Zoliflodacin in Uncomplicated Gonorrhoea: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Zoliflodacin in Uncomplicated Gonorrhoea (NCT03959527), a randomized phase 3 study. The primary outcome is Microbiological Cure Rate for Zoliflodacin Compared to a Combination of a Single Dose of Ceftriaxone and Azithromycin..

2. Clinical Question

The central statistical contrast is between the observed cure proportions in the two treatment groups. The posted results report cure of 90.9% for zoliflodacin and 96.2% for the ceftriaxone and azithromycin combination. These are results in the primary analysis population, not proportions among every randomized participant or everyone enrolled. The registry's population definition matters because it selects participants according to baseline culture and susceptibility findings.

The question is therefore narrower than whether either regimen is effective in every person with gonorrhoea. It concerns the registry-defined microbiological outcome, at specified urogenital sites and at a specified follow-up visit, for the eligible analysis set. Secondary outcomes address other sites and subgroups, but they do not replace the primary comparison. Interpretation also depends on the non-inferiority margin and analysis details, which are not reported in the registry record.

3. Trial Design

This was a completed, phase III, multicenter, randomized, open-label, parallel-group non-inferiority trial. The registry lists an enrollment of 1011 and a condition of gonorrhea. Participants were allocated to a single-dose zoliflodacin arm or to a ceftriaxone-and-azithromycin combination arm. Masking was none, so participants and trial personnel were not described as blinded.

The comparison concerns two different treatment strategies: a single oral dose of zoliflodacin and a combination consisting of a single intramuscular dose of ceftriaxone plus a single oral dose of azithromycin. The brief summary gives doses of 3 g, 500 mg, and 1 g, respectively. The primary outcome was microbiological cure measured by culture at urethral or cervical sites at the test-of-cure visit, specified as Day 6 (+/- 2).

The primary analysis population was the micro-ITT urogenital set. It included randomized participants with a positive NG culture from the relevant anatomical site at baseline and no pre-existing resistance to both comparator drugs on baseline AST. The reported primary outcome denominators were 506.0 for zoliflodacin and 238.0 for the combination. These denominators describe the posted primary analysis, not the total enrollment. The reasons that individual randomized participants were not included in that analysis are not reported in the registry record.

The registry lists a start date of 2019-11-06, primary completion on 2023-08-30, and status as completed. It also lists 35 outcome measures and one analysis. The registry record does not report the trial's original sample-size justification, details of randomization implementation, the non-inferiority margin, or the full statistical analysis plan. The design label establishes that non-inferiority was the stated objective, but a label alone is not enough to reconstruct the formal decision rule.

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.

Before assignment: A total 1011 participants were screened, of which 81 were screen failure

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: micro-ITT (urogenital): all randomized participants who had a positive NG culture from the relevant anatomical site at baseline and whose baseline AST result showed no pre-existing resistance to both ceftriaxone and azithromycin

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.

Population: Randomised population

6. Primary Endpoint

The registry lists the primary outcome as Microbiological Cure Rate for Zoliflodacin Compared to a Combination of a Single Dose of Ceftriaxone and Azithromycin., measured over Day 6 (+/- 2).

The primary endpoint is the proportion of participants with microbiological cure, determined by culture at urethral or cervical sites at the test-of-cure visit on Day 6 (+/- 2). It is reported as a percentage of participants. A culture-based outcome asks whether the organism was detected at the specified site at follow-up; it is distinct from a symptom-based clinical assessment or a nucleic-acid test result.

The analysis population is part of the endpoint definition. Participants had to be randomized, have a positive NG culture from the relevant site at baseline, and have baseline AST results showing no pre-existing resistance to both ceftriaxone and azithromycin. Consequently, the endpoint describes cure in that registry-defined micro-ITT urogenital group rather than a universal outcome for all enrolled participants. The denominators are 506.0 for zoliflodacin and 238.0 for the comparator combination.

Microbiological cure is used because the trial compares treatments intended to address infection, and culture provides a microbiological measure at the relevant anatomical sites. General statistical context: a binary endpoint turns each participant's outcome into a category, such as cure or no cure, and the group proportion estimates how common cure was in that group. That proportion is informative, but its precision depends on the number of observations and on how the analysis handles participants whose outcome is unavailable. The registry record does not report detailed missing-outcome handling.

7. Results Posted in the Registry

• Ceftriaxone and Azithromycin Combination: 96.2% (229/238) versus 90.9% (460/506) on control; risk difference 5.3 percentage points (95% CI 1.8 to 8.8), risk ratio 1.06 (1.02–1.10); unadjusted two-proportion z-test p = 0.010.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Microbiological Cure Rate of Pharyngeal Gonorrhoea of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Ceftriaxone and Azithromycin Combination: 78.6% (22/28) versus 79.2% (42/53) on control; risk difference -0.7 percentage points (95% CI -19.4 to 18.0), risk ratio 0.99 (0.78–1.26); unadjusted two-proportion z-test p = 0.944.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ceftriaxone and Azithromycin Combination and the control. The interval gives the range of effects that remain compatible with the data.

Microbiological Cure Rate of Rectal Gonorrhoea of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Ceftriaxone and Azithromycin Combination: 88.6% (31/35) versus 87.3% (69/79) on control; risk difference 1.2 percentage points (95% CI -11.6 to 14.1), risk ratio 1.01 (0.88–1.17); unadjusted two-proportion z-test p = 0.854.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ceftriaxone and Azithromycin Combination and the control. The interval gives the range of effects that remain compatible with the data.

The Clinical Cure Rate in Male Participants After Administration of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Ceftriaxone and Azithromycin Combination: 88.2% (194/220) versus 81.5% (375/460) on control; risk difference 6.7 percentage points (95% CI 1.1 to 12.2), risk ratio 1.08 (1.01–1.15); unadjusted two-proportion z-test p = 0.028.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Ceftriaxone and Azithromycin Combination than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The posted secondary outcomes cover additional anatomical sites, clinical cure in male participants, microbiological cure among females and males, and nucleic-acid test eradication outcomes. The registry lists 34 posted secondary outcomes overall. The examples with results include pharyngeal and rectal microbiological cure and clinical cure in male participants. These outcomes extend the scope beyond the primary urogenital culture-based endpoint, but each has its own population definition and information base.

Across the posted secondary comparisons with recalculated results, estimates vary in direction and precision. The intervals for the pharyngeal and rectal comparisons include values on both sides of no difference, and the male clinical-cure comparison has a different pattern. These results do not establish a uniform secondary-outcome effect and should not be treated as a substitute for the primary endpoint. Small subgroup denominators in some of these outcomes also mean that their estimates can be less precise; the registry's own intervals are not posted for those secondary endpoints.

General statistical context: multiple outcomes and subgroup comparisons create many opportunities to observe apparently notable results by chance. If many tests are interpreted without an adjustment or a prespecified hierarchy, an unadjusted p-value does not control the overall chance of a false-positive finding across the family of tests. The registry record does not report a multiplicity strategy for the secondary outcomes. Accordingly, unadjusted secondary results carry less weight than the designated primary outcome and should be viewed as exploratory evidence rather than independent confirmation.

The secondary endpoints can help describe whether findings differ by site, sex, or outcome definition, but they address distinct questions. Culture-based cure at urogenital sites is not interchangeable with pharyngeal or rectal cure, clinical assessment, or nucleic-acid test eradication. The record does not report enough detail to assess a confirmatory testing hierarchy or the intended role of each secondary analysis.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Safety of a Single Dose of Zoliflodacin Will be Assessed Compared to a Combination a Single Dose of Ceftriaxone and Azithromycin.
• Microbiological Cure Rate of Pharyngeal Gonorrhoea of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.
• Microbiological Cure Rate of Rectal Gonorrhoea of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.
• The Clinical Cure Rate in Male Participants After Administration of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.
• Microbiological Cure Rate Among Females, After Administration of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin
• Microbiological Cure Rate Among Males, After Administration of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin
• Eradication of Urogenital NG NAAT at TOC After Administration of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.
• Eradication of Pharyngeal NG NAAT at TOC After Administration of a Single Dose of Zoliflodacin Compared to a Single Dose of Ceftriaxone and Azithromycin.

9. Statistical Interpretation

10. Statistical Methods Explained

Several statistical ideas help make sense of the posted results. The trial is randomized, parallel-group, and open-label. Randomization is intended, in general, to make treatment groups comparable at the start by distributing measured and unmeasured factors through an allocation process. It does not guarantee identical groups in a particular trial, and the registry record does not describe implementation details such as the sequence-generation or concealment procedures. Open-label status means treatment assignment was not masked; the primary endpoint is culture-based, but the registry does not state whether laboratory assessment was blinded.

What does a proportion measure?

The primary outcome is binary: each included participant either met the microbiological-cure definition or did not. A group proportion is the count with cure divided by the number evaluated in that group, expressed as a percentage. The registry posts 90.9% for zoliflodacin and 96.2% for the comparator combination. General statistical context: a proportion summarizes the frequency of an outcome in the analyzed group, but does not describe how outcomes vary within individuals over time or establish why an outcome occurred.

What is a risk difference?

A risk difference subtracts one group's event proportion from the other's. It is an absolute contrast, not a relative contrast. The posted recalculation uses the comparator combination minus zoliflodacin, with a reported estimate of 0.053. The sign depends on that ordering; reversing the subtraction reverses the sign. The registry's sponsor analysis reports a risk difference of 5.31, but the analysis method and coding convention are not specified. The units and contrast direction should therefore be checked before directly comparing estimates across analyses.

General statistical context: absolute differences can be easier to relate to changes in outcome frequency than relative measures, but they do not automatically answer whether a difference is important or acceptable. That judgment depends on the trial question and, for non-inferiority, the prespecified margin. The non-inferiority margin is not reported in the registry record.

How should a confidence interval be read?

A confidence interval gives a range of estimates compatible with the observed data under a particular statistical method and its assumptions. It is not a guarantee that the true value lies inside the interval, nor does it capture every source of uncertainty, such as bias from missing outcomes or open-label assessment. The primary arm-level intervals are 88.1 to 93.3 and 92.9 to 98.3. The unadjusted risk-difference interval is reported as 0.018 to 0.088. The sponsor analysis reports an interval from 1.38 to 8.65. Different analysis conventions or methods can produce different interval presentations; the sponsor method is not described in the registry record.

What does non-inferiority require?

A non-inferiority design asks whether the outcome with the new strategy is not worse than the comparator by more than a prespecified amount. General statistical context: this is not the same as showing that the treatments are identical, and a non-significant difference does not establish non-inferiority. The margin must be set before examining the trial results and the analysis must apply a stated decision rule. The registry identifies the trial as non-inferiority and labels the reported analysis accordingly, but the margin and detailed rule are not reported in the registry record. The formal conclusion therefore cannot be reconstructed solely from the label and point estimate.

Why does the analysis population matter?

The primary analysis set includes randomized participants with a positive baseline culture at the relevant urogenital site and no pre-existing resistance to both ceftriaxone and azithromycin. This is a restricted population, defined using baseline findings. The group sizes in the primary outcome are 506.0 and 238.0, while total enrollment is 1011. The registry record does not give a full participant flow or explain all exclusions from the primary analysis. General statistical context: in non-inferiority research, the choice and handling of analysis populations can be especially important because exclusions or non-adherence may make groups appear more similar. The record does not report the protocol's approach to that issue.

What can the p-value add?

The unadjusted recalculation reports p=0.01. General statistical context: a p-value is calculated under a null hypothesis and assumptions about the data and analysis. It is not an estimate of the size of the treatment contrast, does not quantify clinical importance, and does not prove a causal mechanism. It also does not replace a confidence interval or the margin-based decision required for non-inferiority. The registry's sponsor analysis has no p-value posted.

The record reports one analysis for the primary outcome, but does not identify the statistical method used in that sponsor analysis. It also does not report adjustment details, interim-analysis plans, or a complete multiplicity strategy. No such details should be inferred from the trial phase, design label, or number of posted outcomes.

11. Confidence Intervals and Precision

The arm-level confidence intervals convey uncertainty in each group's observed cure proportion. For zoliflodacin, the posted estimate is 90.9%, with a 95% confidence interval from 88.1 to 93.3. For the ceftriaxone and azithromycin combination, the estimate is 96.2%, with a 95% confidence interval from 92.9 to 98.3. These intervals describe the precision of the arm-specific estimates under the methods used for those intervals; the registry does not identify those methods.

The recalculated risk difference has a reported 95% confidence interval from 0.018 to 0.088. It expresses uncertainty in the unadjusted contrast, using the comparator combination minus zoliflodacin. The sponsor's reported analysis gives a risk difference of 5.31 and a 95% confidence interval from 1.38 to 8.65. The sponsor method is not reported, so the two interval presentations should not be treated as though their calculation methods and conventions are known to match.

General statistical context: narrower intervals indicate greater precision under the model and method used, while wider intervals indicate a broader range of values compatible with the data. Precision is not the same as absence of bias. A confidence interval cannot address unreported participant exclusions, outcome ascertainment issues, or a missing non-inferiority margin.

The primary analysis group sizes are 506.0 and 238.0, so the amount of information is not identical between the arms. The interval widths should be read alongside the sample sizes and outcome definition, not in isolation. Because the formal non-inferiority margin is not reported in the registry record, the intervals cannot be compared with the trial's required acceptance boundary. The precision is described by the posted estimates and intervals, but the formal non-inferiority interpretation remains incomplete.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm for 80% power and participants per arm for 90% power. They are not total sample sizes. The assumptions listed for this planning illustration are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. For time-to-event outcomes, the stated convention is total events, but the outcomes discussed for this trial are not time-to-event outcomes.

The 80% power column gives the illustrative number of participants per arm needed, under those assumptions, to have an 80% chance of detecting the chosen effect if that effect were the one underlying the calculation. The 90% column applies the same idea with a higher target chance of detection, which generally requires more participants. For example, planning for 100% of the observed effect gives 335 participants per arm for 80% power and 447 participants per arm for 90% power. Planning for 75% gives 652 and 873 participants per arm, while planning for 50% gives 1,594 and 2,134 participants per arm.

Smaller effects are harder to distinguish from random variation, so the planning illustration requires more participants per arm as the assumed effect becomes smaller. These are planning illustrations based on the observed effect and stated calculation assumptions, not the trial's original design justification. The registry record does not report the original sample-size assumptions. This is not observed power.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.909; treatment proportion p₁ = 0.962; average p̄ = 0.936.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.3470 = 0.6802.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.3450 = 0.2904.
4. n = (0.6802 + 0.2904)² / (0.0531)² = 334.2, rounded up to 335 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.909090909090909                          # control proportion
p1 <- 0.96218487394958                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(3959527)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 335 (80% power), 447 (90% power)
 75% of observed effect: n per arm = 652 (80% power), 873 (90% power)
 50% of observed effect: n per arm = 1,594 (80% power), 2,134 (90% power)
power.prop.test: 334.2 
Simulated power at n = 335 per arm: 0.810 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry posts a sponsor analysis labelled NON INFERIORITY, with a risk difference of 5.31 and a 95% confidence interval from 1.38 to 8.65. The analysis method and p-value are not reported in the registry record. The registry also supports a simple unadjusted recalculation from the posted group summaries; it reports a risk difference estimate of 0.053, a confidence interval from 0.018 to 0.088, and p=0.01. The recalculation is descriptive and does not replace the sponsor's own analysis.

The sponsor and recalculated results should be distinguished by their purpose and reporting. The sponsor result is the trial's posted analysis; the recalculation is an unadjusted check based on summary data. The different numerical scales and reported intervals cannot be reconciled confidently without the sponsor's method, units, and contrast convention. The registry record does not supply those details, nor does it report the non-inferiority margin needed to interpret the sponsor interval against a formal decision boundary.

The discrepancy indicator is false, but that does not fill in the missing methodological information. The posted sponsor estimate and the unadjusted recalculation should be read as separate statistical summaries, not combined into a new estimate. The registry does not provide enough detail to establish whether differences arise from methods, population handling, or presentation conventions.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists 35 outcome measures, including the primary outcome and multiple secondary measures. It reports one analysis for the primary result, but the record does not describe a broader testing hierarchy or how the family of outcomes was handled statistically. A multiplicity adjustment, if used, is not reported in the registry record. The purpose of each secondary outcome as confirmatory or exploratory is also not reported.

General statistical context: when researchers test many outcomes or subgroups, the chance of at least one apparently unusual result can increase if each is interpreted using an unadjusted threshold. Multiplicity procedures can address this in different ways, but no procedure should be assumed. A nominal, unadjusted p-value for one comparison does not account automatically for other outcomes in the same trial.

The registry defines the primary analysis population using baseline culture positivity and susceptibility findings. It posts outcome denominators, but does not report a detailed participant flow, the number of missing outcome assessments, or the method used to handle missing primary outcomes. It also does not state whether participants with missing culture results were counted as failures, excluded, imputed, or handled in another way. Those details are relevant because missingness can affect both the estimated cure proportion and the apparent similarity between groups.

The record does not report the protocol's analysis-population strategy beyond the micro-ITT urogenital definition, nor does it describe how per-protocol or other supportive populations were used for the non-inferiority question. General statistical context: non-inferiority conclusions can depend on how participants who deviate from assigned treatment or lack outcome data are handled. The registry's designation of the trial as non-inferiority does not reveal those methods.

Interim analyses, stopping rules, and any alpha-spending plan are not reported in the registry record. The original sample-size justification and non-inferiority margin are also not reported. These omissions limit independent assessment of the planned inferential framework; they do not establish that the procedures were absent from the protocol.

16. 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 3% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports 0 serious adverse events among 619 participants at risk in the zoliflodacin group and 0 among 308 at risk in the ceftriaxone and azithromycin combination group. Deaths are reported as 0 in both groups. No top serious adverse-event terms are listed, so specific serious-event categories are not reported in the registry record.

The registry also reports 162 participants with adverse events in the other category among 619 at risk for zoliflodacin, and 107 among 308 at risk for the combination. These are safety counts, not the primary microbiological-cure denominators. The safety groups are therefore distinct from the primary micro-ITT urogenital analysis set. The registry does not provide event-level detail or causal attribution in the information.

General statistical context: a zero count in a trial does not prove that an event cannot occur; it describes what was observed in the reported group during the recorded safety assessment. Safety comparisons also depend on follow-up duration, event definitions, and completeness of reporting. Those details are not fully reported in the registry record, so these counts should be read as a descriptive account rather than as a complete comparative safety analysis.

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

The posted primary outcome describes microbiological cure at urogenital sites at the test-of-cure visit in a defined micro-ITT population. Cure was reported for 90.9% of the zoliflodacin group and 96.2% of the ceftriaxone and azithromycin combination group. The arm-specific confidence intervals and the recalculated risk-difference interval express statistical uncertainty around those estimates. The results do not describe every enrolled participant, every infection site, or every possible outcome of treatment.

The trial is designated as a non-inferiority study, and the sponsor analysis is labelled accordingly. However, the non-inferiority margin and detailed decision rule are not reported in the registry record. Without that margin, the posted estimate and confidence interval cannot be used to independently verify the formal non-inferiority criterion. The unadjusted p-value also does not answer that margin-based question.

These data do not establish that the treatments are identical, and a difference in observed proportions alone does not determine clinical importance. General statistical context: statistical evidence, precision, and clinical relevance are related but distinct. A confidence interval describes uncertainty under its analysis assumptions; it does not address all potential sources of bias, nor does it define what difference would matter to patients or clinicians.

The results also do not answer every question raised by the trial. Secondary outcomes concern other sites and measures, and safety counts are descriptive. The registry does not report detailed handling of missing outcomes, the analysis method for the sponsor result, or a multiplicity plan. Those limits constrain how broadly the findings can be generalized or how strongly secondary findings can be interpreted.

The appropriate reading is therefore specific: the posted data give group-level estimates for the registry-defined primary outcome, with reported uncertainty and a sponsor non-inferiority analysis. The record does not contain all design and analysis details needed to independently reconstruct the formal non-inferiority assessment or resolve all possible biases.

18. Why This Trial Matters Statistically

This trial illustrates why the label non-inferiority is not sufficient for statistical interpretation. A non-inferiority question requires a clearly defined margin, an analysis strategy, and a comparison of the relevant interval with that margin. The registry identifies the study as non-inferiority and posts a sponsor analysis under that label, but does not report the margin or detailed decision rule. That omission is central to interpreting the stated objective independently.

It also illustrates the importance of defining the analysis population. The primary outcome concerns randomized participants with baseline culture positivity at the relevant site and no pre-existing resistance to both comparator drugs. That definition is narrower than total enrollment, and the reported primary denominators differ between groups. Without a participant flow and missing-data methods, readers cannot fully assess how the analysis set was formed or what outcomes were unavailable.

General statistical context: effect estimates and confidence intervals answer different questions. A point estimate summarizes the observed contrast, while an interval conveys its precision under a specified method. Neither, on its own, establishes a clinically meaningful difference or a non-inferiority conclusion. The posted recalculation is useful as a transparent unadjusted comparison, while the sponsor analysis remains the trial's own reported analysis and requires its missing method details for fuller appraisal.

Finally, the breadth of secondary outcomes makes multiplicity relevant. Results across anatomical sites, participant groups, and outcome types can add context, but without a reported testing strategy they should not be treated as a collection of independent confirmatory findings. The trial is statistically informative in showing the measured outcomes and their uncertainty, while also demonstrating how registry reporting details shape the strength of conclusions readers can draw.

19. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

Several trial-specific limitations affect interpretation. The study was open-label, with no masking reported. The primary outcome is based on culture, but the registry record does not state whether laboratory staff assessing cultures were blinded to treatment assignment. Open-label status does not automatically invalidate an objective endpoint, but the available record does not allow assessment of all possible influences on outcome assessment or participant management.

The primary analysis population is restricted by baseline culture and susceptibility criteria. The registry reports 506.0 participants in the zoliflodacin primary group and 238.0 in the combination group, but does not provide a detailed flow explaining how those denominators relate to randomized participants and total enrollment of 1011. Missing outcome counts and their handling are not reported. As a result, the effect of exclusions or unavailable cultures cannot be assessed from the registry record.

The non-inferiority margin, original sample-size justification, full statistical analysis plan, sponsor analysis method, and detailed decision rule are not reported. These are important for interpreting a non-inferiority result. The registry also does not report a multiplicity strategy for the large set of secondary measures, or interim-analysis and stopping-rule details.

Some secondary outcomes have limited group sizes, and secondary confidence intervals are not posted for the listed examples. This limits precision and makes subgroup patterns less conclusive. Safety counts are reported, but the registry does not provide detailed event terms for serious adverse events or full event-level information in this record. These limitations reflect gaps in registry reporting and should not be taken as evidence that the underlying trial protocol lacked additional procedures or documentation.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Zoliflodacin in Uncomplicated Gonorrhoea — NCT03959527.
• Registry record last updated 2025-10-08; status last verified 2025-09.
• Results first posted 2024-07-26.
• 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.

23. Record Summary

NCT03959527 is a completed, phase III, multicenter, randomized, open-label, parallel-group non-inferiority trial of a single oral dose of zoliflodacin versus ceftriaxone plus azithromycin for uncomplicated gonorrhoea. Total enrollment was 1011. The primary endpoint was microbiological cure by culture at urethral or cervical sites at Day 6 (+/- 2) in the micro-ITT urogenital analysis population.

The posted cure proportions were 90.9% for zoliflodacin and 96.2% for the comparator combination. The sponsor analysis reports a risk difference of 5.31 with a 95% confidence interval from 1.38 to 8.65. A simple unadjusted recalculation is also reported, but the registry record does not give the non-inferiority margin or the sponsor method needed to independently assess the formal decision rule. Safety counts include 0 serious adverse events and 0 deaths in each group. Missing-data handling, multiplicity procedures, and the original sample-size justification are not reported in the registry record.