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 DuraGen Plus® Adhesion Barrier for Use in Spinal Surgery (NCT00387829), a randomized na study. The primary outcome is Radiological, Pain, and Functional Outcome Assessments.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00387829 |
| Phase | NA |
| Condition | Spinal Injuries, Adhesions |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 347 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Integra LifeSciences Corporation |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerned patients undergoing lumbar discectomy in the setting of spinal injuries and adhesions. The outcome population is described as patients evaluable at 6 months. The registry record does not report further eligibility details, such as specific inclusion or exclusion criteria, or the number of patients evaluable for each assessment.
Intervention
The intervention was DuraGen Plus Adhesion Barrier Matrix used as an adhesion barrier in the spine during surgery. The study aim was to evaluate its safety and effectiveness in relation to peridural fibrosis formation and radicular pain. The registry record does not provide additional procedural details about how the device was applied.
Comparator
The comparator was surgery alone, with no adhesion barrier. This provides a comparison between the device used during surgery and the surgical procedure without an adhesion barrier. The registry record does not describe other differences in care between the groups.
Primary question
The central question was whether use of the adhesion barrier was associated with differences in radiological, pain, and functional outcome assessments at 6 months. The measures described include an MRI outcome score for peridural fibrosis, a Visual Analog Score for pain, and an Oswestry Disability Index score for everyday effects of back or leg pain. The registry record does not provide a single numerical comparison across these measures.
3. Trial Design
This was a randomized, double-masked, parallel-group trial of DuraGen Plus Adhesion Barrier Matrix in spinal surgery. The registry record gives enrollment as 347. Participants were assigned to use of the matrix as an adhesion barrier during surgery or to surgery alone, without an adhesion barrier. Random allocation can support a fair comparison by reducing systematic differences between groups at the outset, although the registry record does not describe the randomization sequence or how allocation was concealed.
The record identifies the masking as double but does not specify which people were masked or how masking was maintained. The parallel design means the two groups received different assigned approaches during the study rather than crossing over between them. The record does not describe any crossover or changes in assigned treatment.
The study began in 2006-10, and the recorded primary completion was 2010-12. Its current status is TERMINATED. The reason for termination is not reported in the registry record. The record does not state whether termination followed a safety concern, operational difficulty, a planned stopping decision, or another reason, so no such explanation can be inferred from status alone.
The outcome timeframe is 6 months, and the listed population for the primary outcome record is patients evaluable at 6 months. Enrollment therefore should not be treated as the number contributing to every outcome assessment. The number assessed for each measure, and the reasons participants may not have been evaluable, are not reported in the registry record. The phase is listed as NA. The record does not report a sample-size justification, details of follow-up procedures, or the planned statistical analysis.
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: A total of 343 patients were randomized in the study (Intent-to-treat population). Four patients received treatment (1 Duragen Plus; 3 Surgery alone), but were not randomized correctly, and were followed-up for safety only. Hence the total patients in the Safety Population is 347.
Safety Population
| Stage | 1- DuraGen Plus During Surgery | 2 - Surgery Alone |
|---|---|---|
| STARTED | 178 | 169 |
| COMPLETED | 139 | 136 |
| NOT COMPLETED | 39 | 33 |
Intent-to-treat Population
| Stage | 1- DuraGen Plus During Surgery | 2 - Surgery Alone |
|---|---|---|
| STARTED | 177 | 166 |
| COMPLETED | 139 | 136 |
| NOT COMPLETED | 38 | 30 |
Analysis population for the primary outcome, as defined in the registry: Data reported for patients evaluable at 6 months.
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: A total of 343 patients were randomized in the study (Intent-to-treat population). Four patients received treatment (1 Duragen Plus; 3 Surgery alone), but were not randomized correctly, and were followed-up for safety only. Hence the total patients in the Safety Population is 347.
| Characteristic | Unit | 1- DuraGen Plus During Surgery | 2 - Surgery Alone | Total |
|---|---|---|---|---|
| Participants analysed | 177 | 166 | 343 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 171 | 162 | 333 |
| Age, Categorical: >=65 years | Participants | 6 | 4 | 10 |
| Age, Continuous | years | 42.7 (SD 11.38) | 43.3 (SD 11.27) | 43.0 (SD 11.31) |
| Sex: Female, Male: Female | Participants | 76 | 74 | 150 |
| Sex: Female, Male: Male | Participants | 101 | 92 | 193 |
| Region of Enrollment: United States | participants | 177 | 166 | 343 |
6. Primary Endpoint
The registry lists the primary outcome as Radiological, Pain, and Functional Outcome Assessments, measured over 6 months.
| Element | Registry entry |
|---|---|
| Result type | Least Squares Mean |
| Measure of spread | Standard Error |
| Unit | Outcome scores |
| Endpoint classification | Continuous Endpoint |
The outcome record is titled Radiological, Pain, and Functional Outcome Assessments, with outcome scores as the unit and a 6-month timeframe. It describes three kinds of assessment. The MRI outcome score assesses peridural fibrosis using 5 consecutive 2-D axial Spin Echo T1 axial slices. The description relates the score to the ratio of available space and identified scar, expressed as a percentage. This radiological measure is relevant to the study question because the stated aim concerns the extent of peridural fibrosis after surgery.
Pain is assessed with a Visual Analog Score (VAS), described as a 100 mm horizontal line. Its endpoints are 0 for no pain and 100 for the worst possible pain. The functional measure is the Oswestry Disability Index (ODI), intended to assess the effect of leg or back pain on everyday life. Its questions concern activities such as walking, lifting, sitting, and travel. The description gives ten questions with scores from 0-5 and says the result is calculated as a percentage of the maximum overall score for worst disability.
Together, these assessments address imaging, reported pain, and daily function rather than a single type of outcome. The record specifies least squares means and standard errors as the summary format. It does not give the actual estimates or a single contrast between groups for these measures.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a randomized comparison of DuraGen Plus Adhesion Barrier Matrix during surgery against surgery alone. It identifies radiological, pain, and functional outcomes at 6 months, but the posted outcome information does not reduce the several categories or time points to one comparison. The record lists 0 analyses. As a result, the record does not provide a single treatment-effect estimate, confidence interval, or test result that can be interpreted as an overall comparison of the groups.
The stated summary measure is a least squares mean with a standard error. A least squares mean is a model-based mean, often adjusted for other terms in an analysis, while a standard error describes the precision of an estimated mean. However, the registry record does not report the model, any adjustment variables, the estimates, or their standard errors. It is therefore not possible to determine from the record how precisely the groups differed on the MRI, pain, or functional measures.
The registry lists patients evaluable at 6 months as the outcome population. That description does not establish how many people contributed to each assessment or whether the analysis included all randomized participants. The participant counts analyzed for each outcome, missing observations, and reasons for missingness are not reported in the registry record. Thus, enrollment of 347 should not be interpreted as the analysis sample size for any particular endpoint.
The safety information lists serious and other adverse-event counts for each group, with the numbers at risk also given. These counts describe events recorded in the registry; they do not by themselves establish whether the groups differed in risk. No statistical comparison, confidence interval, or adjusted analysis of adverse events is reported in the registry record. The listed serious-event terms are not presented as a group-specific comparative analysis.
The study status is TERMINATED, but the reason is not reported in the registry record. Termination alone does not identify whether the study ended early, whether recruitment was completed, or whether a specific outcome or safety issue influenced the decision. It also cannot substitute for results. The available record supports a description of the design, outcome definitions, and adverse-event counts, but not a conclusion about the direction, size, or precision of an outcome difference between groups.
9. Statistical Methods Explained
What does a least squares mean represent?
A least squares mean is an estimated mean produced by a statistical model. Unlike a simple arithmetic average, it can reflect adjustment for variables included in that model. Such adjustment can be useful when researchers want group estimates that account for specified characteristics or design features. It is only possible to understand what the estimate represents by knowing the model and its included terms. Those details are not reported in the registry record, and no least squares mean estimates are posted for interpretation.
For a continuous outcome, a group mean is one way to summarize the typical score in that group. A comparison between means can describe the average difference between groups, but its interpretation depends on the scale, the analysis population, and the uncertainty around the estimate. The registry gives the summary type as least squares mean, but does not give numerical estimates or a single group contrast for the described outcomes.
What does a standard error tell the reader?
A standard error describes the statistical precision of an estimated quantity. It is not the same as the spread of individual participant scores: a standard deviation describes variability among observations, whereas a standard error concerns uncertainty in an estimate. A smaller standard error generally corresponds to a more precise estimate under the assumptions of the analysis. Its interpretation is limited because the registry record does not report the standard errors, the model, or the number of evaluable participants behind each estimate.
A confidence interval is a range constructed using an estimate and its uncertainty, under a specified statistical procedure. It communicates which values remain compatible with the observed data and the method's assumptions. It is not a guarantee that the true value lies within that particular interval. No confidence intervals for the outcome estimates are reported in the registry record, so the precision of any outcome comparison cannot be assessed from the outcome listing alone.
Why does the outcome scale matter?
The MRI score, VAS, and ODI do not measure the same construct. The MRI assessment concerns peridural fibrosis, the VAS records a pain rating, and the ODI concerns the effect of pain on everyday activities. A result on one measure should not automatically be treated as a result on another. A statistical difference in a score would also need to be understood in terms of that score's scale and what changes in the score mean. The registry provides descriptions of the scales but no outcome estimates or interpretation thresholds.
The MRI description refers to a percentage based on available space and identified scar in 5 consecutive 2-D axial Spin Echo T1 axial slices. The VAS is described on a 100 mm horizontal line, with 0 for no pain and 100 for the worst possible pain. The ODI description gives ten questions scored from 0-5, combined as a percentage of the maximum overall score for worst disability. These details indicate how different aspects of the clinical question were operationalized, but do not establish how the scores were analyzed or whether they were combined.
How should a randomized comparison be interpreted?
Random assignment is intended to make treatment groups comparable on average at the start of a trial, including for characteristics that may not have been measured. It does not ensure that groups are identical, and it does not resolve problems such as missing outcome data or departures from assigned treatment. Interpretation also relies on knowing how randomization was implemented and how participants were analyzed. The registry identifies random allocation, but the sequence-generation method, allocation concealment, and analysis population are not reported in the registry record.
In a parallel-group study, the groups are compared according to their assigned approaches over the study period. Whether an analysis follows assignment regardless of treatment received, or includes only participants who meet particular criteria, affects the meaning of the estimate. The registry record does not specify an intention-to-treat analysis or another analysis population. It also does not describe protocol deviations, crossovers, or adherence.
What can be inferred from the listed analysis information?
The registry record lists 0 analyses and does not report a statistical plan, a hypothesis test, or a group comparison for the outcomes. It would be inappropriate to infer an analysis method from the stated use of least squares means alone. Model choice, handling of repeated assessments, covariate adjustment, assumptions, and any approach to multiple outcomes are not reported in the registry record.
General statistical practice distinguishes the magnitude of an estimated effect from its precision. A point estimate describes the result in the analyzed data; its uncertainty indicates how much the estimate might vary under repeated sampling and the chosen model. Neither can be evaluated for the principal outcome measures without posted estimates and uncertainty measures. Nor can a significance test be inferred from the design or endpoint descriptions. The record supports a clear account of the planned clinical comparison and the measurement concepts, but it does not provide the inferential results needed to assess the strength of evidence for a difference.
10. Multiplicity, Missing Data and Analysis Populations
The outcome record combines radiological, pain, and functional assessments, and the registry also lists Radiological, Pain, and Functional Outcome Assessments among secondary outcomes. The record indicates that the outcome information includes several categories or time points and is not reduced to one comparison. When a study examines several outcomes or time points, the chance of at least one apparently notable result can increase if each is tested separately. General approaches to this issue include identifying a primary hypothesis in advance, adjusting for multiple comparisons, or treating additional outcomes as exploratory. The registry record does not report a multiplicity strategy or a hierarchy of tests.
The record identifies patients evaluable at 6 months as the outcome population, but does not report the number evaluated for each measure or the amount and pattern of missing outcome data. It does not describe methods for handling missing scores, whether any values were imputed, or whether sensitivity analyses were conducted. Missingness can affect interpretation if participants with observed measurements differ systematically from those without them. Without these details, the direction or extent of any resulting bias cannot be assessed.
The analysis population is also not specified beyond the evaluable-patient description. The registry record does not state whether all randomized participants were analyzed according to assigned group, or whether exclusions were applied. It does not report protocol deviations or how they were handled. These omissions limit understanding of how the outcome estimates would relate to the randomized comparison.
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 |
|---|---|---|---|
| 1- DuraGen Plus During Surgery | 18 | 178 | 10.1% |
| 2 - Surgery Alone | 19 | 169 | 11.2% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 3% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| 1- DuraGen Plus During Surgery | 100 of 178 |
| 2 - Surgery Alone | 106 of 169 |
Most frequent serious adverse event terms
| Event term | Organ system | 1- DuraGen Plus During Surgery | 2 - Surgery Alone |
|---|---|---|---|
| Inververtebral disc protrusion | Musculoskeletal and connective tissue disorders | 8 of 178 | 9 of 169 |
| Headache | Nervous system disorders | 2 of 178 | 1 of 169 |
| Bradycardia | Cardiac disorders | 0 of 178 | 2 of 169 |
| Intracranial hypotension | Injury, poisoning and procedural complications | 1 of 178 | 1 of 169 |
| Back pain | Musculoskeletal and connective tissue disorders | 1 of 178 | 1 of 169 |
| Arrhythmia | Cardiac disorders | 0 of 178 | 1 of 169 |
| Atrial fibrillation | Cardiac disorders | 1 of 178 | 0 of 169 |
| Cardiac failure congestive | Cardiac disorders | 1 of 178 | 0 of 169 |
| Sinus bradycardia | Cardiac disorders | 1 of 178 | 0 of 169 |
| Faeces Discouloured | Gastrointestinal disorders | 0 of 178 | 1 of 169 |
Most frequent non-serious adverse event terms
| Event term | Organ system | 1- DuraGen Plus During Surgery | 2 - Surgery Alone |
|---|---|---|---|
| Back pain | Musculoskeletal and connective tissue disorders | 33 of 178 | 36 of 169 |
| Pain in extremety | Musculoskeletal and connective tissue disorders | 17 of 178 | 16 of 169 |
| Inververtebral disc protrusion | Musculoskeletal and connective tissue disorders | 16 of 178 | 13 of 169 |
| Muscle Spasms | Musculoskeletal and connective tissue disorders | 7 of 178 | 12 of 169 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 11 of 178 | 6 of 169 |
| Hypoaesthesia | Nervous system disorders | 7 of 178 | 10 of 169 |
| Procedural pain | Injury, poisoning and procedural complications | 5 of 178 | 6 of 169 |
| Headache | Nervous system disorders | 4 of 178 | 7 of 169 |
Serious events with the highest arm-level rate: inververtebral disc protrusion (5.3%), bradycardia (1.2%), headache (1.1%), arrhythmia (0.6%), faeces discouloured (0.6%).
The registry lists 178 participants at risk for serious adverse events in the DuraGen Plus During Surgery group, with 18 affected, and 169 at risk in the Surgery Alone group, with 19 affected. For other adverse events, the corresponding counts are 100 of 178 and 106 of 169. These are counts as recorded for each group; they should not be read as a statistical comparison. No group-comparison estimate, confidence interval, or significance test for these events is reported in the registry record.
The listed serious adverse-event terms include Inververtebral disc protrusion at 5.3%, Bradycardia at 1.2%, Headache at 1.1%, Arrhythmia at 0.6%, Faeces Discouloured at 0.6%, and Intracranial hypotension at 0.6%. The registry record does not identify these terms as a comparative estimate between groups. The figures do not establish whether an event was caused by the assigned treatment or whether the groups differed reliably.
Deaths are not reported in the registry record. The meaning of the event counts is also constrained by the absence of details about event definitions, collection and follow-up procedures, and the analysis of safety data.
12. What the Result Does, and Does Not, Mean
The record describes a trial designed to compare DuraGen Plus Adhesion Barrier Matrix used during spinal surgery with surgery alone. Its clinical question concerns peridural fibrosis, pain, and function, with assessments specified at 6 months. The randomized, double-masked, parallel-group design is relevant to how the comparison was intended to be conducted. The record also gives enrollment and adverse-event counts.
These design details do not establish whether the intervention improved or worsened any outcome. The outcome record provides no single summarized group comparison, and the registry lists 0 analyses. Numerical estimates, standard errors, confidence intervals, and inferential test results for the radiological, pain, and functional outcomes are not reported in the registry record. Without those results, the direction and size of any outcome difference, and the precision with which it was estimated, cannot be assessed.
The adverse-event counts likewise do not, on their own, establish a treatment-related difference. Counts are influenced by the number of people at risk and the way events were defined and collected. The record does not report comparative safety analyses or the number of deaths. The serious-event terms and percentages should therefore be understood as registry listings, not as evidence of a causal relationship.
The study status is TERMINATED, but no reason is given. That status does not show whether the trial met its objectives or whether termination was associated with the results. The record also does not report the analysis population, missing-data approach, multiplicity handling, or statistical plan. The most defensible interpretation is therefore descriptive: the registry documents the study design, the outcome constructs, and adverse-event counts, but does not contain enough reported outcome analysis to judge the comparative results.
13. Why This Trial Matters Statistically
This trial is statistically notable for the gap between a clearly described clinical question and the limited comparative results in the registry record. Randomization, masking, and a parallel-group design describe important features of the intended comparison. The outcome descriptions also span distinct domains: imaging of peridural fibrosis, pain ratings, and the effect of pain on everyday function. These details help readers understand what the study set out to assess, but they do not replace estimates of the differences between groups.
For clinical researchers, the record illustrates why an endpoint label and measurement description are not enough to evaluate evidence. Readers also need the analyzed participant counts, estimates, uncertainty measures, analysis methods, and information about missing data. Without these, a stated outcome timeframe and summary type cannot show how much the groups differed or how precisely that difference was estimated.
The record also illustrates the importance of separating safety counts from comparative safety conclusions. Counts of affected participants are useful descriptive information, but interpretation depends on event definitions, exposure and follow-up, and an analysis that accounts for the groups being compared. A trial status of TERMINATED is another descriptive fact; without a reported reason, it cannot be treated as an explanation of the results.
Statistically, the record is a reminder that transparent reporting is part of interpreting randomized evidence. A design can be described while the inferential results remain unavailable or too incomplete for a comparison. Stating that limitation precisely avoids turning the trial's intended question into a claim about its findings.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The registry record identifies 347 enrolled participants, but gives the outcome population as patients evaluable at 6 months without reporting the number evaluated for each measure. Consequently, the available enrollment figure cannot be assumed to be the denominator for each outcome analysis. The record does not describe attrition, reasons for missing measurements, or whether evaluability differed by group.
The outcome information covers radiological, pain, and functional assessments, yet it is not reduced to a single comparison. The registry lists 0 analyses and does not report estimates, standard errors, confidence intervals, or test results for these measures. It is therefore not possible to assess the magnitude or precision of the group differences from the registry record.
Important design and analysis details are not reported in the registry record. These include how the random sequence was generated and concealed, who was masked, the statistical model, any adjustment variables, the analysis population, and methods for missing data or multiplicity. The reason the study was terminated is also not reported. These gaps limit evaluation of the conduct and interpretation of the trial beyond the design features and outcome descriptions that are documented.
The safety listing gives counts and selected serious-event terms but does not provide a comparative analysis or detail the event-collection procedures. Deaths are not reported in the registry record. These limitations make the safety information descriptive rather than a basis for determining whether the groups differed.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: DuraGen Plus® Adhesion Barrier for Use in Spinal Surgery — NCT00387829.
- Registry record last updated 2017-09-07; status last verified 2017-08.
- Results first posted 2013-11-20.
- 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
NCT00387829 is a randomized, double-masked, parallel-group trial of DuraGen Plus Adhesion Barrier Matrix during spinal surgery compared with surgery alone. Enrollment is 347; the study status is TERMINATED. The recorded primary completion is 2010-12, and the outcome timeframe is 6 months.
The outcome record describes MRI assessment of peridural fibrosis, a Visual Analog Score for pain, and an Oswestry Disability Index for functional effects. It specifies least squares means and standard errors, but no single outcome comparison is reported, and the registry lists 0 analyses. Serious and other adverse-event counts are listed by group; comparative safety results and deaths are not reported in the registry record. The reason for termination, analysis population details, and missing-data methods are not reported in the registry record.