Such interventions would have the potential to reduce the prevalence of chronic pain in the population .
Although certain risk factors can identify individuals who are most likely to develop chronic pain , few interventions to prevent chronic pain have been identified .
To facilitate the identification of preventive interventions , an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain .
We present general design considerations for prevention trials in population s that are at relatively high risk for developing chronic pain .
Randomised trial of epidural bupivacaine and morphine in prevention of stump and phantom pain in lower-limb amputation
BACKGROUND Epidural analgesia before limb amputation is commonly used to reduce postamputation pain . But there have been no controlled studies with large numbers of patients to prove such a pre-emptive effect . We investigated whether postamputation stump and phantom pain in the first year is reduced by preoperative epidural blockade with bupivacaine and morphine . METHODS In a r and omised , double-blind trial , 60 patients scheduled for lower-limb amputation were r and omly assigned epidural bupivacaine ( 0.25 % 4 - 7 mL/h ) and morphine ( 0.16 - 0.28 mg/h ) for 18 h before and during the operation ( 29 patients ; blockade group ) or epidural saline ( 4 - 7 mL/h ) and oral or intramuscular morphine ( 31 patients ; control group ) . All patients had general anaesthesia for the amputation  and were asked about stump and phantom pain after 1 week and then after 3 , 6 , and 12 months by two independent examiners . Study endpoints were rate of stump and phantom pain , intensity of stump and phantom pain , and consumption of opioids . FINDINGS Two patients in each group were withdrawn before amputation . The groups were well matched in baseline characteristics . Median duration of preoperative saline treatment was 18.5 h ( IQR 17 - 20 ) . Median duration of preoperative epidural blockade  in the blockade group was 18 h ( 15 - 20.3 ) . The combined median duration of postoperative epidural pain treatment in both groups was 166 h ( 89.3 - 308.3 ) . After 1 week , 14 ( 52 % ) patients in the blockade group and 15 ( 56 % ) in the control group had phantom pain ( 95 % CI - 30.6 to 22.7 , p = 0.9 ) . The figures for blockade versus control group were : 14 ( 82 % ) vs ten ( 50 % ; 4.0 to 60.8 , p = 0.09 ) at 3 months ; 13 ( 81 % ) vs 11 ( 55 % ; -2.7 to 55.3 , p = 0.2 ) at 6 months ; and nine ( 75 % ) vs 11 ( 69 % ; -27.0 to 39.6 , p = 1.0 ) at 12 months . Intensity of stump and phantom pain and consumption of opioids were similar in both groups at all four postoperative interviews . INTERPRETATION Perioperative epidural blockade started a median of 18 h ( 15 - 20.3 ) before the amputation and continued into the postoperative period does not prevent phantom or stump pain
Such interventions would have the potential to reduce the prevalence of chronic pain in the population .
Although certain risk factors can identify individuals who are most likely to develop chronic pain , few interventions to prevent chronic pain have been identified .
To facilitate the identification of preventive interventions , an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain .
We present general design considerations for prevention trials in population s that are at relatively high risk for developing chronic pain .