Abstract
Duloxetine, an analgesic drug approved for clinical use, reduces the central sensitization to relieve chronic pain. Several clinical trials proved the efficacy and safety of duloxetine monotherapy, and we demonstrated that additional duloxetine administration showed favorable efficacy and safety in our previous study. This study aimed to investigate the characteristics of patients who can obtain a more satisfactory effect of duloxetine. The central sensitization of each patient was evaluated using the central sensitization inventory （CSI）. The efficacy of additional duloxetine administration, which was evaluated by changes in low back pain visual analog scale （VAS） scores, lower limb pain VAS scores, and 36-item Short-Form Health Survey version 2 scores from baseline, was compared between patients with CSI scores of ›34 and those with CSI scores of‹34. In this study, 14 patients were observed for more than 1 month after duloxetine administration. Out of the 14 patients, 7 patients showed high CSI scores （›34）, and the mean low back pain VAS score was higher in patients with high CSI scores than in those with low CSI scores （‹34）, which were insignificant changes. After 1month of duloxetine administration, the changes in the mean low back pain VAS score were −19±4.8mm in patients with high CSI scores and −12±7.2mm in patients with low CSI scores. The “role physical” scores increased by 35.3±5.2 in patients with high CSI scores and 7.0±5.3 in patients with low CSI scores, and the “role emotional” scores increased by 43.6±5.8 in patients with high CSI scores and 9.8±3.6 in patients with low CSI scores. The improvement in patients with high CSI scores was greater than that in patients with low CSI scores with significant changes （p‹0.01, Wilcoxon t-test）. Therefore, duloxetine administration should be considered for patients with central sensitization to improve pain-related disabilities.
