To evaluate the outcomes of PRP treatment in Achilles tendinopathy: An intriguing methodological problem

Introduction: Assessing the outcomes of Platelet Rich Plasma (PRP) treatment in Achilles Tendinopathy (AT) may prove difficult due to several methodological reasons. For example, given that the simple mean of VISA-A score is just the result of positive, negative or null values, this may provide incomplete information, and therefore the size of individual changes can remain unknown. On the contrary, calculating the score changes in each subject after treatment would allow a more appropriate evaluation of the clinical results. However, this method has been applied only to few small-scale studies. Therefore we performed a retrospective study aiming to determine: (1) are the percentages of positive outcomes of the present research comparable to those of previous studies performed in different settings? (2) Is there a relationship between the size of increase of the clinical score and the patient satisfaction? Hypotheses: The percentages of positive outcomes of the present research are comparable to those of previous studies performed in different settings. Material and methods: This is a retrospective observational study. Eighty-four patients submitted to PRP treatment for mid-portion AT were enrolled. Pain and function were evaluated by means of VISA-A scale. Besides the mean, in each subject the pre- and post-treatment difference of VISA-A score was computed and the outcome was defined clinically no detectable, detectable and evident according to the increasing values of the score (0 to 9 points, 10 to 19, and ≥ 20 points change, respectively). The Likert's scale for the patients satisfaction was also used. Results: The mean VISA-A increased significantly after treatment (from 50.1 ± 9.1 at baseline to 63.7 ± 13.8 at 3 months (p = 0.00001) and 67.2 ± 14.1 at 6 months (p = 0.00001)). At 3 and 6 months the subjects belonging to the prefixed categories were 15, 45, 24 and 19, 36, 29, respectively. Moreover, large discrepancies were observed between the size of increase of the clinical score and patients satisfaction, mainly for intermediate increases of the score. Discussion: The percentages of positive outcomes found in this study are slightly lower than those reported in literature. The different patients expectations about the efficacy of the therapy can explain the discrepancies between the size of increase of the clinical score and the individual satisfaction. In comparison to the simple mean, the individual changes of VISA-A score allow a proper evaluation of the outcomes. The research shows that discrepancies can be present in the percentage of positive clinical outcomes between different studies. The size of increase of the clinical score does not always match patient satisfaction. Level of proof: IV retrospective study without control group.