Fig. 3.
BPI scores before surgery and 3, 6, and 12 months after surgery. Pain severity and pain interference (BPI scores) increased significantly over time in both groups (P < 0.001 and P < 0.001, respectively). The increase in pain severity was statistically significant from the preoperative period until the third month, and then from the third to sixth months, while the increase in pain severity from the sixth to twelfth months was not statistically significant. The increase in pain interference was statistically significant from the preoperative period until the third month only. The time × group interaction was tested. P value is associated with the test of group × time effect. BPI = brief pain inventory.