Fig. 1From: The duration of chronic low back pain is associated with acute postoperative pain intensity in lumbar fusion surgery: a prospective observational studyConsumption of postoperative analgesics, hospital stay, pain scores at the day of discharge and after three months among the three groups. Comparisons among groups were performed using analysis of variance and the Kruskal–Wallis test. **indicates P < 0.001, * indicates P < 0.05Back to article page