Treatment of the Rotator Cuff Disease With Platelet Rich Plasma Injection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Treatment of the Rotator Cuff Disease With Platelet Rich Plasma Injection (NCT01123889), a randomized na study. The primary outcome is Pain and Disability of the Shoulder Through Validated Questionnaires.

2. Clinical Question

The registry describes a randomized study of these injection approaches for subacromial impingement syndrome and partial thickness rotator cuff tears. Its brief description says participants would be followed for pain and would complete questionnaires at six weeks and three months. The posted primary endpoint, however, specifies the six-week assessment. The record does not explain whether the three-month assessments were collected or how they were analyzed.

The questionnaire outcome is the American Shoulder and Elbow Surgeons total score, combining pain and function components. The registry describes the scale direction: a score of 100 represents full normal function without pain, while 0 represents severe pain and no function. Consequently, the clinical question concerns a combined measure rather than a pain-only score. The registry does not provide enough information to identify which specific participants were eligible, how many were screened, or how the reported outcome group sizes arose.

3. Trial Design

The record identifies a randomized, parallel-group trial with no masking. Loma Linda University is listed as the sponsor, and the phase is recorded as not applicable. The study status is completed. The registry gives a study start of 2010-05 and a primary completion date of 2011-05.

The brief description says randomization would be done by choosing a slip of paper from an envelope. It describes an intended allocation of 25 patients to the experimental group and 25 to the control group. The registry separately records enrollment of 12. The posted primary outcome summaries list 2 participants in the control group and 6 in the experimental group. These figures do not reconcile in the registry record, and it does not explain whether the planned allocation changed, whether all enrolled participants were randomized, or why outcome group sizes differ from the enrollment entry.

The experimental intervention was platelet rich plasma injection into the subacromial space; the control intervention was corticosteroid injection into that space. The brief description identifies the corticosteroid injection as the control group’s sole treatment. It describes outpatient participation lasting approximately 3 months, with follow-up for pain and questionnaires at six weeks and three months. The posted primary endpoint is specified at six weeks.

The registry does not report the methods used to conceal allocation, whether the randomization process was implemented as described, or whether any participants or outcome assessors were masked. The record states that masking was none. It also does not report protocol deviations, adherence, withdrawals, or the handling of participants who did not complete follow-up. The mismatch between enrollment, planned allocation, and posted outcome group sizes is therefore an important design and reporting limitation.

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 Pain and Disability of the Shoulder Through Validated Questionnaires, measured over 6 weeks from initial injection of corticosteroid versus platelet rich plasma.

The primary endpoint is the mean total score on the American Shoulder and Elbow Surgeons questionnaire at six weeks after injection. The record describes the score as combining pain and function components, with a maximum score of 100 for full normal function without pain and a score of 0 for severe pain and no function. The outcome is recorded in units on a scale.

A combined questionnaire score can summarize aspects of the patient’s shoulder symptoms and functional status in a single measure. Using a validated questionnaire is intended to make assessment more consistent than an informal impression alone. The score’s direction matters for interpretation: higher values represent a better state on the registry’s description of this scale, while lower values represent more pain and less function.

The posted summaries give a mean and standard deviation for each group. The control group has a mean of 81.6 and a standard deviation of 9.4, with 2 participants listed. The experimental group has a mean of 70.0 and a standard deviation of 13.7, with 6 participants listed. These are descriptive summaries, not an adjusted treatment comparison. The registry does not report confidence limits for the means or an estimable statistical test comparing the groups.

The endpoint description focuses on the total score, not separate pain and function results. Although the brief summary mentions questionnaires at six weeks and three months, the primary endpoint’s stated timeframe is six weeks. The record does not report the questionnaire results at the later assessment.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure summarized by its mean and standard deviation. A mean describes the average observed score in a group. A standard deviation describes how dispersed individual scores are around that average. These statistics are useful for describing the posted observations, but neither one is a direct estimate of the uncertainty in a treatment comparison.

What does a comparison of group means represent?

For a continuous outcome, a between-group comparison asks whether the average score differs between the assigned groups. The interpretation depends on how the comparison was defined and analyzed, including whether it was adjusted for other variables and which participants were included. The registry does not report an estimable two-arm comparison for this endpoint, and it does not report an adjusted or unadjusted estimate, confidence interval, or p value. No comparative effect should be inferred from the group means alone.

The posted mean scores are 81.6 for control and 70.0 for experimental. The corresponding standard deviations are 9.4 and 13.7. The group sizes listed with those summaries are 2 and 6, respectively. These are descriptive values. The record does not give participant-level scores, so it is not possible to assess the distribution of scores, identify influential observations, or verify calculations from individual data.

Why does precision matter?

A confidence interval, when reported, expresses the range of values compatible with the data and the specified statistical method. Its width reflects uncertainty in the estimate. With limited outcome data, an estimate can be imprecise even when group means appear different. The registry provides no confidence limits for the group means and no interval for a between-group effect. Statistical uncertainty therefore cannot be quantified from the posted comparative results.

The standard deviation is not a substitute for a confidence interval. It describes variation among observed scores, whereas the confidence interval for a mean or contrast describes uncertainty about an estimated quantity. Likewise, a p value would not show the size or clinical importance of an effect. No p value is reported for the primary comparison, and the record offers no inferential result from which to judge the evidence against a null hypothesis.

What does randomization contribute?

Random allocation is intended to make assigned groups comparable, on average, with respect to measured and unmeasured characteristics. That benefit relies on implementation and analysis consistent with the randomized design. The brief description says allocation would be performed by drawing a slip of paper from an envelope, but the registry does not report allocation concealment procedures or confirm how the process was carried out. It records no masking. With small and unequal posted outcome group sizes, randomization alone cannot resolve uncertainty about baseline comparability or the effect estimate.

The record’s planned allocation, enrollment entry, and outcome group sizes are inconsistent: the description says 25 patients per group were planned, enrollment is 12, and the outcome summaries list 2 in control and 6 in experimental. The registry does not explain this. It is not possible to identify from the record whether the posted summaries follow an intention-to-treat approach, a per-protocol approach, or another analysis population.

How should planning estimates be read?

The registry describes a sample-size planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It describes planning for a stated fraction of the observed effect. Such estimates are planning illustrations, not observed power and not evidence that the trial had a particular chance of detecting a clinically meaningful effect. The record does not report the trial’s own sample-size justification or explain whether the planned enrollment was based on a formal calculation.

The statistical plan is not reported in the registry record. The record does not describe the intended model, assumptions, covariate adjustment, handling of missing observations, or any prespecified approach for the primary analysis. Since the posted comparison is marked as not estimable, no recalculated contrast is available. The sponsor’s own analysis would take precedence if a discrepancy between a sponsor analysis and a simple recalculation were identified, but the registry does not report such an analysis or a discrepancy for this result.

What can the posted summaries support?

They support describing the observed means, standard deviations, and listed group sizes. They do not support a precise treatment-effect estimate or a claim of statistical significance. General statistical interpretation also depends on how the endpoint was collected and whether observations were missing; those details are not reported. The safest reading is therefore descriptive, with explicit recognition that the comparative analysis and its uncertainty are unavailable in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Control", "Experimental")
n   <- c(2, 6)
m   <- c(81.6, 70)
sp  <- c(9.4, 13.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Control  2  81.600  9.400  -2.856  166.056
CARM  Experimental  6  70.000  13.700  55.623  84.377

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures, but it reports no posted secondary outcomes. It identifies the six-week questionnaire score as the primary endpoint. The record does not describe a prespecified hierarchy among outcomes, a multiplicity adjustment, or how any additional analyses were selected. It is therefore not possible to assess how the study handled the possibility of multiple comparisons. The absence of posted secondary results should not be interpreted as evidence that no other outcomes were collected.

The registry reports no analyses and indicates that values were missing or not estimable for a two-arm comparison of the continuous endpoint. The reason that the comparison could not be estimated is not reported in the registry record. The record does not state how missing questionnaire responses were handled, whether participants with incomplete data were excluded, or whether any imputation or other missing-data method was used.

Analysis populations are also not described. The record does not say whether the primary analysis included all randomized participants, only participants with observed outcomes, or a different group. This matters because excluding participants after randomization can affect the comparability created by random assignment. The posted outcome group sizes do not match the enrollment entry or the intended group sizes described in the brief summary, and the registry does not explain the discrepancy.

The brief description refers to questionnaires at six weeks and three months, while the primary endpoint is specified at six weeks. No three-month outcome results or explanation of their availability are reported in the registry record. Without outcome-completion information, missing-data methods, and a defined analysis population, the completeness and representativeness of the posted six-week summaries cannot be assessed.

12. Safety Results

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

Other (non-serious) adverse events

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

The registry lists 0 serious adverse events among 5 participants at risk in the control group and 0 among 7 participants at risk in the experimental group. These are the serious-event figures recorded for the reported groups. No serious adverse event terms are listed. The registry does not report death counts, so deaths cannot be interpreted from these entries.

A zero count means that no serious events were recorded in the listed at-risk group for this registry entry. It does not establish that the risk is absent. Safety summaries with small at-risk groups provide limited information about uncommon events, and the record does not describe how events were collected, assessed, or followed over time. The listed at-risk group sizes also differ from the primary outcome group sizes, and the registry does not explain why.

The record separately lists 0 other adverse events among 5 control participants at risk and 0 among 7 experimental participants at risk. These entries should be read as registry counts, not as evidence that no adverse effects could occur. The record does not provide further detail about adverse-event definitions, severity, timing, or attribution to an injection.

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

The registry records a randomized comparison of platelet rich plasma injection and corticosteroid injection for rotator cuff conditions. For the six-week primary questionnaire outcome, it reports a mean score of 81.6 in control and 70.0 in experimental, with standard deviations of 9.4 and 13.7. The scale description assigns better function and less pain to higher scores, so the experimental mean is numerically lower. These descriptive figures do not establish a treatment effect.

The registry explicitly reports that values were missing or not estimable for a two-arm comparison of the continuous endpoint. There is no posted estimate of the difference between groups, confidence interval, or p value. Without a comparative estimate and its uncertainty, the data as recorded do not show whether an apparent difference is compatible with chance variation, nor do they establish the size or precision of any effect.

The group sizes reported with the outcome are small, and they are inconsistent with the enrollment entry and the planned allocation described in the brief summary. The record does not explain which participants contributed to the summaries or why the counts differ. It also does not report a statistical analysis plan, missing-data methods, or an analysis population. Those omissions prevent a clear assessment of how the posted results relate to the randomized trial.

The registry’s completed status and the presence of outcome summaries should not be taken to mean that all planned assessments were reported. The primary endpoint is specified at six weeks, while the study description mentions follow-up questionnaires at six weeks and three months. The registry does not report three-month results. It also lists no posted secondary outcomes.

In short, the record allows a reader to describe the posted six-week group summaries and the recorded adverse-event counts. It does not support a firm conclusion about comparative benefit, harm, statistical significance, or clinical importance. The limitations concern the information available in the registry record; they do not establish what occurred outside of what was posted.

14. Why This Trial Matters Statistically

This trial is statistically instructive because it illustrates the difference between descriptive results and a comparative analysis. Group means can describe the observed scores, but they do not by themselves quantify an intervention effect or its uncertainty. Here, the registry provides mean scores and standard deviations, yet explicitly indicates that the two-arm comparison was not estimable. A reader should keep those forms of evidence distinct.

The record also illustrates why participant counts and analysis populations matter. The intended allocation, recorded enrollment, and group sizes attached to the posted endpoint do not agree. Randomization supports causal comparison when assignment and subsequent analysis are adequately documented, but unclear denominators make it difficult to establish which observations contribute to the reported summaries. The registry does not explain the mismatch.

Precision is especially important when outcome group sizes are limited. A standard deviation describes observed variation, not the uncertainty around a treatment contrast. Without a confidence interval or another uncertainty measure, the apparent separation of means cannot be interpreted as a precise estimate. The absence of an estimable comparison is therefore central, rather than a minor reporting detail.

Finally, the record highlights the role of transparent reporting. Information about the analysis plan, missing data, analysis populations, follow-up completion, and multiplicity would help readers understand how the results were generated and how much confidence to place in them. These details are not reported in the registry record. The posted data remain useful as a descriptive account, but they do not resolve the comparative question posed by the randomized design.

15. 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 most direct limitation is that the registry reports no estimable two-arm comparison for the continuous primary endpoint. The group means and standard deviations are descriptive, and no confidence interval or p value is reported. A comparative effect and its precision cannot be assessed from the posted primary results.

Reported participant counts are inconsistent. The record lists enrollment of 12, the brief description says 25 patients per group were planned, and the primary outcome summaries list 2 in control and 6 in experimental. The registry does not explain the discrepancy or identify the participants included in the outcome summaries. This leaves the analysis population and completeness of the results unclear.

The registry does not report a statistical analysis plan, sample-size justification for the trial, missing-data methods, allocation concealment details, or protocol deviations. It states that masking was none. The record does not explain how randomization was implemented beyond the brief description of drawing a paper slip from an envelope, nor does it provide baseline characteristics for assessing the groups.

The primary endpoint is specified at six weeks, but the brief summary also describes questionnaires at three months. Three-month results are not reported in the registry record. Although 3 outcome measures are listed, no secondary outcomes are posted. Follow-up completeness and the handling of questionnaire nonresponse are not described.

Safety reporting is limited to the event counts and at-risk group sizes recorded in the registry. Event collection methods, timing, definitions, and death counts are not reported. These limitations do not establish that unreported procedures or data were absent; they mean the registry record does not provide them for evaluation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Treatment of the Rotator Cuff Disease With Platelet Rich Plasma Injection — NCT01123889.
• Registry record last updated 2014-02-11; status last verified 2013-12.
• Results first posted 2014-02-11.
• 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.

19. Record Summary

The registry describes a completed randomized, parallel-group trial without masking, sponsored by Loma Linda University. It concerns platelet rich plasma injection compared with corticosteroid injection for subacromial impingement syndrome and partial thickness rotator cuff tears. The primary outcome is a six-week American Shoulder and Elbow Surgeons total score combining pain and function.

The posted outcome summaries report a control mean of 81.6 and an experimental mean of 70.0, with standard deviations of 9.4 and 13.7. The registry marks the two-arm comparison as not estimable. The listed outcome group sizes, enrollment, and planned allocation do not agree, and the record does not explain why. No analyses or secondary outcomes are posted.

The safety entries report no serious or other adverse events in the listed at-risk groups; death counts are not reported in the registry record. Important details about analysis populations, missing data, follow-up completion, and the statistical plan are also not reported. The record supports a descriptive reading of the posted summaries, not a conclusive comparative interpretation.