The Effect of Prophylactic Ketorolac on Sore Throat After Thyroid Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Prophylactic Ketorolac on Sore Throat After Thyroid Surgery (NCT02039427), a randomized na study. The primary outcome is The Incidence of Postoperative Sore Throat(POST) Using Ketorolac and Dexamethasone in Womend After Thyroidectomy.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group trial with quadruple masking. Its registered enrollment was 192, and its status is completed. The record lists a study start of 2014-01 and primary completion of 2015-10. It names Yeungnam University College of Medicine as sponsor. The phase is listed as NA.

Four groups are described: placebo, preketorolac, postketorolac, and dexamethasone. The ketorolac groups differ in when the active drug was administered: before induction in one group and near the end of surgery in the other. The placebo and dexamethasone regimens use saline at the other administration time, so the registered regimens distinguish both treatment and timing. The record does not describe how participants were assigned among groups, how the random sequence was generated, or how allocation was concealed.

Quadruple masking indicates the registry’s stated masking category, but the record does not identify which participant, clinician, assessor, or other roles were masked, or explain how masking was maintained. Details of surgical and anesthesia procedures beyond the registered drug timing are not reported in the registry record.

The design includes a repeated assessment of sore throat at 1, 6 and 24 hours after thyroidectomy. The registry describes a separate secondary outcome concerning postoperative hoarseness. It lists 3 outcome measures and 0 analyses. The primary sore-throat result is not reduced in the record to a single time point or comparison. A protocol, detailed statistical analysis plan, and sample-size justification are not reported in the registry record, so the intended analysis strategy and rationale for the enrollment target cannot be established from these details.

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: Patients with a airway problem, recent upper respiratory tract infection, obese, inflammation or hemorrhage in the upper gastrointestinal tract, use of NSAID or steroid medication, allergy to the general anesthetic used in this study were excluded.

Overall Study

Reasons for not completing this period:

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 Incidence of Postoperative Sore Throat(POST) Using Ketorolac and Dexamethasone in Womend After Thyroidectomy, measured over at 1, 6 and 24 hours after thyroidectomy.

The primary endpoint is the incidence of postoperative sore throat, recorded as the count of participants meeting the registry’s symptom definition. Patients were asked about symptoms at 1, 6 and 24 hours after extubation. Sore throat was defined as discomfort in the larynx or pharynx at rest or during swallowing after surgery.

Severity was assessed using a verbal-response scale from 0 to 3: 0 means none; 1, mild, less severe than with a cold; 2, moderate, similar to a cold; and 3, severe, more severe than with a cold. The registry says an assessment was recorded as a positive symptom when the sore-throat rating was more than 1. Thus the endpoint concerns whether a participant crossed the specified symptom threshold, rather than the full severity score itself.

In general, an incidence endpoint expresses how many participants meet a prespecified event definition. It can make a symptom outcome easier to interpret than a multi-category severity scale, but it also discards distinctions among ratings that fall on the same side of the threshold. Here, the same outcome was assessed repeatedly after surgery. The registry record does not report the time-specific event counts, a combined measure across times, or an analysis describing change over time. It therefore does not establish which assessment time should carry the primary interpretation.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods determine how trial observations are converted into estimates and how much uncertainty accompanies them. The registry record gives useful design and endpoint details, but it does not report the analysis methods for the primary outcome. The following concepts are general explanations of what would matter for interpreting this kind of trial; they are not claims about analyses conducted in this study.

What does randomization contribute?

In general, random assignment aims to make comparison groups similar, on average, with respect to measured and unmeasured characteristics at the start of a trial. That makes a between-group contrast more interpretable as an effect of assignment to the registered treatment regimen. Randomization does not guarantee exact balance, and its credibility also depends on implementation, concealment, follow-up, and analysis. The record identifies the trial as randomized but does not report the sequence-generation or allocation-concealment methods.

What does masking contribute?

Masking can reduce the influence of expectations on participants’ reports, clinical care, or outcome assessment. This is relevant when the endpoint is a subjective symptom reported in response to questions. The registry lists quadruple masking, but does not specify the masked roles or the procedures used to maintain masking. The label alone does not show whether participants, assessors, or all relevant study personnel remained unaware of group assignment.

How should a binary symptom outcome be understood?

The registered outcome is a count of participants meeting a symptom threshold. In general, a binary endpoint classifies each participant as having or not having the defined event. An analysis might compare event proportions, estimate a relative measure, or use a regression model, but the appropriate choice depends on the protocol, data structure, and intended estimand. The registry record does not report which method was used, and no primary outcome estimates are posted. No effect measure should therefore be attributed to the trial from this record.

The threshold matters: the registry says a rating more than 1 was recorded as a positive symptom, while the rating scale ranges from 0 to 3. General interpretation of such an endpoint should keep the threshold distinct from the underlying severity scale. Turning severity into an event indicator simplifies the outcome but does not retain all information about how severe symptoms were.

How do repeated assessments affect interpretation?

The outcome was assessed at 1, 6 and 24 hours after thyroidectomy. In general, repeated measurements on the same participant are related rather than independent. An analysis that treats each assessment as an independent observation may not account for that relationship. Alternatives can model the time course, define a specific time as primary, or summarize outcomes across times. Each approach answers a somewhat different question. The record does not report which approach was planned or used, and the primary outcome is not reduced to one comparison.

What does a confidence interval add?

In general, a confidence interval describes the uncertainty around an estimated effect under a specified statistical model and procedure. A narrow interval indicates greater precision than a broad interval, though precision is not the same as clinical importance. An interval that includes no effect does not prove there is no effect; it indicates that the data and method do not clearly distinguish the estimate from that reference value at the chosen confidence level. The registry record does not report a primary effect estimate or confidence interval, so precision cannot be evaluated.

Why do multiplicity and missing data matter?

When a trial has multiple groups, outcomes, or assessment times, many possible comparisons may be made. In general, testing several contrasts can increase the chance of a false-positive finding if the testing strategy is not addressed. A prespecified primary contrast and a stated multiplicity procedure help readers understand how confirmatory conclusions should be drawn. The record does not report such a plan. Missing assessments can also affect estimates, particularly if the chance of missing data differs by group or symptom status. The registry record does not describe missing-data handling.

Finally, sample-size calculations are planning tools that depend on assumptions about the target effect, variability or event frequency, allocation, and statistical procedure. A planning illustration based on an observed effect is not the same as the trial’s original design calculation, and it is not observed power. The registry record does not report a sample-size justification or the assumptions behind one. Without those details, enrollment alone cannot establish whether the study was adequately powered for a particular contrast.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome has several assessment times: 1, 6 and 24 hours after thyroidectomy. The record does not identify one time point as the sole primary assessment, define an overall summary across times, or state how the repeated observations were analyzed. It also describes four groups, but does not specify which group comparisons were primary or how multiple comparisons were to be handled. A multiplicity adjustment or other prespecified strategy is not reported in the registry record.

In general, multiplicity matters because making many statistical comparisons can increase the probability of finding an apparently unusual result by chance. A clearly defined primary contrast and an analysis plan help distinguish confirmatory questions from exploratory ones. Since no primary analyses are listed, the registry record cannot establish which comparisons were actually conducted or how their results should be interpreted.

Details about missing outcome assessments, participant withdrawals, exclusions after randomization, and analysis populations are not reported in the registry record. It is therefore not possible to determine whether results, if available elsewhere, would be based on all randomized participants, only participants with observed outcomes, or another population. The record also does not state whether an interim analysis was planned or conducted.

A sample-size justification and its design assumptions are not reported. The listed enrollment and the adverse-event denominators do not establish the statistical power for a particular sore-throat comparison. In general, planning calculations depend on the intended effect, outcome frequency, allocation, and analysis method; they should not be interpreted as observed power. These missing details constrain evaluation of the trial’s confirmatory intent and the robustness of any potential treatment-effect claim.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists serious adverse events, other adverse events, and deaths by group. Each listed count is zero. The at-risk denominators are 45 for placebo, 47 for preketorolac, 45 for postketorolac, and 43 for dexamethasone. These are the posted safety figures, and they should be read as event counts for the groups and denominators recorded, not as proof that the regimens carry no risk.

In general, a zero observed count does not show that an event is impossible or that the underlying risk is zero. The precision of a safety estimate depends on the amount of follow-up and how events were defined, monitored, and reported. The registry record does not provide those details, nor does it list serious adverse-event terms. It also does not describe the severity criteria used for other adverse events or the period over which safety events were collected.

These safety counts do not answer the primary question about sore-throat incidence. They are a separate reporting category and cannot substitute for the unreported primary outcome results. Comparisons of safety between groups also cannot be interpreted from counts alone without further information about ascertainment and analysis.

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

The registry record establishes that a randomized, quadruple-masked, parallel-group trial was conducted to study postoperative sore throat after thyroidectomy. It describes two ketorolac timing regimens, placebo, and dexamethasone, as well as a symptom definition and assessments at 1, 6 and 24 hours. It also records zero serious adverse events, zero other adverse events, and zero deaths in each group using the listed at-risk denominators.

Those details do not show whether ketorolac, dexamethasone, or placebo was associated with a lower or higher incidence of sore throat. The registry record reports no primary outcome estimates, confidence intervals, or analysis results. It also does not establish which treatment contrast or assessment time should be treated as the main comparison. The trial’s completed status and enrolled population cannot stand in for those missing outcome results.

In general, a randomized trial can provide evidence about the effect of treatment assignment when its outcomes are measured and analyzed according to a clear plan. Interpretation also depends on follow-up, missing data, the analysis population, precision, and the relevance of the population and regimens to the question at hand. The registry record does not report enough information to evaluate those elements for the primary endpoint.

The absence of an efficacy result should not be read as evidence of equivalence, no effect, or treatment failure. Those conclusions require estimates and an analysis suited to the intended question. Nor do the posted zero safety counts establish the absence of risk. The appropriate reading is narrower: the record documents the study design, endpoint definition, and selected safety counts, while the primary sore-throat findings and key statistical details are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial illustrates why describing an endpoint is not the same as reporting an analyzable result. The record defines postoperative sore throat using a threshold on a severity scale and identifies assessments at 1, 6 and 24 hours. These details help readers understand what was intended to be measured, but without the group-specific outcome counts and an analysis, they do not reveal the size or direction of any treatment contrast.

The design also highlights the importance of naming the primary comparison. There are four groups, including two ketorolac regimens that differ by timing, as well as placebo and dexamethasone. The brief summary frames ketorolac in comparison with dexamethasone, but the registry does not state one primary contrast or explain how multiple groups and repeated assessments were handled. This leaves readers unable to distinguish the main confirmatory question from other possible comparisons.

For clinical researchers and biostatisticians, the record is a reminder that transparent reporting should connect the research question to the endpoint definition, time point, analysis population, missing-data strategy, and statistical method. A stated masking category and randomization label are useful design information, but do not replace details on implementation or analysis. Safety counts also need context about event definitions and follow-up.

In general, complete reporting makes it possible to assess both the estimated effect and its precision, and to understand what question the estimate answers. In this case, the posted information supports a description of the trial’s intended structure, but not a conclusion about the primary efficacy question.

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 central limitation for interpretation is that primary sore-throat results are not reported in the registry record. There are no group-specific event counts, effect estimates, uncertainty intervals, or tests available for the endpoint. The record lists 0 analyses and does not reduce the multiple assessment times to one comparison, leaving the efficacy question unresolved in the posted information.

The intended primary contrast is also unclear. The brief summary describes evaluating ketorolac in comparison with dexamethasone, yet the registered arms include placebo and two ketorolac timing regimens. The record does not say which comparisons were planned as primary, whether timing was itself a target of comparison, or whether the repeated outcome assessments were analyzed jointly or separately.

Important design and analysis details are not reported: random-sequence generation, allocation concealment, masking roles, the statistical analysis plan, analysis population, missing-data handling, and any interim analysis. A sample-size justification is not reported, so the enrollment cannot be evaluated against a stated target effect or planned statistical procedure. The record also does not provide detail on the conduct of the trial beyond the registered regimens and timing.

The safety information is limited to the reported event counts and denominators. Definitions, monitoring methods, follow-up duration for safety, and detailed adverse-event terms are not reported. The listed zero counts therefore have limited interpretive scope and do not establish absence of risk. These limitations concern what can be concluded from the registry record; they do not establish whether additional information exists elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Effect of Prophylactic Ketorolac on Sore Throat After Thyroid Surgery — NCT02039427.
• Registry record last updated 2017-08-28; status last verified 2017-07.
• Results first posted 2017-07-31.
• 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 describes a completed randomized, quadruple-masked, parallel-group trial with enrollment of 192 and sponsor Yeungnam University College of Medicine. The study evaluated placebo, dexamethasone, and ketorolac administered before induction or near the end of thyroid surgery. Its primary endpoint was postoperative sore-throat incidence assessed at 1, 6 and 24 hours after thyroidectomy, using a symptom threshold based on a 0–3 severity scale.

The record does not report primary outcome results or analyses, and it does not identify a single primary comparison across the groups and times. It lists zero serious adverse events, zero other adverse events, and zero deaths in each group. Key statistical and design details, including the sample-size justification, missing-data handling, analysis population, and multiplicity approach, are not reported in the registry record.