This is why we do randomised trials!
Naylor
A R
AR
D000768:Anesthesia, General / Q000009:adverse effects; D000772:Anesthesia, Local / Q000009:adverse effects; D016894:Endarterectomy, Carotid / Q000009:adverse effects; D019317:Evidence-Based Medicine; D006801:Humans; D017410:Practice Guidelines as Topic; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome