PRP vs PRP Plus IGF for Patellar Tendinosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PRP vs PRP Plus IGF for Patellar Tendinosis (NCT04350827), a randomized na study. The primary outcome is Victorian Institute of Sport Assessment-patellar Tendon (VISA-P).

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-masked, parallel comparative trial of platelet-rich plasma alone versus platelet-rich plasma plus concentrated IGF for patellar tendinosis. The listed phase is NA. Ohio State University is the sponsor, and the registry status is completed. The recorded study start is 2020-02-25 and the primary completion date is 2021-10-16. These are registry dates, not a description of when each participant was treated or assessed.

Registry enrollment is 14. For the six-month primary endpoint, the posted group summaries give n 5 for platelet-rich plasma and n 6 for platelet-rich plasma plus IGF. The registry record does not explain why these endpoint counts differ from the enrollment figure. It also does not describe participant flow, exclusions, withdrawals, or the analysis population used for the reported ANOVA. It is therefore not possible to determine from the record which participants were omitted from the endpoint summaries or why.

The intervention descriptions indicate that the comparison involved PRP alone and PRP with an IGF-related addition. The recorded descriptions are incomplete, so further preparation or administration details are not reported in the registry record. Randomization and masking are recorded, but details about sequence generation, allocation concealment, and masking procedures are not reported. The registry also does not report whether masking was checked or whether any participant or investigator became aware of assignment.

The primary outcome is VISA-P at six months. The registry lists Visual Analog Scale-Pain, Tegner Activity Scale, and Blazina Classification as secondary outcomes. Although the record lists four outcome measures, it gives only the primary endpoint results. The results of the secondary outcomes are not reported in the registry record. The record does not describe a formal sample-size justification, a statistical analysis plan, or interim analyses.

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 Victorian Institute of Sport Assessment-patellar Tendon (VISA-P), measured over 6 months.

The primary endpoint is the Victorian Institute of Sport Assessment-patellar Tendon score, or VISA-P, measured at six months. It is a self-administered questionnaire intended to assess patellar tendinopathy. The registry describes eight items: six address pain or disability in daily activities and functional tests, and two address ability to play sport.

The scale ranges from a theoretical minimum of 0 points to a maximum of 100 points. The maximum represents an asymptomatic athlete able to fully engage in sports. In this context, a higher score represents a better symptom and function profile according to the scale description. The posted endpoint summaries are group means with standard deviations, which describe the average scores and the spread of individual scores within each group.

VISA-P is used as a measure of symptoms and function relevant to patellar tendon problems, rather than as a direct measure of tendon structure or a general measure of health. Its focus gives the comparison a defined clinical outcome at the registered assessment time. The registry does not report baseline VISA-P scores, changes from baseline, or a threshold for interpreting a difference as clinically important. The posted six-month means therefore describe the groups at that assessment; they do not establish how much either group changed over time or whether a particular difference would matter to participants.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry reports an ANOVA for the comparison of the two groups’ six-month mean VISA-P scores. The group summaries use means and standard deviations, appropriate descriptive quantities for a continuous score. The mean indicates the arithmetic center of the observed scores; the standard deviation describes how dispersed scores are around that mean. Neither summary alone gives the uncertainty in a difference between group means.

What does the ANOVA test?

In general, analysis of variance compares group means against a null hypothesis that the population means are equal. Its test statistic assesses whether the observed differences between group means are large relative to variation within groups, under the model’s assumptions. For a comparison involving two groups, an ANOVA addresses the same general question as a test of a mean difference, although the test is expressed through analysis of variance. The registry reports the method as ANOVA and gives p 0.433, but does not report the test statistic, degrees of freedom, model details, or a separate estimate of the mean contrast.

ANOVA relies on assumptions about the outcome and the structure of the observations. In general, observations should be independent, and the model should describe the outcome variation adequately. The usual approach also relies on assumptions about residual distributions and variance structure. The registry record does not report diagnostic checks, any adjustment for covariates, or whether a different analysis was considered. With small group counts, unusual observations or departures from assumptions may have a noticeable influence; the record does not include individual scores that would permit such checks.

How should the p-value be read?

In general, a p-value is calculated under a null hypothesis and a statistical model. It expresses how often a test statistic at least as extreme as the observed one would arise under that null model. It is not a measure of effect size, a measure of clinical importance, or the probability that the null hypothesis is correct. The reported p 0.433 does not provide a direct answer about the range of plausible differences. That is why an estimated contrast and confidence interval are useful alongside a test result.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with the data and the method used to construct it. Its width reflects precision: wider intervals indicate less precise estimation. A confidence interval for a difference in means would help readers judge both the possible direction and the range of magnitudes consistent with the results. No confidence interval for the primary comparison is reported in the registry record. The group standard deviations are not a substitute for that interval because they describe within-group variation, not uncertainty in the between-group contrast.

What do randomization and masking contribute?

In general, random assignment can reduce systematic differences between groups at the point of allocation, while masking can limit some forms of bias in care, assessment, or reporting. These design labels alone do not establish how well those protections were implemented. The record identifies the study as randomized and double masked, but does not report sequence generation, allocation concealment, the masked roles, or procedures for maintaining masking. Those details cannot be inferred from the labels.

How should planning illustrations be understood?

In general, sample-size calculations estimate how many participants would be needed under chosen assumptions, including a target effect, a significance level, and a desired power. The planning assumptions described for this study use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with effects framed as fractions of the observed effect. Any such calculation is a planning illustration, not observed power and not proof that the trial had an adequate sample size. It is not the trial’s own design justification. Numerical planning results and a formal sample-size justification are not reported in the registry record.

In general, over-dispersion refers to variability greater than a model expects; it can make standard errors too small if ignored. It is more often discussed for count outcomes than for a continuous scale such as VISA-P, so it is not a reported feature of this analysis. For continuous outcomes, the relevant concern is whether the model represents the distribution and variability adequately. The registry does not report diagnostic information for assessing this.

The record does not report a prespecified statistical analysis plan, adjustments for baseline scores or other covariates, interim analyses, or missing-data methods. These are not details that can be reconstructed from the group means and p-value. The statistical result should consequently be read as the reported ANOVA, without assuming unreported model choices or procedures.

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("Platelet Rich Plasma", "Platelet Rich Plasma Plus IGF")
n   <- c(5, 6)
m   <- c(66.4, 78.2)
sp  <- c(17.8, 15.3)
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  Platelet Rich Plasma  5  66.400  17.800  44.298  88.502
CARM  Platelet Rich Plasma Plus IGF  6  78.200  15.300  62.144  94.256

11. Analyses Reported by the Sponsor

The sponsor-reported analysis is an ANOVA with p 0.433 for the primary comparison. The registry does not report an estimated difference between means or a confidence interval for that comparison. It also does not provide enough detail to reconstruct the ANOVA from individual observations.

A recalculated unadjusted comparison cannot be reported because the two-arm continuous endpoint comparison is marked as having values missing or not estimable. The posted group means and standard deviations do not resolve that limitation or supply the missing inferential details. No recalculated estimate or p-value should therefore be substituted for the sponsor’s analysis. The discrepancy flag is false, but that does not create an independent recalculation or add precision information absent from the registry.

The reported ANOVA remains the only inferential result for this primary comparison in the registry record. It should be interpreted together with the group means and their standard deviations, while recognizing that the record does not show a confidence interval, analysis population, or detailed model specification. The reported p-value is not a direct estimate of effect magnitude or clinical importance.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists three secondary outcomes: Visual Analog Scale-Pain, Tegner Activity Scale, and Blazina Classification. It also lists four outcome measures and one reported analysis. The record gives the primary VISA-P results but does not report results for the named secondary outcomes. Their absence means that the record does not support conclusions about those measures.

When several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase. In general, multiplicity procedures may adjust significance thresholds or interpret results in a way that accounts for multiple tests. The registry record does not report a multiplicity adjustment, a hierarchy among outcomes, or whether any secondary outcome analyses were conducted. It is not appropriate to infer that no adjustment was needed or that the primary result was selected after examining other results.

The record also does not report whether all randomized participants were included in the primary analysis, how missing endpoint values were handled, or whether any imputation or sensitivity analyses were used. The primary endpoint summaries have n 5 and n 6, while registry enrollment is 14; the reason for this difference is not reported in the registry record. Participant flow, withdrawals, and exclusions are also not described. Without this information, the potential effect of missing outcome data and the relationship between randomization and analysis cannot be assessed.

The analysis population is not named. The registry does not say whether the reported comparison follows an intention-to-treat approach, a per-protocol approach, or another definition. These approaches answer somewhat different questions and can be affected differently by departures from assigned treatment or missing data. No such details should be assumed. A fuller account of outcome availability, analysis populations, and any prespecified multiplicity strategy would be needed to assess those aspects of the reported result.

13. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry reports zero serious adverse events in the platelet-rich plasma group, with 5 at risk, and zero in the platelet-rich plasma plus IGF group, with 6 at risk. It also reports zero other adverse events in each group, using the same group-specific counts at risk. Deaths are reported as zero in both groups. The registry lists no top serious adverse-event terms.

These are counts recorded in the registry, not proof that an event could not occur or that the interventions have equal safety. A zero count in a group means that no event in that category is recorded among the participants represented in that safety summary. It does not quantify the range of possible event rates with precision, particularly when the groups are small.

The registry does not report the duration of safety follow-up, definitions used for event categories, how events were collected, or whether all participants were assessed in the same way. It also does not describe events by severity apart from the serious-event category. The zero counts should therefore be read narrowly as the posted safety figures, without inferring broader safety conclusions or comparing risk beyond what the record states.

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

The results describe six-month VISA-P scores in two randomized groups and report an ANOVA p-value for their comparison. The platelet-rich plasma group mean is 66.4, with standard deviation 17.8 and n 5. The platelet-rich plasma plus IGF group mean is 78.2, with standard deviation 15.3 and n 6. The reported ANOVA p-value is 0.433. These are the posted endpoint summaries and sponsor-reported test result.

They do not establish that the groups are identical, nor do they establish that a difference is clinically important. A nonsmall p-value does not demonstrate equivalence. Evidence for equivalence would require a prespecified margin and an analysis designed to assess whether plausible differences fall within that margin; neither is reported in the registry record. The record also does not give a confidence interval that would show the range of differences compatible with the data.

The summaries do not show change from baseline, because baseline VISA-P results are not reported. They cannot establish the trajectory of symptoms or function over time, and the six-month assessment alone does not describe outcomes at other time points. The registry lists secondary measures, but their results are not reported. No conclusions about those outcomes follow from the primary endpoint result.

The endpoint sample counts are limited, and the record does not explain the difference between registry enrollment of 14 and the group counts used for the primary summary. This makes it difficult to assess missingness and the analysis population. Individual participant data and model diagnostics are also not reported, limiting assessment of how the group summaries and ANOVA depend on distributional assumptions or individual observations.

Accordingly, the result is best understood as a small registry-reported comparison with descriptive six-month scores and an ANOVA p-value, but without a reported contrast estimate, confidence interval, or enough analysis detail to assess precision fully. It does not establish that either intervention works or fails, and it does not justify a treatment recommendation.

15. Why This Trial Matters Statistically

This trial illustrates why descriptive results and inferential results answer different statistical questions. The group means describe the observed VISA-P scores, while the standard deviations describe variation among scores within each group. The ANOVA p-value addresses a hypothesis test under its model. None of these quantities alone gives the full picture of effect magnitude, precision, and clinical relevance.

It also illustrates the value of reporting an estimated contrast with a confidence interval. A p-value can be reported without showing the range of differences consistent with the data. In a small comparison, uncertainty around the estimated difference is especially important for distinguishing a precise estimate from an inconclusive one. The registry does not report a confidence interval or a mean-difference estimate for the primary outcome.

The difference between registry enrollment and the endpoint group counts highlights another reporting issue. Without participant flow and missing-data details, readers cannot tell why the endpoint summaries cover fewer participants than the enrollment figure or determine how exclusions might affect the comparison. Clear reporting of analysis populations and missing outcomes is essential to understand what the result represents.

Finally, the registry identifies multiple secondary outcomes but does not report their results or a multiplicity strategy. This makes it difficult to assess the overall outcome-testing plan. These limitations are not unique to this trial; they illustrate general reasons that transparent reporting of endpoints, analyses, uncertainty, and participant flow matters when interpreting randomized comparisons.

16. 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.

Several trial-specific details needed to interpret the result are not reported in the registry record. The enrollment figure is 14, while the six-month primary-endpoint summaries give n 5 and n 6. The record does not explain this difference, report participant flow, or describe withdrawals and exclusions. It also does not identify the analysis population or explain how missing endpoint values were handled.

The primary comparison is reported with an ANOVA p-value but without a mean-difference estimate or confidence interval. The record does not report the test statistic, degrees of freedom, model details, covariate adjustments, or diagnostic checks. This limits independent assessment of the test and of the precision of the comparison. Individual participant scores and baseline VISA-P results are not reported, so change from baseline and sensitivity to individual observations cannot be assessed.

The registry records randomization and double masking but does not report sequence generation, allocation concealment, the roles that were masked, or how masking was maintained. The intervention descriptions are truncated, limiting assessment of procedural detail. The registry does not report a formal sample-size justification or a prespecified analysis plan.

Although secondary outcomes are listed, their results are not reported in the registry record, and no multiplicity strategy is described. Safety counts are posted, but the duration and methods of safety follow-up are not reported. Together, these gaps limit interpretation of the primary result, assessment of missingness and bias, and evaluation of how broadly the results can be applied.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: PRP vs PRP Plus IGF for Patellar Tendinosis — NCT04350827.
• Registry record last updated 2023-10-30; status last verified 2023-10.
• Results first posted 2023-10-30.
• 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.

20. Record Summary

The registry describes a completed randomized, double-masked, parallel trial sponsored by Ohio State University, comparing platelet-rich plasma with platelet-rich plasma plus concentrated IGF for patellar tendinosis. The primary endpoint is VISA-P at six months. Registry enrollment is 14, while the posted primary endpoint summaries report n 5 and n 6 for the two groups.

The mean VISA-P score is 66.4 with standard deviation 17.8 for platelet-rich plasma and 78.2 with standard deviation 15.3 for platelet-rich plasma plus IGF. The reported ANOVA p-value is 0.433. The registry does not report a confidence interval or estimated mean difference, and the reason for the endpoint counts is not reported. Secondary outcome results are not reported. Safety summaries record zero serious adverse events, zero other adverse events, and zero deaths in each group. These results should be interpreted as limited registry-reported evidence, not as proof of equivalence or a definitive estimate of clinical effect.