Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. Department of Orthopaedic Surgery, University of Puerto Rico Medical Sciences Campus, San Juan, PR. Department of Orthopaedic Surgery, Rutgers New Jersey Medical School, Newark, NJ, USA. Department of Orthopaedic Surgery, Columbia University Mount Sinai Medical Center, Miami, FL, USA.
BACKGROUND Randomized controlled trial (RCT) outcomes reaching statistical significance, frequently determined by P <.05, are often used to guide decision making. Noted lack of reproducibility of some RCTs has brought special attention to the limitations of this approach. In this meta-analysis, we assessed the robustness of RCTs evaluating platelet-rich plasma (PRP) for the treatment of chronic noninsertional Achilles tendinopathy (AT) by using fragility indices. METHODS The present study was a systematic review and meta-analysis of RCTs comparing outcomes after PRP injection vs alternative treatment in patients with AT. Representative data sets were generated for each reported continuous outcome event using summary statistics. Fragility indices refer to the minimal number of
patients whose status would have to change from a nonevent to an event to turn a statistically significant result into a nonsignificant result, or vice versa. The fragility index (FI) and continuous FI (CFI) were determined for dichotomous and continuous outcomes, respectively, by manipulating each data set until reversal of significance (a=0.05) was achieved. The corresponding fragility quotient (FQ) and continuous FQ (CFQ) were calculated by dividing FI/CFI by sample size. RESULTS Of 432 studies screened, 8 studies (52 outcome events) were included in this analysis. The 12 dichotomous outcomes had a median FI of 4.5 (FQ: 0.111), and the 40 continuous outcomes had a median CFI of 5 (CFQ: 0.154). All 52 outcome events included lost-to-follow-up data, and 12 (23.1%) indicated a greater number of patients lost to follow-up than the FI or CFI. CONCLUSION Our findings suggest that RCTs evaluating PRP for AT therapy lack statistical robustness, because changing only a small number of events may alter outcome significance. LEVEL OF EVIDENCE Level II, therapeutic study.