BioFiber Scaffold Post-Market Observational Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for BioFiber Scaffold Post-Market Observational Study (NCT01849458), a registered phase not stated study. The primary outcome is Number of Participants With Device Associated Adverse Events.

2. Clinical Question

3. Trial Design

This is a completed post-market observational study of BioFiber and BioFiber-CM absorbable biologic scaffolds for soft tissue repair and reinforcement. Its stated aim was to collect and report data from a consecutive series of implanted patients as part of a post-market surveillance plan for CE Mark approval in the European Union. The registry lists an enrollment of 50 and describes the intervention as a device.

The listed arm is called BioFiber. Its description includes participants implanted with either BioFiber Scaffold or BioFiber-CM Scaffold. The record does not report the distribution of participants between those products, so the arm description does not support a product-specific comparison. It also does not describe a control group. The allocation method is not stated, and the registry record cautions that the arms are not a like-for-like control comparison.

The study start is recorded as 2013-03, and primary completion as 2015-04. The status is COMPLETED. The primary outcome is the number of participants with device-associated adverse events, with a timeframe of 12 Months. Listed secondary outcomes include the Adjusted Constant-Murley Score, the WORC Index, and the number of study participants with re-tears; some outcome names are repeated in the registry listing. The record lists 7 outcome measures and 4 analyses, but further details linking analyses to particular outcomes are not reported in the registry record.

Randomization, masking, the detailed follow-up schedule, and the statistical analysis plan are not reported in the registry record. Accordingly, the design should be read as descriptive post-market surveillance rather than as a controlled estimate of comparative treatment effects.

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

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Device Associated Adverse Events, measured over 12 Months.

The primary endpoint is the number of participants with device-associated adverse events, measured at 12 Months. It is a participant count: the endpoint concerns how many participants meet the event definition, rather than the total number of event episodes. The registry defines qualifying events as adverse events classified as possibly or definitely related to the study product or procedure, together with anticipated adverse events listed in the product’s Instructions for Use regardless of their relationship to the study device.

This type of endpoint is used in surveillance to describe the occurrence of specified safety events among people who received a device. Its interpretation depends on consistent event identification, classification, and follow-up. The registry’s definition combines events judged possibly or definitely related with anticipated events regardless of relationship, so the endpoint is broader than a count restricted to events judged definitely caused by the device.

The registry record does not report the primary endpoint’s observed count. It therefore does not establish how many participants met the definition, nor does it give an estimate of the endpoint’s precision. Serious adverse-event counts elsewhere in the posted results should not be substituted for this outcome: seriousness and device association are different classifications, and the safety figures do not specify whether each event met the primary endpoint definition.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins with identifying the quantity being counted. The primary endpoint is a count of participants who experienced an event meeting the registry’s device-associated definition within the stated 12 Months timeframe. This differs from counting event episodes: a participant with more than one qualifying event would still contribute as a participant meeting the endpoint, if the outcome is applied as titled. The registry does not describe the operational rules for repeated events or the process used to classify relatedness.

What does a participant count tell the reader?

A participant count describes the observed burden in the people followed, but a count alone does not describe precision. The number at risk, completeness of follow-up, and a clear definition of who was analyzed are needed to understand its denominator and uncertainty. The registry lists 50 participants at risk for the BioFiber safety group, but the primary outcome count is not reported. The enrollment of 50 should not automatically be treated as the analysis population for every outcome; participant flow and endpoint-specific denominators are not reported in the registry record.

In general, binary-event analyses can express results as the number of participants with an event and the number assessed, or as a proportion with an uncertainty interval. Those forms answer related but distinct questions: the count describes observed cases, while a proportion places the count in relation to the assessed group. An interval communicates that a study estimate is uncertain, particularly when event counts are limited. No primary-endpoint proportion or confidence interval is reported in the registry record, so neither can be interpreted for this outcome.

Why does the absence of a comparator matter?

A comparison requires groups that can meaningfully be contrasted. The registry identifies this study as not a randomized comparison, says allocation is not stated, and cautions that the arms are not a like-for-like control comparison. The listed arm description includes recipients of BioFiber Scaffold or BioFiber-CM Scaffold, and the record does not report separate product-specific outcomes. Consequently, the listed safety counts describe the observed group; they do not provide a relative effect estimate against a control. In general, a difference between groups can be interpreted causally only when the design and analysis adequately address alternative explanations such as differences in participant characteristics, clinical setting, or follow-up.

What do the planning calculations represent?

The sample-size assumptions describe planning illustrations computed from an observed effect, not the study’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Time-to-event calculations are described as total events using the Schoenfeld method, while other calculations are described as participants per arm. These are hypothetical planning quantities and should not be read as observed power, as evidence that the study was designed with those assumptions, or as a guarantee that a future study would detect an effect. The trial’s own sample-size justification is not reported in the registry record.

In general, power is a design property tied to an assumed effect, variability, significance level, and sample size. It is not a measure of how convincing a completed study’s results are. A retrospective calculation using an observed effect also inherits uncertainty from that estimate. The registry’s planning illustration therefore cannot replace a direct reading of the outcome estimate and its uncertainty, neither of which is reported for the primary endpoint.

How should event classifications be handled?

Seriousness, event type, and device association are different attributes. A serious adverse event count identifies events classified as serious under the study’s collection rules; a device-associated count requires the separate relatedness or anticipated-event criteria in the primary endpoint definition. The registry does not report a cross-classification connecting the serious-event figures to the primary endpoint. The term percentages are descriptive labels attached to serious-event terms, not a comparative effect estimate. General statistical practice also cautions against adding categories when it is unknown whether they overlap.

The registry lists secondary outcomes including the Adjusted Constant-Murley Score, WORC Index, and re-tears. These outcomes have different measurement structures from a participant event count. Continuous scores require information about the scale, summary measure, and analyzed population; re-tears require an event definition and follow-up information. Those analysis details and the corresponding secondary results are not reported in the registry record. Statistical methods should be matched to each outcome’s structure, and results across different outcomes should not be treated as interchangeable measures of the same effect.

More generally, over-dispersion matters when count data vary more than a chosen statistical model expects: a model that assumes less variability can understate uncertainty. That concept is most relevant to counts of event episodes. The primary endpoint is explicitly a count of participants with events, and no dispersion measure or model specification is reported. It would therefore be inappropriate to claim that a particular over-dispersion adjustment was used. The registry record does not report the statistical plan needed to determine whether any such issue was assessed.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("BioFiber")
n      <- c(46)
events <- c(4)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  BioFiber  46  4  8.7  2.4  20.8  3.4  20.3  3.5  20.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 7 outcome measures and 4 analyses. Listed secondary outcomes include the Adjusted Constant-Murley Score, the WORC Index, and the number of study participants with re-tears; some outcome names appear more than once. The record does not explain the relationship between repeated listings, analyses, timepoints, or outcome definitions. It also does not report a prespecified hierarchy for interpreting multiple outcomes.

Multiplicity is the challenge of interpreting several statistical tests or outcomes together. In general, when many comparisons are examined, the chance of at least one apparently notable result can increase. Methods such as prespecifying a primary outcome or adjusting inference across comparisons can address that issue, but the registry record does not report whether any multiplicity strategy was planned or used. No inference should be made about unreported secondary results.

Missing-data handling is also not reported in the registry record. The record does not describe the number of participants with outcome data at each assessment, reasons for missing observations, imputation, or sensitivity analyses. The enrollment count and safety group at-risk count do not establish complete follow-up for every outcome. The analysis population, including any rules for inclusion or exclusion from particular analyses, is not reported.

The registry does not report an interim-analysis plan or a detailed statistical analysis plan. These omissions leave uncertainty about outcome selection, missing observations, and how multiple analyses were interpreted. They are limitations in what can be learned from the registry record, rather than evidence that a particular procedure was or was not performed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: infection (2.0%), stroke (2.0%), deep vein thrombosis (2.0%).

The BioFiber safety group lists 50 participants at risk, with 3 participants affected by serious adverse events and 1 participant affected by other adverse events. The serious-event terms reported are Infection, Stroke, and Deep Vein Thrombosis, each listed at 2.0%. These figures describe the safety information recorded for the group; they are not a controlled comparison.

The term values should not be added. The registry does not state whether the event terms are mutually exclusive or whether a participant could contribute to more than one category. The reported serious-event figures also do not establish how many participants met the primary device-associated adverse-event definition. Seriousness and device association are separate classifications, and a serious event is not necessarily device-associated under the endpoint criteria.

Deaths are not reported in the registry record; that should not be read as confirmation that no deaths occurred. The record does not report event-level details, follow-up completeness for these counts, or an uncertainty interval. Accordingly, these counts are best read as descriptive surveillance findings, not as evidence of causation or as a precise estimate for a broader population.

13. What the Result Does, and Does Not, Mean

The study’s stated purpose was to collect post-market surveillance data from a consecutive series of patients implanted with BioFiber or BioFiber-CM Scaffold. The registry describes a completed study, an enrollment of 50, and a primary endpoint focused on participants with device-associated adverse events at 12 Months. The posted safety figures provide counts for serious and other adverse events in the BioFiber group.

The primary endpoint result itself is not reported in the registry record. The serious-event counts cannot fill that gap because the record does not show which events, if any, met the endpoint’s device-association definition. The event-term percentages are descriptive and do not establish a relationship to the scaffold. Nor does the record provide a control group against which to compare the observed safety information.

In general, an observational study can describe events among recipients and contribute to surveillance. Its observations do not, on their own, show that a device caused an event or that one device performs better or worse than another. Those conclusions require suitable comparative evidence and clear information about participant selection, follow-up, event classification, and analysis. Relevant details are not reported in the registry record.

The enrollment count does not establish that every participant contributed complete data to every outcome. The record does not describe missing data, analysis populations, or participant flow. It also does not report estimates of uncertainty for the primary endpoint. Therefore, the precision and generalizability of the outcome results cannot be assessed from the registry information described.

The most supportable reading is limited: the registry records a post-market observational surveillance study and some descriptive safety counts, but it does not report the primary outcome count or a controlled comparison. These results should not be interpreted as proof of safety, harm, benefit, or lack of effect.

14. Why This Trial Matters Statistically

This study illustrates an important role for post-market observational research: describing outcomes among people who receive a medical device in clinical practice. The registry’s stated surveillance purpose and its focus on device-associated adverse events make the event definition central to interpretation. Counts are meaningful only when readers can distinguish the outcome being counted from broader categories such as all serious events.

The record also demonstrates why a denominator and follow-up information matter. It lists 50 participants at risk for the BioFiber safety group, but does not report the primary-endpoint count, endpoint-specific analysis population, or completeness of follow-up. A count without an outcome-specific account of who was assessed cannot fully describe the underlying event frequency or its precision.

The lack of a like-for-like comparator sets a clear boundary on inference. Descriptive surveillance can document what was recorded in the treated group, but it does not estimate comparative effects or establish causation. The registry’s caution that the study is not a randomized comparison is therefore important when interpreting the safety counts.

Finally, the listing of multiple outcomes highlights the need for clear outcome definitions and analysis plans. Different score-based outcomes and event counts require different summaries, and multiple analyses can complicate interpretation. The registry does not report the detailed analysis plan, multiplicity approach, or missing-data methods. These are not minor technical details: they determine how reliably findings can be interpreted and compared with evidence from other studies.

15. 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 consequential limitation is that the registry record does not report the observed count for the primary endpoint. Although its definition and timeframe are stated, the endpoint result and its uncertainty cannot be assessed. The serious-event figures are not a substitute because the record does not link them to the device-association criteria.

The study has no reported like-for-like control comparison, and allocation is not stated. The BioFiber arm description includes recipients of BioFiber Scaffold or BioFiber-CM Scaffold, but product-specific participant counts and results are not reported. This prevents product-level comparisons and limits causal interpretation of the group’s safety observations.

Important details needed to judge the data are not reported in the registry record: participant characteristics, eligibility criteria, follow-up completeness, endpoint-specific denominators, event adjudication procedures, missing-data handling, and analysis populations. The record does not report whether serious-event terms overlap, or how the safety counts were classified in relation to the primary endpoint.

The registry lists multiple outcomes and analyses but does not describe a detailed analysis plan or multiplicity approach. It does not report a sample-size justification for the study; the stated sample-size assumptions are planning illustrations based on an observed effect, not the study’s own design. These limitations restrict assessment of precision, selection, and analytical choices. They do not establish that a particular bias or analytic problem occurred, but they constrain what can be concluded from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: BioFiber Scaffold Post-Market Observational Study — NCT01849458.
• Registry record last updated 2017-06-22; status last verified 2017-06.
• Results first posted 2017-06-22.
• 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.

19. Record Summary

The registry record describes NCT01849458, BioFiber Scaffold Post-Market Observational Study, as COMPLETED. The study aimed to collect data from a consecutive series of patients implanted with BioFiber Scaffold or BioFiber-CM Scaffold for post-market surveillance connected with CE Mark approval in the European Union. Enrollment is listed as 50; the start is recorded as 2013-03 and primary completion as 2015-04.

The primary endpoint is the number of participants with device-associated adverse events at 12 Months. Its observed count is not reported in the registry record. The safety results list 50 participants at risk in the BioFiber group, 3 participants with serious adverse events, and 1 with other adverse events. No like-for-like control comparison is described, and the record does not report the detailed analysis plan, missing-data handling, or analysis populations. The findings are therefore descriptive and cannot establish comparative effects or causation.