim analyses were planned. Because the study is open-label and non-randomized, its design is suited to documenting exposure and observed safety outcomes during continued treatment, but it does not provide a randomized estimate of a treatment contrast. The listed enrollment should not be interpreted as the number included in every outcome analysis; the analysis population and denominators may vary by outcome, and further details are 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
| Stage | Adult Participants | Pediatric Participants |
|---|---|---|
| STARTED | 581 | 58 |
| COMPLETED | 218 | 15 |
| NOT COMPLETED | 363 | 43 |
Reasons for not completing this period:
| Reason | Adult Participants | Pediatric Participants |
|---|---|---|
| Adverse Event | 87 | 4 |
| Death | 33 | 0 |
| Lost to Follow-up | 23 | 4 |
| Physician Decision | 39 | 5 |
| Withdrawal by Subject | 57 | 7 |
| Completed month 12 only | 0 | 1 |
| Protocol issues | 14 | 3 |
| Response status | 61 | 9 |
| Other | 49 | 10 |
Analysis population for the primary outcome, as defined in the registry: All participants who received at least one dose of etanercept
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 | Pediatric Participants | Adult Participants | Total |
|---|---|---|---|---|
| Participants analysed | 58 | 581 | 639 | |
| Age, Continuous | Years | 11.02 (SD 3.80) | 52.87 (SD 12.03) | 49.07 (SD 16.66) |
| Sex: Female, Male: Female | Participants | 39 | 465 | 504 |
| Sex: Female, Male: Male | Participants | 19 | 116 | 135 |
| Race/Ethnicity, Customized: American Indian or Alaska Native | Participant | 1 | 4 | 5 |
| Race/Ethnicity, Customized: Asian | Participant | 1 | 10 | 11 |
| Race/Ethnicity, Customized: Black or African American | Participant | 4 | 18 | 22 |
| Race/Ethnicity, Customized: Hispanic or Latino | Participant | 9 | 25 | 34 |
| Race/Ethnicity, Customized: White or Caucasian | Participant | 43 | 522 | 565 |
| Race/Ethnicity, Customized: Other | Participant | 0 | 2 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Total Exposure to Etanercept With Gaps, measured over Up to 10 years.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Participant-years |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is total exposure to etanercept with gaps, measured in participant-years over up to 10 years. Its description specifies that it concerns exposure among participants who received at least one dose. Including gaps signals that exposure is not necessarily treated as uninterrupted: periods away from treatment are relevant to the accumulated exposure measure.
Exposure measures are useful in an extension study because they describe how much treatment experience was accumulated while participants were followed under the study. That context can help readers understand the period over which safety observations arose. Participant-years express accumulated exposure in a time-based form; they are not themselves a count of adverse events or a measure of treatment effect.
The registry record does not report the numerical value for total exposure, nor does it describe the precise calculation rules for gaps or provide a distribution of individual exposure durations. As a result, the endpoint’s definition is available, but its observed magnitude and the amount of variation between participants are not. The outcome also does not, by itself, establish how safety would compare with a different treatment or with no treatment. An exposure total describes treatment experience in the study population; it is not a causal comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a study whose primary objective was to examine safety during continued etanercept treatment. Its primary outcome is total exposure to etanercept with gaps, over up to 10 years. However, no numerical result for that primary outcome is reported in the registry record. Readers therefore cannot determine from this record how many participant-years of exposure were observed, or assess the precision of an exposure estimate.
The study is identified as non-randomized, open-label, and single-group. Those design features matter for interpretation. The extension can document events observed among participants receiving etanercept, but it does not supply a randomized comparison with a concurrent control group. Observed outcomes cannot be attributed to treatment alone on the basis of this design. Differences in participants’ prior treatment, disease course, follow-up, and other factors may affect what is observed; the registry record does not provide enough detail to evaluate those influences.
Serious-event counts are listed separately for adults and pediatric subjects, along with counts for other events. Those figures describe the recorded event categories and their stated denominators; they are not a randomized contrast. The registry also lists percentages for several serious-event terms, but does not report the denominator definition or the detailed calculation method alongside those terms. A term’s listed percentage should therefore be read as registry-reported information, not as an independently verified risk estimate or a comparison with another treatment.
The record also lists secondary clinical measures, including joint counts, disability measures, C-reactive protein, and response outcomes. Their inclusion indicates the kinds of outcomes tracked, but the record does not provide the results for those measures in the registry record for this analysis. It would not be appropriate to infer improvement or worsening from outcome names alone.
Precision cannot be assessed for the primary endpoint because its numerical estimate and uncertainty interval are not reported. The record also does not report a statistical analysis plan, details of missing-data handling, or the specific analysis populations for all outcomes. Overall, the record describes the study’s purpose, design, endpoint, and selected safety counts, but it does not provide enough primary-outcome information to quantify exposure or estimate a comparative treatment effect.
9. Statistical Methods Explained
The statistical interpretation starts with the design. This study is listed as non-randomized, open-label, and single-group. Randomization is a method for making treatment groups comparable on average at the start of a trial. Because the registry record does not describe randomized groups in this extension, it does not support a randomized treatment comparison. An open-label design also means the record does not describe masking of treatment assignment. This can matter for outcomes influenced by reporting, clinical decisions, or assessment, although the record does not specify how individual outcomes were assessed.
What does participant-years measure?
Participant-years are a time-based way to describe accumulated observation or treatment exposure across people. For this endpoint, the registry specifies etanercept exposure with gaps. The measure is intended to reflect exposure over time rather than simply report the number of people treated. General statistical context: time-based exposure summaries can help describe the amount of experience available for safety monitoring, but they do not show whether an event was caused by treatment. The registry record does not report the numerical total or the detailed rules used to count gaps.
How should counts and percentages be read?
A count reports the number of people or events meeting a definition, while a percentage places a count in relation to a denominator. The registry lists serious adverse event counts and other-event counts for adult and pediatric groups, as well as percentages for selected serious-event terms. These are descriptive safety summaries. They do not constitute a comparison against an untreated or randomized control group. The definitions used for each count, the period of risk, and the denominators for the listed term percentages are not fully reported in the registry record.
General statistical context: event rates can depend on the amount of time participants are observed, and simple proportions do not account for differences in follow-up duration. Exposure time can therefore be important when comparing event frequency across groups or studies. No such adjusted comparison is reported in the record, and it would be inappropriate to construct one from the listed summaries without the necessary details.
What would a confidence interval add?
General statistical context: a confidence interval expresses the uncertainty around an estimate under a statistical model and analysis procedure. It helps readers distinguish a relatively precise estimate from one with substantial uncertainty. The registry record does not report a numerical estimate or confidence interval for the primary exposure endpoint. It also does not provide intervals for the safety counts in the registry record for this analysis. Consequently, the precision of these outcomes cannot be evaluated from the listed information.
What can secondary outcomes establish?
The record lists secondary outcomes including dosing period, joint counts, adult and pediatric disability indices, C-reactive protein, and response outcomes at Month 3. Listing an endpoint does not provide its result or show how it was analyzed. The registry record does not report the numerical secondary outcome results here, nor does it specify detailed models, adjustments, or analysis populations for each measure. General statistical context: repeated measurements and multiple outcomes may require choices about how to handle within-participant correlation and the risk of chance findings. Those choices are part of an analysis plan, which is not reported in the registry record.
How should planning calculations be understood?
General statistical context: a sample-size calculation is a planning illustration based on assumptions about a future study, such as the effect to detect and the analysis method. It is not an observed result and is not evidence that a completed study had a particular probability of finding an effect. The record’s planning assumptions describe an illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such planning figures are not observed power. The detailed sample-size values and the effect estimates they rely on are not reported in the registry record for this analysis; the registry record also does not say that these assumptions were the study’s own design basis.
The registry record does not report a formal statistical analysis plan, model specifications, treatment of missing data, or methods for adjusting for confounding. No recalculated treatment comparison is appropriate for this single-group extension on the information available. The key methodological point is that descriptive counts and exposure summaries answer different questions from a comparative estimate: the former describe what was recorded among participants, while the latter would require a suitable comparison and analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 19 outcome measures and 2 analyses. It names the primary outcome and several secondary outcomes, but does not report a detailed statistical analysis plan describing how the analyses were selected, ordered, or interpreted. A multiplicity adjustment or other strategy for controlling the chance of false-positive findings across multiple outcomes is not reported in the registry record.
General statistical context: when many outcomes or comparisons are examined, the chance of obtaining at least one apparently unusual result by chance can increase. Prespecified outcome priorities and an explicit multiplicity strategy help readers understand how strongly to interpret individual findings. The record’s listing of outcomes alone does not establish whether such a strategy was planned or used.
Missing-data methods are not reported in the registry record. The record does not describe how missing measurements, withdrawals, interrupted treatment, or incomplete follow-up were handled in analyses. The primary outcome explicitly concerns exposure with gaps, but its definition does not explain how missing information or gaps were distinguished or counted. The analysis populations for the secondary outcomes are also not reported in the registry record for this analysis.
The primary outcome population is described as participants who received at least one dose of etanercept. That description does not establish that every participant enrolled contributed data to every endpoint. Without outcome-specific denominators and missing-data rules, readers cannot assess whether the analyzed populations differed across outcomes or how incomplete follow-up may have affected estimates. These omissions limit assessment of both bias and precision.
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 |
|---|---|---|---|
| Total Adults | 293 | 581 | 50.4% |
| Pediatric Subjects | 16 | 58 | 27.6% |
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 |
|---|---|
| Total Adults | 484 of 581 |
| Pediatric Subjects | 49 of 58 |
Most frequent serious adverse event terms
| Event term | Organ system | Total Adults | Pediatric Subjects |
|---|---|---|---|
| Pneumonia | Infections and infestations | 36 of 581 | 0 of 58 |
| Rheumatoid arthritis | Musculoskeletal and connective tissue disorders | 28 of 581 | 6 of 58 |
| Condition aggravated | General disorders | 25 of 581 | 3 of 58 |
| Myocardial infarction | Cardiac disorders | 20 of 581 | 0 of 58 |
| Cellulitis | Infections and infestations | 19 of 581 | 0 of 58 |
| Skin infection | Infections and infestations | 14 of 581 | 2 of 58 |
| Osteoarthritis | Musculoskeletal and connective tissue disorders | 15 of 581 | 0 of 58 |
| Cardiac failure congestive | Cardiac disorders | 13 of 581 | 0 of 58 |
| Coronary artery disease | Cardiac disorders | 12 of 581 | 0 of 58 |
| Sepsis | Infections and infestations | 10 of 581 | 1 of 58 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Total Adults | Pediatric Subjects |
|---|---|---|---|
| Upper respiratory tract infection | Infections and infestations | 207 of 581 | 36 of 58 |
| Sinusitis | Infections and infestations | 121 of 581 | 8 of 58 |
| Headache | Nervous system disorders | 80 of 581 | 20 of 58 |
| Bronchitis | Infections and infestations | 89 of 581 | 4 of 58 |
| Skin infection | Infections and infestations | 84 of 581 | 9 of 58 |
| Injection site erythema | General disorders | 65 of 581 | 8 of 58 |
| Influenza | Infections and infestations | 60 of 581 | 7 of 58 |
| Cystitis | Infections and infestations | 57 of 581 | 0 of 58 |
| Rash | Skin and subcutaneous tissue disorders | 50 of 581 | 7 of 58 |
| Diarrhoea | Gastrointestinal disorders | 52 of 581 | 4 of 58 |
Serious events with the highest arm-level rate: rheumatoid arthritis (10.3%), pneumonia (6.2%), condition aggravated (5.2%), abdominal pain upper (3.4%), herpes zoster (3.4%).
The registry lists serious adverse event summaries for Total Adults and Pediatric Subjects. For Total Adults, the serious-event figures are 581 at risk and 293 affected; the other-event figures are 581 at risk and 484 affected. For Pediatric Subjects, the serious-event figures are 58 at risk and 16 affected; the other-event figures are 58 at risk and 49 affected. These are descriptive counts and denominators, not comparisons between randomized treatment groups.
The listed serious-event terms include Rheumatoid arthritis at 10.3%, Pneumonia at 6.2%, Condition aggravated at 5.2%, Abdominal pain upper at 3.4%, Herpes zoster at 3.4%, and Skin infection at 3.4%. The registry record does not fully specify the denominator definition or calculation details for these percentages. They should be read as reported summaries rather than interpreted as comparative risks.
No death counts are reported in the record. The summaries do not establish whether an event was caused by etanercept, and the single-group, non-randomized design provides no concurrent randomized safety comparison. The registry record also does not provide event timing or exposure-adjusted rates for these terms in the registry record for this analysis.
12. What the Result Does, and Does Not, Mean
The study record documents an open-label extension intended to offer continued etanercept treatment to adult and pediatric arthritis patients who had participated in etanercept clinical trials. Its stated primary objective was to examine safety parameters, and its primary endpoint was total exposure to etanercept with gaps, measured in participant-years over up to 10 years.
The registry record does not report a numerical result for that primary endpoint. It therefore does not show the amount of exposure accumulated or provide a basis for judging the precision of an exposure estimate. The record does list serious and other adverse event counts and selected serious-event percentages. These summaries describe events recorded in the study, but they do not show that treatment caused the events or how event frequency would compare with another treatment.
The study’s non-randomized, single-group design is central to what can be concluded. It can provide descriptive information about treatment exposure and safety observations in the people who took part. It cannot, by itself, estimate a causal difference between etanercept and a control treatment. Prior participation in trials involving placebo or etanercept does not turn the extension into a randomized comparison.
The registry also lists secondary outcomes in joint counts, disability assessments, C-reactive protein, and response measures. Their presence does not establish what happened on those outcomes; numerical results for them are not reported in the registry record for this analysis. The record does not report detailed analysis methods, missing-data handling, or uncertainty intervals for the primary endpoint.
Thus, the record supports a description of the study’s purpose, design, endpoint definition, and selected safety summaries. It does not support a conclusion about comparative efficacy, causal safety effects, or the size and precision of the primary exposure result. Those questions require results and analysis details not reported in the registry record.
13. Why This Trial Matters Statistically
This study illustrates why the design label matters when reading clinical trial records. A Phase 3 study can be non-randomized and single-group; its phase does not imply that it provides a randomized treatment comparison. Here, the stated purpose was to examine safety during continued etanercept treatment, and the study offered an extension opportunity to participants from etanercept clinical trials.
The primary endpoint also highlights a distinction between treatment exposure and a clinical outcome. Total exposure with gaps, expressed in participant-years, describes accumulated experience on treatment. It can provide context for safety observations, but it is not itself a measure of benefit, harm, or comparative effect. The registry record defines this endpoint but does not report its numerical result, which limits what can be learned from the primary outcome.
Safety counts need similar care. The record lists counts for adults and pediatric subjects and percentages for selected serious-event terms. Without a randomized comparator, detailed event definitions, or full information about follow-up and denominators, these summaries are descriptive rather than comparative. They can identify what was recorded, but they cannot establish causation or determine how the findings compare with another treatment.
Finally, the record demonstrates the importance of reporting analysis details. The outcomes are listed, but the statistical plan, missing-data procedures, and outcome-specific analysis populations are not reported in the registry record. These details affect how confidently readers can interpret estimates and assess possible bias. A clear outcome definition is useful, but interpretation also depends on numerical results, uncertainty, and a transparent account of how the data were analyzed.
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 most direct limitation for interpreting the primary endpoint is that its numerical result is not reported in the registry record. Although the endpoint is defined as total etanercept exposure with gaps, in participant-years over up to 10 years, the record does not state the observed total or its uncertainty. This prevents assessment of the magnitude and precision of the primary outcome.
The non-randomized, open-label, single-group design limits causal interpretation. There is no concurrent randomized control group described, so the study cannot establish a treatment contrast on the basis of its design. The record does not report details that would allow adjustment for differences in prior treatment, follow-up, or other factors.
The safety summaries have further limitations. The registry lists counts and selected percentages, but detailed event definitions, timing, follow-up duration by group, and the percentage denominators are not reported in the registry record for this analysis. Death counts are not reported. The summaries therefore cannot establish treatment causation or support a direct comparison with another study or treatment.
Analysis details are also limited. The statistical analysis plan, missing-data methods, and outcome-specific analysis populations are not reported in the registry record. The listed secondary outcomes do not include numerical results in the registry record for this analysis. The record also does not report the rationale for enrollment or whether interim analyses were planned. These omissions constrain evaluation of bias, precision, and the interpretation of secondary findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Open-Label Extension Treatment With Etanercept (TNFR:Fc) for Participating Patients in Etanercept (TNFR:Fc) Clinical Trials — NCT00357903.
- Registry record last updated 2017-02-09; status last verified 2017-02.
- Results first posted 2010-12-06.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes a completed Phase 3, open-label, non-randomized, single-group extension study of etanercept for adult and pediatric arthritis patients who had participated in etanercept clinical trials. Enrollment is listed as 639. The study began in 1997-04, with primary completion in 2008-12.
The primary objective was to examine safety parameters. The primary outcome was total exposure to etanercept with gaps, measured in participant-years over up to 10 years among participants who received at least one dose. Its numerical result is not reported in the registry record. The record lists serious and other adverse event counts by adult and pediatric group and selected serious-event percentages, but provides no randomized safety comparison. Secondary outcomes are listed, while their numerical results are not reported in the registry record for this analysis.