Rapid Diagnostic Assay for Gonorrhea and Chlamydia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Rapid Diagnostic Assay for Gonorrhea and Chlamydia (NCT05564299), a randomized na study. The primary outcome is Mean Antibiotic Days of Therapy (DOT) Administered Per Patient With Symptomatic Urethritis or Cervicitis.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group pilot trial with no masking. The registry lists the study as completed, with an enrollment of 98. The two arm records each list 49 participants. The brief summary describes a planned stopping point of 100 enrollments, while the posted enrollment is 98; the reason for that difference is not reported in the registry record.

The study compared a rapid 30-minute desktop assay with point-of-care gram stain in the Massachusetts General Hospital Sexual Health Clinic. Participants presenting with symptoms of urethritis or cervicitis and meeting the inclusion criteria were to be randomized for testing during the clinical encounter. For those assigned to the rapid assay, a gram stain was also created and held for clinician interpretation after the encounter. The registry does not describe the randomization sequence or allocation concealment, so those procedures are not reported in the registry record.

The registry dates the study start to 2023-03-22 and primary completion to 2024-06-30. It says patients would not be followed longitudinally. The primary outcome timeframe is Day 1, consistent with assessment at the initial visit. The posted secondary outcomes cover visit duration, sample processing and result timing, antibiotic use, and invalid or unavailable test results. The brief summary describes the study as a pilot randomized controlled trial, but detailed operational procedures beyond those descriptions 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

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 Mean Antibiotic Days of Therapy (DOT) Administered Per Patient With Symptomatic Urethritis or Cervicitis, measured over Day 1.

The primary endpoint concerns antibiotic days of therapy (DOT) administered per patient at the initial clinical visit for symptomatic urethritis or cervicitis. DOT is a measure of treatment exposure: it counts antibiotic treatment days, rather than simply whether an antibiotic was given. The registry says the investigators intended to compare this measure between patients evaluated with point-of-care gram stain and those evaluated with the rapid desktop test. It specifies the timeframe as Day 1.

There is an important distinction in the registry’s description. The endpoint title and narrative use the word “mean,” but the statistical parameter is listed as “median,” with an inter-quartile range for dispersion. The posted arm summaries are therefore reported as medians and inter-quartile ranges: Standard of Care, 7.0 DOT with an inter-quartile range from 0.0 to 8.0; Rapid STI Test, 1.0 DOT with an inter-quartile range from 0.0 to 7.0. The registry does not resolve whether “mean” in the title and narrative is a wording error or whether a different summary was intended.

In general, DOT can describe the amount of antibiotic exposure more fully than a yes-or-no measure of treatment. A median is useful when a distribution may be asymmetric or contain values that are not well represented by an arithmetic average. The posted endpoint is therefore interpreted according to its listed median parameter, while retaining the registry’s wording inconsistency as a limitation.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the primary test compare?

The primary analysis uses a Wilcoxon (Mann-Whitney) test to compare the two groups. In general, this is a rank-based method: it orders observed values and assesses whether values in one group tend to rank higher or lower than values in the other. It does not require the comparison to be framed as a difference between arithmetic means. Its interpretation is most straightforward when group distributions have similar shapes; if shapes differ, a rank-test result can reflect more than a shift in central location. The registry does not report whether the investigators checked distributional assumptions or how they handled ties.

The primary summaries are listed as medians and inter-quartile ranges, while the title and narrative call the endpoint a mean. A median describes the middle observation in an ordered set, whereas a mean uses all observations in an arithmetic average. They answer different descriptive questions. The inconsistency is not resolved in the registry record, and the reported Wilcoxon test should not be mistaken for a direct estimate of a mean difference.

What does a p-value say?

In general, a p-value measures how surprising the observed data, or data more extreme, would be under a specified null model and test assumptions. It does not give the probability that a treatment effect is absent, and it does not measure the size of an effect. The primary comparison reports p = 0.053. The registry does not state a decision rule for interpreting this result, nor does it post a confidence interval or a numerical effect estimate for the primary contrast.

How should confidence intervals be read?

In general, a confidence interval describes the uncertainty around an estimated effect under the method used to construct it. A wide interval signals that a range of effect sizes is compatible with the data; a narrow interval indicates greater precision. For the primary outcome, no interval is reported in the registry record. Some secondary comparisons include intervals for risk differences. Those are unadjusted estimates derived from posted group counts, not replacements for the trial’s own primary analysis.

Why do binary outcomes use different summaries?

For secondary outcomes reported as participant counts, the comparison is expressed as a risk difference: the estimated proportion with the outcome in the rapid-test arm minus the estimated proportion in Standard of Care. In general, risk differences express an absolute contrast in outcome frequency. The intervals and p-values attached to these comparisons describe uncertainty under the calculation used. These analyses are not identified as sponsor-reported analyses in the registry; they are presented as unadjusted recalculations from the posted counts. The registry does not report adjusted models for these endpoints.

The reported values should not be read as evidence that the groups were otherwise identical or that all relevant factors were controlled. Random assignment is intended to support a fair comparison, but the registry does not report the allocation procedure, baseline characteristics, or any covariate-adjusted analysis. No claims about balance or adjustment can be made from the posted results alone.

What are the planning illustrations?

In general, a sample-size calculation estimates how many participants per arm might be needed to detect an assumed effect under stated design assumptions. The registry’s planning illustrations are explicitly based on the observed effect, not on the trial’s own design. They use a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustrated effect sizes are fractions of the observed effect. These are planning scenarios, not observed power and not evidence that the trial was designed around those assumptions. The registry does not report the original sample-size justification.

For example, for the test-concordant antibiotic-use comparison, the illustration lists 150 participants per arm for 80% power when planning for 100% of the observed effect, and 292 participants per arm when planning for 75% of the observed effect. For diagnosis-concordant antibiotic use, the corresponding illustrations are 99 and 206 participants per arm. These figures are exploratory planning aids based on the observed differences. They do not establish what sample size was originally intended or what effect size is clinically important.

What is not specified?

The registry does not report the prespecified statistical analysis plan, the handling of missing observations, the definition of analysis populations, or whether interim analyses were planned. It also does not report whether the primary test was selected before examining the results. These omissions limit assessment of whether the posted analyses follow a prespecified plan. No assumptions about those methods should be inferred from the posted p-values or summaries.

10. Analyses Reported by the Sponsor

The registry posts a sponsor-reported primary comparison using a Wilcoxon (Mann-Whitney) test, with p = 0.053. This is the primary analysis available for the antibiotic DOT endpoint. The arm summaries are medians and inter-quartile ranges, but no sponsor-reported estimate of the between-arm contrast or confidence interval is posted. The title and narrative call the endpoint a mean, whereas its parameter and summaries are medians; that mismatch remains unresolved.

The recalculated estimates elsewhere are unadjusted re-calculations from the posted secondary outcome counts. They do not replace the sponsor’s primary analysis, and they should not be treated as analyses reported by the investigators. For the primary endpoint, the registry does not contain the summary statistics needed for a comparable unadjusted re-calculation of a between-group effect and interval. There is no reported discrepancy between a sponsor estimate and a re-calculation.

The distinction matters because a p-value from a rank-based test, a median summary, and a risk-difference calculation answer different statistical questions. The primary result should be read as the sponsor-reported rank comparison, with the limitations of the missing effect estimate and confidence interval. The secondary calculations can add descriptive context but cannot clarify the primary endpoint’s estimand or settle the wording discrepancy.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and several secondary outcomes, but a complete statistical analysis plan is not reported in the registry record. In particular, the record does not state whether a formal testing hierarchy was prespecified, whether secondary hypotheses were exploratory or confirmatory, or whether the investigators adjusted for the number of comparisons. Without that information, the secondary p-values should be treated as unadjusted. Multiple testing increases the chance that at least one result will appear noteworthy by chance, so individual secondary findings carry less evidential weight when considered as a group.

Missing-data procedures are not reported in the registry record. The registry does not describe whether participants with unavailable test results were excluded from particular analyses, how missing outcome measurements were handled, or whether any imputation was used. The secondary outcome concerning invalid or unavailable results is itself informative about test availability, but it does not explain how unavailable results were handled in analyses of other outcomes. The number analyzed for each endpoint beyond the arm counts in the posted summaries is not reported in the registry record.

Analysis populations are also not described. The record does not state whether the primary analysis included all randomized participants, only participants with an observed outcome, or another defined group. It does not report whether participants were analyzed according to randomized assignment or whether any protocol deviations affected inclusion. These details matter because different analysis populations can yield different estimates, particularly when outcomes or test results are unavailable.

The trial is randomized, but the registry does not provide a detailed account of the sequence generation or allocation concealment. It also does not report interim analyses or stopping rules. The study is marked completed, and the brief summary describes recruitment ending at 100 participants, whereas the posted enrollment is 98; an explanation is not reported in the registry record. These reporting gaps do not establish that any particular procedure was or was not used. They mean that the reader cannot assess those methods from the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event summary lists 49 participants at risk in each arm. It reports zero serious adverse events in the Standard of Care arm and zero in the Rapid STI Test arm. It also lists zero other adverse events and zero deaths in each arm. These figures describe the events recorded in the registry’s adverse-event summary for the listed participants.

Zero reported events does not establish that the interventions or clinical approaches carry no risk. In general, event counts are interpreted in relation to the size of the study, the period of observation, how events were defined and collected, and the completeness of reporting. The registry says patients were not followed longitudinally, but does not provide detailed safety-collection procedures or an observation window for the adverse-event data. Those details are not reported in the registry record.

The posted counts therefore support only a narrow statement: no serious adverse events, other adverse events, or deaths are listed for either arm in this record. With 49 participants at risk per arm and no longitudinal follow-up described, the summary is not a precise estimate of uncommon or later events. It should not be interpreted as evidence that such events cannot occur.

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

The results describe a randomized comparison of two testing approaches during the initial clinical encounter in a sexual health clinic. The primary summaries report different medians for antibiotic days of therapy, with inter-quartile ranges that overlap, and a Wilcoxon (Mann-Whitney) p-value of 0.053. The registry does not provide a primary effect estimate or confidence interval, so the size and precision of the between-group contrast cannot be fully assessed from the posted primary analysis.

The result does not establish that one approach is better or worse. A p-value does not quantify clinical importance, and the registry does not give a prespecified decision threshold for the primary outcome. The inconsistency between a “mean” endpoint title and median-based parameter and summaries further limits clarity about precisely which treatment contrast was intended. The primary test is rank-based, and it does not itself provide a direct difference in medians or means.

The secondary results describe antibiotic-use concordance and test-result availability at Day 1. They are unadjusted, multiple comparisons are listed, and no multiplicity procedure is reported. They should be considered supportive or exploratory rather than definitive, and they do not substitute for the primary endpoint. The registry provides no longitudinal outcome data, so these findings do not address later symptoms, subsequent care, or longer-term effects.

The study’s setting and population are specific: patients with symptomatic urethritis or cervicitis evaluated at the Massachusetts General Hospital Sexual Health Clinic. The registry does not report enough detail to determine how closely the enrolled group represents other settings or populations. The observations should therefore be understood within the context described in the record rather than generalized without qualification.

In general, randomized evidence is most informative when the allocation process, analysis plan, outcome definitions, missing-data handling, and estimates with uncertainty are clearly reported. Important details are absent from this record. The findings are useful as a pilot comparison of initial-visit measures, but they do not resolve the uncertainty around the primary effect or establish outcomes beyond the clinic encounter.

14. Why This Trial Matters Statistically

This trial raises a useful statistical question about how a diagnostic approach can be evaluated through downstream clinical decisions. The primary outcome is not simply whether the assay returns a result; it is antibiotic days of therapy during the initial visit. That makes the endpoint a measure of management, while the secondary outcomes separately address concordance and availability. Keeping these concepts distinct is important: a diagnostic test measure and a treatment-use measure are related but not interchangeable.

The record also illustrates why an endpoint’s definition and summary measure need to align. Calling an endpoint a mean while specifying a median and inter-quartile range creates uncertainty about the intended estimand. A rank-based test can compare distributions, but it does not automatically supply a mean difference or a median difference. Clear reporting of an effect estimate and confidence interval would help readers understand both magnitude and precision.

The pilot setting and enrollment of 98 make the results useful as an initial description, but the registry’s planning illustrations are not evidence of observed power and are not the original sample-size justification. The record does not report that justification. Similarly, unadjusted secondary comparisons can generate questions for later research, but without a stated multiplicity plan they should not be treated as a collection of confirmatory claims.

Finally, this registry record demonstrates the importance of transparent reporting beyond a p-value. Information about analysis populations, missing data, allocation procedures, and the primary analysis plan would make the findings easier to evaluate. These points matter statistically because they shape what the estimated contrasts mean and how much confidence readers can place in them.

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.

Several limitations specific to this trial affect interpretation. First, the primary endpoint is described as a mean in its title and narrative but as a median in its statistical parameter, with inter-quartile ranges in the posted arm summaries. The record does not resolve this discrepancy. Second, although a rank-based primary test and p-value are posted, there is no primary between-group effect estimate or confidence interval. This limits assessment of the magnitude and precision of the contrast.

The registry identifies the study as a pilot, with 98 participants enrolled and 49 listed in each arm. The brief summary states that recruitment would conclude at 100 participants, but the reason the posted enrollment is 98 is not reported in the registry record. The original sample-size justification is not reported; the planning illustrations are expressly based on observed effects and should not be taken as the trial’s design rationale.

The analysis plan, analysis populations, and handling of missing outcome data are not reported in the registry record. The record also does not describe the randomization sequence or concealment. These omissions make it difficult to assess whether all participants were analyzed as assigned and whether missing observations could have affected the results. Secondary analyses are unadjusted, and multiplicity handling is not reported.

The summary describes no longitudinal follow-up, and the primary endpoint is assessed on Day 1. The findings therefore concern the initial visit rather than subsequent outcomes. The study was conducted among symptomatic patients at one named sexual health clinic, and the registry does not report sufficient participant characteristics to assess generalizability. Safety procedures and the adverse-event observation window are also not described in detail. These limitations constrain what can be concluded from the posted data without implying that unreported procedures were absent.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Rapid Diagnostic Assay for Gonorrhea and Chlamydia — NCT05564299.
• Registry record last updated 2025-09-23; status last verified 2025-09.
• Results first posted 2025-09-23.
• 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

NCT05564299 is a completed, randomized, parallel-group pilot trial comparing a rapid 30-minute desktop assay with point-of-care gram stain for patients with symptomatic urethritis or cervicitis evaluated at the Massachusetts General Hospital Sexual Health Clinic. The registry reports enrollment of 98, with 49 participants listed in each arm, and no masking.

The primary outcome concerns antibiotic days of therapy at the initial visit. The arm summaries are medians with inter-quartile ranges, although the endpoint title and narrative call the measure a mean. The sponsor-reported primary comparison uses a Wilcoxon (Mann-Whitney) test and reports p = 0.053. A primary effect estimate and confidence interval are not reported in the registry record.

Secondary results concern antibiotic-use concordance and invalid or unavailable test results at Day 1. The registry describes no longitudinal follow-up. It does not report the analysis plan, missing-data methods, analysis populations, or multiplicity procedure, which limits interpretation of the posted comparisons.