Prediction of outcome: Predicting chronic pain in persons with amputations: The role of pain before and after amputation

Abstract

Previous research suggests that greater pre-amputation pain may increase the risk of developing phantom limb pain (PLP), although the role of acute pain after amputation is unknown. This longitudinal study was undertaken to determine if chronic phantom limb pain (PLP) could be predicted by pain level before or after amputation. Participants were recruited from consecutive admissions for lower limb amputation. Sixty-five patients scheduled for amputation provided ratings of pre-amputation pain on 0-10 numerical rating scales (NRS). After amputation, participants provided ratings of acute PLP and residual limb pain (RLP) during the first 5 days after amputation, as well as ratings of PLP and RLP at 6, 12, and 24 months after amputation. Multiple regression analyses were used to examine the associations of pre-amputation pain levels and acute post-amputation pain (PLP and RLP, each averaged over post-operative days 4-5) with chronic PLP, controlling for demographic variables and acute post-operative opiate use. Greater pre-amputation pain and acute post-operative PLP intensity were associated with greater chronic PLP intensity at follow-up, accounting for 36%, 50%, and 29% of the variance at 6-, 12-, and 24-months, respectively. Acute post-operative PLP intensity was the strongest individual predictor of PLP intensity at 6 and 12 months (β = 0.48 and 0.54, ps < .001 and .01, respectively), while pre-amputation pain intensity was the strongest individual predictor of PLP intensity at 24 months (β = 0.29, p < .05). Age, gender, acute opiate use, acute RLP, and duration of pre-amputation pain did not predict chronic PLP intensity at any follow-up. Because greater pre-amputation pain and acute post-operative PLP may increase the risk of chronic PLP, future research should further examine their potential role in the development and maintenance of chronic PLP.