Twenty studies were summarised in the results section of the review. Nineteen of these were rated against the quality and clinical relevance criteria.
Single blocks 50% to 75% pain relief threshold (one study, 24 participants): Pain prevalence was 55% with low-volume bupivacaine and 25% with high volume.
Single blocks 75% to 100% pain relief threshold (two studies, 374 participants): Pain prevalence estimates ranged from 25% to 64%.
Placebo/active-controlled blocks 50% to 75% pain relief threshold: No studies were found.
Placebo/active-controlled blocks 75% to 100% pain relief threshold (nine studies, 1,145 participants): Point estimates of pain prevalence ranged from 36% to 67%. Point estimates of false-positive rate ranged from 27% to 63%.