Patients undergoing various elective and sub-acute surgical procedures including thoracic, cardiac, abdominal, vascular, plastic, spinal neurosurgery, and orthopaedic procedures.

Worst pain intensity score at rest ≥ 4 on an 11-point numeric rating scale (NRS; 0-10) in the post-anaesthesia care unit (PACU) following surgery, where 0=no pain and 10=worst pain imaginable.

Pain related to the surgical procedure measured as average pain intensity on rest or movement ≥ 3 in the past one week using an 11-point numeric rating scale (NRS; 0-10) where 0=no pain and 10=worst pain imaginable and average pain interference ≥ 3 using 11-point NRS among any one of seven short-form Brief Pain Inventory items (general activity, mood, walking ability, normal work (including housework), relations with other people, sleep, enjoyment of life) in the past one week, where 0=pain does not interfere and 10=pain completely interferes.

Worst pain intensity score at rest ≥ 7 on an 11-point numeric rating scale (NRS; 0-10) in the post-anaesthesia care unit (PACU) following surgery, where 0=no pain and 10=worst pain imaginable.