Prospective Observational Study of Clostridium Difficile Infection in Asian Pacific Countries: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prospective Observational Study of Clostridium Difficile Infection in Asian Pacific Countries (NCT02223715), a registered phase not stated study. The primary outcome is Patient Demographics.

2. Clinical Question

The study was designed to characterize patients with Clostridium difficile infection (CDI) in an Asia-Pacific, multi-center setting and to describe treatment and management. Its registered primary outcome is titled “Patient Demographics”; the accompanying description identifies medical history collected at CDI diagnosis, including concomitant diseases. The registry does not give detailed demographic categories or numerical results for this outcome.

In statistical terms, the central aim is descriptive: to document characteristics and management in the observed CDI population, rather than estimate the causal effect of a study-assigned intervention. Observational descriptions can help characterize the patients included and the outcomes recorded in that setting. They do not, by themselves, establish whether any treatment caused an outcome or whether the findings apply to patients outside the observed study population.

3. Trial Design

This is a prospective observational study. The registry title and brief summary describe a multi-center study in Asian Pacific countries, intended to characterize patients with CDI and understand treatment and disease management. Prospective observation means that information is collected according to a study process as participants are followed, rather than the study assigning treatments for comparison. The registry does not provide further detail about visit schedules, data-collection procedures, or the specific countries and centers.

The registry lists enrollment of 600 and gives a status of COMPLETED. The recorded study start is 2014-03, and primary completion is 2015-01. Those entries describe the registered study timeline; the registry record does not provide a detailed account of recruitment progress or explain whether the enrollment entry represents the final number analyzed for each outcome.

The listed intervention is “CDI Pts,” and the arm description names CDI without further detail. No assigned treatment arm or randomized allocation is described. The registry explicitly cautions that allocation was not stated and that the arms are not a like-for-like control comparison. Consequently, any apparent difference between groups, if one were reported, could not automatically be attributed to treatment. Patient characteristics, clinical circumstances, and treatment selection may differ across observed groups.

The primary outcome is Patient Demographics, with a unit of participants and a parameter described as NUMBER. Its timeframe is at the time of CDI diagnosis enrollment, and its description focuses on medical history at diagnosis, including concomitant diseases. The registry lists four outcome measures and two secondary outcome topics: clinical complication, and recurrence or not after 2 months of follow-up. It does not describe the outcome definitions in enough detail to determine the precise criteria used for each measure.

The sponsor is Otsuka Pharmaceutical Co., Ltd. Statistical analysis details, allocation procedures, eligibility criteria, and sample-size justification are not reported in the registry record. The study’s observational purpose should therefore guide interpretation: the registered design supports characterization of the recorded cohort, not a randomized efficacy 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Medical history is information which was collected at the CDI diagnosis in this study. The items of the Medical history are indicated below. Concomitant diseases at the CDI diagnosis were included in the Medical history.

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 Patient Demographics, measured over At the study at the time of CDI diagnosis enrollment.

The registered primary endpoint is titled Patient Demographics. It is expressed as a number of participants, and the endpoint description states that medical history was collected at CDI diagnosis. The medical-history items included concomitant diseases at diagnosis. The timeframe is recorded as “At the study at the time of CDI diagnosis enrollment.” This indicates that the primary outcome concerns characteristics recorded around diagnosis and enrollment, rather than a treatment response measured after an assigned intervention.

Descriptive demographic and medical-history information is useful for showing who was included in a clinical study and what conditions were recorded alongside the diagnosis. In general, describing the study population helps readers judge the setting and population to which the observed experience may be relevant. It can also help put later outcome summaries into context, since patients may have differing clinical histories and circumstances.

The registry record does not list the individual demographic or medical-history categories, their counts, or their results. Therefore, it is not possible to describe the distribution of those characteristics from the registry information available for this analysis. The title alone should not be taken to mean that every conventional demographic measure was reported: the accompanying description specifically refers to medical history and concomitant diseases.

The primary endpoint is not a comparative measure of treatment benefit or harm. No intervention assignment or control comparison is described, and no numerical endpoint results are reported in the registry record. The outcome’s role is descriptive: it defines a category of participant information collected at the time of CDI diagnosis and enrollment.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins with the study design. This study is described as prospective and observational. In general, a prospective design collects information as participants are followed through the study process. An observational design does not assign participants to treatments for the purpose of estimating treatment effects. It can describe care and outcomes as they occur, but comparisons between naturally occurring groups may reflect differences in patient characteristics, clinical decisions, or circumstances as well as any differences associated with treatment.

What does a descriptive endpoint tell us?

The primary outcome is titled Patient Demographics and is measured as a number of participants. Its description identifies medical history collected at CDI diagnosis, including concomitant diseases. A count is an absolute number of recorded participants or events, depending on the measure. To interpret a count as a frequency in the study population, readers also need a relevant denominator and a clear definition of who was eligible for that count. The registry does not report the primary outcome’s component categories, numerical counts, or outcome-specific denominators.

General descriptive statistics organize observations without necessarily testing a hypothesis. For categorical characteristics, counts may be presented alongside proportions; for continuous characteristics, summaries may describe a central value and variability. These are general approaches, not methods reported for this study. The registry record does not state which summaries were used or provide the underlying results. It is therefore not possible to identify which characteristics were summarized or how their distributions were handled.

Why does the observational design affect comparisons?

In a randomized study, random assignment is intended to make treatment groups comparable, on average, with respect to both measured and unmeasured factors. This record does not describe randomization, and it expressly warns that the arms are not a like-for-like control comparison. In general, an observed association between a treatment and an outcome can be confounded when factors related to treatment choice are also related to the outcome. Statistical adjustment may reduce bias from measured confounders, but it cannot guarantee removal of unmeasured or poorly measured confounding.

The registry does not report whether any regression, stratification, matching, weighting, or other adjustment was used. Nor does it report a prespecified comparison, a treatment contrast, or an analysis population for such a contrast. As a result, methods that could support adjusted comparisons should not be attributed to this study based on the registry information alone.

What do uncertainty intervals usually mean?

In general, a confidence interval describes the range of estimates compatible with the observed data under a statistical model and its assumptions. A narrow interval generally indicates greater statistical precision than a wide interval, while neither width nor statistical significance addresses all sources of bias. An interval can reflect sampling variability but does not automatically account for selection, measurement error, missing outcomes, or confounding. No confidence intervals are reported in the registry record, so the precision of the study’s outcome estimates cannot be evaluated from it.

A p-value, in general, measures how unusual data at least as inconsistent with a specified null model would be if that model and the statistical assumptions held. It does not measure the size or clinical importance of an effect, and it is not the probability that a hypothesis is true. The record lists zero analyses and reports no p-values. No test or null hypothesis should therefore be inferred.

Why can over-dispersion matter?

General count models sometimes assume that variability follows a particular relationship to the average count. Over-dispersion occurs when observed variability is greater than that assumption allows. If it is ignored, standard errors may be too small and uncertainty intervals or tests may be overly optimistic. Researchers may use alternative variance estimates or models when the data and design justify them. This is general statistical context only: the registry record does not report a count model, a dispersion assessment, or evidence of over-dispersion. The primary outcome’s description as a number of participants is not enough to establish that any particular count model was used.

How should the planning illustrations be read?

The record describes sample-size illustrations based on a stated fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. In general, a planning calculation estimates the number of participants or events needed under specified assumptions to detect a target effect with a chosen level of statistical power. The listed assumptions describe an illustration, not proof that the study was designed or analyzed that way. The registry does not report a sample-size justification for the observational study.

The planning description says that non-time-to-event calculations concern participants per arm and that time-to-event calculations concern the total number of events. Those are general conventions for the illustrations, not evidence that the registry’s observational cohort was allocated equally or analyzed as two comparable arms. Because no observed effect size is given in the registry record, the numerical basis for the illustrations cannot be assessed from the record. Planning values must not be interpreted as observed power, nor as a substitute for examining outcome estimates and their precision.

In general, observed power is not a useful replacement for an estimate and its uncertainty: after data collection, power calculations based on the observed effect largely restate the result while obscuring its precision. The relevant information would be the estimated outcome quantities, denominators, and uncertainty measures, interpreted in light of the design. Those results are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures, including the primary Patient Demographics outcome and secondary topics of clinical complication and recurrence or not after 2 months of follow-up. It does not report how these measures were prioritized analytically, whether any outcome definitions were changed, or whether multiple comparisons were planned. The multiplicity strategy is not reported in the registry record.

In general, assessing many outcomes or making many statistical comparisons can increase the chance of obtaining at least one apparently unusual result by chance. A prespecified analysis plan can clarify which outcomes and contrasts are primary, whether adjustment for multiple testing is intended, and how exploratory analyses will be labeled. No such plan is described in the registry record. Since no analyses are listed, there are no reported tests whose multiplicity adjustment can be evaluated.

Missing-data procedures and analysis populations are also not reported in the registry record. The enrollment entry is 600, but the record does not provide endpoint-specific denominators, the number with complete follow-up, or reasons for missing observations. Without those details, the extent and possible consequences of missing data cannot be assessed. A denominator can differ across outcomes when not all participants have the relevant measurement; the registry does not say whether that occurred.

In general, missingness can affect descriptive estimates if participants with recorded outcomes differ systematically from those without them. Researchers may describe missingness, use methods based on explicit assumptions, or conduct sensitivity analyses. The appropriate approach depends on the nature and amount of missing information. None of these approaches should be attributed to this study without a registry report. The record also does not define analysis populations, such as whether all enrolled participants or only participants with evaluable measurements were included for each endpoint.

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

The registry record documents a completed prospective observational study intended to characterize patients with CDI and understand treatment and management in Asian Pacific countries. It identifies medical history at CDI diagnosis, including concomitant diseases, as the focus of the registered primary outcome. It also identifies clinical complication and recurrence after 2 months of follow-up as secondary outcome topics. These details describe the study’s scope, not the numerical findings.

Because numerical outcome results are not reported in the registry record, the listed outcomes cannot be used to state how many participants had a characteristic, complication, or recurrence. There are no outcome estimates or uncertainty intervals in the record to show the precision of any such quantities. The enrollment entry of 600 does not fill that gap: it does not give the denominator for each outcome or establish how many participants contributed data to each measure.

The design also sets limits on causal interpretation. The record describes observation rather than treatment assignment and cautions that the arms are not a like-for-like control comparison. Consequently, the registry does not support a conclusion that a particular management approach caused an outcome. Even a difference between naturally occurring groups can reflect patient characteristics, clinical circumstances, or decisions about care. An adjusted analysis can address some measured differences but depends on assumptions and cannot automatically remove all bias.

More generally, a study’s findings are most directly informative about the participants and care settings actually represented. The registry does not identify the participating countries or centers, eligibility criteria, or detailed population characteristics. The extent to which results might apply to other settings therefore cannot be judged from this record alone.

What can be concluded is limited but important: the registered purpose was descriptive and observational, the primary outcome concerned participant characteristics at diagnosis, and the registry names additional clinical outcomes. What cannot be concluded from this record is the frequency of those outcomes, the size or precision of any association, or the causal effect of a treatment. Those conclusions require outcome results and methods that are not reported in the registry record.

12. Why This Trial Matters Statistically

Observational studies address questions about clinical populations and care as it occurs in practice. A prospective, multi-center description can organize information about patients with CDI, their recorded medical histories, and the management and outcome topics selected for study. This kind of work can provide context for clinical research by making clear which population and outcomes investigators set out to characterize. In this registry record, however, the numerical findings needed to describe those characteristics and outcomes are not reported.

The study is statistically notable for the distinction between characterization and comparison. The primary outcome is demographic and medical-history information recorded at CDI diagnosis; it is not a comparative treatment endpoint. The registry also warns that the arms are not a like-for-like control comparison. That warning highlights a central interpretive issue in nonrandomized research: observed groups can differ in ways that influence both treatment selection and outcomes. Treating such groups as though treatment assignment had been randomized would overstate what the design can establish.

Clear reporting of outcome definitions, denominators, missing-data handling, and analysis methods would help readers assess the evidence. Those details are not reported in the registry record, nor are numerical estimates or uncertainty intervals. The record therefore illustrates why registration information and outcome reporting serve different purposes. A study description can clarify aims and timing, but it cannot replace results when the statistical question concerns frequency, association, or precision.

The registry lists enrollment of 600 and a completed status, along with the study timeline and its outcome topics. These registry entries establish the registered scope without revealing the distribution of observed results. For statistical interpretation, the most important distinction is between what the design intended to describe and what the record quantifies: the former is stated, while the latter is not available.

13. 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 registry record provides limited detail for evaluating the study’s methods and findings. It describes the work as prospective, observational, multi-center, and conducted in Asian Pacific countries, but does not identify the participating countries or centers. Eligibility criteria, recruitment procedures, and participant flow are not reported in the registry record. This limits assessment of which patients the enrolled population represents.

The primary outcome is titled Patient Demographics, while its description focuses on medical history and concomitant diseases at CDI diagnosis. The specific items collected, operational definitions, and numerical results are not reported in the registry record. That makes it difficult to determine the breadth of the endpoint or assess consistency of measurement across centers. The definitions of clinical complication and recurrence are also not reported in detail.

The registry lists enrollment of 600, but does not give outcome-specific denominators, missing-data counts, or analysis populations. It is therefore unclear how much data contributed to each listed outcome. Statistical methods, adjustment procedures, uncertainty estimates, and a multiplicity strategy are not reported in the registry record. The registry lists zero analyses, so quantitative findings and their precision cannot be assessed from this information.

The observational design and lack of a like-for-like control comparison limit causal interpretation. Allocation is not stated, and no randomized comparison is described. Any treatment-group contrast would require careful consideration of confounding and selection, but the registry does not report a comparison or the methods used to address those issues. Finally, the record does not provide the sample-size justification for the study; the described planning illustrations do not establish the study’s original design rationale.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Prospective Observational Study of Clostridium Difficile Infection in Asian Pacific Countries — NCT02223715.
• Registry record last updated 2016-10-17; status last verified 2016-08.
• Results first posted 2016-10-17.
• 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.

17. Record Summary

The registry identifies NCT02223715 as a completed prospective observational study of Clostridium difficile infection in Asian Pacific countries, sponsored by Otsuka Pharmaceutical Co., Ltd. The study’s stated aim was to characterize patients with CDI and understand treatment and management. The registry lists enrollment of 600, a start date of 2014-03, and primary completion at 2015-01.

The primary outcome is Patient Demographics, described as medical history collected at CDI diagnosis, including concomitant diseases. Secondary outcome topics are clinical complication and recurrence or not after 2 months of follow-up. The registry lists four outcome measures but zero analyses. Numerical outcome results, detailed outcome definitions, analysis methods, and missing-data procedures are not reported in the registry record.

The record describes no randomized treatment assignment and cautions that the arms are not a like-for-like control comparison. Its information supports a description of study aims and design, but not estimates of outcome frequency, precision, or causal treatment effects.