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 Two Different Antibiotic Agents to Treat Generalized Aggressive Periodontitis (NCT02969928), a randomized phase 2, phase 3 study. The primary outcome is Change in Clinical Attachment Level (CAL).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02969928 |
| Phase | Phase 2, Phase 3 |
| Condition | Aggressive Periodontitis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 46 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Universidade Estadual Paulista Júlio de Mesquita Filho |
| Results posted | Yes |
2. Clinical Question
Population
Participants with generalized aggressive periodontitis. The recorded enrollment was 46, with 23 participants described in each treatment group.
Intervention
Full-mouth ultrasonic debridement combined with clarithromycin 500 mg bid for 7 days.
Comparator
Full-mouth ultrasonic debridement combined with Amoxicillin 500 mg tid for 7 days and Metronidazole 400 mg tid for 7 days.
Primary question
How did Clinical Attachment Level change from baseline to 6 months in the two groups, and what difference between the regimens was observed?
The registry describes a comparison of two active antibiotic regimens, both used alongside the same debridement procedure. The primary outcome is change in Clinical Attachment Level (CAL), measured in mm. The stated endpoint description focuses on the difference between baseline and 6 months, while the recorded timeframe also includes 3 months.
This is a question about comparative clinical measurements, not about antibiotics in isolation: each group received full-mouth ultrasonic debridement. The registry also lists Change in Probing Depth (PB) and Change in Bleeding on Probe (BoP) as secondary outcomes. Their numerical results are not reported in the registry record.
The record does not report the numerical CAL changes, a between-group estimate, or a confidence interval. It therefore does not establish from the posted results which group had a larger change or how precisely any group difference was estimated. The primary question is identifiable, but the numerical answer is not reported in the registry record.
3. Trial Design
NCT02969928 is recorded as a randomized, parallel-group clinical trial with triple masking. Its listed phases are PHASE2 and PHASE3, and its status is COMPLETED. The sponsor is Universidade Estadual Paulista Júlio de Mesquita Filho. The recorded start is 2015-03 and the primary completion is 2016-12.
The trial enrolled 46 participants. The arm descriptions list 23 participants in the Amoxicillin and Metronidazole group and 23 in the Clarithromycin group. Both groups received full-mouth ultrasonic debridement. The first group also received Amoxicillin 500 mg tid for 7 days and Metronidazole 400 mg tid for 7 days; the second received Clarithromycin 500 mg bid for 7 days.
Randomization indicates that assignment was intended to be by chance, while a parallel-group design means participants were assigned to one of the compared regimens rather than crossing between them. The registry labels masking as triple, but does not report which roles were masked or how masking was implemented. The method used to generate the random sequence and the allocation-concealment procedure are not reported in the registry record.
The primary outcome is Change in Clinical Attachment Level, measured as a mean with Standard Deviation. The timeframe is Baseline, 3 and 6 months, and the description specifies evaluation of the difference between baseline and 6 months. Secondary outcomes listed are Change in Probing Depth (PB) and Change in Bleeding on Probe (BoP). Numerical outcome results and details of the analysis population 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 | Amoxicillin and Metronidazole | Clarithromycin |
|---|---|---|
| STARTED | 23 | 23 |
| COMPLETED | 23 | 23 |
| NOT COMPLETED | 0 | 0 |
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 | Amoxicillin and Metronidazole | Clarithromycin | Total |
|---|---|---|---|---|
| Participants analysed | 23 | 23 | 46 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 23 | 23 | 46 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 16 | 19 | 35 |
| Sex: Female, Male: Male | Participants | 7 | 4 | 11 |
| Region of Enrollment: Brazil | participants | 23 | 23 | 46 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Clinical Attachment Level (CAL), measured over Baseline, 3 and 6 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mm |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is Change in Clinical Attachment Level (CAL), measured in mm. The registry describes a mean and Standard Deviation and specifies evaluation of the difference between baseline and 6 months. The recorded timeframe also lists Baseline, 3 and 6 months.
In general, CAL is a clinical measure used to assess periodontal attachment. Expressing its change over time allows investigators to describe how the measurement differs from baseline after treatment. Comparing changes between randomized groups can address whether the observed course differed between the two treatment regimens, while recognizing that both groups also received full-mouth ultrasonic debridement.
A mean summarizes the average measurement or change across participants; a Standard Deviation describes how dispersed individual measurements are around that mean. These are different quantities: the Standard Deviation describes participant-level variability, not the precision of the estimated group mean or the between-group difference. A confidence interval for a treatment contrast would be needed to communicate that estimate's precision, but no such interval is reported in the registry record.
The numerical CAL values, the direction and size of change, and the between-group comparison are not reported in the registry record. The endpoint definition therefore explains what was intended to be measured, but does not by itself show the result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a randomized comparison of two antibiotic regimens used with full-mouth ultrasonic debridement. It names Change in Clinical Attachment Level as the primary outcome and specifies baseline-to-6-month change in its description. However, numerical outcome results are not reported in the registry record. There is no posted mean change for either group, no between-group estimate, and no confidence interval or statistical test result for the primary outcome.
Without those quantities, the magnitude and direction of any observed difference cannot be assessed. It is also not possible to judge the precision of a comparison or distinguish a small estimate from a large one. No conclusion about statistical compatibility with no difference can be drawn from a p-value because a p-value is not reported. A statistically significant or non-significant result should not be inferred from the trial design, enrollment, or adverse-event counts.
The registry lists Change in Probing Depth (PB) and Change in Bleeding on Probe (BoP) as secondary outcomes, but does not report numerical results for them. It records five outcome measures and zero analyses. The relationship between the listed outcome measures and any complete analysis set is not described in the registry record.
The safety entries report zero serious adverse events in each group and zero deaths in each group. They also report 18 other adverse events in each group, with 23 participants at risk in each. These are descriptive counts. The record does not provide event details or a statistical comparison, and the counts do not substitute for the missing CAL efficacy results. Equal counts do not establish that the underlying event types, severity, or individual experiences were the same.
The registry's planning assumptions describe a sample-size illustration based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. This is a planning framework, not observed power and not evidence that a particular effect was detected. The observed effect and numerical planning results are not reported in the registry record. The assumptions also do not constitute a reported trial design justification.
Overall, the record supports a description of the trial's comparison, endpoint, and recorded adverse-event counts. It does not support a quantitative estimate of the primary treatment contrast or a conclusion about its statistical precision. The absence of numerical outcome results should be kept distinct from evidence of no effect: without the outcome estimates, the comparative result remains unknown from the registry record.
9. Statistical Methods Explained
What does a mean change represent?
The primary outcome is a continuous measurement: Change in Clinical Attachment Level, expressed in mm. In general, a mean change describes the average difference between measurements at two times for the participants included in an analysis. A comparison of the two groups would ordinarily summarize the difference between their mean changes. Such a contrast would describe the average difference between regimens in the analyzed participants; it would not imply that every participant had the same change.
The registry specifies baseline, 3 and 6 months as the timeframe, while the outcome description emphasizes the difference between baseline and 6 months. A measurement at more than one follow-up can be analyzed in different ways. For example, an analysis might focus on a particular follow-up change or model measurements over time. Which approach was used is not reported in the registry record, so no particular model or handling of repeated measurements can be attributed to this trial.
What does the Standard Deviation describe?
In general, the Standard Deviation describes variation among individual observations around their group mean. It is not a measure of uncertainty in the estimated group difference. A confidence interval, when reported for an estimate, describes a range of values compatible with the data and the statistical method under its assumptions. A narrow interval indicates greater precision than a wide interval, but neither the interval nor the underlying CAL estimates are reported in the registry record.
The endpoint is specified as a mean with Standard Deviation. The registry does not report the group means, Standard Deviations, number analyzed, or a between-group estimate. As a result, the form of the intended summary is known, but the numerical evidence needed to interpret the result is absent.
How should a randomized comparison be read?
In general, random assignment is used to create groups whose differences at the start are not systematically determined by treatment choice. It does not guarantee that groups are identical in every characteristic, particularly in a trial with limited enrollment. A comparative analysis should report an estimate and its uncertainty, and should identify the participants included. The registry records randomization and 23 participants in each arm description, but the sequence-generation method, allocation concealment, baseline outcome values, and analysis population are not reported in the registry record.
The parallel design compares participants assigned to one regimen with participants assigned to the other. Because both groups also received full-mouth ultrasonic debridement, any between-group contrast would relate to the two complete treatment regimens as described, not to antibiotic use versus no antibiotic treatment. The record does not describe a group receiving debridement alone.
What can a p-value and confidence interval tell a reader?
In general, a p-value measures how unusual the observed data, or data more extreme, would be under a specified statistical model and null hypothesis. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. A confidence interval communicates uncertainty around an estimated effect and helps readers assess both the range of plausible values under the method and the precision of the estimate. These quantities answer different questions and are most informative when interpreted alongside the effect estimate.
No primary-outcome p-value, confidence interval, or test method is reported in the registry record. Therefore, none should be reconstructed from the group enrollment counts or from the safety counts. No claim of statistical significance or lack of significance can be made from the information recorded.
What do the planning assumptions mean?
The record describes a planning illustration using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It defines the target effect as a stated fraction of the observed effect. In general, a sample-size calculation estimates the number of participants needed under chosen assumptions to detect a specified effect with a chosen level of statistical power. It is a planning exercise rather than an outcome of the trial.
The illustration is explicitly not the trial's own design. Its assumptions should not be treated as the trial's sample-size justification or as evidence of observed power. The numerical observed effect and numerical planning results are not reported in the registry record. The registry also does not report the original sample-size rationale, any interim analyses, or the statistical analysis plan.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and secondary outcomes, but the numerical results and the statistical analysis plan are not reported in the registry record. The primary outcome is Change in Clinical Attachment Level; the listed secondary outcomes are Change in Probing Depth (PB) and Change in Bleeding on Probe (BoP). The record identifies five outcome measures and zero analyses, but does not explain how the outcome measures relate to analyses or identify which were analyzed.
In general, testing multiple outcomes or multiple time points can increase the chance of at least one apparently unusual result when each test is considered separately. Statistical plans may address this through a prespecified hierarchy or adjustment, or may report the results as exploratory. Whether any such approach was used is not reported in the registry record. The record does not report an adjustment for multiple comparisons or explain how the 3-month and 6-month measurements were handled together.
The enrollment and arm descriptions state 46 participants overall and 23 in each group. They do not establish how many participants contributed data at each follow-up. The number analyzed, withdrawals, missing measurements, reasons for missingness, and methods for handling missing data are not reported in the registry record. The analysis population, including whether results were based on assignment as randomized or another set of participants, is also not reported.
These omissions matter because the interpretation of a mean change depends on which observations contributed to it and how missing follow-up measurements were addressed. No specific missing-data method or multiplicity procedure should be assumed.
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 |
|---|---|---|---|
| Amoxicillin and Metronidazole | 0 | 23 | 0.0% |
| Clarithromycin | 0 | 23 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Amoxicillin and Metronidazole | 0 of 23 |
| Clarithromycin | 0 of 23 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Amoxicillin and Metronidazole | 18 of 23 |
| Clarithromycin | 18 of 23 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Amoxicillin and Metronidazole | Clarithromycin |
|---|---|---|---|
| Metallic taste | General disorders | 7 of 23 | 13 of 23 |
| Nausea/vomiting | General disorders | 3 of 23 | 6 of 23 |
| Stomach pain | Gastrointestinal disorders | 4 of 23 | 3 of 23 |
| Diarrhea/ abdominal pain | Gastrointestinal disorders | 3 of 23 | 3 of 23 |
| Drowsiness | General disorders | 2 of 23 | 3 of 23 |
| Headache | General disorders | 1 of 23 | 2 of 23 |
| Itching | Skin and subcutaneous tissue disorders | 1 of 23 | 0 of 23 |
| Skin wounds | Skin and subcutaneous tissue disorders | 0 of 23 | 0 of 23 |
The registry records zero serious adverse events among 23 participants at risk in the Amoxicillin and Metronidazole group, and zero among 23 at risk in the Clarithromycin group. It records zero deaths in each group. For other adverse events, the record gives 18 affected participants in each group, with 23 at risk in each.
These are counts, not comparative effect estimates. The record does not provide event descriptions, timing, severity details for other adverse events, or a statistical comparison. Equal counts do not show that the same events occurred in each group, nor do they establish that the event experiences were otherwise alike. The serious-event count of zero is a report for this trial record; it is not proof that serious events cannot occur.
In general, safety counts should be read with their definitions, follow-up period, and population at risk. Those details are not fully described in the registry record. The counts should not be converted into a claim about overall safety or used as a substitute for the unreported primary outcome results.
12. What the Result Does, and Does Not, Mean
The record describes a randomized, triple-masked, parallel-group comparison of two antibiotic regimens used with full-mouth ultrasonic debridement. It identifies a primary clinical measurement, Change in Clinical Attachment Level, and specifies that baseline-to-6-month change is evaluated. The listed timeframe includes baseline, 3 and 6 months. This establishes the focus of the trial, but the numerical results needed to estimate the comparison are not reported in the registry record.
Without group-level CAL changes or a between-group estimate, it is not possible to state which regimen had a larger average change, the size of a difference, or how precisely that difference was estimated. The registry does not report a confidence interval, p-value, or analysis method for the primary comparison. The listed secondary outcomes also lack numerical results.
The adverse-event entries provide descriptive counts: zero serious adverse events and zero deaths in each group, alongside 18 other adverse events in each group. These counts are not evidence that the regimens have identical safety profiles, because event details and comparative analyses are not reported.
In general, a trial's estimate applies most directly to the population and treatment conditions studied, while its uncertainty depends on the data and analysis. The record identifies generalized aggressive periodontitis and the two treatment regimens, but does not provide further participant characteristics or the numerical outcome evidence needed to assess applicability or precision. The trial's recorded completion status and design do not fill that gap.
The appropriate statistical reading is therefore limited: the registry specifies what was compared and what was intended to be measured, but it does not report the quantitative primary result. This absence is not a finding of no difference. It leaves the comparative CAL outcome unresolved in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable as a randomized comparison between two active regimens rather than a comparison with no treatment. Both groups received full-mouth ultrasonic debridement, while the antibiotic regimen differed. Consequently, the main comparative question concerns the regimens as delivered together with that procedure.
The primary outcome is a continuous clinical measurement summarized as a mean with Standard Deviation. This makes the distinction between average change, participant variability, and uncertainty in the treatment contrast important. In general, a mean describes the group average, a Standard Deviation describes variation among observations, and a confidence interval describes uncertainty around an estimate. The registry names the outcome and summary form but does not report the numerical estimates or their uncertainty.
The trial also illustrates why design labels do not replace outcome reporting. Randomization, triple masking, a parallel design, and completed status describe important features of conduct, but they do not establish the direction, magnitude, or precision of an outcome difference. Similarly, the adverse-event counts are useful descriptive information but cannot answer the primary efficacy question.
The record lists several outcomes and more than one follow-up time, yet does not report the analysis plan, multiplicity approach, missing-data handling, or analysis population. These details would help readers understand how the reported endpoint was selected and how measurements over time were treated. Their absence limits statistical interpretation, independently of the trial's stated design.
Finally, the planning assumptions are explicitly an illustration rather than the trial's design rationale. Keeping planning calculations separate from observed results prevents a sample-size scenario from being mistaken for evidence about what the trial found.
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 most important limitation for interpreting the posted results is that numerical results for the primary endpoint are not reported in the registry record. The group-level CAL changes, between-group estimate, uncertainty interval, and test result are absent. Numerical results for the listed secondary outcomes are also not reported. The clinical comparison can be described, but its observed outcome cannot be quantified from this record.
The endpoint timeframe lists baseline, 3 and 6 months, while the description focuses on baseline-to-6-month difference. The analysis used for these measurements is not reported. Neither the statistical model nor the handling of repeated measurements is identified.
The record states enrollment and arm sizes but does not report the number analyzed at each follow-up, missing measurements, withdrawals, or reasons for missingness. The analysis population and missing-data method are not reported in the registry record. The random-sequence generation, allocation concealment, and the roles included in triple masking are also not described.
The registry does not report the statistical analysis plan, the multiplicity approach, interim analyses, or the original sample-size justification. The stated sample-size illustration is not the trial's own design and should not be interpreted as observed power. The record does not provide further participant characteristics that would allow detailed assessment of how well these findings might apply to other populations.
For safety, counts are available, but event descriptions and a comparative analysis are not. These reporting gaps limit interpretation of both outcome estimates and safety. They do not establish that an unreported result was null or that an unreported method was or was not used.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Two Different Antibiotic Agents to Treat Generalized Aggressive Periodontitis — NCT02969928.
- Registry record last updated 2021-12-28; status last verified 2021-12.
- Results first posted 2020-09-07.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT02969928 is a completed randomized, triple-masked, parallel-group trial listed as PHASE2 and PHASE3. It enrolled 46 participants with aggressive periodontitis. The two arm descriptions each list 23 participants. Both groups received full-mouth ultrasonic debridement; one received Clarithromycin 500 mg bid for 7 days, and the other received Amoxicillin 500 mg tid for 7 days plus Metronidazole 400 mg tid for 7 days.
The primary outcome is Change in Clinical Attachment Level, measured in mm as a mean with Standard Deviation. The timeframe is Baseline, 3 and 6 months; the description focuses on baseline-to-6-month change. Secondary outcomes are Change in Probing Depth (PB) and Change in Bleeding on Probe (BoP).
Numerical outcome results and the primary statistical comparison are not reported in the registry record. Safety entries report zero serious adverse events and zero deaths in each group, and 18 other adverse events in each group.