Greater Occipital Nerve Block Versus Metoclopramide: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Greater Occipital Nerve Block Versus Metoclopramide (NCT03269435), a randomized phase 4 study. The primary outcome is 0-10 Pain Score.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group phase 4 trial. It reports quadruple masking, while the brief summary calls the study double-blind and double-dummy. The arm descriptions show that each group received an active treatment alongside a matching saline procedure or infusion: the nerve-block arm received bupivacaine with intravenous normal saline, and the metoclopramide arm received the drug with a bilateral saline nerve block. The record does not identify the roles covered by the masking description.

Enrollment was 99. The primary outcome lists 51 participants for the greater occipital nerve block arm and 48 for the metoclopramide arm. The registry lists the study as completed, with a start date of 2017-11-01 and primary completion date of 2020-03-21. The sponsor is Montefiore Medical Center. These administrative details describe the registered study; they do not establish how participants were recruited, how allocation was generated or concealed, or whether the planned procedures were followed. Those details are not reported in the registry record.

The primary outcome is a continuous pain measure assessed at baseline and one hour, expressed as change in pain. The secondary outcomes concern sustained headache relief and sustained headache freedom at 48 hours. The record posts participant counts for these secondary outcomes and recalculated comparisons, but reports no sponsor analyses. Details of the analysis population, handling of missing observations, protocol deviations, and the statistical analysis plan 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

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 0-10 Pain Score, measured over one hour.

The primary endpoint is the change in pain score from baseline to one hour. Pain is assessed on a 0-10 scale, with 0 defined as no pain and 10 as the worst imaginable pain. A change score is intended to capture how a participant’s reported pain differs across the specified assessment times, rather than the score at one time alone. The registry identifies the outcome statistic as a mean and gives a 95% confidence interval for each arm.

Repeated measurement of pain can make an early symptom outcome relevant to the acute emergency-department setting described in the trial summary. The one-hour assessment specifies a short-term time point; it does not, by itself, describe the later course of headache. The registry separately lists sustained headache outcomes at 48 hours.

The posted primary values are 5.0 for the greater occipital nerve block arm, with a 95% confidence interval from 4.1 to 5.8, and 6.1 for the metoclopramide arm, with a 95% confidence interval from 5.2 to 6.9. The record does not explain the direction or coding convention for the change score beyond describing it as change in pain. It also does not report a between-arm estimate or inferential analysis for this continuous outcome. Consequently, the arm summaries alone do not provide a directly reported estimate of the comparative treatment effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: each participant’s pain score is measured on a 0-10 scale, and the endpoint is described as change between baseline and one hour. For a continuous outcome, a mean summarizes the center of the observed values. A confidence interval expresses the statistical uncertainty associated with that mean, conditional on the analysis and its assumptions. It does not show the range of individual scores or guarantee that the true value lies within the interval.

The registry lists a mean and 95% confidence interval for each primary-outcome arm. It does not post a standard deviation, standard error, or a direct contrast between arms. Nor does it provide an inferential analysis for the comparison. An arm-level interval cannot substitute for an interval around the between-arm difference: the latter depends on the uncertainty of the contrast and the relationship between the arm estimates. The registry’s note says values are missing or not estimable for a two-arm comparison of this continuous endpoint. As a result, no comparative confidence interval or p-value can be interpreted for the primary outcome from this record.

What do the secondary risk differences represent?

The secondary outcomes are binary: a participant either is or is not counted as having sustained headache relief or sustained headache freedom at 48 hours. A risk difference expresses the difference between the outcome proportions in the groups being compared. The posted recalculations compare metoclopramide with greater occipital nerve block. A positive estimate indicates that the observed outcome proportion is higher in the metoclopramide group in that calculation; it is not, by itself, proof of a difference beyond sampling uncertainty.

For sustained headache relief, the recalculated risk difference is 0.167, with a 95% confidence interval from -0.012 to 0.346. For sustained headache freedom, it is 0.087, with a 95% confidence interval from -0.032 to 0.206. Both intervals include zero, the value corresponding to no difference in proportions. Their widths indicate uncertainty about the size and direction of the underlying difference. The unadjusted p-values are 0.07 and 0.151, respectively. A p-value measures how compatible the observed data are with a specified null model under the analysis assumptions; it is not the probability that the null hypothesis is true, and it does not measure clinical importance.

Why distinguish registry analyses from recalculations?

The registry reports participant counts for the secondary outcomes but lists no reported analyses. The comparisons and associated p-values are recalculated from the posted summary counts. They are simple, unadjusted comparisons and may not reproduce an analysis that accounts for design features, covariates, missing observations, or prespecified modeling choices. No such sponsor analysis is available in the registry record. The record indicates no discrepancy between the posted figures and the recalculations, but a sponsor’s own analysis would take precedence if a discrepancy were present.

How should the planning illustrations be read?

The planning illustrations use the observed secondary-outcome effects as starting points. They assume a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. They show participants per arm for 80% power and participants per arm for 90% power when planning for 100%, 75%, or 50% of the observed effect. For sustained headache relief, the listed values range from 117 participants per arm for 80% power when planning for 100% of the observed effect to 428 participants per arm for 80% power when planning for 50% of the observed effect; the corresponding 90% planning values are 156 and 573. For sustained headache freedom, the corresponding 80% values are 190 and 614, and the 90% values are 253 and 821.

These are planning illustrations, not observed power and not evidence that the trial was designed around those assumptions. The registry does not report the trial’s sample-size justification. Planning from an observed effect can be unstable, particularly when estimates are imprecise, and a smaller assumed effect generally requires more participants to detect under otherwise fixed assumptions. The calculations do not establish that a future study will achieve its target power if actual outcomes, allocation, missingness, or analysis differ from the assumptions.

What statistical details remain unavailable?

The registry does not report the primary comparison method, the handling of missing outcome data, whether analyses followed randomized assignment, how any protocol deviations were handled, or whether covariate adjustment was planned. It also does not report interim analyses or a multiplicity procedure. Such details affect how estimates and uncertainty should be interpreted. Without them, the posted arm summaries and unadjusted recalculations are informative descriptions, but they cannot be treated as a complete prespecified analysis of the trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and two secondary outcomes, but it does not report a multiplicity procedure or a hierarchy specifying how the outcomes were to be interpreted. When several outcomes are tested, unadjusted p-values do not account for the fact that multiple opportunities to observe a seemingly noteworthy result may exist. This does not make the posted results unusable; it means that individual unadjusted secondary p-values should not be treated as if they were the sole planned test. Whether an adjustment or another prespecified strategy was used is not reported in the registry record.

Missing-data handling is also not reported. The primary outcome lists 51 participants in the block arm and 48 in the metoclopramide arm. Sustained headache relief lists 51 and 47, while sustained headache freedom lists 51 and 48. These are the denominators shown for the respective outcome summaries. The record does not explain why the listed denominators differ, whether observations were missing, how missing observations were handled, or whether the analysis included all randomized participants. It is not appropriate to infer reasons from the counts alone.

The registry does not identify an intention-to-treat, per-protocol, or other analysis population. It also does not report how protocol deviations, withdrawals, or unavailable follow-up assessments were handled. A complete interpretation would benefit from knowing whether the analysis population and missing-data methods were prespecified and whether sensitivity analyses were performed. Those details are not reported in the registry record.

No interim analyses or stopping rules are reported, and no statistical analysis plan is described. Their absence from the record does not establish that they were not used; it means their role cannot be assessed from the registry entry. Similarly, no sponsor-reported analyses are listed for the secondary outcomes, and the primary comparison is not available. The recalculated secondary comparisons should therefore be distinguished from a complete, documented analysis plan.

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.

Most frequent non-serious adverse event terms

The safety summary records zero serious adverse events in each arm: 0 of 51 participants in the greater occipital nerve block arm and 0 of 48 in the metoclopramide arm. It also records zero deaths in each arm. These counts describe what is posted in the registry; they do not establish that the treatments have equivalent safety or that serious events could not occur.

Other adverse events are recorded for 16 of 51 participants in the block arm and 18 of 48 in the metoclopramide arm. The registry does not provide event-level descriptions in the listed safety summary, and no top serious-event terms are listed. The record does not specify the observation period, event definitions, severity grading, or whether participants could contribute more than one event. The counts therefore should not be converted into claims about event rates or compared as if the event types and ascertainment were fully characterized.

Rare events are difficult to assess from a trial of this size, and a zero count is a statement about the observed record, not proof of absence of risk. These figures are descriptive and should be read alongside the limited safety detail available in the registry record.

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

The registry records arm-specific mean values for the one-hour change-in-pain endpoint and participant counts for the 48-hour secondary outcomes. These summaries describe the outcomes posted for this randomized trial. They do not, on their own, establish that one treatment caused a better or worse outcome than the other. The primary continuous outcome lacks a reported between-arm estimate and inferential analysis, leaving the central comparative question without a directly posted statistical contrast.

The secondary recalculations show positive risk-difference estimates for metoclopramide relative to the block, but their confidence intervals include no difference and span a range of possible effects. The p-values are unadjusted and are based on recalculations from the posted counts, not on sponsor-reported analyses. The trial’s registry record does not state how multiplicity was addressed or how missing observations were handled. Those limits matter when weighing secondary results.

Neither the arm-level confidence intervals nor the secondary comparisons describe the experience of every participant. A mean can conceal variation among individual responses, and a count does not explain the timing, duration, or severity of each person’s symptoms. The registry does not provide the full outcome distributions or detailed analysis populations needed to examine those aspects.

The results should also not be generalized beyond the study context without further evidence. The registry summary describes people presenting to an emergency department for acute migraine, but details of eligibility and participant characteristics are not reported in the registry record. The posted statistics are not medical advice and do not determine an appropriate treatment for an individual. They characterize the registered trial record and its statistical reporting, with important comparative and methodological details unavailable.

13. Why This Trial Matters Statistically

This trial is statistically instructive because it distinguishes an arm-level summary from a treatment comparison. The primary outcome is a continuous measure, and the registry gives a mean and confidence interval for each arm. Those values can describe each group, but the comparative question requires an estimate of the difference between groups and its uncertainty. That contrast is not reported for the primary outcome. Readers should not reconstruct it from the separate intervals or treat visual proximity of arm summaries as a formal test.

The secondary results illustrate a different issue: a point estimate can suggest a direction while the confidence interval remains compatible with no difference and with a range of possible effects. The recalculated risk differences are based on posted counts, and their uncertainty is substantial. The unadjusted p-values do not resolve the uncertainty, especially when the registry does not describe a multiplicity plan or sponsor analyses.

The record also makes clear why analysis details matter. Denominators vary across the posted outcomes, but explanations for those differences and the handling of missing data are not reported. Without a stated analysis population, missing-data strategy, or statistical plan, readers cannot determine whether the available summaries represent the intended analysis or how robust conclusions might be to alternative choices.

Finally, planning illustrations based on observed effects are not retrospective proof that a study had adequate power. They are conditional calculations for future planning under explicit assumptions, while the trial’s own sample-size justification is not reported. Together, these points show how careful separation of descriptive results, inferential comparisons, and planning calculations helps prevent stronger conclusions than the registry record supports.

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 trial-specific limitation in the registry record is the missing comparative analysis for the primary endpoint. Although arm-level means and confidence intervals are posted, the record does not provide an estimate or uncertainty interval for the between-arm difference. Its note states that values were missing or not estimable for the continuous two-arm comparison. This limits direct interpretation of the outcome identified as primary.

The secondary comparisons are recalculated from participant counts, and the record lists no sponsor analyses. The recalculations are unadjusted, and the record does not report a multiplicity approach. It also does not report the statistical analysis plan, the analysis population, handling of missing outcome data, interim analyses, or the sample-size justification. Those omissions prevent assessment of whether the posted statistics match prespecified methods.

The outcome denominators are not identical across the primary endpoint and all secondary outcomes. The registry does not explain the differences or say whether they reflect missing follow-up, eligibility for a particular outcome, or another reason. No reason should be inferred from the denominators alone. The record also provides limited information about participant characteristics and eligibility, constraining assessment of how well the enrolled group represents the emergency-department population described in the summary.

The safety summary provides counts but limited event detail. Serious-event counts and deaths are zero in both arms, while other adverse-event counts are posted without listed event terms or a stated observation period. The record does not describe event definitions or severity. These reporting limits mean the safety figures should be treated as a brief registry summary rather than a comprehensive characterization.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Greater Occipital Nerve Block Versus Metoclopramide — NCT03269435.
• Registry record last updated 2021-09-22; status last verified 2021-08.
• Results first posted 2021-09-22.
• 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

NCT03269435 is a completed, randomized, parallel-group phase 4 trial sponsored by Montefiore Medical Center. The registry reports enrollment of 99 and describes a comparison of bilateral greater occipital nerve block with bupivacaine 0.5% against metoclopramide 10mg intravenously, with matching saline procedures or infusions. The brief summary describes a double-blind, double-dummy study; the design fields list quadruple masking.

The primary outcome is mean change in pain score from baseline to one hour on a 0-10 scale. The record posts arm-specific means and 95% confidence intervals but no comparative analysis. Secondary outcomes are sustained headache relief and sustained headache freedom at 48 hours. Recalculated, unadjusted comparisons are available for those outcomes, while sponsor-reported analyses are not listed.

The record does not report key statistical details, including the analysis plan, missing-data methods, multiplicity approach, or sample-size justification. Serious adverse events and deaths are recorded as zero in both arms; other adverse-event counts are also posted, with limited event detail.