Cesarean Trial of Staples vs. Sutures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cesarean Trial of Staples vs. Sutures (NCT01211600), a randomized na study. The primary outcome is Number of Participants With Wound Complications.

2. Clinical Question

This is a question about the skin-incision closure method, not a comparison of cesarean delivery with another delivery approach. The registered secondary outcomes include scar assessment and satisfaction, pain perception, additional provider visits, primary versus repeat cesarean status, details of the operation and closure, and hospital stay. Those outcomes broaden the questions considered, but they do not change the stated primary question about wound complications.

3. Trial Design

The registry identifies this study as a randomized, parallel trial with single masking. It lists 746 participants enrolled and Thomas Jefferson University as the sponsor. The listed start is 2010-06, primary completion is 2014-10, and the status is completed. The phase is recorded as NA. The record does not identify who was masked, describe the randomization procedure, or provide further details of how participants were assigned.

The two arms differed in the skin closure method. The Staples arm used interrupted Ethicon Staples. The Suture arm used a subcuticular continuous suture, specified as 4-0 Monocryl Plus on a PS2 needle or 4-0 Vicryl Plus on an FS2 or PS2 needle. The registry does not explain how the choice between the listed suture materials or needles was made.

The primary outcome was the number of participants with wound complications within 6 weeks postpartum. The registry lists 13 outcome measures, including outcomes concerning scar appearance, satisfaction, pain, visits, operative details, and length of hospital stay. It does not report the schedule or details of assessments for these secondary outcomes.

For the adverse-event record, the Suture group lists 370 participants at risk and the Staples group lists 376. These are the denominators attached to the adverse-event counts; they should not be assumed to document the analysis population for every outcome. The registry record does not describe participant flow, withdrawals, exclusions, or outcome-specific denominators. It also does not report the eligibility criteria or the characteristics of participants enrolled.

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

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 Wound Complications, measured over Within 6 weeks of postpartum.

The primary endpoint counts participants with a wound complication within 6 weeks postpartum after cesarean delivery. The listed complications are infection, hematoma, seroma, separation, and readmission for a wound complication. It is therefore a composite outcome: a participant may meet the endpoint through one of several kinds of wound problem. The registry does not report the number of participants with each component separately or explain how multiple complications in one participant were handled.

Counting affected participants gives a clinically interpretable measure of how many people experienced at least one qualifying complication during the stated follow-up period. Comparing the outcome between closure methods addresses the trial’s stated question about whether the rate differs by method. The chosen time window matters because the endpoint concerns complications occurring within 6 weeks postpartum, rather than complications at any later time.

For a binary endpoint, each participant is generally classified as having or not having the event according to the outcome definition and observation window. This is a general description of binary outcomes, not a claim about the trial’s unreported analysis procedure. The registry record does not present a consolidated primary-outcome result, a comparison estimate, or component-specific results. The adverse-event counts should not be read as the primary endpoint unless the record explicitly identifies them as such; it does not do so.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomized allocation is intended to make treatment groups comparable, on average, with respect to factors that could affect outcomes. This is a general property of randomized designs, not a report of the allocation procedure used in this trial. The registry labels the study randomized and parallel, but the sequence-generation method, allocation concealment, and implementation details are not reported in the registry record. Single masking is recorded, but the identity of the masked party is not reported.

What does a binary outcome mean?

The primary outcome is a count of participants with an event. A binary outcome classifies each participant according to whether the defined event occurred during the defined period. Here, the definition covers several kinds of wound complication and specifies follow-up within 6 weeks postpartum. A participant-level endpoint is different from a count of every complication episode: the registry names the number of participants as its unit. The record does not report component counts or explain how repeat events were treated.

For binary outcomes, an analysis may compare the proportion of participants with an event, estimate a contrast between groups, or use a model suited to the data and design. These are general options, not methods documented for this trial. The registry record does not report which method was used for the primary outcome, nor does it report an adjusted or unadjusted estimate. Since it does not provide a single primary comparison, no particular effect measure should be attributed to the trial.

Why does uncertainty matter?

A point estimate, when reported, describes the observed contrast in the analyzed data. A confidence interval is a general statistical device for showing the precision of an estimate: a narrower interval indicates greater precision under the method’s assumptions, while a wider interval indicates more uncertainty. A hypothesis test addresses compatibility between data and a specified null model, but its p-value does not measure the size or clinical importance of an effect. The registry record does not report a primary estimate, confidence interval, or p-value, so those interpretations cannot be made for the primary endpoint.

How should the planning illustrations be read?

The planning illustrations are described as calculations based on the observed effect, not as the trial’s original design justification. Their stated assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. They are planning illustrations rather than evidence that the trial had a particular probability of detecting an effect. They are not observed power. The registry record does not report the original sample-size justification or protocol assumptions, and the illustration should not be mistaken for them.

Sample-size planning asks how much information a future study might need under specified assumptions. Results depend on the chosen effect to detect, outcome frequency, significance criterion, allocation, and analysis method. Changing an assumed effect changes the planning result. Because the illustration is tied to fractions of an observed effect, it is conditional on that effect and the stated calculation assumptions. It cannot establish whether the original study was adequately powered, particularly when the registry does not give a single primary effect estimate or its uncertainty.

What is not documented about the analysis?

The registry lists zero analyses. It does not report a statistical analysis plan, adjustment variables, interim analyses, multiplicity handling, or outcome-specific analysis populations. Those details should not be inferred from the randomized design or from the list of outcomes. In a general trial analysis, the chosen population and handling of missing outcomes can affect estimates; the record does not explain these choices. It also does not report whether the primary comparison was adjusted, whether a model was used, or how the listed outcome components were combined in analysis.

The adverse-event counts are descriptive entries with group denominators. They do not give an uncertainty interval or test. General statistical methods could compare event proportions while accounting for the binary nature of the data, but no such method is reported in the registry record. Likewise, the counts do not reveal whether adverse events were independently reviewed, how severity was defined, or how the reporting period was set beyond what is recorded for the primary outcome.

Over-dispersion is a general issue in count data: variation can exceed what a simple model assumes, which can make conventional uncertainty estimates too optimistic if the model is not suitable. It is not a documented issue for this trial’s participant-level binary primary endpoint, and no over-dispersion method is reported. The primary outcome is defined as participants with an event, not as a rate of repeated events per person-time.

Overall, the record supports description of the design and the posted adverse-event counts, but it does not supply enough analysis detail to reproduce or evaluate a primary statistical comparison. The planning assumptions clarify how the illustrative calculations were framed; they do not establish what method the investigators used for the trial’s outcomes.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures, including the primary wound-complication outcome and several secondary outcomes related to scars, satisfaction, pain, visits, operative details, and hospital stay. Considering multiple outcomes can raise a multiplicity question: when several statistical tests are conducted, the chance of at least one apparently notable result can increase. This is a general concern, not evidence that a particular correction was required or used in this trial. The registry record does not report a multiplicity strategy, outcome hierarchy beyond the primary designation, or which outcomes were analyzed.

The record lists zero analyses and does not present a single primary-outcome comparison. It does not report whether outcomes had multiple time points, how the several wound-complication categories were combined in the analysis, or whether any planned comparisons were omitted. The primary-outcome entry itself is flagged as not reduced to one comparison because it has several categories or time points. Without a reported analysis plan, the intended handling of these features is not reported in the registry record.

Missing-data handling and analysis populations are also not described. The record does not state how many participants had complete outcome information, whether any participants withdrew, how missing observations were handled, or whether all randomized participants were included in an analysis. The adverse-event denominators are recorded by group, but they should not be treated as proof of denominators for the primary endpoint or every secondary outcome.

These omissions limit reproducibility and make it difficult to assess whether the outcome results correspond to the registered question. They do not establish that the investigators did or did not use a particular method; those details are simply not reported in the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The serious adverse-event entries list zero affected participants in the Suture group and zero in the Staples group. The record lists zero deaths in both groups. For other adverse events, it records 18 in the Suture group, where 370 participants were at risk, and 40 in the Staples group, where 376 participants were at risk. The record lists no serious adverse-event terms.

These figures are safety-record entries, not a reported statistical comparison. The registry does not describe the specific other events, their severity, timing, relatedness to closure method, or whether one participant could contribute more than one event. The counts therefore should not be interpreted as event rates or as an estimate of causal effect. Zero recorded serious events does not establish that serious events are impossible; it states what was entered for this record. These safety entries also do not replace the defined primary endpoint of wound complications within 6 weeks postpartum.

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

The record establishes that the trial was designed as a randomized, parallel comparison of staples with suture for cesarean skin closure. It identifies wound complications within 6 weeks postpartum as the primary outcome and gives a definition covering infection, hematoma, seroma, separation, and readmission for wound complication. It also records adverse-event counts by arm and identifies a range of secondary outcomes.

What the record does not establish is the size or precision of the primary-outcome contrast. It does not report a single primary comparison, an estimate, a confidence interval, or a test. Consequently, the posted information does not justify a conclusion that one closure method had a higher or lower primary-outcome rate. The adverse-event counts describe entries in those categories; they do not answer the primary question on their own.

The randomized design is relevant to the intended comparison, but a trial’s design label is not itself a result. Interpretation of a trial requires outcome data and a documented analysis that identifies the population and method. Those details, along with missing-data handling and multiplicity procedures, are not reported in the registry record.

The planning illustrations have a separate purpose. They use an observed effect and specified assumptions to illustrate sample-size planning. They are not an independent validation of the trial result, a report of the original design rationale, or observed power. Their interpretation depends on the assumptions stated for the illustration.

Thus, the registry record is useful for identifying the question, interventions, outcome definition, and recorded safety counts, while leaving the central comparative result unresolved. That distinction is important: absence of a reported analysis is not evidence that the methods are equivalent, nor is it evidence that they differ.

13. Why This Trial Matters Statistically

This trial poses a focused statistical question: whether the rate of defined wound complications differs between two skin-closure methods after cesarean delivery. It is a useful setting for understanding how a clinical question becomes an estimand, or target comparison: the population, the intervention and comparator, the outcome definition, and the follow-up window all need to be specified. Here, the record identifies the methods, defines a composite outcome, and sets follow-up within 6 weeks postpartum.

The composite outcome illustrates a common trade-off. Combining several kinds of complication can create a single participant-level endpoint, but the combined result can conceal differences among its components. Infection, hematoma, seroma, separation, and readmission are all included in the definition, yet the registry does not report their separate counts or a single analyzed composite result. Clear reporting of both the composite and its components can help readers understand what contributes to an overall finding.

The record also illustrates why registration and results reporting are distinct. The design and outcome definitions can be documented while the primary statistical comparison remains unavailable in the registry record. Readers need an estimate and its precision, together with enough methods detail to judge how the result was obtained. The presence of randomized allocation does not replace those elements.

Finally, planning calculations should remain distinct from trial findings. An illustration based on an observed effect can help communicate how assumptions influence a future sample-size plan, but it cannot establish the trial’s original rationale or observed power. Keeping design, analysis, safety description, and planning separate prevents readers from treating one kind of information as another.

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 central limitation for interpreting this trial record is that it does not report a single primary-outcome comparison, despite identifying wound complications as the primary endpoint. No effect estimate or uncertainty interval is given, and the record lists zero analyses. The available adverse-event counts cannot be substituted for the missing primary result.

The endpoint combines several types of wound complication, but component-specific results and details about multiple events in one participant are not reported. The record also notes that the primary outcome involves several categories or time points and is not reduced to one comparison. Without a single stated comparison, it is difficult to know which result was intended to answer the primary question.

Further trial-specific information is absent from the registry record: participant eligibility and characteristics, the randomization procedure, the identity of the masked party, participant flow, outcome-specific denominators, missing-data handling, analysis populations, and statistical analysis methods. The relationship between the adverse-event reporting and the primary endpoint is not specified. The serious adverse-event list contains no terms, and details of other adverse events are not reported.

The registry lists secondary outcomes but does not report their results or describe how multiplicity was handled. It also does not report the original sample-size justification, interim analyses, or a statistical analysis plan. These limitations concern what can be learned from the registry record; they do not prove that the omitted methods or results were absent from other study documents.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cesarean Trial of Staples vs. Sutures — NCT01211600.
• Registry record last updated 2019-11-26; status last verified 2019-11.
• Results first posted 2019-11-26.
• 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.

18. Record Summary

NCT01211600, titled Cesarean Trial of Staples vs. Sutures and officially titled Cesarean Randomized Control Trial Of Sutures vs. Staples (CROSS), is listed as a completed randomized, parallel trial with single masking. Thomas Jefferson University is the sponsor. The record lists enrollment of 746, a start of 2010-06, and primary completion of 2014-10.

The trial compares interrupted Ethicon Staples with subcuticular continuous suture for cesarean skin closure. Its primary outcome is participants with wound complications within 6 weeks postpartum, including infection, hematoma, seroma, separation, and readmission for wound complication. The registry lists 13 outcome measures and zero analyses.

Adverse-event entries list zero serious events and zero deaths in each arm, with 18 other adverse events in the Suture group and 40 in the Staples group. The registry record does not report a single primary-outcome comparison or its statistical analysis.