The Statistical Fragility of Platelet-Rich Plasma as Treatment for Plantar Fasciitis: A Systematic Review and Meta-Analysis

Abstract

Category: Basic Sciences/Biologics; Hindfoot; Sports Introduction/Purpose: Plantar fasciitis (PF) is estimated to account for 8% of all running-related injuries, affecting nearly 1 out of every 10 adults aged 50 and older. Recent randomized controlled trials (RCTs) suggest platelet-rich plasma (PRP) injection may be an effective non-operative treatment option for chronic, refractory PF. However, RCTs in general have come under scrutiny due to a frequent lack of reproducibility, which is largely attributable to shortcomings of the commonly used p=9 patients. Outcome events that were originally reported as significant (p<0.05) were considerably more fragile (CFI=5; CFQ=0.122) than events that were reported as nonsignificant (CFI=10; CFQ=0.179). Conclusion: Fragility indices are a useful adjunct to p-values and provide an assessment of how easily statistical significance can be overturned. While there is some preliminary evidence supporting the clinical efficacy of PRP, our fragility analysis suggests that RCT findings may be underpowered in some cases. Over 27% of outcome events may have experienced a reversal of significance if the studies had simply maintained follow-up. Given the importance of RCTs in clinical decision-making, fragility indices should be reported alongside p-values to indicate the strength of statistical findings.