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 Study Of Azithromycin Intravenous Formulation Against Pelvic Inflammatory Disease (PID) In Japan (NCT00871494), a non-randomized phase 3 study. The primary outcome is Response Rate (Clinical Response, Data Review Committee Assessment) in Participants Who Enrolled After Protocol Amendment (the Inclusion Criterion Regarding Fever of 37℃ or Higher Was Option).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00871494 |
| Phase | Phase 3 |
| Condition | Pelvic Inflammatory Disease |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 76 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Japanese adults with pelvic inflammatory disease who required initial intravenous therapy. The primary efficacy population was the clinical per protocol set among participants enrolled after the protocol amendment.
Intervention
Azithromycin switch therapy: intravenous administration followed by oral administration.
Comparator
There was no separate comparator group. The study used a single-group, non-randomized design.
Primary question
What clinical response rate, assessed by the Data Review Committee, was recorded at the end of treatment and on Day 15 and Day 29 among participants enrolled after the protocol amendment?
This is a question about the observed response in a treated group, not a randomized comparison of azithromycin with another treatment. Without a concurrent control group, the study cannot estimate how outcomes would have differed under an alternative treatment or no treatment. The open-label design also means treatment was not masked, although the primary response was assessed by a Data Review Committee.
The protocol amendment changed the fever criterion from required to optional, following consultation with the regulatory authority. The registry identifies participants enrolled after that amendment as the primary analysis set for efficacy. The primary endpoint description specifies a clinical per protocol population, but the number included in that population and the primary response estimate are not reported in the registry record.
3. Trial Design
The registry describes a completed Phase 3, multicenter, non-randomized, open-label study of azithromycin in Japanese adults with pelvic inflammatory disease requiring initial intravenous therapy. It lists a single group and an enrollment of 76. The intervention is described as switch therapy, with intravenous azithromycin followed by oral azithromycin. No separate control arm is described, so the study does not provide a randomized treatment comparison.
The primary efficacy outcome was clinical response assessed by the Data Review Committee in participants enrolled after the protocol amendment. The specified assessment times were the end of treatment, Day 15 and Day 29. The registry also lists secondary response and bacteriological eradication outcomes assessed by investigators or a Data Review Committee in the post-amendment participants.
The amendment changed the fever inclusion criterion: fever of 37℃ or higher was changed from a required criterion to an optional criterion. The registry says the change followed consultation with the regulatory authority. It identifies the post-amendment participants as the primary efficacy analysis set. The clinical per protocol population is described as participants who received at least one dose, had no significant protocol violation and underwent the prescribed evaluations during the observation period.
The record does not report the number of participants in that efficacy population, the numerical primary response rate, or its confidence limits. Although the registry status is completed, completion alone does not provide those missing outcome details. A statistical analysis plan, details of any interim analyses, and a justification for the enrollment target are not reported in the registry record.
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
| Stage | Azithromycin |
|---|---|
| STARTED | 76 |
| COMPLETED | 62 |
| NOT COMPLETED | 14 |
Reasons for not completing this period:
| Reason | Azithromycin |
|---|---|
| Protocol Violation | 5 |
| Lack of Efficacy | 4 |
| Adverse Event | 4 |
| Lost to Follow-up | 1 |
Analysis population for the primary outcome, as defined in the registry: Clinical per protocol set consisted of all participants who received at least one dose, had no significant violation of protocol, and underwent prescribed evaluations during the observation period. No imputation was used for missing data. "n" in the Measure Categories means total participants excluding ones assessed as indeterminate.
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 | Azithromycin |
|---|---|---|
| Participants analysed | 76 | |
| Age Continuous | years | 32.2 (SD 10.7) |
| Sex: Female, Male: Female | Participants | 76 |
| Sex: Female, Male: Male | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Response Rate (Clinical Response, Data Review Committee Assessment) in Participants Who Enrolled After Protocol Amendment (the Inclusion Criterion Regarding Fever of 37℃ or Higher Was Option), measured over End of Treatment, Day 15 and Day 29.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is a clinical response rate assessed by the Data Review Committee among participants enrolled after the protocol amendment. The registry defines the rate as the number of participants assessed as effective divided by the total participants, excluding those assessed as indeterminate, multiplied by 100. The measure is reported as a percentage of participants, with a 95% confidence interval specified as the dispersion measure. Assessments were scheduled at the end of treatment and on Day 15 and Day 29.
A response rate is a binary-outcome summary: each participant contributes to a response category, and the result describes the proportion meeting the stated response definition among those included in the denominator. Excluding indeterminate assessments means the denominator is not necessarily the same as the number enrolled or treated. The registry record does not give the count assessed as effective, the denominator used at each time point, or the numerical percentage and confidence interval.
In general, a clinical response endpoint is used to summarize whether participants meet a prespecified clinical assessment rather than to describe a continuous measurement. The endpoint is informative only in context: its interpretation depends on the response definition, assessment timing, population analyzed, and handling of indeterminate or missing assessments. The endpoint definition and timing are stated in the registry, but the numerical results needed to judge the observed response and its precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinical response endpoint but does not report its numerical result. It therefore does not establish what proportion of the primary efficacy population was assessed as effective, nor how precise that estimate was. A 95% confidence interval is named as the dispersion measure, but its limits are not reported in the registry record. Without the estimate and interval, the magnitude and uncertainty of the primary response cannot be evaluated from this record.
The study design also limits the kind of conclusion that can be drawn. It was single-group, non-randomized and open-label, with intravenous azithromycin followed by oral administration. There is no concurrent comparison group. The posted data therefore describe outcomes among participants receiving the switch therapy; they do not quantify a treatment difference against another option. Differences in participant characteristics, disease course, assessment practices or other influences cannot be separated from treatment effects using a single-group outcome alone.
Use of a Data Review Committee for the primary clinical assessment specifies who assessed the response, but the record does not state whether that assessment was blinded. The trial is explicitly open-label and masking is listed as none. The available description does not explain further safeguards used in outcome adjudication, so no additional assumptions about masking or independence of assessment are warranted.
The primary efficacy set was limited to participants enrolled after an amendment that made fever of 37℃ or higher optional. This makes the analyzed population specifically tied to the amended eligibility criterion. The registry does not report the number included in that set or how its composition compared with participants enrolled under the earlier criterion. The stated enrollment of 76 is not the same as an efficacy denominator, and should not be treated as one.
The record lists safety counts, including participants with serious adverse events and participants with other adverse events. These counts provide descriptive context, but they do not replace the missing efficacy estimate or support a randomized safety comparison. In particular, no comparator group is available to distinguish event frequencies associated with treatment from background risks or other factors.
Overall, the registry supports a description of the study question, design, endpoint definition and some safety counts. It does not report the numerical primary efficacy outcome or its uncertainty. Interpretation should remain at that level rather than treating the study title, completion status, or stated endpoint as evidence of a particular response magnitude.
9. Statistical Methods Explained
What does a response rate summarize?
A response rate is a proportion expressed as a percentage. For this study, the registry defines the numerator as participants assessed as effective and the denominator as total participants after excluding those assessed as indeterminate. This definition matters because a percentage is meaningful only when its numerator and denominator are clear. The record gives the rule but not the counts or resulting rate.
Participants who are indeterminate are excluded from the stated denominator, while the population description also says no imputation was used for missing data. These are related but distinct points. Excluding an indeterminate assessment from a response-rate denominator is not the same as assigning a response value to a participant with missing data. The registry does not give the number of indeterminate assessments or explain further how missing assessments affected inclusion at each scheduled assessment.
How should a confidence interval be read?
The endpoint specifies a 95% confidence interval. In general, a confidence interval expresses statistical uncertainty around an estimate under the method used to calculate it. A narrower interval indicates greater precision under that method; a wider interval indicates less precision. It does not by itself correct for limitations in study design, selection into the analysis population, or measurement.
The confidence interval calculation method is not reported in the registry record, and neither the primary estimate nor the interval limits are available. Thus, the interval cannot be used to evaluate the precision of this study's observed response from the registry record. A confidence interval is also not a range in which every individual participant's outcome lies; it concerns uncertainty in the estimated group response.
What does the single-group design permit?
A single-group study can describe outcomes observed in the enrolled and analyzed participants. It cannot, without a suitable comparison, directly estimate a contrast between treatments. Random allocation is not used in this study, and the registry explicitly identifies the allocation as non-randomized. There is no like-for-like control group against which to compare the response or event counts.
Open-label means masking was absent. In general, knowledge of treatment can influence behavior, reporting or assessment, depending on the outcome and study procedures. The primary outcome was assessed by a Data Review Committee, but the registry does not state whether committee members were masked to treatment or other participant information. It is therefore appropriate to report the named assessor without inferring additional protections against assessment bias.
Why does the analysis population matter?
The registry describes the clinical per protocol set as participants who received at least one dose, had no significant protocol violation and completed the prescribed evaluations during the observation period. This definition selects participants according to treatment exposure, protocol adherence and evaluation availability. Such a population can differ from all enrolled participants. The record does not provide its size or detailed participant flow, so the extent of any difference cannot be assessed.
The primary efficacy set is further specified as participants enrolled after the protocol amendment. The amendment made the fever criterion optional rather than required. Accordingly, the primary response question applies to this post-amendment group, not automatically to every participant enrolled in the study. The record does not report the numerical result for this group or the number of people it contained.
What can be inferred from the listed safety counts?
Safety outcomes are descriptive counts in the registry. A count of participants with an event records how many people in the stated at-risk group were affected; it is not a treatment-effect estimate. Without a comparison group, a count cannot establish whether an event was more or less frequent than it would have been under another treatment. The registry lists serious adverse-event and other adverse-event counts, along with several serious-event terms, but does not provide a comparative analysis.
In general, adverse-event summaries require attention to the event definition, observation period, population at risk and whether counts refer to people or events. The record identifies participants at risk and participants affected for the overall categories, but further detail on event timing and exposure duration is not reported. The death count is not stated in the registry record and should not be interpreted as zero.
What statistical analysis details remain unavailable?
The registry lists a 95% confidence interval for the primary endpoint, but does not report the interval method, a formal statistical analysis plan, or numerical outcome results. It lists secondary outcomes but does not report their numerical estimates. The record also does not state a multiplicity strategy for interpreting multiple outcomes or assessment times. In general, multiplicity concerns arise when several hypotheses or endpoints are examined, because the chance of a false-positive finding can increase across repeated testing. Without the analysis plan and reported tests, the degree to which that issue was addressed cannot be determined.
These absences do not show that a particular method was or was not used outside the registry information. They mean that the method is not reported in the registry record. The appropriate statistical reading is therefore limited to the design, definitions and descriptive counts actually recorded, without reconstructing an unreported analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies a primary clinical response outcome and lists secondary clinical response and bacteriological eradication outcomes. It also specifies multiple primary assessment times: the end of treatment, Day 15 and Day 29. The record does not describe how results across outcomes or assessment times were prioritized for statistical interpretation, or whether any adjustment for multiple comparisons was planned. A multiplicity strategy is not reported in the registry record.
The primary efficacy population consists of the clinical per protocol set among participants enrolled after the protocol amendment. The set required at least one dose, no significant protocol violation and prescribed evaluations during the observation period. The record does not state the number meeting these criteria. The stated enrollment of 76 is an enrollment figure, not a reported primary analysis denominator.
The registry says no imputation was used for missing data. It also defines the response-rate denominator to exclude participants assessed as indeterminate. The number of indeterminate assessments, the number of missing assessments, and their distribution across assessment times are not reported. The record therefore does not permit an assessment of how much the available-case denominator differed across time or how missingness might affect interpretation.
Because the primary efficacy group was defined by enrollment after the amendment, its results would apply to that specified population. The registry does not report a comparison of this group with those enrolled before the amendment. No numerical primary or secondary efficacy results are reported in the registry record, so multiplicity and missing-data considerations cannot be evaluated against observed estimates.
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 |
|---|---|---|---|
| Azithromycin | 3 | 76 | 3.9% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 2% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Azithromycin | 35 of 76 |
Most frequent serious adverse event terms
| Event term | Organ system | Azithromycin |
|---|---|---|
| Lymphadenitis | Blood and lymphatic system disorders | 1 of 76 |
| Ileus | Gastrointestinal disorders | 1 of 76 |
| Ovarian haemorrhage | Reproductive system and breast disorders | 1 of 76 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Azithromycin |
|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 10 of 76 |
| Injection site pain | General disorders | 5 of 76 |
| Nausea | Gastrointestinal disorders | 4 of 76 |
| Nasopharyngitis | Infections and infestations | 4 of 76 |
| Abdominal tenderness | Gastrointestinal disorders | 3 of 76 |
| Constipation | Gastrointestinal disorders | 3 of 76 |
| Headache | Nervous system disorders | 3 of 76 |
| Abdominal pain upper | Gastrointestinal disorders | 2 of 76 |
| Gastritis | Gastrointestinal disorders | 2 of 76 |
| Vaginitis bacterial | Infections and infestations | 2 of 76 |
Serious events with the highest arm-level rate: lymphadenitis (1.3%), ileus (1.3%), ovarian haemorrhage (1.3%).
The registry lists 76 participants at risk for serious adverse events and 3 participants affected. It lists 76 at risk for other adverse events and 35 affected. These are descriptive counts for the azithromycin group; the study has no separate comparison group. They do not establish whether the observed event frequencies differ from those under another treatment or from background event rates.
The serious adverse-event terms listed include lymphadenitis, ileus and ovarian haemorrhage, each reported as 1.3%. These term-specific percentages should be read as registry entries, not as a complete account of every safety event or as evidence of causation. The record does not provide additional detail about event timing, duration, severity beyond the serious classification, or the relationship of each event to treatment.
The death count is not reported in the registry record. A missing death count should not be read as confirmation that no deaths occurred. Overall, the safety information permits a limited descriptive reading of the listed participants and terms, but not a comparative safety conclusion.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed Phase 3, multicenter, non-randomized, open-label, single-group study examined intravenous azithromycin followed by oral administration in Japanese adults with pelvic inflammatory disease requiring initial intravenous therapy. It also defines the primary clinical response measure, its assessor, its post-amendment efficacy population and its assessment times. Those details describe what the study was designed to assess.
The record does not report the numerical primary response rate or the 95% confidence interval. It therefore does not show the observed magnitude of clinical response or its statistical precision. The enrollment figure cannot substitute for an endpoint result, and completion status does not imply that a particular result was achieved. The listed secondary outcomes likewise have no numerical results reported in the registry record.
Even if an observed response estimate were available, the single-group, non-randomized design would not supply a direct estimate of the difference between azithromycin and a control treatment. Outcomes in a treated group may reflect factors beyond treatment, and the design does not separate those influences through random allocation and a concurrent comparator. The open-label nature also warrants attention when considering outcome assessment, although the primary outcome was assigned to a Data Review Committee.
The record supports a limited description of safety counts but not a comparative safety assessment. It does not report a death count, so that information cannot be treated as evidence of no deaths. More generally, the absence of an item from the registry record is not evidence for a particular clinical outcome; it marks a limit on what can be concluded from this record.
Statistically, the study is best understood as a single-group assessment with an explicitly defined response endpoint and analysis population, but without the primary numerical result needed to characterize observed efficacy. No claim about treatment benefit or lack of benefit follows from the information recorded.
13. Why This Trial Matters Statistically
This study illustrates why design and reporting details are essential when interpreting a clinical response rate. The registry specifies a percentage endpoint, a rule for excluding indeterminate assessments, a clinical per protocol population, and the assessment schedule. Each detail affects what the final percentage would represent. Without the numerator, denominator and estimate, readers cannot judge the response magnitude or its precision.
The post-amendment analysis population is also statistically important. The protocol changed the fever criterion from required to optional, and the registry identifies participants enrolled after that change as the primary efficacy set. This means the target population for the primary question is defined partly by enrollment timing relative to the amendment. The record does not give the size or outcome of that subset, underscoring why participant-flow and analysis-population counts matter.
The design demonstrates the difference between describing an outcome and estimating a comparative effect. A single-group study can report what occurred among participants receiving a treatment, but it cannot by itself show how outcomes compare with an alternative. Non-random allocation and lack of masking further shape the interpretation, while the use of a Data Review Committee identifies the assessor without resolving all questions about masking.
Finally, a completed study record may still leave key statistical results unavailable. The primary confidence interval is named but its limits and the response estimate are not reported. The analysis plan and multiplicity approach are also not reported. This case therefore emphasizes that endpoint definitions and study status are not substitutes for numerical results, analysis details and clear reporting of who contributed to each estimate.
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 of the registry record is that it does not report the numerical primary clinical response rate or its 95% confidence interval. The number assessed as effective, the denominator at each assessment time and the size of the primary efficacy population are also not reported. Consequently, the observed response and its precision cannot be evaluated from this record.
The study was non-randomized, open-label and single-group, with no separate comparator. Its outcomes can be described for the treated participants, but the design does not support a direct treatment contrast. Masking is listed as none; the registry does not state whether the Data Review Committee assessment was blinded.
The primary efficacy set was restricted to participants enrolled after the fever criterion was amended from required to optional. The record does not report the number enrolled before or after the amendment, or how the groups differed. The stated enrollment of 76 should not be mistaken for the post-amendment clinical per protocol denominator.
Missing data were not imputed, and indeterminate response assessments were excluded from the specified denominator. The counts of missing or indeterminate assessments are not reported. The statistical analysis plan, confidence interval method, multiplicity handling, sample-size justification and interim analyses are not reported in the registry record. Numerical results for the listed secondary outcomes are also absent. Safety reporting is limited to the listed counts and terms, and the death count is not reported.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study Of Azithromycin Intravenous Formulation Against Pelvic Inflammatory Disease (PID) In Japan — NCT00871494.
- Registry record last updated 2011-11-03; status last verified 2011-09.
- Results first posted 2011-11-03.
- 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.
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18. Record Summary
NCT00871494 is a completed Phase 3, multicenter, non-randomized, open-label, single-group study of intravenous azithromycin followed by oral azithromycin in Japanese adults with pelvic inflammatory disease requiring initial intravenous therapy. The registry lists enrollment of 76.
The primary outcome was clinical response assessed by a Data Review Committee at the end of treatment, Day 15 and Day 29 in participants enrolled after a protocol amendment. The amendment made fever of 37℃ or higher optional. The primary population was described as a clinical per protocol set, with no imputation for missing data and indeterminate assessments excluded from the response denominator.
The primary response estimate and its 95% confidence interval are not reported in the registry record. Safety entries list 3 participants with serious adverse events and 35 with other adverse events among 76 at risk in each category. The death count is not reported.