Randomised controlled trials in chronic wounds typically exclude patients with comorbidities and confounding factors. Well-designed observational studies can provide complementary clinical evidence that randomised trials cannot address. This study determined if wound care registry outcomes could be an alternative data source and if the results would be robust and valid. Changes in wound area and depth were hypothesised to be different between run-in therapies and platelet-rich plasma (AutoloGel™, Cytomedix, Inc) treatment. From a treatment registry of 285 chronic wounds, 46 had run-in and post-treatment data. Seven chronic wound categories were identified. Mean wound age at study start was 52·4 days. General linear model repeated measures showed a credible and robust data set. Statistically significant differences for wound area and depth were observed between run-in and post-treatment period at multiple time points. Wound area and depth ≥50% reduction were analysed using Kaplan–Meier methods. During run-in, 15% of wound area improved compared to 28% post-treatment and 11% of wound depth improved during run-in compared to 39% post-treatment. Significant clinical outcomes indicated many previously non responsive wounds began actively healing in response to platelet-rich plasma therapy, indicating that registry data can be used as a complementary source of evidence.