Epidemiology of Thromboembolism Disease: A Cohort Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Epidemiology of Thromboembolism Disease: A Cohort Study (NCT00670540), a registered phase not stated study. The primary outcome is Percentage of Participants Who Developed a New or Recurrence of Venous Thromboembolism (VTE).

2. Clinical Question

The broader study purpose was to investigate risk factors for thromboembolic disease and whether clinical significance, risk factors, and prognosis differ across disease presentations. Questions also addressed detailed histories of prior thromboembolic disease, older patients, preventive treatment, clinical prediction scores, people with potential risk but no symptoms, and follow-up after positive or negative exploratory VTE tests. These are stated study aims, not evidence that each question was answered or that a particular finding was established. Results addressing these aims are not reported in the registry record.

3. Trial Design

The registry describes a prospective epidemiological multicenter cohort study of patients clinically suspected of DVT or PE. The listed intervention is a diagnostic procedure for DVT and PE, not an assigned therapeutic intervention. The registered arm description identifies patients with suspected DVT or PE. No randomized allocation or like-for-like control comparison is described; the registry record does not state an allocation method. Accordingly, the study is best read as observational evidence about disease occurrence, clinical features, and follow-up, rather than as a randomized estimate of a treatment effect.

The listed enrollment is 8256. The sponsor is University Hospital, Grenoble. The registry dates the study start to 2004-11 and primary completion to 2009-01, and its status is COMPLETED. Completion status does not itself establish that every intended analysis was performed, reported, or free of missing observations. The registry record does not report the recruitment sites, detailed eligibility criteria, participant flow, duration of individual follow-up, or the extent of follow-up after inclusion.

The registered primary outcome is the percentage of participants who developed a new or recurrent VTE at 3 years. Its definition distinguishes participants without VTE at inclusion, for whom a new event during follow-up is counted, from participants with VTE at inclusion, for whom recurrence is counted. Secondary outcome descriptions cover major bleeding, anticoagulant treatment, cardiovascular events, death from any cause, cancer onset, and venous insufficiency described as leg ulcer. The registry record does not report operational definitions, event adjudication procedures, or outcome-specific analysis results.

The study description raises several additional epidemiological questions, including variation by disease presentation and the performance of predictive clinical scores in inpatients and outpatients. These aims do not establish that corresponding comparisons were prespecified in a formal analysis plan. Statistical analysis procedures, handling of confounding, and the analysis populations are not reported in the registry record. No analysis is listed in the registry record, so the completed status should not be taken as a substitute for reported estimates.

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 Percentage of Participants Who Developed a New or Recurrence of Venous Thromboembolism (VTE), measured over at 3 years.

The primary endpoint measures the percentage of participants who develop a new or recurrent venous thromboembolism at 3 years. For participants without VTE at inclusion, the endpoint concerns a new event during follow-up. For participants with VTE at inclusion, it concerns recurrence. The registry gives the unit as percentage of participants and specifies a 95% confidence interval as the measure of dispersion.

This kind of endpoint is useful for describing how often an event occurs in a defined cohort over a stated follow-up horizon. A percentage is an accessible summary of event occurrence, while its confidence interval conveys statistical uncertainty around the estimate. General: an interval that is narrower indicates greater precision under the method used; it does not remove possible bias from selection, measurement, incomplete follow-up, or other design limitations.

The endpoint combines new events and recurrences, but its definition distinguishes them according to VTE status at inclusion. These are clinically and analytically different paths to an event. Without subgroup estimates, the overall percentage would not show whether the observed events arose mainly among participants with or without VTE at baseline. The registry record does not report the endpoint percentage, the confidence interval, subgroup results, or the event-counting and censoring rules. Thus, the measure is specified, but its observed magnitude and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The design and endpoint are stated, but the registry record does not report a detailed statistical analysis plan. The following explanations describe general statistical concepts relevant to interpreting this kind of cohort record; they do not claim that a particular method was used unless the registry explicitly identifies it.

What does a cohort estimate describe?

In a prospective cohort, people are identified and followed forward in time, and outcomes are recorded as follow-up proceeds. A percentage with an event can describe observed event occurrence among the participants included in that analysis. Its interpretation depends on who entered the cohort, how the outcome was defined, how long participants were observed, and whether outcome information was available. The registry calls the primary outcome a percentage of participants and specifies a 3-year timeframe. It does not report the actual estimate or the detailed rules used to establish that a participant had a new event or recurrence.

General: a percentage is most straightforward when participants have comparable opportunities for outcome observation. If follow-up duration differs, or if some participants leave observation before the endpoint horizon, the percentage may require a method that accounts for time and censoring. The registry record does not report whether such methods were used, how losses to follow-up were handled, or whether all participants had outcome status assessed at the stated horizon. It would be inappropriate to infer these procedures from the fact that the study was prospective.

What does a confidence interval add?

The endpoint specifies a 95% confidence interval. General: a confidence interval expresses uncertainty around an estimated quantity under the statistical method and assumptions used. It is not a guarantee that the true value falls inside the interval, nor does it account automatically for selection bias, outcome misclassification, or unmeasured confounding. The estimate and interval are not reported in the registry record, so neither the central estimate nor its precision can be described. The specified confidence level alone does not reveal whether the result was precise or imprecise.

Confidence intervals are also useful when comparing estimates, but comparisons require the estimates for the relevant groups and a method that accounts for their uncertainty. This cohort record poses questions about differences among disease presentations and about clinical scores for inpatients and outpatients. The corresponding group-specific results and uncertainty estimates are not reported in the registry record. No conclusion about similarity, difference, or score performance can be drawn from the stated questions alone.

Why does the observational design matter?

Participants were clinically suspected of DVT or PE, and no randomized assignment is described. General: in an observational study, exposure groups may differ in baseline characteristics that also relate to outcomes. For example, clinical decisions about preventive or anticoagulant treatment may be related to a person's health status or perceived risk. A crude comparison can therefore mix the association of interest with differences in who received or did not receive an exposure. Adjustment can address measured covariates under appropriate assumptions, but it cannot ensure that all confounding has been removed.

The registry's stated questions include risk factors, preventive treatments, disease categories, and prediction scores. These questions could require different analytical approaches. A risk-factor analysis needs a clear exposure definition and a strategy for confounding. A score-performance analysis needs a defined score, threshold or prediction output, outcome, and performance metric. Comparative prognosis across disease categories requires clear group membership and follow-up rules. Such details and the analyses themselves are not reported in the registry record. No specific modeling approach should be assumed.

How should event percentages be read?

General: a proportion summarizes the share of an analyzed group meeting an event definition. The denominator matters: it should correspond to the population eligible for that outcome and to available outcome information. In a cohort with a 3-year endpoint, incomplete observation may affect which participants can be classified. A reported proportion without its denominator, event definition, and missing-data approach can be difficult to interpret. The primary result and its denominator are not reported in the registry record.

The registry labels the primary endpoint as a percentage of participants and distinguishes new VTE from recurrence by VTE status at inclusion. This distinction should be preserved when interpreting any future estimate. A combined proportion may not describe the event experience of either baseline subgroup. The registry does not state whether separate subgroup estimates were planned or reported.

What can the planning illustrations establish?

The stated planning assumptions describe illustrations based on an observed effect, two-sided significance level 0.05, equal allocation, a normal approximation, and effects expressed as fractions of the observed effect. They are planning illustrations, not observed outcomes or evidence that a study had a particular probability of detecting an effect. The registry record does not provide the illustration values in the registry record for this explanation, nor does it report a sample-size justification from the study's own design. No participant-per-arm requirement or detectable effect should be inferred from the assumptions alone.

General: planning calculations depend on assumptions about the outcome, effect size, variability, allocation, significance threshold, and analysis method. If those assumptions do not match the intended study, the resulting planning estimate may not apply. An illustration anchored to an observed effect is especially dependent on how that effect was estimated and on uncertainty in the estimate. It should not be described as observed power. The record does not report whether these illustrations were used when planning the cohort.

What remains unavailable?

The registry record lists no analyses. It also does not report a model specification, adjustment set, handling of competing events, confidence-interval construction, or prespecified subgroup strategy. These omissions prevent a technical assessment of how the outcome estimates were generated. General statistical principles can explain why such choices matter, but they cannot establish which choices were made in this study. The result is a clear description of the intended endpoint and study questions without the analysis details and numerical primary findings needed for independent statistical interpretation.

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("OPTIMEV")
n      <- c(4931)
events <- c(441)
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  OPTIMEV  4931  441  8.9  8.2  9.8  8.2  9.8  8.2  9.8

11. Multiplicity, Missing Data and Analysis Populations

The study description includes a primary endpoint and several secondary outcomes, alongside questions about disease categories, risk factors, clinical scores, preventive treatments, and follow-up after exploratory tests. The registry record does not report a multiplicity strategy for handling the possibility of multiple outcomes or comparisons. It is therefore not possible to determine whether any adjustment, hierarchy, or other prespecified approach was used to control interpretation across analyses.

The registry record lists no statistical analyses. It does not report whether an analysis plan was prespecified, which outcomes were analyzed, how subgroup comparisons were selected, or whether any analyses were exploratory. This absence should not be read as evidence that analyses were not conducted; it means that analysis details are not reported in the registry record.

Missing-data procedures are also not reported in the registry record. There is no stated method for handling missing baseline covariates, unavailable endpoint assessments, withdrawal, or loss to follow-up. The record does not indicate whether the primary outcome was assessed for all participants or how incomplete follow-up was reflected in the estimate. Those details matter because observed proportions can be affected by who has complete outcome information and by whether missingness is related to risk.

The analysis populations are not described. The registry does not state whether all enrolled participants, only those with confirmed suspected disease, or another defined group contributed to each outcome analysis. Nor does it describe how participants were assigned to baseline VTE subgroups for the endpoint. Without these definitions, the intended denominator and the relationship between enrollment and analysis cannot be assessed.

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 0.1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death (16.7%), cardiovascular (6.3%), cancer (3.7%), haemorrhage (2.7%), pulmonary embolism (pe) (2.5%).

The registry lists an OPTIMEV group with 4931 participants at risk for serious events and 1147 affected, and 4931 at risk for other events and 273 affected. These are the registry's recorded at-risk and affected figures; they are not the primary VTE endpoint. The record also lists serious-event terms with percentages: death, 16.7%; cardiovascular, 6.3%; cancer, 3.7%; haemorrhage, 2.7%; and Pulmonary Embolism (PE), 2.5%.

The registry information described does not clarify the denominator used for each serious-event percentage, whether event terms can overlap within a participant, or whether the listed events were considered related to a treatment or procedure. Therefore, these percentages should be read as recorded serious-event term figures, not as treatment-attributable risks or as mutually exclusive categories. A person or event may be represented in more than one term unless the record specifies otherwise; that relationship is not reported in the registry record.

The study is a cohort, not a randomized safety comparison. The serious-event listing does not provide a comparator group suitable for estimating a relative treatment effect. It also does not establish that every listed event occurred during the same observation period as the primary endpoint. The registry record's secondary outcomes separately name major bleeding and other clinical events, but outcome-specific definitions and analyses are not reported. These safety figures describe registry entries; their causal interpretation is limited by the missing context.

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

The registry identifies a clinically relevant epidemiological question: among people suspected of DVT or PE, how often is there a new or recurrent VTE during follow-up? It defines the primary endpoint at 3 years and distinguishes new events from recurrences according to VTE status at inclusion. It also records a prospective multicenter cohort design and a listed enrollment of 8256. Those details describe the intended scope and structure of the investigation.

The registry record does not report the primary outcome percentage or its 95% confidence interval. Consequently, it does not establish the observed frequency of new or recurrent VTE, how precisely that frequency was estimated, or whether the outcome differed across disease presentations. The registry record also does not report analyses of risk factors, preventive treatments, clinical prediction scores, or the other stated aims. The study questions should not be confused with results.

This record does not establish a treatment effect. No randomized allocation is described, and no suitable like-for-like comparator is identified. Even if associations were reported elsewhere in a complete analysis, an observational association would require careful consideration of confounding and selection. In this registry information, the adjustment approach and comparative estimates are not reported.

The record also does not show that no events occurred, that groups were equivalent, or that a particular risk factor is unimportant. Absence of a reported result is not evidence of a null finding. Likewise, a COMPLETED status does not by itself demonstrate that the primary outcome was fully analyzed or published in the registry record.

The serious adverse-event terms and percentages provide descriptive entries, but the denominator, overlap among terms, and relationship to treatment are not specified in the registry information described. They cannot replace the missing primary result or support a causal safety conclusion. Overall, the record communicates the cohort's purpose and endpoint, while leaving the numerical outcome and the analytical information needed to judge it unreported.

14. Why This Trial Matters Statistically

This study is statistically notable for framing thromboembolism as a set of related but potentially different clinical presentations. The registry asks whether distal DVT, proximal DVT, PE, and PE without DVT share risk factors and prognosis. That framing highlights an important epidemiological issue: an aggregate outcome may conceal variation among clinically distinct groups. The stated questions are valuable context, but group-specific results are not reported in the registry record.

The cohort also aims to connect clinical history, preventive treatment, age, and prediction scores with subsequent disease. Such questions are relevant to how observational evidence can describe risk and evaluate prediction. They also require careful definitions and analysis: treatment may be related to baseline risk, and a score's performance depends on the population, outcome, and performance measure. The registry record does not report the methods or estimates needed to evaluate these issues.

The primary endpoint's distinction between a new VTE and recurrence is another meaningful statistical feature. Baseline disease status changes what counts as an endpoint event, so subgroup reporting would help readers understand whether the overall estimate combines different event pathways. The endpoint is specified at 3 years, but the observed percentage, confidence interval, and subgroup estimates are not reported in the registry record.

Finally, the record illustrates why completion status and enrollment are not substitutes for transparent outcome reporting. Without the primary estimate, uncertainty interval, analysis population, and missing-data approach, readers cannot evaluate the magnitude or precision of the study's main outcome. The cohort's stated questions indicate a broad epidemiological agenda; the reported registry information does not establish what the analyses found.

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 principal limitation for interpretation is that the registry record does not report the primary endpoint result or its 95% confidence interval. The endpoint is defined, but its observed percentage and precision are unavailable. The registry record also lists no analyses, leaving the stated epidemiological questions without reported estimates in the information described.

Important design details are not reported, including detailed eligibility criteria, recruitment procedures, participating centers, baseline characteristics, and participant flow. The record gives an enrollment of 8256 but does not explain how many participants contributed to each outcome analysis or how the analysis populations were defined. It does not report outcome ascertainment procedures, event adjudication, diagnostic criteria, or the handling of incomplete follow-up.

The observational design limits causal interpretation. No randomized allocation or like-for-like comparator is described, and statistical adjustment methods are not reported. The record does not identify a confounding-control strategy, prespecified subgroup methods, or a plan for evaluating predictive score performance. The stated questions about preventive treatments and risk factors therefore cannot be interpreted as causal findings.

Multiplicity, missing-data methods, and analysis choices are not reported in the registry record. It is also unclear how competing events or varying follow-up were addressed. These omissions make it difficult to assess bias, precision, and the robustness of any estimate. The serious adverse-event listings lack reported denominator and overlap details in the registry information described, as well as a stated relationship to treatment. These limitations do not imply that the study was invalid; they define what cannot be assessed from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Epidemiology of Thromboembolism Disease: A Cohort Study — NCT00670540.
• Registry record last updated 2012-05-08; status last verified 2012-05.
• Results first posted 2012-05-03.
• 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

NCT00670540 is a prospective epidemiological multicenter cohort study sponsored by University Hospital, Grenoble. It enrolled 8256 participants and focused on patients clinically suspected of DVT or PE. The registry records the study start as 2004-11, primary completion as 2009-01, and status as COMPLETED.

The primary endpoint is the percentage of participants with a new or recurrent VTE at 3 years, with a 95% confidence interval specified. The registry describes new VTE for participants without VTE at inclusion and recurrence for participants with VTE at inclusion. Secondary outcome topics include major bleeding, anticoagulant treatment, cardiovascular events, all-cause death, cancer onset, and venous insufficiency.

The registry record does not report the primary outcome estimate, its confidence interval, or statistical analyses. Detailed analysis populations, missing-data methods, and multiplicity procedures are not reported in the registry record. The serious adverse-event listing includes event terms and percentages, but denominator and overlap details are not reported in the registry information described. Thus, the record establishes the study's design and questions, but does not provide the primary results needed to assess the outcome's magnitude or precision.