Comparative effectiveness of amitriptyline vs duloxetine in the treatment of chronic low back pain: An observational study

BACKGROUND Chronic nonspecific low back pain is defined as pain that persists for greater than 12 weeks and mainly occurs in the lower back with no evidence of associated underlying serious conditions [like malignancy, inflammation (like ankylosing spondylitis) or infection, vertebral fracture, etc. ]. AIM To compare the efficacy and safety of amitriptyline with duloxetine in treating chronic low back pain (CLBP). METHODS The present study was a two-arm observational study conducted over 18 months in a tertiary rehabilitation setting. A total of 254 patients were included in the study. RESULTS The mean age was significantly higher in the amitriptyline group (34.78 ± 8.22 years) compared with the duloxetine group (29.98 ± 7.28 years, P < 0.0001). Baseline visual analog scale (VAS) scores were also significantly different between groups (amitriptyline: 7.92 ± 0.56; duloxetine: 8.46 ± 0.79; P < 0.0001). Within-group analysis showed a significant reduction in VAS scores over time in both groups (P < 0.001). At 12 weeks the duloxetine group showed significantly lower VAS scores (0.92 ± 0.78) compared with the amitriptyline group (1.87 ± 1.71; P < 0.0001). Analysis of variance, adjusting for age and baseline VAS, confirmed a significant group effect on pain reduction at 12 weeks (P < 0.001), favoring duloxetine. Side effects were generally mild. The most common in the amitriptyline group were dry mouth (17.3%) and drowsiness (7.9%) while in the duloxetine group, dry mouth (15.7%) and constipation (2.4%) were most reported. CONCLUSION Amitriptyline and duloxetine effectively treat CLBP; however, considering side effects and more sustained pain relief, duloxetine appears to be the better option. Nonetheless, treatment choice should consider individual patient profiles.