Explanation of clinical usefulness/uselessness of SR; classification based on Ioannidis’3 suggestions
| Classification | Descriptor |
| Redundant and unnecessary | Low-quality SRs at high risk of bias (ie, AMSTAR score 3–7), and without a definitive conclusion regarding whether PRP should be used to treat Achilles tendinopathy, or not |
| Flawed beyond repair | Low-quality SRs at very high risk of bias (AMSTAR score <3) irrespective of the conclusion regarding whether PRP should be used to treat Achilles tendinopathy, or not |
| Decent but not clinically useful | High-quality SRs at low or very low risk of bias (AMSTAR score >7), and without a conclusive statement regarding whether PRP should be used to treat Achilles tendinopathy, or not |
| Might be clinically useful | Low-quality SRs at high risk of bias (AMSTAR score 3–7), and with a definitive conclusion regarding whether PRP should be used to treat Achilles tendinopathy, or not |
| Decent and clinically useful | High-quality SRs at low or very low risk of bias (AMSTAR score >7), and with a definitive conclusion regarding whether PRP should be used to treat Achilles tendinopathy, or not |
SR, systematic review; AMSTAR, Assessing Methodological Quality of Systematic Reviews; PRP, platelet-rich plasma.