2.5. Study endpoints and measurements
Pain, pain
The primary endpoint of this study was the intensity of surgical pain from post-anesthetic care unit to 7 days postoperatively. Pain intensity was assessed by ward nurses using the visual analog scale (VAS, 0 represents “no pain” and 10 represents “worst pain”) in 4-hours intervals from 0 to 48 hours after operation. The numeric rating scale (0 represents “no pain” and 10 represents “worst pain”) was used to evaluate the pain intensity at 72 hours and 7 days postoperatively by the outcome assessors who did not participate in the clinical care. Acute postsurgical pain was defined as unpleasant sensation related to tissue injury during the acute phase after surgical intervention.