Safety and Efficacy of D-PLEX in the Prevention of Sternal Infection Post Cardiac Surgery.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of D-PLEX in the Prevention of Sternal Infection Post Cardiac Surgery. (NCT02731573), a randomized phase 1, phase 2 study. The primary outcome is Decrease of Infection Rate as Measured by the Proportion of Subjects With at Least 1 Identified Sternal Infection Within 90 Days Post-cardiac Surgery..

2. Clinical Question

The study’s stated aim also included safety assessment over 6 months, while its primary efficacy endpoint focused on infection within 90 days. These are distinct questions: the infection endpoint counts participants with an event, whereas safety outcomes concern reported adverse events and deaths. The registry record does not report detailed eligibility criteria, the precise high-risk definition, or how participants were selected for the two parts of the study. The comparison therefore needs to be read as a small registry-reported trial result, with limits on what can be inferred about the broader population of people undergoing cardiac surgery.

3. Trial Design

NCT02731573 is listed as a Phase Ib/II, prospective, multicenter study with two parts. Part 1 was open-label and single-arm; Part 2 was randomized and single-blinded. The registry lists a parallel model and random allocation for the study. It does not report the number enrolled in each part, how the single-blind masking was implemented, or whether the primary outcome result combines participants from both parts or comes only from the randomized part. Those details matter when interpreting the arm comparison.

The registry reports total enrollment of 81. The posted primary outcome arms contain 60 participants assigned to D-PLEX plus standard care and 21 assigned to standard care. The D-PLEX arm received open heart surgery according to standard care with D-PLEX treatment; the comparator arm received surgery according to standard care. The allocation procedure, allocation concealment, and reasons for the unequal arm sizes are not reported in the registry record, so the observed allocation should not be used to infer those procedures.

The primary endpoint was the proportion of participants with at least one identified sternal infection within 90 days after cardiac surgery. Secondary outcomes listed in the record include readmissions, surgical re-interventions, time to infection, infection counts over specified periods, and hospitalization days associated with sternal infection. The record also lists safety assessment over 6 months. The full operational definitions and analysis procedures for these outcomes are not reported in the registry record.

The study is marked completed, and its listed start was 2016-10-12, with primary completion in 2018-02. The registry does not report a sample-size justification or the detailed statistical plan. The design information establishes that a randomized, single-blinded component was planned, but does not establish the exact analysis population or analysis method used for the posted primary comparison.

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 81 subjects were enrolled in the study as follows: Part 1 Open Label, Single Arm: Twenty (20) subjects were enrolled in Part 1 of the study and treated with D-PLEX concomitantly with SOC (Standard of Care). Part 2 Randomized, Single-blinded: Sixty-one (61) subjects were enrolled in Part 2 of the study and randomized to the D-PLEX + SOC (Standard of Care) treatment arm (40 subjects) or to the SOC (Standard of Care) arm (21 subjects).

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 Decrease of Infection Rate as Measured by the Proportion of Subjects With at Least 1 Identified Sternal Infection Within 90 Days Post-cardiac Surgery., measured over Within 90 days post-cardiac surgery..

The primary endpoint counts whether each participant had at least one identified sternal infection within 90 days after cardiac surgery. It is a participant-level binary outcome: each person is classified as having or not having at least one event during the specified period. The endpoint includes both deep sternal wound infections and superficial sternal wound infections.

A participant-level proportion is useful for expressing how often an event occurred in each treatment group. It avoids counting multiple infections in one person as multiple participants with the endpoint, although the registry record does not explain how repeated events were handled beyond the “at least one” definition. The outcome is clinically specific to the study’s prevention question and gives a fixed time window for comparison. It does not, on its own, describe infection severity, duration, recurrence, or the consequences of infection.

The registry’s narrative says that one participant in the control arm had a superficial sternal wound infection on day 6 after surgery, confirmed by a positive bacteriology test for Proteus mirabilis. It also states that no participants in the D-PLEX arm experienced a sternal wound infection and that no infection was confirmed during 90 days after surgery. These details clarify the event counted in the primary comparison, but do not replace the need to consider the small event count and the uncertainty around the estimated difference.

Using a fixed 90-day window makes the endpoint interpretable as a risk over that period. It does not establish what happened after the window, and the registry does not report whether follow-up was complete for every participant.

7. Results Posted in the Registry

• Standard of Care (SoC): 4.8% (1/21) versus 0.0% (0/60) on control; risk difference 4.8 percentage points (95% CI -4.3 to 13.9); unadjusted two-proportion z-test p = 0.089.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Decrease of Sternal Infection Rate, DSWI (Deep Sternal Wound Infections) and SSWI (Superficial Sternal Wound Infection) During the First 30 Days Post Operation.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Standard of Care (SoC): 4.8% (1/21) versus 0.0% (0/60) on control; risk difference 4.8 percentage points (95% CI -4.3 to 13.9); unadjusted two-proportion z-test p = 0.089.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Standard of Care (SoC) and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists secondary questions spanning readmissions, surgical re-interventions, time to infection, infection rates during the first 30 days, infection counts between day 30 and 3 months, and hospitalization days due to sternal infection. Together, these outcomes extend the study’s focus beyond whether a participant experienced at least one infection within the primary 90-day window. They concern consequences, timing, and different summaries of infection occurrence.

The relationship to the primary result is necessarily limited by the sparse primary event count. When the principal event is rare in the observed groups, related secondary measures may also be based on few events. That makes their estimates potentially unstable and means they should be considered alongside the primary endpoint rather than as independent confirmation of it. The registry does not report enough quantitative secondary results to describe a consistent pattern across all the listed outcomes.

Secondary outcomes are often interpreted with less weight when many outcomes are examined without a stated multiplicity strategy. In general, each additional statistical comparison creates another opportunity for an apparently notable result to arise by chance. The record lists six secondary outcomes, but does not report a multiplicity adjustment or a plan for prioritizing them. The registry does not report a detailed analysis plan or a complete set of quantitative results for those outcomes. Consequently, any individual secondary finding, if considered, would need to be interpreted cautiously and in the context of the primary result and the full set of questions examined.

The record identifies a secondary 30-day infection outcome with zero participants in the D-PLEX arm and one in standard care, matching the primary event pattern over the stated shorter period. This is not independent evidence that the primary finding is replicated: the outcomes cover overlapping time periods and are based on the same trial participants. The other listed secondary questions should not be taken as supportive or contradictory without their actual estimates and analysis details. Overall, the secondary outcomes broaden the questions the study sought to address, but the available registry information does not establish a coherent secondary pattern that resolves the uncertainty in the primary comparison.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Decrease in the Number of Readmissions Due to Sternal Surgical Site Infection
• Decrease in Number of Surgical Re-interventions Due to Sternal Surgical Site Infection.
• Time to Sternal Infection Post-cardiac Surgery.
• Decrease of Sternal Infection Rate, DSWI (Deep Sternal Wound Infections) and SSWI (Superficial Sternal Wound Infection) During the First 30 Days Post Operation.
• Decrease in the Total Number of Sternal Infections, DSWI (Deep Sternal Wound Infections) and SSWI (Superficial Sternal Wound Infection) Between Day 30 and 3 Months.
• Decrease in the Number of Hospitalization Days Due to Sternal Surgical Site Infection.

9. Statistical Interpretation

10. Statistical Methods Explained

The main comparison is between two proportions: the fraction of participants in each arm who experienced at least one sternal infection within the 90-day endpoint window. Because the outcome is whether a participant had an event, each participant contributes an event or a non-event classification. This is different from comparing the total number of infections if one participant could have more than one infection.

What does the risk difference represent?

A risk difference subtracts one group’s event proportion from the other group’s event proportion. It is an absolute contrast, expressed in the same scale as the proportions. The posted estimate is 0.048 for the standard-care comparison against D-PLEX plus standard care. The posted interval runs from -0.043 to 0.139. Because the interval includes zero, the result does not rule out no difference at the confidence level used for that interval. The confidence level is not reported in the registry record, so it should not be assumed from the interval alone.

The direction of a risk difference depends on the order of the groups. Here, the registry’s comparison is standard care relative to D-PLEX plus standard care. The observed proportions are 4.8% in standard care and 0.0% in the D-PLEX arm, so the point estimate is in the direction of a higher observed event proportion in the standard-care arm. The interval’s negative and positive limits indicate that plausible values under the interval procedure include either direction. This interpretation concerns the estimated contrast, not a causal conclusion by itself.

How should the p-value be read?

The unadjusted p-value is 0.089. In general, a p-value describes how unusual the observed data, or more extreme data, would be under a specified statistical model and a null hypothesis. It is not the probability that the null hypothesis is true, and it is not a measure of the size or clinical importance of an effect. The registry does not report the exact test or model used to obtain this p-value. The label “unadjusted” indicates that it is not presented as adjusted for multiple comparisons or other covariates.

The sample-size assumptions mention a two-sided significance level of 0.05 for planning illustrations. That planning assumption is not a substitute for a reported analysis plan. Comparing the posted p-value with that stated threshold is a conventional way to describe the result, but it does not erase the uncertainty from the small event count or establish that an effect is absent.

Why do rare events make the estimate unstable?

When events are rare, estimates of group proportions and their difference depend heavily on a small number of observations. In this trial record, the primary comparison contains one event overall. General statistical reasoning therefore cautions against treating the point estimate as a stable estimate of the difference that would occur in other samples. The interval is useful because it communicates uncertainty that a point estimate alone cannot show.

For binary outcomes, different statistical methods can produce different interval limits, particularly with sparse events. The registry does not report the method used for the primary interval or p-value. The available result should therefore be read as the posted estimate and uncertainty interval rather than as a basis for reconstructing an unstated analysis method.

What do the planning illustrations mean?

The registry describes sample-size illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning illustrations, not observed power and not evidence that the trial was designed or justified using those assumptions. The registry does not report the trial’s own sample-size justification. With only one primary event, using the observed effect as a planning input is especially sensitive to random variation. The illustrations should be treated as conditional examples of what might be required under their assumptions, not as proof that the study had adequate or inadequate power.

In general, over-dispersion matters when observed variation is greater than a statistical model expects; a model that ignores it can understate uncertainty. The primary endpoint is a binary participant-level outcome, and the registry does not report a count model or an over-dispersion analysis. Over-dispersion should not be assumed to have been assessed or to be relevant to the posted primary comparison.

Finally, an analysis of randomized groups is most informative when the population analyzed, follow-up, outcome definition, and handling of missing observations are clear. The registry does not report the primary analysis population, missing-data procedures, or a detailed statistical analysis plan. Those omissions limit independent assessment of how the estimate was produced and how robust it is to analytic choices.

11. Confidence Intervals and Precision

The primary comparison is numerically sparse: there are no recorded infections in the D-PLEX arm and one in the standard-care arm. The estimated risk difference is 0.048. Its interval extends from -0.043 to 0.139. The range crosses zero and includes values on both sides, so the posted result does not locate the difference precisely enough to determine its direction with confidence. The confidence level and interval method are not reported in the registry record.

An interval is a way to express uncertainty around an estimate under a statistical procedure. It is not a range containing every possible true value with certainty, nor does it show the probability that a particular value is correct. Its interpretation depends on the procedure and assumptions used. Since the record does not identify the interval method or confidence level, interpretation should remain descriptive rather than attributing a specific coverage meaning.

The small event count is central to precision. A point estimate can look substantial when one group has an event and the other does not, but the estimate can be sensitive to the limited number of observations. The unequal arm sizes also mean that the groups contribute different amounts of information. The broad interval reflects that the result leaves considerable uncertainty about the size and direction of the difference.

Precision is distinct from statistical significance and from clinical importance. A p-value of 0.089 does not describe the range of plausible effect sizes; the interval does. Neither measure establishes whether a difference would be important in practice. The registry does not report a threshold for a clinically important difference, so the clinical meaning of particular values in the interval cannot be determined from this record alone.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary infection endpoint and six secondary outcomes. It does not report a multiplicity strategy, such as a hierarchy of hypotheses or an adjustment to account for testing several outcomes. In general, when multiple outcomes are tested, the chance of at least one apparently unusual result can increase if each is treated as a separate confirmatory test. This is why unadjusted secondary results generally carry less evidential weight than a clearly prespecified primary comparison. The record does not establish whether multiplicity was considered in the study’s analysis plan.

The registry does not report the detailed statistical analysis plan, the primary analysis population, or whether the primary analysis followed intention-to-treat principles. It also does not report how missing endpoint assessments, withdrawals, or incomplete follow-up were handled. These are important because the interpretation of an event proportion depends on knowing who was included in the denominator and whether outcome status was ascertained consistently.

The record states the total enrollment and the arm counts in the primary result, but does not describe participant flow by study part or explain whether all enrolled participants contributed to that endpoint analysis. The study had an open-label single-arm part and a randomized single-blinded part; how these parts relate to the posted arm comparison is not reported in the registry record. The identity of the blinded party and details of outcome adjudication are also not reported.

These gaps do not change the posted counts, but they limit assessment of possible bias and reproducibility. Without a reported analysis plan, missing-data approach, analysis population, and multiplicity procedure, readers cannot determine whether the posted analysis was the prespecified one or how much flexibility there was in outcome selection and analysis. No assumption should be made that an unreported procedure was or was not used.

13. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: post procedural discharge (9.5%), postpericardiotomy syndrome (5.0%), acute myocardial infarction (4.8%), aortic valve incompetence (4.8%), atrial fibrillation (4.8%).

The registry reports serious adverse events among 22 of 60 participants in the D-PLEX plus standard-care group and 12 of 21 in the standard-care group. It reports other adverse events among 48 of 60 and 18 of 21 participants, respectively. One death is listed in the D-PLEX arm and none in the standard-care arm. These are descriptive counts from groups of different sizes; they should not be read as proof that treatment caused or prevented any event.

The listed serious adverse-event terms include post procedural discharge (9.5%), postpericardiotomy syndrome (5.0%), acute myocardial infarction (4.8%), aortic valve incompetence (4.8%), atrial fibrillation (4.8%), and bradycardia (4.8%). The registry record does not provide enough detail to determine the denominators or overlap for these listed terms, their timing, severity, relatedness to D-PLEX, or whether the same participant contributed to more than one category.

Safety comparisons require caution because the sample is small and the arm sizes differ. These figures describe events recorded in the study; they do not establish comparative safety beyond the observed participants and follow-up. The registry summary describes safety assessment over 6 months, but detailed safety analysis methods and follow-up completeness are not reported.

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

The result establishes what was recorded in this trial: within 90 days after cardiac surgery, no sternal infections were reported among 60 participants in the D-PLEX plus standard-care arm, while one was reported among 21 participants receiving standard care. The estimated risk difference is 0.048, and its interval, -0.043 to 0.139, includes zero. The unadjusted p-value is 0.089.

These observations do not establish that the true infection risk differs between the groups, nor do they establish that the risks are the same. With one event, the study result is imprecise. The interval covers values consistent with a difference in either direction, and the registry does not report the interval’s confidence level or method. The point estimate should not be treated as a reliable prediction of the size of an effect in another group of participants.

The result also does not answer every question about D-PLEX. The primary endpoint addresses at least one identified deep or superficial sternal infection within 90 days. It does not establish effects on infections after that period, other postoperative infections, recovery, or the full set of listed secondary outcomes. Nor does the primary endpoint alone determine the balance of benefits and harms. The safety figures are descriptive and require their own cautious interpretation.

The registry record has important reporting gaps for independent evaluation, including the study’s sample-size justification, detailed statistical plan, analysis population, missing-data handling, and the relationship between the two study parts and the posted arm comparison. Those omissions do not invalidate the recorded result, but they constrain how confidently its methods and generalizability can be assessed.

The most defensible reading is therefore narrow: the observed primary event count was lower in the D-PLEX arm, but the data are too sparse and the estimate too uncertain to support a definitive claim about the underlying difference. The result is a description of this study’s posted findings, not medical advice or a basis for an individual treatment decision.

15. Why This Trial Matters Statistically

This trial illustrates why a point estimate should not be read without its event count and uncertainty interval. The observed primary outcome pattern has no infections in one arm and one in the other, and the estimated difference is accompanied by an interval that spans zero. The apparent separation between the observed proportions is therefore not a precise estimate of the difference that would be expected across other samples.

It also demonstrates how trial structure affects interpretation. The registry describes both an open-label single-arm part and a randomized single-blinded part, but does not explain how these parts contribute to the posted comparison. A randomized comparison can support a more direct assessment of group differences than a single-arm observation, yet the specific analysis population and procedures still need to be clear to evaluate the result fully.

The study’s primary question is important statistically because sternal infection is the event of interest, but few events make conventional estimates difficult to pin down. A large-looking contrast in observed proportions can coexist with substantial uncertainty when the denominator and event count are limited. The risk difference and interval convey information that a simple statement about which group had fewer observed events would miss.

Finally, the registry record distinguishes the primary endpoint from multiple secondary questions and safety outcomes. Without a reported multiplicity strategy and fuller outcome analyses, secondary results cannot automatically be treated as confirmation. This example underscores the value of transparent reporting of analysis methods, missing data, study-part contributions, and outcome definitions alongside the numerical findings.

16. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

Several limitations are specific to interpreting this registry record. The primary comparison contains only one infection event overall, so the estimated difference is highly dependent on a sparse count. The interval is broad and includes values on both sides of zero; its confidence level and calculation method are not reported. The unadjusted p-value is available, but the test or model producing it is not identified.

The study is described as having two parts with different designs: an open-label single-arm part and a randomized single-blinded part. The registry does not report how many participants entered each part or whether both parts contribute to the posted primary comparison. The posted arm counts are unequal, and the reason for that imbalance is not reported. Details of randomization, allocation concealment, and who was blinded are also absent.

The registry does not report the sample-size justification, primary analysis population, missing-data procedures, or a complete statistical analysis plan. It does not describe participant flow or confirm whether endpoint follow-up was complete for all participants. The six listed secondary outcomes are not accompanied by a reported multiplicity strategy, limiting their use as confirmatory evidence. Detailed quantitative results for the full set of secondary outcomes are not reported in the registry record.

The available description also gives limited information about the intervention’s administration, eligibility criteria, and participant characteristics. These omissions constrain assessment of how closely the enrolled group represents other cardiac-surgery populations and how the results might apply beyond this study. The safety figures lack reported details about event relatedness, timing, overlap, and the denominators for individual listed serious adverse-event terms. These limitations call for a cautious, narrowly scoped reading rather than a broader conclusion about efficacy or safety.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Safety and Efficacy of D-PLEX in the Prevention of Sternal Infection Post Cardiac Surgery. — NCT02731573.
• Registry record last updated 2026-04-13; status last verified 2026-03.
• Results first posted 2026-04-13.
• 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.

20. Record Summary

NCT02731573 is a completed Phase Ib/II prospective, multicenter study with an open-label single-arm Part 1 and a randomized single-blinded Part 2. The study examined D-PLEX with standard care compared with standard care alone after open heart surgery. Total enrollment was 81.

The primary endpoint was at least one identified sternal infection within 90 days after cardiac surgery. The posted results record zero events among 60 participants in the D-PLEX arm and one among 21 participants in the standard-care arm. The estimated risk difference is 0.048, with an interval from -0.043 to 0.139 and an unadjusted p-value of 0.089.

The registry also lists six secondary outcomes and reports descriptive serious and other adverse-event counts. Important details, including the statistical analysis plan, analysis population, missing-data handling, and the contribution of each study part to the primary comparison, are not reported in the registry record. The sparse event count and interval spanning zero mean that the posted primary comparison remains imprecise.