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 Trial of Randomized Antibiotic Administration in Percutaneous Nephrolithotomy (NCT02579161), a randomized phase 3 study. The primary outcome is Number of Participants With Infectious Complications.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02579161 |
| Phase | Phase 3 |
| Condition | Kidney Stones |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 98 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Northwell Health |
| Results posted | Yes |
2. Clinical Question
Population
Patients undergoing percutaneous nephrolithotomy for kidney stones. The registry record reports an enrollment of 98 and describes random assignment through stratified randomization. Further eligibility criteria and details of the analysis population are not reported in the registry record.
Intervention
Antibiotics for a 24-hour period after the procedure, in addition to perioperative antibiotics. The specific drug was to be determined based on patient history and other considerations, according to the arm description.
Comparator
Continued antibiotics until removal of any external catheters, such as nephrostomy tubes. The specific drug was also to be determined based on patient history and other considerations.
Primary question
Did the two antibiotic-duration protocols differ in the number of participants with infectious complications during 0-30 days post-operatively? The registry description identifies fever, sepsis and systemic inflammatory response as examples of complications of interest. A numerical primary-outcome comparison is not reported in the registry record.
The clinical contrast concerns duration of antibiotic administration after percutaneous nephrolithotomy, rather than a comparison of a named drug against a different named drug. The registry lists cephalosporins, fluoroquinolones, clindamycin, and ampicillin/gentamicin as interventions. It does not assign these drug options to specific participants or provide results by drug.
The investigators’ stated objective was to compare a single-day protocol with a short-course protocol. Their stated rationale was to reduce potentially unnecessary prolonged antibiotic use, hospital costs, and the further propagation of resistant microbes. Those are motivations for the study, not findings from its outcome data. The registry record does not report whether either duration protocol achieved those aims.
3. Trial Design
The registry identifies this as a randomized, parallel-group phase 3 trial with no masking. Participants were assigned to one of two antibiotic-duration strategies following percutaneous nephrolithotomy. The primary-outcome description says assignment used stratified randomization, but the stratification factors are not reported in the registry record. With no masking, participants and clinical staff were not described as blinded to assignment.
The planned contrast was antibiotics for a 24-hour period after the procedure versus continued antibiotics until removal of external catheters. Both arm descriptions state that the intervention drug would be determined based on patient history and other considerations. The listed drug options are cephalosporins, fluoroquinolones, clindamycin, and ampicillin/gentamicin. The record does not specify how the choice among these options was made, or whether particular choices were balanced between the groups.
The registry reports enrollment of 98. The safety record lists 49 participants at risk in each group for the reported serious and other adverse-event counts. The trial is marked completed. Its listed start was 2014-09, and its primary completion was 2018-03. These dates describe the registry timeline and do not provide details about recruitment pace or follow-up completeness.
The primary outcome was the number of participants with infectious complications during 0-30 days post-operatively. Length of stay and the number of participants with an associated Clavien Grade of adverse event are listed as secondary outcomes. The record identifies three outcome measures overall, but a complete account of all outcome definitions and their results is not reported in the registry record.
The registry does not report detailed eligibility criteria, a sample-size justification for the original trial, allocation concealment procedures, protocol deviations, or the statistical analysis plan. The design information therefore establishes the broad randomized comparison, but does not support assumptions about implementation or analysis details beyond those explicitly described.
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 | Antibiotics for a 24 Hour Period | Continued Antibiotics |
|---|---|---|
| STARTED | 49 | 49 |
| COMPLETED | 49 | 49 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Patients were randomly assigned to the interventional arm or the control arm through stratified randomization. In addition to perioperative antibiotics, those in the interventional arm only received antibiotic course for up to 24 hours after procedure while those in the control arm received antibiotics until external catheters were removed based on surgeon preference
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: Patients were randomly assigned to the interventional arm or the control arm through stratified randomization. In addition to perioperative antibiotics, those in the interventional arm only received antibiotic course for up to 24 hours after procedure, while those in the control arm received antibiotics until external catheters were removed based on surgeon preference.
| Characteristic | Unit | Antibiotics for a 24 Hour Period | Continued Antibiotics | Total |
|---|---|---|---|---|
| Participants analysed | 49 | 49 | 98 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 37 | 31 | 68 |
| Age, Categorical: >=65 years | Participants | 12 | 18 | 30 |
| Age, Continuous | years | 57.1 (SD 11.3) | 59.7 (SD 11.9) | 58.9 (SD 11.5) |
| Sex: Female, Male: Female | Participants | 13 | 13 | 26 |
| Sex: Female, Male: Male | Participants | 36 | 36 | 72 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | participants | 49 | 49 | 98 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Infectious Complications, measured over 0-30 days post-operatively.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with infectious complications in the period from 0-30 days post-operatively. It is a participant-count outcome: each participant is counted according to whether an infectious complication was recorded, rather than by how many separate symptoms or episodes that participant experienced. The registry’s description gives fever, sepsis, and systemic inflammatory response as examples of complications of interest.
A count of affected participants can make a treatment-duration comparison easier to interpret than a list of individual symptoms, because the unit is the participant. It can capture whether an event occurred within the specified follow-up period, but it does not by itself describe severity, duration, or the number of events per participant. The registry record does not report a detailed operational definition, adjudication process, or rules for combining the listed complication types into the endpoint.
In this trial, the endpoint addresses the central safety and efficacy question of whether infectious complications differed between the 24-hour protocol and continued antibiotics. The outcome description says the rate was to be compared, but the posted registry record contains no numerical primary-outcome results or analysis. Consequently, the endpoint’s definition establishes what was intended to be measured; it does not establish the observed event frequency or the size, direction, or precision of any difference.
Length of stay and participants with an associated Clavien Grade of adverse event are also listed as secondary outcomes. Their presence indicates additional outcomes of interest, but their definitions, values, and analyses are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a randomized comparison of two antibiotic-duration strategies after percutaneous nephrolithotomy. It identifies infectious complications during 0-30 days post-operatively as the primary outcome, but it does not report a primary-outcome result. There is therefore no posted estimate of the event frequency in either group, no estimated between-group contrast, and no confidence interval or p-value for that endpoint. The direction and precision of the primary comparison cannot be assessed from this record.
This absence matters for interpretation. The fact that a trial was randomized does not, by itself, reveal whether the groups had different outcomes. Random assignment is a design feature intended to support a fair comparison; the outcome data and the analysis are needed to quantify what happened. Without the primary-outcome results, it would be inappropriate to claim that one protocol had fewer or more infectious complications, or that the protocols were similar.
The safety figures reported in the registry show one serious adverse event among participants at risk in the 24-hour group and two in the continued-antibiotics group. The registry also lists nine other adverse events in the 24-hour group and ten in the continued-antibiotics group, with zero deaths in each group. These are descriptive counts. The record does not provide an inferential comparison, confidence intervals, event-level detail, or enough information to assess whether the categories overlap or how events were classified. The serious-event terms listed are Hemothorax/Pneumothorax and Fevers with Hydronephrosis, each at 2.0%; the record does not state an arm-specific attribution for those terms.
Neither these safety counts nor the trial’s stated objective answers the primary question. The safety counts are not substitutes for the primary infectious-complication result, and the investigators’ aims concerning antibiotic use, costs, and resistant microbes are not outcomes that can be inferred from the record. Length of stay and Clavien Grade adverse events are listed as secondary outcomes, but results for them are not reported in the registry record.
Overall, the registry supports a description of the comparison and some adverse-event counts, but not an estimate of the primary treatment contrast. Any conclusion about the relative event rates, uncertainty, or statistical evidence would require results not reported in the registry record.
9. Statistical Methods Explained
The trial’s central endpoint is a binary participant outcome: whether each participant had an infectious complication during the specified follow-up period. Although the registry calls the measure a number of participants, the comparison of interest is between the groups’ event counts or rates. A count alone is easier to interpret when its denominator is also known; the primary-outcome denominators and event counts are not reported in the registry record.
What randomization contributes
Randomization assigns participants to treatment strategies by chance. In general, this can reduce systematic differences between groups at the point of assignment, including differences that are known and those that are not measured. It does not guarantee that groups will be identical, and it does not replace reporting the outcome data. Here, the registry describes stratified randomization but does not report the stratification factors, sequence generation, allocation concealment, or any balance assessment. Those details are therefore not available for judging how assignment was carried out.
The parallel-group design means the two duration protocols are compared across separate groups of participants. The registry reports no masking. In general, lack of masking can matter when decisions about outcome identification, additional care, or reporting may be influenced by knowledge of treatment assignment. The record does not describe outcome adjudication or procedures to limit such influence, so their role cannot be assessed.
Counts, rates, and uncertainty
For a binary outcome, an event count describes how many participants experienced the outcome, while a rate or proportion relates that count to the number assessed. A comparison may be expressed as a difference or another relative measure, depending on the analysis plan. These measures answer related but distinct questions, and their uncertainty is commonly represented with a confidence interval. In general, a confidence interval describes a range of values compatible with the data and the method used; it does not guarantee that the true value lies within that range. No primary-outcome count, rate, contrast, confidence interval, or p-value is reported in the registry record, so none can be interpreted for this trial.
A p-value, in general, assesses how compatible the observed data are with a specified null model under the assumptions of the test. It is not the probability that a treatment works, nor does it measure the size or clinical importance of an effect. Because the registry records no primary-outcome analysis, there is no posted p-value to interpret. The absence of a listed analysis does not establish that no analysis was conducted elsewhere; it means the registry record does not report one.
Analysis choices and outcome definitions
Interpreting a randomized trial also depends on knowing which participants were included in each analysis, how missing outcomes were handled, and what counted as an event. For example, an intention-to-treat analysis generally evaluates participants according to their randomized assignment, while other analysis populations can use different inclusion rules. These are general methodological distinctions; the registry record does not name an analysis population or describe an analysis approach for the primary endpoint. It also does not report missing-data handling, event adjudication, or a detailed definition for classifying infectious complications.
Because the endpoint refers to complications over a follow-up period, completeness of follow-up can affect the number of observed events. In general, an unobserved outcome is not the same as an outcome with no event. Without follow-up and missingness information, the reader cannot assess whether all randomized participants contributed outcome data or how incomplete observations were treated. Those details are not reported in the registry record.
Planning calculations are not trial findings
Planning illustrations associated with this analysis use a two-sided significance level of 0.05, equal allocation, and a normal approximation. The stated effect to detect is a fraction of the observed effect. The record does not report the original trial’s sample-size justification, so these illustrations should not be read as the trial’s own design calculation. They are hypothetical planning scenarios, not observed power and not evidence about the treatment comparison. A planning estimate depends on assumptions about an effect and analysis method; it does not show whether an observed result is statistically persuasive or clinically important.
The registry identifies zero analysis entries. It also lists multiple outcomes, but does not provide a statistical plan explaining which analyses were primary, how they were to be performed, or whether any adjustment was planned for testing multiple outcomes. In general, analyzing multiple outcomes or making multiple comparisons can increase the chance of at least one apparently unusual result. Whether and how that issue applies to the trial cannot be determined without a prespecified analysis plan and reported results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and secondary outcomes, and reports three outcome measures overall. It does not report an analysis plan specifying which comparisons were planned, how outcomes were prioritized for inference, or whether any adjustment for multiple testing was intended. When several outcomes are examined, multiplicity can affect how statistical evidence is interpreted; in general, the chance of a false-positive finding can increase across multiple tests. No adjustment method or multiplicity strategy is reported in the registry record, so no claim about its use is justified.
The registry records zero analyses. This means the registry record does not present analysis entries; it does not establish that no statistical analysis was performed outside the record. For the primary outcome, the event counts, comparison estimate, confidence interval, and p-value are not reported in the registry record. The listed secondary outcomes, length of stay and participants with an associated Clavien Grade of adverse event, also have no reported results.
Missing-data handling and analysis populations are not reported in the registry record. It is therefore unknown whether every randomized participant had outcome follow-up, how incomplete follow-up was treated, or whether analyses followed randomized assignment. In general, missing outcome data can affect the interpretation of a comparison if the participants without observed data differ in relevant ways from those with data. The record does not provide enough information to evaluate that possibility.
The primary endpoint description identifies the follow-up window and gives examples of infectious complications, but detailed event definitions and adjudication procedures are not reported. These omissions limit assessment of outcome ascertainment as well as statistical analysis. The record also does not report interim analyses or stopping rules; their presence or absence cannot be inferred.
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 |
|---|---|---|---|
| Antibiotics for a 24 Hour Period | 1 | 49 | 2.0% |
| Continued Antibiotics | 2 | 49 | 4.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Antibiotics for a 24 Hour Period | 0 of 49 |
| Continued Antibiotics | 0 of 49 |
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 |
|---|---|
| Antibiotics for a 24 Hour Period | 9 of 49 |
| Continued Antibiotics | 10 of 49 |
Most frequent serious adverse event terms
| Event term | Organ system | Antibiotics for a 24 Hour Period | Continued Antibiotics |
|---|---|---|---|
| Hemothorax/Pneumothorax | Surgical and medical procedures | 1 of 49 | 1 of 49 |
| Fevers with Hydronephrosis | Renal and urinary disorders | 0 of 49 | 1 of 49 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Antibiotics for a 24 Hour Period | Continued Antibiotics |
|---|---|---|---|
| fevers post operative | Blood and lymphatic system disorders | 2 of 49 | 5 of 49 |
| Post-operative embolization | Surgical and medical procedures | 3 of 49 | 2 of 49 |
| Post operative urinary retention | Renal and urinary disorders | 3 of 49 | 1 of 49 |
| Post operative pain | General disorders | 1 of 49 | 1 of 49 |
| Post operative anemia requiring transfusion | Surgical and medical procedures | 0 of 49 | 1 of 49 |
Serious events with the highest arm-level rate: hemothorax/pneumothorax (2.0%), fevers with hydronephrosis (2.0%).
The registry’s safety figures are descriptive counts, with 49 participants at risk in each group. In the 24-hour antibiotics group, one serious adverse event and nine other adverse events are recorded. In the continued-antibiotics group, two serious adverse events and ten other adverse events are recorded. Deaths are recorded as zero in both groups.
The serious adverse-event terms listed are Hemothorax/Pneumothorax at 2.0% and Fevers with Hydronephrosis at 2.0%. The registry does not give an arm-specific assignment for these terms in the information reported, so they should not be attributed to a particular group. Nor does the record explain whether a participant could contribute to more than one category or how the categories relate to the primary infectious-complication endpoint.
These counts do not establish whether the groups differ in safety. The registry record does not report a statistical comparison, uncertainty intervals, or event-level descriptions. In general, small descriptive counts can be imprecise, and a numerical difference between counts is not itself evidence of a reliable group difference. The listed adverse-event figures should therefore be read as the events recorded in the registry, not as a complete account of comparative risk or as a substitute for the missing primary-outcome analysis.
12. What the Result Does, and Does Not, Mean
The registry establishes that the trial was designed to compare two antibiotic-duration protocols after percutaneous nephrolithotomy and that infectious complications during 0-30 days post-operatively were the primary outcome. It also reports the trial’s enrollment, broad design, arm descriptions, and selected safety counts. These details clarify the clinical question and provide a limited descriptive record of adverse events.
The record does not report the primary outcome results. As a result, it does not show how many participants in either group experienced infectious complications, whether the groups’ outcomes differed, or how precise an estimated difference might be. It cannot establish that the 24-hour protocol and continued antibiotics had equivalent outcomes, nor can it establish that one protocol had better or worse outcomes. A lack of a posted comparison is not evidence that the treatments were the same.
The trial’s stated goals concerning prolonged antibiotic use, hospital costs, and resistant microbes are motivations, not reported results. The registry does not provide comparative data on antibiotic exposure, costs, or microbial resistance. Length of stay is listed as a secondary outcome, but its results are not reported in the registry record. No conclusion about those goals follows from the safety counts alone.
In general, a treatment effect estimate describes the observed contrast, while its uncertainty helps show how much precision the data provide. Neither is available for the primary endpoint in this record. The descriptive adverse-event counts can be stated as recorded, but they do not support a formal inferential conclusion. Further outcome and analysis information would be needed to assess the trial’s primary question and its secondary outcomes.
13. Why This Trial Matters Statistically
This trial asks a statistical question about treatment duration: whether infectious complications differed between a 24-hour antibiotic protocol and continued antibiotics after percutaneous nephrolithotomy. That is distinct from asking whether any particular antibiotic drug is superior. The listed drug options could be selected based on patient history and other considerations, while the randomized strategy of interest is how long antibiotics continued.
Randomized allocation is relevant because it provides a design basis for comparing groups. But a sound design does not replace transparent outcome reporting. To interpret the clinical question, readers need event counts and denominators, a measure of the between-group contrast, and information about uncertainty. Those primary-outcome results are not reported in the registry record. This makes the trial a useful example of why design details and results must be considered separately.
The registry also illustrates how a trial can list several outcomes without presenting analyses for them. Length of stay and Clavien Grade adverse events are named as secondary outcomes, while the record includes selected adverse-event counts. Without results for the planned outcomes, definitions, and analysis methods, readers cannot determine the strength of evidence or how the findings relate to the investigators’ stated aims.
Statistically, the key lesson is not a conclusion about which protocol should be used. It is that an intended comparison, a completed status, and descriptive safety counts do not substitute for a reported estimate of the primary effect with its uncertainty. The registry record documents the trial question and some design features, while leaving the central outcome comparison unreported.
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 main limitation for interpretation is that the registry record does not report the primary infectious-complication results. Without event counts and a between-group estimate, the central comparison cannot be quantified. The record also does not report confidence intervals, p-values, or other inferential results for the primary outcome.
The primary outcome description gives examples of complications but does not report a detailed case definition, event-adjudication method, or rules for combining event types. As the trial had no masking, details about outcome assessment could be especially useful for understanding how events were identified; those details are not reported in the registry record. This does not establish that assessment was biased, only that the record does not allow that possibility to be evaluated.
Information about eligibility criteria, baseline characteristics, follow-up completeness, protocol deviations, and analysis populations is not reported in the registry record. The missing information limits assessment of who was included, whether all randomized participants were followed, and how the analysis related to random assignment. Handling of missing data and outcome definitions beyond the brief description are also not reported.
The registry names two secondary outcomes but does not report their results. It does not state whether multiplicity adjustments, interim analyses, or stopping rules were planned. The specific antibiotic choice is described as based on patient history and other considerations, but the selection process and distribution of drug choices are not reported. These gaps make it difficult to separate the effect of duration from any other variation in treatment delivery or to assess the full set of outcomes.
Finally, the safety record provides descriptive counts but no comparative analysis or event-level context. The serious-event terms are listed without arm-specific attribution in the information reported. These figures therefore offer limited context and should not be treated as a complete comparative safety assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Trial of Randomized Antibiotic Administration in Percutaneous Nephrolithotomy — NCT02579161.
- Registry record last updated 2023-09-06; status last verified 2023-09.
- Results first posted 2023-03-14.
- 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
NCT02579161 is a completed randomized, parallel-group phase 3 trial sponsored by Northwell Health. It enrolled 98 participants and compared antibiotics for a 24-hour period after percutaneous nephrolithotomy with continued antibiotics until removal of external catheters. Masking is listed as none. The registry timeline lists a start of 2014-09 and primary completion of 2018-03.
The primary outcome was the number of participants with infectious complications during 0-30 days post-operatively. Length of stay and participants with an associated Clavien Grade of adverse event are listed as secondary outcomes. The registry record does not report the primary-outcome comparison, secondary-outcome results, or analysis methods. It does report selected adverse-event counts and zero deaths in each group.
The record describes the trial question and broad design, but does not provide enough outcome information to estimate the primary treatment contrast or its precision.