Japanese traditional herbal medicine reduces use of pregabalin and opioids for pain in patients with lumbar spinal canal stenosis: a retrospective cohort study

Background There has been an increase in the number of Japanese patients with lumbar spinal canal stenosis (LSCS) who complain of chronic pain or motor disturbance in the lower back or extremities. These patients are often treated with anti-convulsive drugs, opioids, antidepressants, acetaminophen, or nonsteroidal anti-inflammatory drugs, all of which can cause side effects. For this reason, Japanese traditional herbal medicine (Kampo) is of interest, because it produces fewer adverse reactions. The aim of this retrospective cohort study was to analyze the effects of Kampo in patients with LSCS. Findings A total of 151 patients with LSCS were divided into two groups based on treatment with (n = 111, group K) and without (n = 40, group N) Kampo. Use of pregabalin and opioids decreased significantly in group K (p < 0.001). The hazard ratio for opioid discontinuation was 0.220 (p = 0.004) for group N vs. group K, while that for pregabalin and antidepressants discontinuation were 0.589 (p = 0.202) and 0.509 (p = 0.377), respectively. The mean duration of hospital visits and treatment did not differ between the groups, but the number of dropouts was significantly higher in group N (p < 0.0001). The hazard ratio for patient dropout was 4.118 (p = 0.001) for group N vs. group K. Conclusions Kampo led to discontinuation of opioid use for pain in patients with LSCS, and patients who were treated with Kampo were more likely to continue treatment.