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 Greater Occipital and Supraorbital Nerve Blockade in Migraine Patients (NCT03435185), a randomized na study. The primary outcome is Change of Frequency of Headache.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03435185 |
| Phase | NA |
| Condition | Migraine Disorders |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 103 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Dr. Lutfi Kirdar Kartal Training and Research Hospital |
| Results posted | Yes |
2. Clinical Question
Population
People with migraine without aura were the intended population in the investigators’ summary. The condition is listed as migraine disorders. Further eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
The blockade group received lidocaine injections to the greater occipital and supraorbital nerves. Injections were repeated weekly for three weeks, followed by clinical follow-up for two months.
Comparator
The placebo group received saline injections at the same nerve locations, also repeated weekly for three weeks, followed by two months of clinical follow-up.
Primary question
The primary question was whether the groups differed in change in headache frequency, measured as headache days in a month and averaged across both months of follow-up. Lower scores indicate a better outcome.
The study is registered as NCT03435185 and is titled “Greater Occipital and Supraorbital Nerve Blockade in Migraine Patients.” Its stated aim was to evaluate nerve blockade with local anesthetics as preventive treatment for migraine without aura. The registry identifies lidocaine and saline as the two procedures compared. It does not report additional clinical questions, eligibility details, or a more specific description of the intended patient population.
The primary outcome is a group-level comparison of a continuous measure, not a count of the number of participants who improved. The posted results describe the average score in each group and a mean difference between groups. Those summaries address the observed average outcome; they do not describe how every participant responded or establish that the intervention caused any observed difference.
3. Trial Design
The registry describes a randomized, single-masked, parallel-group trial. Random allocation means assignment to the study groups was intended to use a random process. Single masking indicates that one party was masked, but the registry record does not identify who was masked or provide details of how masking was maintained. In a parallel-group design, participants are assigned to a group and receive that group’s intervention rather than crossing between interventions.
The two groups were the Blockade Group and the Placebo Group. The former received lidocaine injections at the greater occipital and supraorbital nerves; the latter received saline injections at those sites. Both procedures were repeated weekly for three weeks. The descriptions say that participants were followed at a polyclinic for two months after treatment to assess clinical response. The outcome timeframe describes follow-up from baseline to two months after the first injection.
The record lists enrollment as 103. The posted primary-outcome results include 43 participants in the Blockade Group and 28 in the Placebo Group. These are the group sizes reported with the outcome, and they need not describe the full enrollment or the analysis population without further information. The reason for any difference between enrollment and the numbers contributing to the outcome is not reported in the registry record.
The study status is completed. The listed start date is 2014-09-01 and the primary completion date is 2015-06-01. The phase is recorded as NA. The sponsor is Dr. Lutfi Kirdar Kartal Training and Research Hospital. The registry record does not provide the original design assumptions, details of the allocation sequence, or a fuller account of masking and conduct.
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: 16 patients were excluded due to not meeting inclusion criteria
Overall Study
| Stage | Blockade Group | Placebo Group |
|---|---|---|
| STARTED | 44 | 43 |
| COMPLETED | 43 | 28 |
| NOT COMPLETED | 1 | 15 |
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 | Blockade Group | Placebo Group | Total |
|---|---|---|---|---|
| Participants analysed | 44 | 43 | 87 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 44 | 43 | 87 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 36 | 37 | 73 |
| Sex: Female, Male: Male | Participants | 8 | 6 | 14 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: Turkey | Participants | 44 | 43 | 87 |
6. Primary Endpoint
The registry lists the primary outcome as Change of Frequency of Headache, measured over Patients were followed up from baseline to 2 months after first injection..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled “Change of Frequency of Headache.” It measures the number of headache days in a month, on a score scale with a minimum of 0 and a maximum of 30. Scores from both follow-up months were averaged. Lower scores mean a better outcome. The timeframe is follow-up from baseline to two months after the first injection.
Headache frequency is a continuous outcome: it can take a range of score values rather than simply classifying participants as having or not having an event. The registry reports the mean and standard deviation for each group. The mean describes the group’s average score, while the standard deviation describes how dispersed individual scores are around that average. A group average is useful for comparing overall outcome levels, but it does not show the range of individual experiences or the proportion of participants with a particular response.
In general, repeated measurement over follow-up can provide information about the outcome across the specified period. In this record, the endpoint description says the monthly scores from both months were averaged; it does not give separate month-specific results. The title refers to change, but the posted group summaries are presented as scores and the comparison is a mean difference. Further details about the calculation of each participant’s change score are not reported in the registry record.
The endpoint is relevant to the stated preventive-treatment question because it captures headache frequency over time. It is not, by itself, a complete account of migraine burden, functioning, or other outcomes. The registry lists two outcome measures but identifies no posted secondary outcomes.
7. Results Posted in the Registry
- Blockade Group: mean 5.30 versus 7.50 on control; difference -2.20 (95% CI -5.66 to 1.26), standardized effect d = -0.30; z-test p = 0.213.
Mean difference: Blockade Group
95% CI: -5.66 to 1.26
Recalculated from the posted summary statistics
8. Statistical Interpretation
The posted primary-outcome means are 5.3 in the Blockade Group and 7.5 in the Placebo Group. The reported mean difference for Blockade Group compared with Placebo Group is -2.2, with an interval from -5.665 to 1.265 and an unadjusted p-value of 0.213. Because lower scores indicate a better outcome, the negative point estimate is in the direction of a lower average headache-frequency score in the Blockade Group. The interval includes values on either side of zero, so the posted estimate is compatible with a range of differences, including no difference.
The standard deviations are 7.4 for the Blockade Group and 7.2 for the Placebo Group. These values indicate substantial spread in scores relative to the group means, so the averages do not describe every participant’s outcome. The endpoint is based on a score with a specified range, and the registry provides no participant-level distribution or additional summary of how outcomes varied.
The unadjusted p-value is a measure of how unusual data at least as incompatible with a null hypothesis of no group difference would be under the statistical test’s assumptions. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of the difference. The registry record does not report an adjusted analysis or a broader statistical analysis plan. Thus the posted comparison should be read as the unadjusted summary that is available, not as evidence about analyses that are not reported.
The reported interval communicates uncertainty around the estimated mean difference. Its inclusion of zero indicates that the result does not pin down the direction of the underlying group difference precisely. The point estimate alone should not be treated as a definitive estimate of benefit or harm. Nor does the p-value establish equivalence: the record does not report an equivalence or non-inferiority design or a margin for such a conclusion.
The results are based on the outcome group sizes reported as 43 and 28, while the registry lists enrollment as 103. The relationship between those counts, the handling of missing observations, and the analysis population are not reported in the registry record. These gaps limit assessment of how representative the posted outcome comparison is of all enrolled participants. Overall, the record presents a lower average score in the blockade group, alongside uncertainty that spans both lower and higher scores relative to placebo. The results alone do not establish a causal or clinical conclusion.
9. Statistical Methods Explained
The posted primary comparison is a mean difference for a continuous outcome. The outcome is the number of headache days in a month, averaged across the two follow-up months. A mean difference subtracts one group’s average from the other group’s average according to the stated comparison direction. Here, the comparison is Blockade Group relative to Placebo Group, and the reported estimate is -2.2. The negative sign therefore describes a lower observed group mean in the Blockade Group. It does not mean that every participant had a lower score.
What does the standard deviation describe?
The standard deviation summarizes dispersion among scores within a group. A larger standard deviation means that individual observations tend to lie farther from their group mean; a smaller one indicates less spread. The reported standard deviations are 7.4 for the Blockade Group and 7.2 for the Placebo Group. These measures are not standard errors and do not directly quantify uncertainty in the group means. Standard errors concern how precisely a mean is estimated, while standard deviations describe variation among observed scores.
In general, variability matters because a noisy outcome can make a group difference harder to estimate precisely. The posted comparison incorporates uncertainty around the estimated difference, while the standard deviations give context about outcome spread. The registry does not report participant-level data, so distribution shape, outliers, or other features that could affect an analysis cannot be assessed from these summaries alone.
How should the mean difference be read?
The estimate of -2.2 is the observed difference in group averages, with the stated direction of Blockade Group compared with Placebo Group. Because lower outcome scores are defined as better, the point estimate favors a lower average score in the blockade group in a descriptive sense. This wording describes the direction of the posted estimate, not proof of a treatment effect. Randomized assignment can support a causal comparison when design and analysis are appropriately conducted, but the available record does not report all details needed to evaluate that process.
In general, a confidence interval gives a range of estimates compatible with the data and the interval’s statistical procedure. The posted interval is -5.665 to 1.265. Since this range includes zero, it includes the possibility of no mean difference and values on either side of zero. It also expresses that the estimate is not very precise about the direction and size of the underlying difference. The confidence level for this interval is not reported in the registry record, so it should not be assigned a level that the record does not state.
What does the p-value add?
The unadjusted p-value is 0.213. In general, a p-value describes the compatibility of the observed data with a specified null model, under the assumptions of the analysis. It is not a measure of the probability that a treatment works, and it does not quantify the probability that the observed result occurred by chance. It also does not measure the magnitude or importance of the estimated difference. The registry does not report a multiplicity adjustment or a test specification beyond the posted unadjusted result.
The estimate, interval, and p-value answer related but different questions. The estimate gives the direction and size of the observed difference; the interval conveys uncertainty around it; and the p-value describes compatibility with a null hypothesis under a test. None alone can establish a clinical conclusion. Reading them together avoids overemphasizing a single threshold or treating a point estimate as exact.
Why does randomization matter?
In general, random assignment is intended to make groups comparable, on average, with respect to factors present before treatment. It does not guarantee identical groups in a particular trial, especially when group sizes are limited, and it cannot correct problems arising after allocation. The registry identifies the trial as randomized but does not report sequence generation, concealment, baseline balance, or the methods used to handle departures from assigned treatment. Consequently, the label alone does not resolve questions about implementation.
The design is described as single-masked, but the masked party and details of the masking procedure are not reported. Masking can help reduce certain biases in outcome assessment or participant behavior, depending on who is masked and how it is carried out. Without those details, the possible role of masking cannot be evaluated fully.
What information is absent from the analysis record?
The registry reports zero analyses and does not provide a fuller statistical plan. The original sample-size rationale, assumptions behind the trial’s design, and handling of missing outcome data are not reported in the registry record. The outcome group sizes are 43 and 28, while listed enrollment is 103; the record does not explain the relationship. No adjusted result is posted. The reported comparison should therefore be interpreted as the available summary, with these limits on reconstructing the analysis.
In general, a complete analysis account would clarify which participants contributed to each endpoint, how missing data were handled, whether the model adjusted for baseline values or other factors, and how multiple outcomes or analyses were addressed. Those details are not available. The methods that can be described with confidence are limited to the registry’s stated randomized, single-masked, parallel design and the posted unadjusted mean comparison.
10. Confidence Intervals and Precision
The reported mean difference is -2.2, and its interval extends from -5.665 to 1.265. The interval is important because it shows that the estimate is uncertain: it includes zero as well as differences on both sides of zero. The point estimate is therefore not a precise determination of the direction or magnitude of the underlying group difference.
In general, an interval is a range produced by a statistical procedure to convey uncertainty about an estimate. A narrower interval indicates greater precision than a wider interval, all else equal. An interval that includes zero does not prove there is no difference; it indicates that the data and method remain compatible with zero as well as with nonzero values in the interval. The confidence level used for the posted interval is not reported in the registry record.
The group standard deviations are 7.4 and 7.2, and the outcome group sizes are 43 and 28. These summaries give context for the observed variation and the comparison, but they do not remove uncertainty. The registry does not report participant-level data, a model-based adjusted estimate, or details of missing-data handling. It is therefore not possible from the posted summaries alone to assess sensitivity to those choices.
The unadjusted p-value is 0.213. It should be read alongside the interval and estimate rather than as a stand-alone verdict. The results do not precisely establish whether the average score is lower or higher in the underlying groups, and the interval should not be interpreted as a range containing every participant’s outcome.
11. Planning a Similar Trial: Sample Size
This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.
| Effect to detect | Participants per arm, 80% power | Participants per arm, 90% power |
|---|---|---|
| 100% of the observed effect | 174 | 233 |
| 75% of the observed effect | 310 | 414 |
| 50% of the observed effect | 696 | 932 |
The planning figures are illustrations based on the observed effect, not the trial’s original design assumptions. The record states a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The planning exercise considers detecting the stated fraction of the observed effect. For this continuous outcome, the figures are participants per arm; the record’s distinction about total event counts applies to time-to-event calculations, not this comparison.
The column for 80% power gives the planned number of participants per arm under the stated assumptions for a hypothetical study to have an 80% chance of detecting the selected effect if that effect were the true one and the assumptions held. The 90% power column expresses the corresponding planning target for a 90% chance. These are design probabilities for hypothetical studies, not probabilities that this trial’s result is correct. This is not observed power.
The rows consider planning for 100% of the observed effect, planning for 75% of the observed effect, and planning for 50% of the observed effect. The listed figures are participants per arm for 80% power and participants per arm for 90% power. Smaller effects are harder to distinguish from random variation, so they require more participants under the same planning assumptions. This is a general feature of statistical planning, not evidence that a future study would necessarily observe any particular effect.
Because the observed estimate itself is uncertain, planning directly from it is only an illustration. A different assumed effect, variability, allocation, significance level, or analysis method could change the required number. The trial’s own original sample-size justification and assumptions are not reported in the registry record.
12. How the Sample Size Is Derived
Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z1−α/2 = 1.960) and the desired power (z1−β = 0.842 for 80% and 1.282 for 90%).
Formula
n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.
Worked calculation for this trial
- Observed difference Δ = -2.200; pooled standard deviation σ = 7.322.
- n = 2 × (1.96 + 0.842)2 × 7.3222 / -2.2002 = 173.9, rounded up to 174 participants per arm for 80% power.
The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).
R code
alpha <- 0.05
z_a <- qnorm(1 - alpha / 2) # two-sided
delta <- -2.2 # observed difference in means
sigma <- 7.32238972633578 # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))
# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")
# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3435185)
n <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n)) # difference in sample means
s2 <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1)) # pooled sample variance
tstat <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))
Output from running the code
100% of observed effect: n per arm = 174 (80% power), 233 (90% power)
75% of observed effect: n per arm = 310 (80% power), 414 (90% power)
50% of observed effect: n per arm = 696 (80% power), 932 (90% power)
power.t.test: 174.9
Simulated power at n = 174 per arm: 0.800 (20000 replicates)The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.
13. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures and identifies the headache-frequency measure as primary. It lists zero posted secondary outcomes and zero analyses. No multiplicity procedure is reported. Multiplicity arises when researchers examine multiple outcomes, comparisons, time points, or analyses; in general, considering more opportunities for a positive finding can affect the interpretation of statistical evidence. The available record does not establish what analyses were conducted beyond the posted result, so the extent of any multiplicity issue cannot be assessed.
The primary result is reported as an unadjusted mean difference with an unadjusted p-value. The registry does not identify any adjustment for baseline score or other variables, and it does not report a model description or a detailed analysis plan. The absence of those details does not show that no such methods were used; it means they are not reported in the registry record.
Missing-data handling is also not reported. The posted outcome group sizes are 43 in the Blockade Group and 28 in the Placebo Group, while enrollment is listed as 103. The record does not explain whether every enrolled participant was randomized, whether all randomized participants contributed to the endpoint, or why the outcome counts differ from enrollment. It does not state how missing scores, withdrawals, or incomplete follow-up were handled.
The analysis population is not reported in the registry record. In general, an analysis account may specify whether participants are analyzed according to their assigned group, whether only participants completing treatment are included, or whether another population is used. Those distinctions can affect interpretation, particularly when outcomes are missing or participants do not follow assigned treatment. No such population definition is posted for this comparison.
These reporting gaps limit assessment of the robustness of the primary result. They do not justify assuming that a particular analysis or missing-data approach was used. The posted mean difference, interval, and p-value should be understood as the available unadjusted comparison, with no reported information to establish how it relates to other possible analyses.
14. 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 |
|---|---|---|---|
| Blockade Group | 0 | 43 | 0.0% |
| Placebo Group | 0 | 28 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Blockade Group | 0 of 43 |
| Placebo Group | 0 of 28 |
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 |
|---|---|
| Blockade Group | 37 of 43 |
| Placebo Group | 19 of 28 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Blockade Group | Placebo Group |
|---|---|---|---|
| Minor Bleedings | Skin and subcutaneous tissue disorders | 37 of 43 | 19 of 28 |
The adverse-event record reports zero serious adverse events in the Blockade Group among 43 at risk and zero in the Placebo Group among 28 at risk. It reports no deaths in either group. The record also lists other adverse events affecting 37 in the Blockade Group and 19 in the Placebo Group, with 43 and 28 respectively at risk.
These figures should be read as the counts recorded in the registry, not as a complete description of the nature, timing, severity, or duration of events. No serious adverse-event terms are listed. The registry does not provide a breakdown of the other adverse events or say how they were defined, collected, or judged to be related to the procedures. The adverse-event follow-up period is not specified separately in the posted safety information.
Zero reported serious events does not establish that no such event could occur, and the counts do not permit a broad conclusion about comparative safety. In general, safety interpretation depends on event definitions, observation time, completeness of reporting, and the size and characteristics of the population observed. The available figures are descriptive registry counts and do not provide medical advice or determine an individual’s risk.
15. What the Result Does, and Does Not, Mean
The posted data show lower average headache-frequency scores in the Blockade Group than in the Placebo Group: the means are 5.3 and 7.5, respectively. The reported mean difference is -2.2. Since lower scores are defined as better, the point estimate is in the direction of a lower average score with blockade. The interval, from -5.665 to 1.265, includes zero and values on both sides, so the result does not precisely determine the direction or size of the underlying group difference.
The unadjusted p-value of 0.213 does not establish that the groups are the same, and it does not show that the treatment is ineffective. It describes the data’s compatibility with a null model under the test assumptions. The interval and point estimate are more informative about the range and direction of possible differences, while neither establishes clinical importance. The registry does not report a threshold for a clinically meaningful difference.
The result is an average across a specified outcome: monthly headache days averaged over the two follow-up months. It does not show how outcomes differed month by month, what happened to each participant, or how other aspects of migraine were affected. The outcome group sizes and missing-data methods are not fully explained, so the relationship between the posted results and the listed enrollment cannot be determined from the record.
In general, randomized comparisons can help estimate differences between assigned groups, but conclusions depend on implementation, outcome measurement, analysis, and reporting. Details about sequence generation, masking, baseline balance, analysis populations, and handling of missing observations are not reported. The registry record also does not provide an adjusted analysis or posted secondary outcomes.
Accordingly, the finding is best described as an imprecise unadjusted comparison with a point estimate favoring a lower average score in the blockade group. It does not establish a causal conclusion, equivalence, or an individual treatment response. It also does not support medical advice. Interpretation should remain limited to the stated endpoint and the information recorded.
16. Why This Trial Matters Statistically
This trial offers a useful example of why an observed difference and its precision must be considered together. The point estimate is -2.2, but the interval extends from -5.665 to 1.265. The point estimate gives a simple summary of the direction and size of the observed contrast; the interval makes clear that uncertainty remains about the underlying difference. Focusing only on the point estimate or only on the unadjusted p-value would omit important information.
The endpoint is a continuous average of headache days across the two follow-up months. Continuous outcomes preserve more graded information than a simple classification of participants into response categories, but group means can obscure variation between people. The standard deviations of 7.4 and 7.2 provide context for that variation. In general, substantial outcome variability can make a mean difference less precise, which is one reason the uncertainty interval matters.
The record also illustrates a common distinction between trial enrollment and endpoint analysis counts. Enrollment is listed as 103, whereas the primary outcome is reported for groups of 43 and 28. Without an account of participant flow, missing observations, and analysis population, readers cannot fully reconstruct how the endpoint results relate to the enrolled study population. Reporting those details is important for assessing the credibility and applicability of a comparison.
Finally, the sample-size illustration is not a substitute for the original design rationale. Planning from an observed effect can show how assumptions about the target effect influence a future study’s size, but the observed estimate is uncertain. Distinguishing such planning illustrations from observed power and from the trial’s original design helps avoid overstating what the registry result can tell readers.
17. 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 several trial-specific uncertainties. It identifies randomization but does not report the sequence-generation method or allocation concealment. It says the study was single-masked but does not identify who was masked or explain how masking was maintained. These omissions make it difficult to assess potential sources of bias in assignment, participant experience, or outcome assessment.
The record lists enrollment as 103, but the primary outcome group sizes are 43 and 28. It does not provide a participant-flow account explaining the relationship between these counts, nor does it state how missing outcome values, withdrawals, or incomplete follow-up were handled. The analysis population is also not reported. These details matter when judging whether the posted estimates reflect all randomized participants or a subset defined in another way.
The outcome title refers to change in headache frequency, while the description says monthly scores from both follow-up months were averaged. The record does not explain in further detail how individual change was calculated or provide separate results for each month. It reports group means and standard deviations, but not participant-level distributions, baseline group summaries, or an adjusted comparison. The interval’s confidence level is not stated.
The registry lists two outcome measures but no posted secondary outcomes or analyses. It does not report a full analysis plan, multiplicity handling, a clinically meaningful threshold, or the original sample-size justification. Safety reporting is limited to counts of serious events, deaths, and other events affected; event descriptions and collection details are not included. These reporting limitations should be kept distinct from claims about what investigators did: the missing information is not reported in the registry record.
18. Related Tutorials
19. Related Statistical Calculators
20. Sources
- ClinicalTrials.gov: Greater Occipital and Supraorbital Nerve Blockade in Migraine Patients — NCT03435185.
- Registry record last updated 2022-03-23; status last verified 2022-03.
- Results first posted 2019-07-22.
- 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.
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.
21. Record Summary
NCT03435185 is a completed, randomized, single-masked, parallel-group trial titled “Greater Occipital and Supraorbital Nerve Blockade in Migraine Patients.” Its stated aim was to evaluate greater occipital and supraorbital nerve blockade with local anesthetics for preventive treatment of migraine without aura. The intervention was lidocaine injections and the comparator was saline injections, each repeated weekly for three weeks.
The primary outcome was headache frequency, measured as monthly headache days averaged across both months of follow-up; lower scores indicate a better outcome. The posted means were 5.3 for the Blockade Group and 7.5 for the Placebo Group, with a mean difference of -2.2 and an unadjusted p-value of 0.213. The interval for the difference was -5.665 to 1.265.
The registry lists enrollment as 103 and reports primary-outcome group sizes of 43 and 28. It also records zero serious adverse events and zero deaths in both groups. The record does not explain the difference between enrollment and outcome counts or report full methods for missing data and analysis populations.