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 GSK1322322 Versus Linezolid in the Treatment of Acute Bacterial Skin and Skin Structure Infection (NCT01209078), a randomized phase 2 study. The primary outcome is Number of Participants With Any Adverse Events (AE) and Serious Adverse Events (SAE).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01209078 |
| Phase | Phase 2 |
| Condition | Skin Infections, Bacterial |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 84 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
Participants with acute bacterial skin and skin structure infection (ABSSSI), a type of bacterial skin infection. The safety population included participants who received at least one dose of study medication.
Intervention
GSK1322322 1500 mg twice a day for 10 days, with linezolid placebo.
Comparator
Linezolid 600 mg twice a day for 10 days, with GSK1322322 placebo.
Primary question
How many participants experienced any adverse event or a serious adverse event through follow-up? The study also listed clinical, microbiological, therapeutic, and symptom outcomes as secondary measures.
The registry describes a randomized comparison of two treatment regimens. Its primary outcome is a safety measure: the number of participants with any adverse event (AE) and the number with a serious adverse event (SAE), assessed up to the 28 Day Follow-up, Day 40. The outcome is about recorded events during the specified period, not a direct measure of symptom improvement or bacterial clearance.
The registry's study summary describes safety, tolerability, and efficacy as objectives. However, the posted primary outcome concerns adverse events, while clinical response, microbiological outcomes, therapeutic success, pain, and skin-infection scores appear among the secondary outcomes. Numeric findings for those secondary outcomes are not reported in the registry record. The available safety counts can describe events in each regimen group, but without comparative estimates and their uncertainty they do not answer whether the regimens differ in safety.
3. Trial Design
This was a randomized, quadruple-masked, parallel-group phase IIa study. The official title describes it as double blind and double dummy, and as a multicenter study. The registry lists an enrollment of 84 and a completed status. The study start is recorded as 2010-08-17, with primary completion on 2011-01-18.
The two regimens paired each active drug with a placebo for the other drug. One group received GSK1322322 1500 mg and linezolid placebo twice a day for 10 days; the other received linezolid 600 mg and GSK1322322 placebo twice a day for 10 days. This double-dummy arrangement describes the treatment regimens, but details such as the allocation ratio and the specific masking procedures are not reported in the registry record.
The primary safety outcome covers events up to follow-up, described as a 28 Day Follow-up at Day 40. The record defines the safety population as participants who received at least one dose of study medication. The reported safety results list 57 participants at risk in the GSK1322322 group and 27 in the linezolid group. These are the group-specific figures in the safety results; they should not be taken as evidence about the planned allocation method.
The registry lists clinical success, microbiological success at end of therapy and follow-up, therapeutic success, pain scores, and skin-infection scores among secondary outcomes. The record does not report the protocol's sample-size justification, detailed randomization procedure, or a complete statistical analysis plan.
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 of 84 participants were enrolled in the study; of which, 57 participants were randomized in a ratio of 2:1 to receive GSK1322322 1500 milligram (mg) twice a day (BID) and 27 were randomized to receive linezolid 600 mg BID for 10 days.
Overall Study
| Stage | GSK1322322 1500 mg BID | Linezolid 600 mg BID |
|---|---|---|
| STARTED | 57 | 27 |
| COMPLETED | 41 | 24 |
| NOT COMPLETED | 16 | 3 |
Reasons for not completing this period:
| Reason | GSK1322322 1500 mg BID | Linezolid 600 mg BID |
|---|---|---|
| Adverse Event | 5 | 0 |
| Lost to Follow-up | 4 | 0 |
| Physician Decision | 5 | 2 |
| Withdrawal by Subject | 2 | 1 |
Analysis population for the primary outcome, as defined in the registry: Safety Population was defined as all participants who received at least one dose of study medication.
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 | GSK1322322 1500 mg BID | Linezolid 600 mg BID | Total |
|---|---|---|---|---|
| Participants analysed | 57 | 27 | 84 | |
| Age, Continuous | Years | 44.4 (SD 11.87) | 41.5 (SD 11.00) | 43.5 (SD 11.61) |
| Sex: Female, Male: Female | Participants | 14 | 4 | 18 |
| Sex: Female, Male: Male | Participants | 43 | 23 | 66 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 2 | 0 | 2 |
| Race (NIH/OMB): Asian | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 1 | 2 | 3 |
| Race (NIH/OMB): Black or African American | Participants | 4 | 2 | 6 |
| Race (NIH/OMB): White | Participants | 47 | 23 | 70 |
| Race (NIH/OMB): More than one race | Participants | 2 | 0 | 2 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Any Adverse Events (AE) and Serious Adverse Events (SAE), measured over Up to Follow-up (28 Day Follow-up, Day 40).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary outcome is the number of participants with any adverse event and the number with serious adverse events, assessed up to the 28 Day Follow-up, Day 40. An AE is defined as an untoward medical occurrence temporally associated with use of a medicinal product, whether or not it is considered related to that product. An SAE is an event meeting specified seriousness criteria, including death, a life-threatening event, hospitalization or prolonged hospitalization, disability or incapacity, a congenital anomaly or birth defect, or an event that may jeopardize the participant or require medical or surgical intervention to prevent one of these outcomes. The SAE definition also includes specified liver injury and impaired liver function criteria.
Counting participants with events is a direct way to describe how many people in the safety population experienced recorded harms during the assessment period. The AE count covers events regardless of whether investigators considered them related to treatment. The SAE count focuses on events meeting the registry's seriousness definition. These are distinct safety summaries; an event count alone does not indicate its cause, duration, severity beyond the SAE classification, or the certainty of a difference between regimens.
The endpoint is useful for describing safety during the recorded follow-up, but it does not summarize clinical benefit. The registry record does not report an inferential comparison for this primary outcome.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted safety results report 1 participant with a serious adverse event in the GSK1322322 group, with 57 at risk, and 1 in the linezolid group, with 27 at risk. The record also reports 38 participants with other adverse events among 57 at risk for GSK1322322, and 16 among 27 at risk for linezolid. Deaths are listed as 0 in each group. These figures describe the recorded counts within each group; they do not, by themselves, establish a difference between treatments.
A comparison needs to account for the group sizes and the uncertainty around the event estimates. The registry record does not report a comparative effect estimate, confidence interval, or inferential test for the primary safety outcome. A raw count is especially limited when the groups have different numbers at risk: equal counts do not imply equal event risks, and a difference in counts is not itself an estimate of a treatment effect. No new event proportions or comparative values can be inferred without performing calculations that are not part of the posted results.
The serious-event terms listed include Abscess limb at 3.7%, Cellulitis at 3.7%, and Multiple drug overdose at 1.8%. The record does not specify in the listed information how these terms are distributed by treatment group, or the denominator used for these percentages. They therefore add descriptive detail but cannot support an arm-specific comparison.
The study's primary outcome is a safety endpoint, while its stated aims also include efficacy. The registry lists a range of secondary outcomes, including clinical and microbiological success, but numeric results for them are not reported in the registry record. It is therefore not possible to use the available information to characterize efficacy, weigh safety against efficacy, or determine whether the observed counts are compatible with a meaningful difference.
The study is identified as phase IIa and has a registry enrollment of 84. Those details provide context for the trial but do not replace estimates of precision. The absence of reported uncertainty is consequential: the counts may be informative as a record of observed events, but they do not show how precisely the underlying event rates are estimated. The evidence should be read descriptively rather than as a definitive comparative safety finding.
9. Statistical Methods Explained
The primary outcome is a count of participants with events, rather than a continuous measurement such as a symptom score. For this kind of outcome, the registry reports how many participants were at risk and how many experienced the event. The count is a direct description of what was recorded in the study group. It is not automatically a comparison of treatment effects, and it does not convey uncertainty on its own.
What does a confidence interval add?
In general, a confidence interval expresses the statistical uncertainty around an estimated effect. It indicates a range of effect values that are reasonably compatible with the data and the statistical model used. A narrow interval indicates greater precision than a wide interval, though interpretation also depends on which effects are substantively important. The registry record does not report a confidence interval for the primary safety comparison, so the precision of a comparative effect cannot be assessed from the posted counts alone.
Why distinguish counts from risks?
A count is the number of participants with an event; a risk is the proportion of participants in a defined group who experience an event during a specified period. Counts are useful for describing observations, but their scale depends on how many participants are included. When group sizes differ, comparing counts alone can be misleading. The posted results include group-specific numbers at risk, but no calculated comparative risk estimate is reported. No unadjusted re-calculation is presented for this primary outcome.
The endpoint also combines a broad AE concept with the more restricted SAE classification. AEs include untoward medical occurrences whether or not they are judged related to the study medication. SAEs are identified using seriousness criteria. Thus, the categories answer different descriptive questions. They should not be treated as interchangeable, and an SAE count does not capture every relevant feature of an event. The registry record's event definitions and assessment period are essential to interpreting the counts.
What can masking and randomization contribute?
In general, randomization is intended to make treatment groups comparable with respect to both measured and unmeasured characteristics, on average, while masking can reduce the influence of expectations on care or assessment. These design features strengthen a comparison when the study's conduct and analysis preserve the randomized comparison. The registry describes the study as randomized and quadruple masked, and its official title describes a double-blind, double-dummy design. Details about sequence generation, concealment, departures from assigned treatment, and masking success are not reported in the registry record. The design labels alone do not establish that every potential source of bias was eliminated.
How should the secondary outcomes be understood?
The registry lists clinical response, microbiological outcomes at end of therapy and follow-up, therapeutic success, pain sub-scores, and skin-infection scores. These outcomes address different aspects of the illness and may have different measurement scales and assessment times. The record lists 36 outcome measures and 39 analyses, but does not report a complete statistical analysis plan or numeric results for the secondary outcomes in the registry record described. Without those details, the definitions, analysis populations, handling of repeated assessments, and methods for estimating effects cannot be fully evaluated.
Multiplicity is a general concern when many outcomes or analyses are considered: the chance of at least one apparently unusual result can rise as the number of statistical tests increases, unless the analysis plan addresses this issue. The registry record does not report whether or how multiplicity was handled. That limitation does not invalidate descriptive findings, but it makes isolated inferential claims across numerous outcomes difficult to evaluate.
What do sample-size illustrations mean?
In general, a sample-size calculation estimates how many participants would be needed under specified assumptions to detect a chosen effect with a chosen error threshold and power. It is a planning tool, not a statement about what the completed trial observed. The registry describes its sample-size assumptions as an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such an illustration is not observed power, and it is not evidence that the original study was designed around those assumptions. The study's own sample-size justification is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 36 outcome measures and 39 analyses, spanning safety, clinical response, microbiological outcomes, therapeutic success, pain, and skin-infection scores. With multiple outcomes or assessment times, a statistical analysis can involve many opportunities to observe an apparently notable result. In general, prespecifying a primary outcome and a limited set of confirmatory comparisons can help distinguish planned inference from exploratory findings. The registry record does not report whether a multiplicity adjustment or another strategy was used.
The primary outcome is described as having several categories or time points and is not reduced to one comparison in the posted results. A complete statistical plan, including any hierarchy among outcomes, analysis time points, and inferential procedures, is not reported in the registry record. Numeric results for the listed secondary outcomes are also not reported in the registry record, limiting assessment of their estimates and uncertainty.
The safety population is defined as all participants who received at least one dose of study medication. The registry does not report details of missing outcome data, exclusions after randomization, adherence, or analysis populations for the secondary outcomes. It also does not describe methods used to handle missing observations. These omissions matter because the analyzed population and missing-data approach can affect the interpretation of a treatment comparison. The available safety counts should therefore be understood within the stated safety-population definition, without assuming how other analyses were conducted.
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 |
|---|---|---|---|
| GSK1322322 1500 mg BID | 1 | 57 | 1.8% |
| Linezolid 600 mg BID | 1 | 27 | 3.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| GSK1322322 1500 mg BID | 0 of 57 |
| Linezolid 600 mg BID | 0 of 27 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| GSK1322322 1500 mg BID | 38 of 57 |
| Linezolid 600 mg BID | 16 of 27 |
Most frequent serious adverse event terms
| Event term | Organ system | GSK1322322 1500 mg BID | Linezolid 600 mg BID |
|---|---|---|---|
| Multiple drug overdose | Injury, poisoning and procedural complications | 1 of 57 | 0 of 27 |
| Abscess limb | Infections and infestations | 0 of 57 | 1 of 27 |
| Cellulitis | Infections and infestations | 0 of 57 | 1 of 27 |
Most frequent non-serious adverse event terms
| Event term | Organ system | GSK1322322 1500 mg BID | Linezolid 600 mg BID |
|---|---|---|---|
| Nausea | Gastrointestinal disorders | 14 of 57 | 4 of 27 |
| Diarrhoea | Gastrointestinal disorders | 8 of 57 | 2 of 27 |
| Vomiting | Gastrointestinal disorders | 9 of 57 | 1 of 27 |
| Blood glucose increased | Investigations | 6 of 57 | 3 of 27 |
| Headache | Nervous system disorders | 7 of 57 | 2 of 27 |
| Alanine aminotransferase increased | Investigations | 4 of 57 | 2 of 27 |
| Dizziness | Nervous system disorders | 5 of 57 | 1 of 27 |
| Pruritus | Skin and subcutaneous tissue disorders | 3 of 57 | 1 of 27 |
| Blood creatine phosphokinase increased | Investigations | 1 of 57 | 2 of 27 |
| Haemoglobin decreased | Investigations | 3 of 57 | 0 of 27 |
Serious events with the highest arm-level rate: abscess limb (3.7%), cellulitis (3.7%), multiple drug overdose (1.8%).
The serious adverse event results list 1 participant with an SAE among 57 at risk in the GSK1322322 group and 1 among 27 at risk in the linezolid group. The posted death count is 0 in each group. These are observed participant counts within the registry's defined safety population and follow-up period. They are not a statistical test or an estimate of the uncertainty in a difference between regimens.
The record also lists Abscess limb at 3.7%, Cellulitis at 3.7%, and Multiple drug overdose at 1.8% among the top serious terms. The group assignment and denominator for these percentages are not reported in the registry record, so they should not be interpreted as treatment-specific percentages. The event descriptions also do not establish that a study medication caused an event.
For other adverse events, the registry reports 38 participants among 57 at risk for GSK1322322 and 16 among 27 at risk for linezolid. The broad AE definition includes events whether or not considered related to study medication. These counts describe recorded safety experience; they do not alone establish comparative safety or the clinical importance of individual events.
12. What the Result Does, and Does Not, Mean
The results establish that the registry reports adverse events in both treatment groups during the stated safety follow-up, including serious adverse events and other adverse events. They also report no deaths in either group. This is useful descriptive information about the participants included in the safety population. It does not establish why an event occurred or whether the event was caused by a study drug.
The results do not establish that the regimens have the same safety profile, or that one has a higher or lower risk. The SAE count is 1 in each group, but the numbers at risk differ and no comparative estimate or uncertainty interval is reported. The other-event counts likewise cannot be interpreted as a treatment difference using counts alone. A formal comparison requires an analysis that accounts for group sizes and provides uncertainty.
The primary endpoint is safety, not clinical success. Although the registry lists clinical, microbiological, therapeutic, pain, and skin-infection outcomes, their numeric findings are not reported in the registry record. Consequently, the available information does not establish comparative efficacy, and it cannot provide a complete benefit-risk assessment.
The study's randomized, masked design is relevant context, but a design label does not substitute for outcome estimates, analysis details, and transparent reporting of missing data. The phase IIa designation and enrollment of 84 describe the trial's registry record; neither on its own determines the strength or precision of a treatment comparison. The most defensible interpretation is limited to the reported safety counts and event descriptions, with comparative conclusions left unresolved.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between describing events and estimating a treatment effect. The registry reports counts of participants with adverse events and numbers at risk, which allow readers to see the observed safety experience by regimen. But those counts do not provide the uncertainty around a comparison or show whether any apparent difference is compatible with chance variation.
The study also illustrates why endpoint definitions and assessment windows matter. The primary outcome covers events through follow-up, and the registry distinguishes any adverse event from a serious adverse event using explicit definitions. A count is interpretable only in the context of who was included, what qualified as an event, and when events were assessed. The stated safety population and follow-up period help define that context.
Finally, the breadth of the listed secondary outcomes makes reporting of a prespecified analysis plan important. The record lists clinical, microbiological, therapeutic, pain, and skin-infection outcomes, as well as multiple analyses. Without reported methods for multiplicity, missing data, and inferential comparisons, readers cannot tell which findings were intended to be confirmatory or how precisely outcomes were estimated. These are not merely reporting details: they determine what conclusions the evidence can support.
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 registry record leaves important gaps for interpreting this trial's comparative results. It does not report a comparative effect estimate, confidence interval, or inferential test for the primary safety outcome. The event counts can be read descriptively, but the precision of a between-group comparison cannot be assessed from the listed figures alone.
The record does not report the allocation ratio, randomization sequence procedures, concealment procedures, or details of how masking was maintained. Although the study is described as randomized and quadruple masked, those procedural details would help assess risk of bias. The study's own sample-size justification and complete statistical analysis plan are also not reported in the registry record.
For safety, the listed serious-event terms lack reported group attribution and denominator information in the registry record described. Missing-data handling, adherence, post-randomization exclusions, and the analysis populations for secondary outcomes are not reported. The registry lists numerous outcomes and analyses but does not report how multiplicity was handled. Numeric results for the secondary efficacy and symptom outcomes are not reported in the registry record, so the safety information cannot be considered alongside those outcomes.
These limitations do not erase the recorded safety counts. They restrict what can be inferred from them: the posted data support a description of events, but not a precise or conclusive comparative assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: GSK1322322 Versus Linezolid in the Treatment of Acute Bacterial Skin and Skin Structure Infection — NCT01209078.
- Registry record last updated 2017-12-04; status last verified 2017-09.
- Results first posted 2017-12-04.
- 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
NCT01209078 is a completed randomized, quadruple-masked, parallel-group phase IIa study of GSK1322322 versus linezolid for acute bacterial skin and skin structure infection. The regimens were GSK1322322 1500 mg with linezolid placebo, or linezolid 600 mg with GSK1322322 placebo, twice a day for 10 days. The registry lists enrollment of 84.
The primary outcome was the number of participants with any adverse event and serious adverse events through the 28 Day Follow-up, Day 40. The safety results report serious adverse events in 1 participant in each group, other adverse events in 38 participants in the GSK1322322 group and 16 in the linezolid group, and 0 deaths in each group. The registry record does not report a comparative estimate or its uncertainty, and numeric results for the listed secondary outcomes are not reported in the registry record.