Appendicectomy Versus Antibiotics in the Treatment of Acute Uncomplicated Appendicitis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Appendicectomy Versus Antibiotics in the Treatment of Acute Uncomplicated Appendicitis (NCT01022567), a randomized na study. The primary outcome is The Success of Antibiotic and Surgical Treatment in the Treatment of Acute Uncomplicated Appendicitis.

2. Clinical Question

The clinical question concerns the success of two assigned treatment strategies, not simply whether an operation or antibiotic was given. Under the registry definition, treatment is successful when appendicitis resolves by means of the assigned treatment. This definition makes the treatment strategy central to the outcome: success in the antibiotic arm is resolution through antibiotic treatment, while success in the surgical arm is resolution through appendicectomy.

The registry summary describes the motivation as examining whether antibiotic treatment could successfully manage uncomplicated appendicitis and potentially avoid appendicectomies. That is the study rationale, not a result. The posted arm estimates describe treatment success in each group, but the registry record does not provide a formal estimate of the difference between groups or a test of the primary comparison. The results therefore describe the recorded success percentages and their precision, rather than establishing a comparative conclusion.

3. Trial Design

The record describes a randomized, prospective study comparing operative treatment with conservative treatment using antibiotics. It lists the allocation as randomized, masking as none, and the model as parallel. Participants were assigned to one of two treatment arms: regular open appendicectomy or ertapenem. The study concerns acute appendicitis, with the brief summary specifying acute uncomplicated appendicitis diagnosed by CT scan before randomization.

Enrollment is listed as 530. The registry reports 273.0 participants in the appendectomy arm and 257.0 in the antibiotic therapy arm for the primary outcome. These are the arm counts accompanying the posted outcome estimates; the record does not explain whether every randomized participant was included in each outcome analysis or how any exclusions were handled.

The sponsor is Turku University Hospital. The recorded start is 2009-11 and the primary completion is 2012-06. The phase is listed as NA, and the overall study status is UNKNOWN. These registry fields describe the record and do not establish whether the study is currently active or whether follow-up continued for the full outcome timeframe.

The primary outcome timeframe is up to 10 years. The secondary outcomes listed concern possible complications, morbidity and mortality; direct and indirect costs; and recurrence of conservatively treated appendicitis. The registry lists 3 secondary outcomes and 4 outcome measures, but supplies no further outcome-specific results in the secondary-outcome descriptions. Details such as the allocation-generation procedure, concealment, eligibility criteria beyond the summary, treatment adherence, and follow-up schedule are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Treatment success

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as The Success of Antibiotic and Surgical Treatment in the Treatment of Acute Uncomplicated Appendicitis, measured over Up to 10 years.

The primary endpoint is the percentage of successful treatment, with success defined as resolution of appendicitis by means of the assigned treatment. It is reported for appendectomy and antibiotic therapy, with a 95% confidence interval for each arm and a timeframe of up to 10 years. The endpoint therefore captures whether the assigned approach achieved the stated resolution criterion, rather than reporting a continuous measure such as symptom severity or time to recovery.

This kind of endpoint is used to summarize the proportion of participants meeting a clinically interpretable outcome definition. Because the trial compares treatment strategies, the definition ties success to the assigned strategy. That distinction matters for interpreting the result: the endpoint does not by itself describe all complications, recurrence, costs, or other aspects of care. Those topics appear among the listed secondary outcomes, but corresponding secondary results are not reported in the registry record.

The posted success estimate is 99.6% for appendectomy, with a 95% confidence interval from 98.0% to 100.0%, among 273.0 participants. For antibiotic therapy, the estimate is 72.7%, with a 95% confidence interval from 66.8% to 78.0%, among 257.0 participants. These are arm-specific estimates. The registry does not report a direct between-arm estimate or an inferential test for this endpoint, and the arm estimates should not be mistaken for such a comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What do the arm estimates describe?

The outcome is expressed as a percentage of successful treatment rather than as a mean or median. For appendectomy, the posted estimate is 99.6%, with a 95% confidence interval from 98.0% to 100.0%, among 273.0 participants. For antibiotic therapy, the estimate is 72.7%, with a 95% confidence interval from 66.8% to 78.0%, among 257.0 participants. Each percentage is an arm-level summary of the participants counted for that outcome. The record does not provide a more detailed account of the denominator or analysis population.

In general, an arm-specific proportion describes how common an outcome was in that arm under the study’s outcome definition. A proportion alone does not give the uncertainty around the result, so the confidence interval is also useful. It conveys precision under the statistical method used to construct it. The registry identifies the interval as a 95% confidence interval but does not report the calculation method, so the interval should be interpreted as posted rather than reverse-engineered from the available summary.

Why is a direct comparison important?

The trial’s randomized design sets up a comparison between assigned strategies, but the registry’s posted primary results are arm-specific. To quantify a comparative effect, an analysis would ordinarily state a contrast, such as a difference in success proportions, and report its uncertainty. A comparative test might also be reported. Neither a between-arm estimate nor a p-value appears in the registry record. The separate arm confidence intervals are not substitutes for a confidence interval on a contrast: they answer a different question.

In general, the choice of comparative measure and model should follow the outcome type and the prespecified analysis plan. The record does not report the planned statistical model, test, adjustment variables, or analysis population. It is therefore not possible to determine from the registry entry whether a planned comparison used an unadjusted or adjusted method, or how the analysis addressed departures from the assumptions of any chosen model.

What does randomization contribute?

Randomized allocation is intended to make treatment groups comparable at the point of assignment, on average, and to reduce the risk that treatment choice is driven by participant characteristics. The record identifies allocation as randomized, but does not describe the sequence-generation method or allocation concealment. It also identifies masking as none. In a trial without masking, awareness of assigned treatment can potentially influence care, reporting, or outcome assessment; whether and how that possibility was managed is not reported in the registry record.

Randomization does not remove the need to define and report the analysis. The account does not state whether the primary comparison was intended to follow all randomized participants according to assignment, or whether another analysis population was planned. Nor does it explain how crossover, treatment failure, missing observations, or withdrawals were handled. Those omissions limit the ability to evaluate the analysis as an implementation of the randomized design.

How should the planning illustrations be understood?

The sample-size illustrations use the observed effect as a planning reference and assume a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. They consider detecting a stated fraction of the observed effect. These are illustrative assumptions for planning, not a description of the trial’s original design calculations. The registry does not report the trial’s own sample-size justification, target power, or design effect.

In general, such illustrations estimate how many participants per arm might be needed under the stated assumptions to detect a specified effect with a selected power. They are not evidence about the power actually achieved in the completed trial. The registry record does not report the original design assumptions that led to enrollment, so the illustrations cannot be treated as a reconstruction of the study plan. No further sample-size values are stated in the registry record.

Planning from an observed effect also requires caution in general: an estimate from a particular study can be imprecise, and planning for a fraction of it explores a hypothetical smaller effect. The resulting participant counts are not new observations, and they do not repair missing details about the original protocol or the primary analysis. Interpretation should keep these planning scenarios distinct from the reported arm outcome estimates.

What can be concluded from the reported methods?

The registry provides enough information to identify the broad design, the treatment arms, the endpoint definition, and the arm-level success estimates with confidence intervals. It does not provide the detailed statistical analysis plan, the interval method, a formal comparative analysis, or the handling of missing data. In general, those details help readers judge whether an estimate answers the trial’s intended question and how robustly it was obtained. Their absence does not change the reported values, but it limits the depth of statistical interpretation possible from this record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 secondary outcomes: possible complications, morbidity and mortality; direct and indirect costs; and recurrence of conservatively treated appendicitis. It lists 4 outcome measures overall, but does not include secondary-outcome results in the record. A multiplicity plan—such as a hierarchy of outcomes, an adjustment to account for multiple statistical tests, or a specification that secondary results are exploratory—is not reported in the registry record. There is also no posted set of secondary analyses from which to assess how multiple comparisons were handled.

Multiplicity matters in general because examining several outcomes or comparisons can increase the chance of finding an apparently notable result by chance. A prespecified strategy can clarify which outcome is primary and how other findings should be interpreted. The record identifies a primary outcome, but does not report a broader multiplicity strategy or the planned statistical tests.

Missing-data handling is also not reported. The arm counts accompanying the primary estimates are given, but the record does not say whether these represent all randomized participants, how missing outcome assessments were treated, or whether any imputation or sensitivity analysis was used. It does not report the number of missing primary outcomes or reasons for missingness. Analysis populations, including whether an intention-to-treat analysis was planned or conducted, are not reported in the registry record.

These omissions are relevant to precision and potential bias. In general, missing outcomes can affect a proportion if participants without an observed outcome differ from participants with one. Without information about follow-up completeness and analysis rules, the posted percentages cannot establish how such cases were addressed. The registry also does not report interim analyses or stopping rules; their presence or absence cannot be inferred from that omission.

11. Safety Results

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

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The registry reports serious adverse events for 273 participants at risk in the appendectomy group and 257 participants at risk in the antibiotic therapy group, with 0 affected participants in each group. Death counts are null for both arms, so deaths are not reported in the registry record. These entries should be read as the values recorded in the adverse-event fields, not as a complete narrative of safety monitoring.

Other adverse events are reported for 45 participants in the appendectomy group and 6 in the antibiotic therapy group, with 273 and 257 participants at risk, respectively. The record does not identify the events contributing to these counts in the posted adverse-event summary. It also does not provide event-level descriptions, timing, severity grading for these other events, or an assessment of whether events were caused by treatment.

In general, a zero count in a registry field means no affected participants were recorded for that field; it does not establish that an event is impossible or that no safety issue occurred outside the field’s definition or reporting scope. The record does not provide enough detail to compare event rates formally or to assess how adverse events were solicited and classified. These figures should therefore be interpreted as limited recorded counts, not as a complete characterization of comparative safety.

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

The posted primary outcome values show that the registry recorded a higher treatment-success percentage in the appendectomy arm than in the antibiotic therapy arm: 99.6% versus 72.7%. The corresponding 95% confidence intervals are 98.0% to 100.0% and 66.8% to 78.0%. These figures describe the outcome as defined in the registry: resolution of appendicitis by means of the assigned treatment. They do not, by themselves, provide a formal estimate of the difference between the randomized groups.

The result does not establish why the arm estimates differ, whether the difference is statistically significant under a prespecified analysis, or how the result would change under a different analysis population or treatment definition. No comparative test or contrast is reported. The record also does not provide enough information to determine how missing outcomes, follow-up, or treatment deviations were handled. Those gaps are important when moving from descriptive arm results to conclusions about the effect of assignment.

The primary outcome is not a complete measure of every consequence of treatment. Complications, morbidity and mortality, costs, and recurrence are listed among the secondary outcomes, but their results are not reported in the registry record. The posted safety counts are limited and lack detailed event descriptions. Consequently, the primary success percentages cannot answer all questions about the broader balance of outcomes.

The trial’s stated motivation was to compare open appendicectomy with antibiotic treatment in acute uncomplicated appendicitis. The registry reports randomized allocation, but the available outcome record should be read with the distinction between a study question and a complete statistical answer in mind. The posted percentages offer information about each arm’s recorded success; a fully documented comparative interpretation would require the analysis methods and outcome-handling details that are not reported in the registry record.

In general, statistical uncertainty and clinical interpretation are related but distinct. A confidence interval describes precision for an estimate under its method; it does not determine the importance of an outcome or resolve questions not measured by that outcome. The registry results do not support medical advice or a recommendation about treatment choice. They should be understood as the trial results reported in this record, with its stated endpoint and reporting limitations.

13. Why This Trial Matters Statistically

This trial raises a central statistical challenge in clinical research: how to compare two treatment strategies when the primary result is presented as success within each arm. Arm-specific proportions are readily interpretable, but the research question is comparative. A direct treatment contrast and its uncertainty are needed to quantify that comparison statistically. The registry record reports the arm estimates and confidence intervals, but not a comparative estimate or inferential test.

The endpoint definition also illustrates why outcome wording matters. Success is defined as resolution of appendicitis by means of the assigned treatment. This focuses the outcome on whether the assigned strategy achieved resolution, but it does not cover every consequence that may matter to patients or clinicians. The listed secondary outcomes—possible complications, morbidity and mortality, costs, and recurrence—address other dimensions, yet their results are not reported in the registry record.

The randomized design is relevant because random allocation is intended to support comparisons between treatment groups. At the same time, statistical interpretation depends on how assignment, follow-up, and analysis are carried through. Details about allocation procedures, analysis populations, missing outcomes, and the formal statistical plan are not reported. Their absence illustrates why identifying a randomized design alone is not equivalent to having a complete account of the analysis.

The record is also a useful example of separating outcome estimates from planning calculations. Sample-size illustrations based on an observed effect can explore hypothetical design choices, but they are not the trial’s original justification and are not observed power. That distinction helps prevent post hoc planning scenarios from being mistaken for evidence about how the trial was designed or what its analysis established.

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.

Several limitations arise from what the registry record does not report. It gives no detailed eligibility criteria beyond the summary description, and does not describe the randomization sequence or allocation concealment. Masking is recorded as none, while methods for limiting bias in outcome assessment are not described. The record does not detail the treatment and follow-up procedures sufficiently to assess adherence or how treatment deviations were handled.

The primary outcome is reported as success over a timeframe of up to 10 years, but the timing and completeness of outcome ascertainment are not described. The record does not state whether all participants were followed for the same period, how success was assessed, or how recurrent disease or other events affected endpoint classification. Those details matter for understanding what the arm estimates represent over the stated timeframe.

Although confidence intervals are reported for both arms, their calculation method is not described, and there is no formal between-arm estimate or test. The registry lists 0 analyses. It does not report the analysis population, missing-data methods, sensitivity analyses, or adjustment for covariates. A sample-size justification for the trial and any interim analyses or stopping rules are not reported in the registry record.

Safety information is also limited. Serious adverse-event counts are reported as 0 in each arm, but death counts are null and the other adverse-event summary gives no event descriptions. The secondary outcomes are listed without results. These omissions mean the posted record cannot support a comprehensive assessment of comparative benefits, harms, costs, recurrence, or the robustness of the primary analysis. They are reporting limitations; they do not establish that the unreported procedures or outcomes were absent from the study.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Appendicectomy Versus Antibiotics in the Treatment of Acute Uncomplicated Appendicitis — NCT01022567.
• Registry record last updated 2018-06-28; status last verified 2018-05.
• Results first posted 2017-02-23.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes a randomized, unmasked, parallel-group study of open appendicectomy versus ertapenem for acute uncomplicated appendicitis. Enrollment is listed as 530, with primary outcome results reported for 273.0 participants in the appendectomy arm and 257.0 in the antibiotic therapy arm. The primary endpoint is the percentage of successful treatment, defined as resolution of appendicitis by means of the assigned treatment, over a timeframe of up to 10 years.

Success is reported as 99.6% for appendectomy, with a 95% confidence interval from 98.0% to 100.0%, and 72.7% for antibiotic therapy, with a 95% confidence interval from 66.8% to 78.0%. No formal comparative analysis is posted. Serious adverse events are recorded for 0 participants in each arm; death counts are null. Other adverse-event counts are reported, but event details are not. The record lists secondary outcomes but does not report their results. Analysis methods, missing-data handling, analysis populations, and the trial’s sample-size justification are not reported in the registry record.