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 Deep Vein Thrombosis (DVT) Prevention in Total Hip Arthroplasty: Continuous Enhanced Circulation Therapy (CECT) Versus Low Molecular Weight Heparin (LMWH) (NCT00358735), a randomized na study. The primary outcome is Events of Deep Vein Thrombosis (DVT).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00358735 |
| Phase | NA |
| Condition | Deep Vein Thrombosis of Lower Limb, Pulmonary Embolism (PE), Bleeding |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 411 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medical Compression Systems |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerns patients undergoing total hip arthroplasty (THA). The record’s title and description place the question in the context of preventing deep vein thrombosis (DVT) during and after surgery. It does not give further eligibility details or describe the enrolled population beyond the surgical setting.
Intervention
The intervention is ActiveCare continuous enhanced circulation therapy (CECT), described as a mobile compression device used after induction of anesthesia, throughout surgery and for 10-12 days after surgery. The brief summary mentions CECT with or without baby-dose aspirin, 81 mg QD; the arm description does not clarify how aspirin use was assigned or whether it was used.
Comparator
The active comparator is low molecular weight heparin (LMWH), identified as enoxaparin. The arm description specifies 40mg QD for the remainder of the 10 days and characterizes the regimen as a standard-of-care protocol for this patient population. Further details about treatment adherence or changes are not reported in the registry record.
Primary question
The primary outcome is the number of DVT events. Routine bilateral compression Doppler was used 10-12 days after surgery; suspected clinical signs and symptoms from the day of surgery through up to 3 months post-op were to be confirmed by objective diagnostic methods. The registry record does not report an outcome comparison, so it does not establish how event counts differed between the treatment groups.
3. Trial Design
This was a randomized, parallel-group trial with single masking. The record lists an enrollment of 411 and a status of completed. It identifies Medical Compression Systems as the sponsor. The recorded start was 2006-06 and primary completion was 2008-09. The phase is listed as NA.
The comparison was ActiveCare CECT against LMWH (enoxaparin). The device description says it was used after induction of anesthesia, during surgery, and for 10-12 days after surgery. Enoxaparin is described as 40mg QD for the remainder of the 10 days. The brief summary additionally refers to CECT with or without baby-dose aspirin, 81 mg QD, but the arm descriptions do not specify the aspirin arrangement. The record does not resolve that difference in wording.
Random allocation means that assignment is intended to distribute measured and unmeasured participant characteristics across treatment groups by chance. It does not guarantee that the groups will be identical, particularly in a finite trial. The record does not describe the allocation sequence or concealment procedures. Single masking is recorded, but the identity of the masked party or parties is not reported in the registry record.
The primary outcome concerns DVT events, assessed at an early post-operative assessment and, for suspected clinical events, through up to 3 months. Secondary outcomes include major bleeding complication, outpatient patients' compliance, serious adverse events, and in-patients' compliance. The registry record does not provide a detailed analysis plan, eligibility criteria, or participant flow by treatment group.
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: Per protocol:. The pre-randomization evaluation (within 3 days of surgery, may be completed on admission) includes the following: * Review of inclusion/exclusion criteria (including evaluation for clinical signs and symptoms of DVT or PE) * Demographic parameters * Medical history
Overall Study
| Stage | ActiveCare+SFT (Experimental) | LMWH (Enoxaparin) (Active Comparator) |
|---|---|---|
| STARTED | 204 | 207 |
| Completed Safety | 198 | 194 |
| Not Completed Safety | 6 | 13 |
| COMPLETED | 196 | 190 |
| NOT COMPLETED | 8 | 17 |
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 | ActiveCare+SFT (Experimental) | LMWH (Enoxaparin) (Active Comparator) | Total |
|---|---|---|---|---|
| Participants analysed | 198 | 194 | 392 | |
| Age, Continuous | years | 63 (20 to 84) | 62 (32 to 88) | 62.5 (20 to 88) |
| Sex: Female, Male: Female | Participants | 109 | 105 | 214 |
| Sex: Female, Male: Male | Participants | 89 | 89 | 178 |
| body-mass index (Kg/m2) | Kg/m^2 | 28 (17 to 43) | 29 (16 to 49) | 28.5 (16 to 49) |
| Diagnosis of osteoarthritis (n): Diagnosis | participants | 186 | 184 | 370 |
| Diagnosis of osteoarthritis (n): No Diagnosis | participants | 12 | 10 | 22 |
| Duration of surgery (minutes) | Minutes | 91 (44 to 168) | 96 (41 to 190) | 93.5 (41 to 190) |
| length of hospital stay (days) | days | 3.2 (2 to 8) | 3.2 (2 to 10) | 3.2 (2 to 10) |
6. Primary Endpoint
The registry lists the primary outcome as Events of Deep Vein Thrombosis (DVT), measured over 10-12 days post-op; and from day of surgery and up to 3 months if symptomatic.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of DVT events. This is a count outcome: it records how many events occurred rather than measuring a continuous quantity such as a laboratory value. The registry describes two routes for identifying events. At 10-12 days post-op, all patients underwent routine bilateral compression Doppler. From the day of surgery through up to 3 months post-op, suspected clinical signs and symptoms of DVT were to be confirmed using standard diagnostic objective methods.
In general, measuring clinically relevant events can help researchers assess whether an intervention is associated with different event occurrence over a specified follow-up period. Routine assessment may identify events that would not be detected by symptoms alone, while diagnostic confirmation of suspected cases sets out how potential clinical events are classified. The registry record does not give further detail about event adjudication, whether recurrent events were counted separately, or how events were attributed to participants.
The endpoint description is not itself a result. The record does not report event counts by group, an estimated between-group effect, or a confidence interval. It also lists multiple time points or categories and states that the primary outcome has not been reduced to one comparison. Consequently, no single primary endpoint contrast can be interpreted from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The available record describes the design and endpoint but does not report the primary DVT outcome results. There are no group-specific primary event counts, effect estimate, confidence interval, or p-value in the recorded primary outcome information. The direction, magnitude, and precision of a difference between CECT and enoxaparin therefore cannot be assessed from this record. This is an absence of a reported comparison, not evidence that the groups had the same outcome.
The primary outcome is described as events of DVT, with routine Doppler assessment at 10-12 days post-op and objective confirmation of suspected clinical cases from the day of surgery through up to 3 months post-op. Because the record notes multiple categories or time points and does not reduce the outcome to one comparison, it is not possible to identify a single estimate that represents the primary question. The registry record does not report how those possible outcome components were combined or prioritized in the analysis.
The safety information includes serious adverse-event counts for the two listed groups. The ActiveCare+SFT group has 3 serious events among 198 at risk, and the LMWH (Enoxaparin) group has 10 among 194 at risk. Those are descriptive counts in the record. No comparative estimate, uncertainty interval, or statistical test for these serious-event counts is reported. They should not be treated as proof of a difference between groups, nor do they substitute for the missing DVT outcome comparison.
Other adverse-event counts are also recorded: 89 among 198 at risk in the ActiveCare+SFT group and 102 among 194 at risk in the LMWH (Enoxaparin) group. The record does not define the full scope of these other events in the information available for interpretation, nor does it provide a comparative analysis. Counts without a clear analytic definition or uncertainty estimate have limited use for judging between-group differences.
The registry lists an enrollment of 411, while the reported at-risk denominators for the adverse-event groups are 198 and 194. The record does not explain the relationship between enrollment and those denominators, or provide participant flow and analysis-population definitions. No inference about reasons for exclusions or missing observations is justified from those figures alone.
Overall, the registry record supports a description of the trial question, intervention, comparator, endpoint approach, and selected adverse-event counts. It does not support a quantitative conclusion about the primary DVT comparison. Any conclusions about treatment effects, precision, or statistical significance would require results not reported in the registry record.
9. Statistical Methods Explained
The statistical information available is limited. The record identifies a randomized, parallel-group, single-masked design, a count-based primary outcome, and several outcome and analysis entries. It does not report the statistical analysis plan, the model used for the primary outcome, an adjustment strategy, or a primary result estimate. The concepts below explain how such analyses are generally approached; they should not be read as a description of methods used in this trial unless the registry record explicitly states them.
Why the outcome type matters
In general, count outcomes are analyzed with methods suited to event counts. A simple count comparison may be informative when the number of events is the main quantity of interest, but a model can also account for exposure time or other design features when those are relevant and recorded. Which approach is appropriate depends on how events are defined, whether multiple events per participant are possible, the observation period, and the planned estimand. Those details and the selected model are not reported in the registry record. It therefore is not possible to say whether the eventual analysis treated the endpoint as a count per participant, a count over a period, or another form.
In general, count data can show more variability than a basic model assumes. Over-dispersion means that the observed variability is greater than the model’s assumed variability. If it is present and not accommodated, uncertainty estimates can be too small, making findings appear more precise than they are. A model that allows extra variability may be considered when its assumptions fit the data. The registry record does not report whether over-dispersion was assessed or how it was handled.
What a treatment-effect estimate would convey
In general, a treatment-effect estimate describes the contrast between groups according to a defined measure. For a count endpoint, the measure might compare event counts or event rates, depending on the study’s analysis plan and data structure. The estimate must be interpreted in relation to its definition: a ratio and a difference do not answer precisely the same question. No primary DVT effect estimate is reported in this registry record, so neither its direction nor its size can be described.
A confidence interval expresses the range of values compatible with the data and the statistical model at a stated confidence level. Narrower intervals generally indicate greater precision than wider intervals, while the interval’s position relative to a null value helps assess compatibility with no difference under the chosen measure. A confidence interval does not represent the probability that the true effect lies within that particular interval. There is no primary-outcome confidence interval reported for this comparison.
What a p-value would and would not say
In general, a p-value describes how unusual data at least as extreme as those observed would be under a specified null hypothesis and model. It does not measure the probability that the null hypothesis is true, the probability that a result occurred by chance, or the clinical importance of an effect. Interpretation also depends on which outcomes and analyses were planned and how many comparisons were considered. The registry record does not report a primary DVT p-value or the analysis plan needed to interpret one.
The record states that the primary outcome has several categories or time points and was not reduced to one comparison. That matters because multiple possible comparisons can create more opportunities for apparently notable findings. In general, a prespecified hierarchy, a clearly defined primary contrast, or a multiplicity adjustment can help manage this issue. Whether any such approach was planned or applied is not reported in the registry record.
How to read planning calculations
In general, a sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. The registry’s sample-size assumptions describe illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event tables, the assumptions refer to total events using Schoenfeld; other calculations are described in terms of participants per arm.
Such illustrations do not establish the trial’s original design rationale, and they are not observed power. The registry record does not report the original sample-size justification. Planning estimates based on an observed effect are especially dependent on the observed estimate, and they do not resolve uncertainty about the true effect. The record does not provide calculated planning values in the registry record for interpretation.
Randomization supports a comparison by assigning participants to groups by chance, but valid interpretation also depends on outcome definitions, follow-up, adherence, missingness, and analysis choices. The record identifies ten analyses and thirteen outcome measures, but does not give the corresponding analysis methods or a complete account of which analyses address which outcomes. Those omissions limit the ability to evaluate the statistical evidence beyond the descriptive registry entries.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists thirteen outcome measures and ten analyses. The primary outcome itself is described as having several categories or time points, and the record does not reduce it to one comparison. Multiple outcomes and analyses raise the general issue of multiplicity: the more comparisons considered, the greater the chance that at least one will appear notable by chance alone. In general, prespecifying a primary contrast and using an appropriate strategy for secondary comparisons can help readers distinguish confirmatory from exploratory findings. Whether that was done is not reported in the registry record.
The record does not report a statistical analysis plan, an outcome hierarchy, multiplicity adjustments, or whether analyses were prespecified. It therefore is not possible to determine how the ten analyses relate to the thirteen measures, which comparisons were considered primary, or how selective reporting was managed. The presence of several outcomes does not by itself indicate that the analysis was inappropriate; it does mean that interpretation requires details absent from the record.
Missing-data methods and analysis populations are also not reported in the registry record. There is no account of participant flow by arm, withdrawals, incomplete outcome assessments, or how missing measurements were handled. The enrollment is 411, while the adverse-event at-risk denominators are 198 and 194, but the record does not explain the relationship between these counts. They should not be used to infer how many participants were excluded or why.
The record does not state whether the primary analysis followed intention-to-treat, per-protocol, or another population definition. In general, intention-to-treat analysis retains participants in their randomized groups and can preserve the benefits of randomization, while other analysis populations answer different questions and can be more vulnerable to bias. Without the planned and reported population definitions, the impact of adherence, withdrawals, and missing outcomes cannot be assessed.
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 |
|---|---|---|---|
| ActiveCare+SFT (Experimental) | 3 | 198 | 1.5% |
| LMWH (Enoxaparin) (Active Comparator) | 10 | 194 | 5.2% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 4% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| ActiveCare+SFT (Experimental) | 89 of 198 |
| LMWH (Enoxaparin) (Active Comparator) | 102 of 194 |
Most frequent serious adverse event terms
| Event term | Organ system | ActiveCare+SFT (Experimental) | LMWH (Enoxaparin) (Active Comparator) |
|---|---|---|---|
| Dislocation | Musculoskeletal and connective tissue disorders | 0 of 198 | 5 of 194 |
| supraventricular cardiac arrhythmia | Cardiac disorders | 1 of 198 | 2 of 194 |
| Cardiac Disorders | Cardiac disorders | 0 of 198 | 1 of 194 |
| Fever due to aspiration | Infections and infestations | 1 of 198 | 0 of 194 |
| Parkinson (new event) | Nervous system disorders | 1 of 198 | 0 of 194 |
| Stress fracture | Musculoskeletal and connective tissue disorders | 0 of 198 | 1 of 194 |
| Thrombocytopenia (HIT?) | Blood and lymphatic system disorders | 0 of 198 | 1 of 194 |
Most frequent non-serious adverse event terms
| Event term | Organ system | ActiveCare+SFT (Experimental) | LMWH (Enoxaparin) (Active Comparator) |
|---|---|---|---|
| Minor Bleeding | Blood and lymphatic system disorders | 74 of 198 | 78 of 194 |
| Edema | Blood and lymphatic system disorders | 7 of 198 | 22 of 194 |
| Skin irritation | Skin and subcutaneous tissue disorders | 8 of 198 | 2 of 194 |
Serious events with the highest arm-level rate: dislocation (2.6%), supraventricular cardiac arrhythmia (1.0%), cardiac disorders (0.5%), stress fracture (0.5%), thrombocytopenia (hit?) (0.5%).
The registry reports serious adverse events for two groups. In ActiveCare+SFT (Experimental), 3 serious events are listed among 198 at risk; in LMWH (Enoxaparin) (Active Comparator), 10 are listed among 194 at risk. The record also lists other adverse events: 89 among 198 at risk in the ActiveCare+SFT group and 102 among 194 at risk in the LMWH group. These figures are counts, not comparative estimates.
In general, adverse-event counts need context: the event definition, observation period, severity criteria, whether people or events are counted, and completeness of follow-up all affect interpretation. Those details are not fully reported in the registry record. The record does not provide a confidence interval, a statistical test, or a comparative safety analysis for these counts. The group labels for these data also use ActiveCare+SFT, whereas the intervention description refers to ActiveCare CECT; the registry record does not explain the wording difference.
The serious-event terms listed include Dislocation (2.6%), supraventricular cardiac arrhythmia (1.0%), Cardiac Disorders (0.5%), Stress fracture (0.5%), Thrombocytopenia (HIT?) (0.5%), and Fever due to aspiration (0.5%). These entries do not establish that an event was caused by a treatment. The listed death counts are null, which is not a reported numerical death total. Neither the serious-event counts nor the other-event counts replace the unreported primary DVT comparison.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, parallel-group comparison was conducted between ActiveCare CECT and enoxaparin in the context of DVT prevention around total hip arthroplasty. It describes the device schedule, the enoxaparin regimen, and the intended DVT assessment approach. It also records adverse-event counts and identifies several secondary outcomes.
What the record does not establish is the comparative effect on the primary DVT outcome. Group-specific DVT event counts, an effect estimate, its precision, and a statistical test are not reported. The endpoint has multiple time points or categories, and the record does not reduce it to a single comparison. It is therefore not possible to infer whether either group had more or fewer DVT events, or how uncertain any difference would be.
The serious adverse-event counts are descriptive. Without a reported comparative analysis and fuller information about definitions and follow-up, they cannot by themselves establish a between-group safety difference. The same caution applies to the other adverse-event counts. The registry’s listed event terms and percentages describe recorded categories but do not establish that an event was caused by a study treatment.
In general, a randomized design can support causal comparisons when the analysis respects the randomized assignment and other key assumptions are met. The record does not provide enough information about the analysis population, missing outcomes, adherence, or statistical methods to assess those conditions fully. Randomization alone does not supply a result when the outcome comparison is absent.
The record also does not report an original sample-size justification or explain the relationship between total enrollment and the adverse-event denominators. Those gaps limit interpretation of the trial’s precision and participant accounting. The appropriate reading is therefore narrow: the record documents the trial’s intended comparison and some safety counts, but it does not provide the primary outcome evidence needed to estimate the DVT contrast.
13. Why This Trial Matters Statistically
This trial is statistically notable because it combines a randomized comparison with an endpoint that can be recorded across more than one assessment route and time frame. The registry describes routine bilateral compression Doppler at 10-12 days post-op, alongside objective confirmation of suspected clinical DVT through up to 3 months. Those design features make clarity about the endpoint definition and analysis important: the meaning of a count depends on which events are included, how repeated events are treated, and how the assessment periods relate to one another.
The registry states that the primary outcome includes several categories or time points and is not reduced to one comparison. This highlights a central principle of trial reporting: a clearly identified primary contrast helps readers understand which estimate is intended to answer the main research question. Where outcomes have multiple components or time points, the analysis plan should make clear how each contributes to interpretation. The needed detail is not reported in the registry record.
The record also illustrates why design information and outcome results must be read separately. Randomization, masking, enrollment, and treatment schedules describe how a study was structured. They do not tell readers what the primary outcomes were or how precisely a treatment difference was estimated. Here, adverse-event counts are reported, but the primary DVT comparison is not. A transparent account of both planned methods and results is essential for assessing evidence.
Finally, the difference between enrollment and the adverse-event at-risk denominators underscores the value of participant-flow reporting. Without an explanation of which participants contributed to each analysis and why, readers cannot judge the completeness of follow-up or the population represented by the reported counts. These are general statistical reporting concerns, not evidence that a particular bias occurred in this trial.
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 statistical interpretation is that the registry record does not report the primary DVT outcome comparison. There are no group-specific primary event counts, effect estimate, confidence interval, or p-value. Since the primary endpoint is not reduced to one comparison, the intended summary contrast is also unclear. The treatment effect and its precision cannot be assessed from the record.
The assessment description gives time frames and diagnostic approaches, but the record does not explain how events across those time points were handled analytically. It does not report whether multiple events per participant were possible or how they were counted, whether event adjudication was used, or whether follow-up was complete. These details matter for understanding a count endpoint.
The statistical analysis plan is not reported in the registry record. Model choice, covariate adjustment, multiplicity control, and analysis-population definitions are not described. Missing-data methods, participant flow by arm, and the reasons for any differences between enrollment and adverse-event denominators are also absent. These gaps prevent assessment of how robust a reported comparison might be, even apart from the missing primary result.
The record’s treatment descriptions are not fully aligned: the brief summary mentions CECT with or without baby-dose aspirin, 81 mg QD, while the arm descriptions do not clarify aspirin assignment or use. The adverse-event group label uses ActiveCare+SFT, while the intervention description names ActiveCare CECT. The record does not explain these wording differences.
Finally, serious adverse-event counts are reported without a comparative estimate or uncertainty interval, and the other adverse-event categories are not fully defined in the information available. The record does not report an original sample-size justification. These limitations constrain conclusions about both efficacy-related outcomes and safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Deep Vein Thrombosis (DVT) Prevention in Total Hip Arthroplasty: Continuous Enhanced Circulation Therapy (CECT) Versus Low Molecular Weight Heparin (LMWH) — NCT00358735.
- Registry record last updated 2014-10-30; status last verified 2014-10.
- Results first posted 2014-10-21.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT00358735 is a completed, randomized, parallel-group, single-masked trial sponsored by Medical Compression Systems. The record lists enrollment of 411, phase NA, a start of 2006-06, and primary completion in 2008-09. It compares ActiveCare CECT with enoxaparin for DVT prevention in total hip arthroplasty.
The primary outcome is the number of DVT events, with routine bilateral compression Doppler at 10-12 days post-op and objective confirmation of suspected clinical events through up to 3 months. The registry record does not report a primary-outcome comparison and notes that the outcome has multiple categories or time points without a single reduced comparison.
Serious adverse-event counts are 3 among 198 at risk for ActiveCare+SFT and 10 among 194 at risk for LMWH (Enoxaparin). The record does not report a comparative safety analysis. Further statistical methods, missing-data handling, analysis populations, and the original sample-size justification are not reported in the registry record.