Comparison of the Efficacy of Two Different Suprascapular Nerve Block Techniques in Patients With Chronic Shoulder Pain: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of the Efficacy of Two Different Suprascapular Nerve Block Techniques in Patients With Chronic Shoulder Pain (NCT04938037), a randomized na study. The primary outcome is Change of Shoulder Pain and Disability Index (SPADI).

2. Clinical Question

The clinical question concerns the relative outcomes of two block locations, rather than a comparison between receiving a block and receiving no block. The registry describes the suprascapular notch as the most commonly used technique and identifies the spinoglenoid notch as the alternative under study. Because both arms are described as receiving the same medications, the main contrast is the recorded injection approach. The record also lists changes in Visual Analog Scale (VAS), Range of Motion (ROM), and Pain Pressure Threshold (PPT), along with patient satisfaction, as secondary outcomes.

The primary outcome is evaluated across baseline and several follow-up assessments. That makes the time course relevant: a difference at one follow-up would not by itself establish that the approaches differ at every assessment. The registry record does not report a single numerical contrast, an estimate of change in either group, or a statistical test for the primary outcome. It therefore does not establish from the recorded primary results whether the observed SPADI patterns favored either approach, or how precisely any difference was estimated.

3. Trial Design

The registry describes a prospective, randomized, double-blinded, parallel-group study of two ultrasound-guided suprascapular nerve block techniques in people with chronic shoulder pain. Enrollment is recorded as 80. The study status is completed; its start date is 2021-06-01 and its primary completion date is 2022-08-05. TC Erciyes University is listed as sponsor. The phase is recorded as NA.

Both groups are described as receiving 1ml methylprednisolone acetate (1ml / 40mg) and 5ml 0.5% bupivacaine under ultrasound guidance. The listed difference is the anatomical route: through the spinoglenoid notch or through the suprascapular notch. This design makes the location of the block the intended comparison, while the recorded medication regimen is the same in both arm descriptions.

Random allocation can help balance participant characteristics across groups on average, including characteristics that may not have been measured. It does not guarantee that groups are identical, especially in a study of this size, and the registry record does not give details of the allocation sequence or concealment. Double masking is recorded, but the record does not specify which study roles were masked or how masking was maintained when the two procedures were performed.

The registry lists SPADI change as the primary outcome, assessed at baseline and 1, 4, and 12 weeks after injection. It lists four secondary outcome categories: VAS change, ROM change, PPT change, and patient satisfaction. The record reports 5 outcome measures and 0 analyses. It does not report the statistical plan, the analysis population, participant flow, or numerical primary-outcome estimates. A completed status indicates the study is recorded as completed; it does not itself provide the results needed to assess the comparative outcome.

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

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 Change of Shoulder Pain and Disability Index (SPADI), measured over Baseline and 1, 4, and 12 weeks after injection.

The primary endpoint is change in the Shoulder Pain and Disability Index (SPADI). The registry describes SPADI as a 13-item measure covering pain and disability: a 5-item pain subscale and an 8-item disability subscale. Each item is scored between 0 and 10, with pain, disability, and total scores converted separately to a 100-point scale. Higher scores indicate greater shoulder-related pain and disability.

SPADI is used to represent patients’ shoulder-related symptoms and functional difficulty in a structured, score-based form. A continuous measure can capture differences across a range of reported severity rather than reducing the outcome to a simple event/no-event category. The registry records the outcome as a mean with standard deviation, and specifies baseline and follow-up assessments at 1, 4, and 12 weeks after injection.

Interpreting change requires knowing the direction of scoring: because higher SPADI scores indicate more pain and disability, a decrease in score corresponds to improvement on the scale, while an increase corresponds to worsening. That scale interpretation does not establish what happened in this trial. The registry record does not report group means, mean changes, a between-group contrast, or uncertainty estimates for SPADI. It also does not state which SPADI score—pain, disability, or total—was used as the reported primary comparison, beyond describing the measure and its score components.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on distinguishing the study design, the outcome definition, the estimand of interest, and the uncertainty around an estimate. The registry identifies a randomized parallel-group comparison, a continuous primary outcome, and repeated assessments. It does not report the primary-outcome analysis or the statistical plan, so general statistical concepts can clarify what such an analysis would mean without implying that any particular method was used.

What is the treatment contrast?

In general, a randomized two-arm study estimates a contrast between outcomes under the two assigned approaches. For a continuous endpoint, that contrast might be expressed as a difference in mean score or a difference in mean change. These are not interchangeable unless the analysis and assumptions make them so. A comparison of change would use information from baseline and follow-up; a comparison of follow-up scores could account for baseline in another way. The registry does not state which contrast was planned or used.

Within-arm change alone is not the randomized comparison. If one group’s score changes, that does not show that its change differs from the other group’s change. The comparative estimate needs to directly contrast the groups, and its interpretation depends on how baseline values, follow-up timing, and repeated observations are handled. No such estimate is reported in the registry record.

What does a mean and standard deviation describe?

For a continuous measure, the mean describes the average score in the group being summarized. The standard deviation describes the spread of individual scores around that average. It is not the same as a confidence interval: a standard deviation describes variation among observations, whereas a confidence interval describes uncertainty about an estimated quantity, such as a group mean or a between-group difference.

A confidence interval gives a range of values compatible with the data under the statistical model and procedure used. Its width reflects precision: narrower intervals indicate greater precision, while wider intervals indicate more uncertainty. The interval should be interpreted alongside the estimate and the clinical scale. The registry record does not report SPADI confidence intervals, standard deviations by group, or a between-group estimate, so the precision of the primary comparison cannot be evaluated.

How do repeated assessments affect interpretation?

SPADI is scheduled at baseline and 1, 4, and 12 weeks after injection. Repeated observations from the same participant are generally related rather than independent. General statistical approaches can account for that dependence by modeling the repeated measurements or by selecting a defined follow-up comparison. Which approach is appropriate depends on the study question, data structure, and prespecified analysis.

Multiple follow-up times can also create multiple opportunities to identify an apparent difference. General statistical practice distinguishes a prespecified primary contrast from exploratory or secondary comparisons and considers whether adjustment for multiple testing is needed. The registry record does not report a multiplicity strategy, a prespecified primary follow-up among the listed assessments, or the results at individual time points. Its outcome description notes several categories or time points and the record does not reduce them to a single comparison.

Why report uncertainty and not only a significance test?

A p-value, when reported, describes how compatible the observed data are with a specified null model under the assumptions of the test. It does not measure the probability that the null hypothesis is true, and it does not show the size or clinical importance of an effect. An estimate with a confidence interval is more informative about the magnitude and precision of the comparison. Neither p-values nor confidence intervals for the primary outcome are reported in the registry record.

Statistical significance and clinical importance are also distinct. A small estimated difference may be statistically distinguishable from no difference under some conditions but not necessarily meaningful to patients; conversely, a potentially meaningful estimate may be imprecise. Interpreting SPADI would require the actual comparative estimate and context for what magnitude of change is meaningful. The registry record does not specify a meaningful-change threshold or report the estimate needed for that assessment.

What can planning illustrations tell a reader?

General sample-size calculations illustrate the amount of information a future study might need to detect a chosen effect under specified assumptions. The planning illustration associated with this record is described as being computed from the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such planning values are not observed power and do not demonstrate that the completed trial was adequately powered. They also do not replace the study’s own design justification, which is not reported in the registry record.

For continuous outcomes, planning calculations depend on assumptions about the target effect and variability. If those assumptions differ from the values that apply in a future setting, the illustration may not transfer directly. The registry record does not report its original sample-size justification. The calculated planning values therefore have a different purpose from an analysis of the randomized participants and should not be read as evidence about the primary outcome.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists SPADI change as the primary outcome at baseline and 1, 4, and 12 weeks after injection. It also lists VAS change, ROM change, PPT change, and patient satisfaction as secondary outcomes. Considering several outcomes and follow-up assessments can create multiplicity: the more comparisons examined, the more opportunities there may be for a chance finding. General approaches include identifying a primary comparison in advance, controlling the family of tests, or clearly distinguishing confirmatory analyses from exploratory ones.

The record does not report a multiplicity adjustment, a hierarchy among the outcomes, or a single primary follow-up comparison. It records 5 outcome measures and 0 analyses, and indicates that the primary outcome has several categories or time points and is not reduced to one comparison. The statistical plan, prespecified contrasts, and any distinction between confirmatory and exploratory analyses are not reported in the registry record.

Missing-data handling is also not reported in the registry record. There is no account of withdrawals or missing outcome measurements, the assumptions used for any missing observations, or whether sensitivity analyses were conducted. These details matter because the interpretation of repeated-measure outcomes can depend on who contributes data at each follow-up and how incomplete observations are handled.

The analysis population and whether participants were analyzed according to randomized assignment are not reported in the registry record. Details of protocol deviations, adherence, and exclusions are also not reported. Without this information, readers cannot determine how closely the analysis follows the randomized comparison or how missingness might affect the estimated contrast.

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 registry records 0 serious adverse events and 0 deaths in each arm. For other adverse events, the suprascapular-notch group records 4 affected among 40 at risk, and the spinoglenoid-notch group also records 4 affected among 40 at risk. These are the counts entered in the registry; they are not a statistical comparison.

The record does not describe the other adverse events, their timing, severity, duration, or relationship to the procedure. It also does not report how adverse events were collected or whether participants with incomplete follow-up contributed to these entries. The listed at-risk counts should be read as the registry’s denominators for these safety entries, not as evidence that every other aspect of safety was measured or reported.

Equal recorded counts do not establish that the approaches have identical safety. Small or unreported differences, the types of events, and the precision of any comparison cannot be assessed from counts alone. No uncertainty interval or formal safety analysis is reported in the registry record. The entries describe what was recorded, not a complete assessment of comparative safety.

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

The registry record establishes that a randomized, double-blinded, parallel-group study was completed to compare two ultrasound-guided suprascapular nerve block locations in chronic shoulder pain. The arm descriptions specify the same medication regimen and distinguish the approaches by the notch through which the block was performed. The primary outcome was change in SPADI, with assessments scheduled at baseline and 1, 4, and 12 weeks after injection.

That design identifies the intended clinical and statistical question, but the registry record does not report numerical primary-outcome results. It gives no group means, changes, between-group estimate, confidence interval, or p-value for SPADI. It therefore does not support a conclusion about the direction, size, or precision of the comparative outcome. Completion status and the existence of an outcome definition do not substitute for those results.

The record does include adverse-event counts: 0 serious events and 0 deaths in each group, and 4 other adverse events among 40 at risk in each group. These entries do not identify the nature of the other events or show whether any difference is compatible with chance. They should not be generalized into a claim that the approaches have the same safety.

In general, a randomized design can support a causal comparison when allocation and follow-up are implemented appropriately and the analysis respects the assignment and outcome structure. The registry does not report enough detail to assess those conditions, including the analysis population, missing data, or statistical methods. It also does not report the threshold for a meaningful SPADI change. The appropriate conclusion is therefore about the scope of the evidence recorded: the trial was designed to compare two techniques, but its primary comparative results and important analysis details are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial presents a useful statistical question because the two arms are described as sharing a medication regimen while differing in the ultrasound-guided block location. A randomized comparison can focus attention on that procedural contrast, provided assignment, follow-up, and analysis are carried out and reported adequately. The registry gives the design and outcome framework needed to understand the intended comparison, even though it does not provide the primary estimates.

The repeated SPADI assessments also make the analysis question more than a simple comparison of two isolated scores. Change over time, the relation among repeated measurements, and the choice of the main follow-up contrast all matter. Clear reporting of the intended estimand, time-specific estimates, uncertainty, and multiplicity strategy would help readers distinguish a consistent pattern from a result that depends on selecting one assessment or outcome.

There is also a broader reporting lesson. A completed trial record can describe design, measures, and some adverse-event counts while leaving readers unable to judge the main comparative endpoint. Reporting group-level summaries alongside a direct contrast and its uncertainty is central to assessing both effect size and precision. The absence of those details in the registry record limits interpretation independently of the randomized design.

Finally, the safety entries illustrate why counts need context. Event descriptions and collection methods help readers understand what was recorded; uncertainty estimates and an analysis plan help assess comparative evidence. These elements are not reported in the registry record. The trial matters statistically because it frames a randomized comparison and repeated continuous outcome, while also demonstrating how missing outcome and analysis reporting constrains the conclusions that can be drawn.

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 primary limitation for interpretation is that numerical SPADI results are not reported in the registry record. There are no group summaries, change estimates, direct contrasts, confidence intervals, or tests. Although the outcome is described at baseline and 1, 4, and 12 weeks after injection, the record does not report results by time point or clarify which score component was used for the primary comparison.

The record also does not report participant characteristics, baseline SPADI values, participant flow, withdrawals, or missing outcome data. Without those details, readers cannot assess the comparability of the groups at baseline, the completeness of follow-up, or how the analysis may have handled incomplete observations. Allocation concealment, the specific roles included in double masking, and implementation details are not reported in the registry record.

The statistical analysis plan, analysis population, prespecified contrasts, and multiplicity approach are not reported. The record lists secondary outcomes but does not provide their numerical results or analyses. It also does not report the original sample-size justification. These omissions prevent assessment of whether analyses followed a prespecified plan and whether their precision was adequate for the intended question.

For safety, the registry provides counts but not descriptions of other adverse events, severity, timing, collection methods, or comparative uncertainty. The counts therefore cannot characterize the full nature of the safety findings. These limitations concern what is reported in the registry record; they do not establish that information was not collected outside the record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of the Efficacy of Two Different Suprascapular Nerve Block Techniques in Patients With Chronic Shoulder Pain — NCT04938037.
• Registry record last updated 2025-05-20; status last verified 2025-05.
• Results first posted 2025-05-20.
• 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

NCT04938037 is recorded as a completed, prospective, randomized, double-blinded, parallel-group study sponsored by TC Erciyes University. The registry records enrollment of 80, a start date of 2021-06-01, and a primary completion date of 2022-08-05. It compares ultrasound-guided suprascapular nerve block through the spinoglenoid notch with block through the suprascapular notch. Both arm descriptions specify 1ml methylprednisolone acetate (1ml / 40mg) and 5ml 0.5% bupivacaine.

The primary outcome is SPADI change, assessed at baseline and 1, 4, and 12 weeks after injection. Secondary outcomes listed are VAS change, ROM change, PPT change, and patient satisfaction. Numerical results and statistical analyses for the primary outcome are not reported in the registry record. Safety entries report 0 serious adverse events and 0 deaths in each arm, with 4 other adverse events among 40 at risk in each arm.