Bayesian Re-analysis of Two-Year Outcomes in the Platelet-Rich Plasma in Achilles Tendon Healing 2 (PATH-2) Trial: Platelet-Rich Plasma for Achilles Tendon Rupture

The platelet-rich plasma in achilles tendon healing 2 (PATH-2) trial is the largest randomized study of platelet-rich plasma (PRP) in acute Achilles tendon rupture. While the original frequentist analysis showed no significant benefit, such methods cannot quantify the probability of clinically meaningful improvement. We conducted a Bayesian re-analysis of PATH-2 data (n = 177) with Achilles tendon total rupture score (ATRS) and patient-specific functional scale (PSFS) at 24 months as outcomes. Minimally clinically important differences (MCIDs) were defined as 8 ATRS points and 2.3 PSFS points. Across flat, neutral, optimistic, and pessimistic priors, posterior probabilities of PRP providing benefit ≥MCID were <0.001% for ATRS and ~5×10^-13 for PSFS. Probabilities of any benefit were 39.6% and 47.0%, respectively, with posterior mean differences close to zero. Results were robust across priors. This analysis demonstrates that PRP is unlikely to yield clinically meaningful functional improvement after Achilles tendon rupture.