Summary

Among 791 patients from 13 RCTs undergoing platelet rich plasma (PRP) injection for lateral epicondylitis vs. control, a direct, linear relationship was observed between the concentration factor of PRP used and the magnitude of patient-reported symptom relief after PRP injection.

Abstract

Introduction

Randomized controlled trials (RCTs) evaluating the efficacy of platelet-rich plasma (PRP) for the management of lateral epicondylitis (LE) have been characterized by substantial variability in reported outcomes. The source of this heterogeneity is uncertain. The purpose of this study was to determine the effect of estimated platelet concentration on the efficacy of PRP for the management of LE.

Methods

This was a systematic review and meta-analysis of RCTs evaluating the efficacy of PRP in managing LE. RCTs were classified according to whether the study documented a PRP concentration factor representing a greater than three-fold increase over whole blood or a supraphysiologic platelet dose (high-dose vs. low-dose PRP). The primary outcome was the mean difference (MD) in Visual Analogue Scale (VAS) score at latest follow-up. Random and mixed effects meta-analyses were performed, and meta-regression was used to evaluate whether differences in outcomes after treatment with PRP could be explained by differences in the concentration of PRP used.

Results

Thirteen RCTs totaling 791 patients were included in this analysis, with five utilizing low-dose PRP and eight using high-dose PRP. Meta-analysis of VAS scores reported by studies using high-dose PRP resulted in a MD [95% CI] of -1.31 [-1.87;-0.75] in favor of PRP over all alternative treatment strategies (p<0.001). Meta-analysis of VAS scores reported by studies using low-dose PRP resulted in a MD [95% CI] of 0.08 [-0.51;0.68], suggesting no difference in effect between PRP and all alternative treatment strategies (p=0.79). The concentration factor of the PRP used in each RCT was found to be strongly predictive of VAS score at final follow-up based on meta-regression (p<0.001), with 58.5% of heterogeneity in outcomes of PRP between studies explained by concentration factor alone.

Conclusion

Platelet concentration of PRP appears to play a significant role in the outcomes of patients with LE. A direct, linear relationship was observed between the concentration factor of PRP used and the magnitude of patient-reported symptom relief after management of LE with PRP. Clinicians should ensure a supraphysiologic platelet concentration when preparing PRP for management of LE.