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 Evaluation of Fusion Rate Using K2M VESUVIUS® Demineralized Fibers With K2M EVEREST® Spinal System (NCT02064855), a registered phase not stated study. The primary outcome is Number of Participants With Adverse Events.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02064855 |
| Phase | Phase not stated |
| Condition | Spinal Stenosis, Spondylolisthesis, Degenerative Disc Disease |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 108 |
| Arms in the primary outcome | n/a |
| Lead sponsor | K2M, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The registry lists 108 participants and identifies spinal stenosis, spondylolisthesis, and degenerative disc disease as conditions of interest. Further eligibility criteria and the characteristics of participants enrolled are not reported in the registry record.
Intervention
The study evaluates K2M VESUVIUS Demineralized Fibers used with the K2M EVEREST Spinal System. The brief summary describes the aim as evaluating fusion status and patient outcomes observed with this combination.
Comparator
The stated benchmark is literature-reported outcomes for spinal fusion using autologous bone graft with posterior stabilization. Allocation is not stated, and the registry record does not establish a randomized comparison or a like-for-like control comparison.
Primary question
The primary outcome is the number of participants with adverse events over 24 months. The description says adverse events include device-related, procedure-related, and additional serious adverse events. Fusion status and patient outcomes are part of the study's broader purpose, but the primary endpoint is adverse events.
The clinical question therefore has two distinct parts: what fusion and patient outcomes were observed with the device and graft combination, and how those outcomes compare with published autograft experience. The registry record does not report a statistical analysis comparing the study participants with a concurrent control group. The listed adverse-event counts describe events among participants, but by themselves do not answer whether fusion outcomes differ from those in the literature. The record also does not report fusion results or numerical results for the listed secondary outcomes. Any interpretation should keep the stated clinical aim separate from the evidence actually recorded for the primary outcome.
3. Trial Design
The study is titled as an evaluation of fusion rate using VESUVIUS Demineralized Fibers with the EVEREST Spinal System. Its official title frames fusion with that combination against autologous bone graft with posterior stabilization. The brief summary clarifies that the intended comparison is to outcomes reported in the literature, rather than explicitly identifying a concurrent control group. The allocation method is not stated, and the registry record indicates that the arms are not a like-for-like control comparison.
The registry lists enrollment of 108. The study start is recorded as 2014-08, and primary completion as 2019-08-29. Its status is TERMINATED. The reason for termination is not reported in the registry record, so the status alone cannot establish why the study ended or whether any particular outcome was affected.
The primary outcome is the number of participants with adverse events at 24 months. The description includes device-related, procedure-related, and additional serious adverse events. The record also lists radiographic assessments, changes from baseline in ODI daily functional ability scores, VAS pain scores at 24 months, SF-12v2 quality-of-life scores at 24 months, patient satisfaction, surgery time, and anesthesia time. Radiographic Assessments appears twice in the listed secondary outcomes.
The registry records 14 outcome measures but no analyses. It does not report the statistical analysis plan, the number of participants included in each outcome analysis, or the details of any comparison with literature outcomes. Thus, enrollment and outcome definitions provide some design context, but they do not supply enough information to reconstruct the study's analysis or determine how the intended comparison was carried out.
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 | EVEREST/VESUVIUS Demineralized Fibers |
|---|---|
| STARTED | 108 |
| COMPLETED | 53 |
| NOT COMPLETED | 55 |
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 | Demographics and Baseline Characteristics |
|---|---|---|
| Participants analysed | 108 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 63 |
| Age, Categorical: >=65 years | Participants | 45 |
| Age, Continuous | years | 59.45 (SD 13.31) |
| Sex: Female, Male: Female | Participants | 56 |
| Sex: Female, Male: Male | Participants | 52 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 108 |
| Height | inches | 66.57 (SD 4.09) |
| Weight | pounds | 187.19 (SD 37.67) |
| Body Mass Index (BMI) | lbs/(in^2)*703 | 29.61 (SD 4.86) |
| Tobacco Use: Never | Participants | 47 |
| Tobacco Use: Quit | Participants | 45 |
| Tobacco Use: Currently Use | Participants | 16 |
| Tobacco Use: Missing | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Adverse Events, measured over 24 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with adverse events over 24 months. It is a binary outcome at the participant level: a participant is counted as having an event or not having an event within the outcome definition. The record's description includes device-related events, procedure-related events, and additional serious adverse events. It does not provide further operational details about how events were classified, how recurrent events were handled, or how the 24-month observation period was applied to participants with incomplete follow-up.
Participant counts are useful for describing how many people experienced an event, but they do not convey every aspect of safety. A count does not indicate how many events each participant experienced, the timing or duration of events, or their clinical severity. Nor does a count alone support a comparison unless the groups, denominators, and analysis method are clearly defined. The record reports counts for serious and other adverse-event categories, each with 108 participants at risk; it does not report a comparative estimate or uncertainty interval for the primary outcome.
Adverse-event monitoring is used to characterize harms observed during a study, including events that may be related to a device or procedure. The endpoint is not itself a measure of fusion success. Although fusion status is central to the study's stated purpose, the primary outcome named in the registry is adverse events, and no fusion outcome results are reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary outcome is a participant count, not a treatment-effect estimate. The record reports 25 participants with serious adverse events and 73 with other adverse events, with 108 participants at risk in each reported category. It also reports 0 deaths. These counts describe the posted safety data; they do not establish a comparative difference between the device combination and autologous bone graft.
The reason is partly design-related. The record describes a comparison with literature-reported autograft outcomes, while allocation is not stated and the arms are identified as not being a like-for-like control comparison. No numerical autograft results or comparative analyses appear in the registry record. A comparison with results from other sources can be affected by differences in participant characteristics, follow-up, outcome definitions, and how events are collected. The registry record does not give enough detail to assess whether those features align.
The record lists 108 participants enrolled, but the counts alone do not establish that all participants had complete follow-up through 24 months. The analysis population, missing outcome data, and handling of incomplete follow-up are not reported in the registry record. The denominators shown for the adverse-event categories are 108; the information available does not explain whether the same participants contributed complete data for every other outcome.
No statistical analyses are recorded. There are no reported estimates of comparative effect, confidence intervals, or p-values for the primary endpoint. A confidence interval, in general, describes the uncertainty around an estimated quantity; without a reported estimate and interval, the precision of a comparative effect cannot be assessed. The absence of an analysis does not mean that the groups were equivalent, nor does it establish that a difference exists.
The status is TERMINATED, but the reason for termination is not reported in the registry record. It would be inappropriate to infer that termination was caused by safety, lack of benefit, recruitment, or another issue. Likewise, enrollment of 108 is not evidence by itself that the study had adequate precision or was designed to detect a particular effect.
For the study's broader questions about fusion and patient outcomes, the record lists relevant outcome types but does not report their numerical results or analyses. The available information therefore supports a limited descriptive reading of adverse-event counts, not a conclusion about comparative safety, fusion rates, or changes in pain, function, or quality of life.
9. Statistical Methods Explained
The primary outcome is binary at the participant level: the registry counts whether participants experienced adverse events. A binary outcome can be presented as counts in categories, as this record does. To compare groups meaningfully, an analysis would also need clearly defined groups, a common outcome definition, denominators, and a method for estimating uncertainty. The record does not report a comparative analysis for this endpoint.
What does a confidence interval communicate?
In general, a confidence interval expresses the uncertainty around an estimated effect or quantity. Its width reflects how precisely that quantity is estimated under the analysis assumptions. A narrow interval indicates greater precision than a wide interval, while an interval that includes values on both sides of a null effect can be compatible with a range of interpretations. These general principles do not supply an interval for this study: the registry record reports no confidence interval or comparative effect estimate.
What would a p-value add?
In general, a p-value measures how surprising data would be under a specified null model and its assumptions. It is not the probability that a treatment works, and it does not measure the size or clinical importance of an effect. The registry record reports no p-value or analysis for the primary endpoint. A p-value cannot be inferred from the participant counts alone, particularly when the comparison groups and analysis details are not established.
Why does the comparison structure matter?
A randomized, concurrent comparison can help separate differences associated with the study treatment from differences in participant mix and care over time. Here, allocation is not stated, and the registry identifies the arms as not being a like-for-like control comparison. The stated benchmark is literature-reported autograft outcomes. In general, external comparisons require careful alignment of eligibility, endpoint definitions, follow-up, and data collection. The registry record does not report the details needed to evaluate that alignment, and it contains no comparative statistical analysis.
Why can over-dispersion matter?
In general, over-dispersion occurs when observed variation is greater than a statistical model expects. For event counts, this can make a model that assumes less variation produce uncertainty estimates that are too narrow. The primary endpoint in this record is a count of participants with an event, not a reported recurrent-event rate, and no model or dispersion estimate is recorded. Over-dispersion therefore cannot be evaluated as an analysis feature for the posted primary result. The concept is relevant more broadly to event-count analyses, but should not be used to infer an unreported method.
What do the planning illustrations represent?
The sample-size illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They are planning illustrations based on a stated fraction of the observed effect, not the trial's own design justification and not observed power. For time-to-event outcomes, the illustrations use a total number of events; for other outcomes, they use participants per arm. These are general planning calculations, not evidence that the trial recruited a particular number needed to detect a clinically meaningful difference. The registry record does not report the study's own sample-size justification.
The record also does not report whether there were interim analyses, which statistical tests were prespecified, how covariates were handled, or whether analyses were adjusted. It reports 14 outcome measures and no analyses. Consequently, neither the precision nor the statistical significance of the primary or secondary outcomes can be assessed from the posted results. Statistical concepts can clarify what an analysis might answer, but cannot substitute for estimates and methods that are not reported.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 14 outcome measures, including radiographic assessments, ODI functional ability scores, VAS pain scores at 24 months, SF-12v2 quality-of-life scores at 24 months, patient satisfaction, and surgery and anesthesia time. Radiographic Assessments is listed twice. The primary outcome is the number of participants with adverse events at 24 months. The registry records no analyses, so it does not show which outcomes were analyzed or how results were evaluated.
When many outcomes are assessed, the chance of finding at least one apparently notable result can increase. Statistical approaches can address multiplicity, for example by adjusting how evidence is interpreted across outcomes or by defining a primary outcome in advance. Whether any such approach was planned or used is not reported in the registry record. The record also does not state whether outcomes were prioritized in a prespecified hierarchy.
Missing-data handling and analysis populations are not reported in the registry record. It does not say how participants with incomplete follow-up were treated, whether all enrolled participants were included in each analysis, or whether any sensitivity analyses were conducted. These details matter because the amount and pattern of missing data can affect both the estimate and its uncertainty. The registry's stated enrollment and adverse-event denominators do not resolve those questions for the other outcomes.
Without analysis methods, outcome-level denominators, or missing-data details, the posted record does not permit assessment of multiplicity control or robustness to incomplete data. Those omissions should be read as limits on what can be evaluated, not as evidence that a particular method was or was not used outside the registry record.
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 |
|---|---|---|---|
| Participants With Adverse Events | 25 | 108 | 23.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Participants With Adverse Events | 0 of 108 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Participants With Adverse Events | 73 of 108 |
Most frequent serious adverse event terms
| Event term | Organ system | Participants With Adverse Events |
|---|---|---|
| Wound dehiscence | Injury, poisoning and procedural complications | 2 of 108 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 2 of 108 |
| Peroneal nerve palsy | Nervous system disorders | 2 of 108 |
| Coronary artery disease | Cardiac disorders | 1 of 108 |
| Gastrointestinal anastomotic stenosis | Gastrointestinal disorders | 1 of 108 |
| Chest Pain | General disorders | 1 of 108 |
| Incision site pain | Injury, poisoning and procedural complications | 1 of 108 |
| Pseudarthrosis | Musculoskeletal and connective tissue disorders | 1 of 108 |
| Lung Neoplasm malignant | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 1 of 108 |
| Carpal tunnel syndrome | Nervous system disorders | 1 of 108 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Participants With Adverse Events |
|---|---|---|
| Back Pain | Musculoskeletal and connective tissue disorders | 27 of 108 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 19 of 108 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 14 of 108 |
| Musculoskeletal pain | Musculoskeletal and connective tissue disorders | 9 of 108 |
| Fall | Injury, poisoning and procedural complications | 6 of 108 |
| Neck pain | Musculoskeletal and connective tissue disorders | 6 of 108 |
| hypoaesthesia | Nervous system disorders | 6 of 108 |
| Impaired healing | General disorders | 4 of 108 |
| Peripheral swelling | General disorders | 4 of 108 |
| Coccydynia | Musculoskeletal and connective tissue disorders | 4 of 108 |
Serious events with the highest arm-level rate: wound dehiscence (1.9%), pain in extremity (1.9%), peroneal nerve palsy (1.9%), coronary artery disease (0.9%), gastrointestinal anastomotic stenosis (0.9%).
The registry reports 25 participants with serious adverse events and 73 with other adverse events. Each category lists 108 participants at risk. It reports 0 deaths. The record lists wound dehiscence, pain in extremity, and peroneal nerve palsy at 1.9% each among the top serious adverse-event terms; coronary artery disease, gastrointestinal anastomotic stenosis, and chest pain are each listed at 0.9%.
These figures are descriptive. The record does not explain whether a participant could appear in both serious and other adverse-event categories, so the counts should not be added to create a total number of participants with any event. The denominator basis for the listed term percentages is not reported in the registry record. The terms and percentages also do not describe event timing, recurrence, severity beyond the serious-event classification, or attribution to the device or procedure.
The endpoint description says adverse events include device-related, procedure-related, and additional serious adverse events, but the posted counts do not provide a comparative estimate against autograft outcomes. They should not be interpreted as proving that the device combination caused an event or that it did not. The registry record does not report a statistical safety comparison or uncertainty intervals.
12. What the Result Does, and Does Not, Mean
The result supports a narrow statement: the registry record reports participant counts for serious and other adverse events, lists selected serious adverse-event terms and their percentages, and reports 0 deaths. This is descriptive information about the posted study record. It is not a comparative estimate of safety, and no uncertainty interval or statistical test is reported.
The record does not establish that the device and graft combination has a higher, lower, or equivalent adverse-event burden than autologous bone graft with posterior stabilization. The stated benchmark is literature-reported outcomes, allocation is not stated, and the arms are not described as a like-for-like control comparison. Without corresponding comparator data and an analysis, a treatment effect cannot be inferred.
Nor do the adverse-event counts answer the stated question about fusion. The record identifies fusion status and patient outcomes as part of the study's purpose, and it lists radiographic and patient-reported outcomes. However, numerical results for fusion, ODI, VAS, SF-12v2, patient satisfaction, or operating times are not reported in the registry record.
The 108 participants enrolled do not by themselves establish that the study was adequately powered or that all outcomes were observed through their stated timeframes. The registry does not report its sample-size justification, analysis populations, missing-data handling, or statistical plan. The status TERMINATED is recorded, but the reason is not reported.
Accordingly, the posted information can describe the listed adverse-event counts, but it cannot support a conclusion that the intervention does or does not improve fusion, patient function, pain, or quality of life. It also cannot establish causal attribution for reported events or a reliable comparison with external literature.
13. Why This Trial Matters Statistically
This trial is statistically important because its stated clinical purpose and its registered primary endpoint are different kinds of questions. Fusion status and patient outcomes motivate the study, while the primary outcome counts participants with adverse events. Keeping those endpoints distinct prevents a safety count from being mistaken for a measure of fusion success.
The record also illustrates why comparator design matters. A comparison with literature-reported outcomes is not automatically equivalent to a concurrent, randomized comparison. Differences in eligibility, follow-up, outcome definitions, and event ascertainment can complicate interpretation. Here, allocation is not stated, and the record identifies the arms as not being a like-for-like control comparison. No comparative analysis is recorded.
Reporting participant counts is useful, but counts alone cannot convey precision or quantify a difference between groups. Comparative estimates and uncertainty intervals would be needed to understand how compatible the data are with a range of possible effects. The registry record provides neither for the primary endpoint.
The entry also shows why a listed outcome is not the same as a reported result. It names 14 outcome measures, yet records no analyses. As a result, readers cannot assess findings for fusion, functional ability, pain, quality of life, satisfaction, or operating time from this record. The missing analysis and follow-up details further limit appraisal of completeness and robustness.
These features do not make the adverse-event counts meaningless. They define what the counts can support: a descriptive account of the posted safety data, rather than a causal or comparative conclusion. That distinction is central to responsible statistical interpretation.
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 is limited by the absence of reported analyses. It includes no comparative effect estimates, confidence intervals, or p-values for the primary endpoint, and no numerical results for the listed fusion and patient outcomes. The record therefore does not permit an assessment of effect size or precision.
The design details are incomplete for evaluating the intended comparison. Allocation is not stated, the arms are identified as not being a like-for-like control comparison, and the comparator is described through literature-reported outcomes. The registry record does not report how those external outcomes were selected or whether participants, endpoint definitions, follow-up periods, and ascertainment methods were aligned.
Additional limitations include unreported eligibility criteria, participant characteristics, analysis populations, missing-data handling, and the statistical analysis plan. The registry does not report why the study was terminated. It also does not describe how adverse events were attributed, whether event categories could overlap, or the denominator used for the listed serious-event term percentages.
The record lists 14 outcome measures, including a duplicate listing of Radiographic Assessments, but reports no analyses. It does not state how multiplicity was handled or which outcomes, if any, were prioritized beyond naming the primary endpoint. These gaps prevent evaluation of whether the posted data represent all planned outcomes or how results were selected and interpreted.
Finally, enrollment of 108 is not enough to judge statistical adequacy without a reported design justification and analysis details. The planning illustrations are not the trial's own sample-size rationale and do not constitute observed power. Taken together, the record supports only a limited descriptive reading of the reported adverse-event counts.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Evaluation of Fusion Rate Using K2M VESUVIUS® Demineralized Fibers With K2M EVEREST® Spinal System — NCT02064855.
- Registry record last updated 2021-03-01; status last verified 2021-02.
- Results first posted 2021-03-01.
- 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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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 study of K2M VESUVIUS Demineralized Fibers used with the K2M EVEREST Spinal System, with literature-reported outcomes for autologous bone graft and posterior stabilization as the stated benchmark. It lists 108 participants, a start date of 2014-08, primary completion on 2019-08-29, and status TERMINATED.
The primary outcome is the number of participants with adverse events at 24 months. The record reports 25 participants with serious adverse events, 73 with other adverse events, and 0 deaths, with 108 participants at risk in each category. It lists 14 outcome measures and records no analyses. Allocation is not stated, and the comparison is not described as like-for-like. Numerical results for fusion and the listed secondary outcomes, the reason for termination, and the statistical analysis plan are not reported in the registry record.