Effectiveness of Acceptance and Commitment Therapy ( <scp>ACT</scp> ) for the Management of Postsurgical Pain: A Randomized Controlled Trial ( <scp>SPINE</scp> ‐ <scp>ACT</scp> Study)

BACKGROUND: This randomized controlled trial evaluated the effectiveness of group-based online Acceptance and Commitment Therapy (ACT) compared with treatment as usual (TAU) in improving postsurgical outcomes in patients with degenerative lumbar conditions. METHODS: A total of 91 participants scheduled for lumbar surgery were randomly assigned to either ACT or TAU, with primary analyses conducted in a modified intention-to-treat sample of participants who underwent surgery (n = 54). Outcomes and process variables were assessed at baseline, post-treatment (pre-surgery), and at 3-, 6- and 12-month post-surgery follow-up. RESULTS: Linear mixed model analysis showed that ACT (vs. TAU) produced larger reductions in pain interference (primary outcome) at post-treatment (d = 1.86) and at 3-month (d = 1.82), 6-month (d = 1.49) and 12-month post-surgery follow-up (d = -1.68). ACT yielded greater improvements than TAU in secondary outcomes, including depressive/anxiety symptoms (d = 1.69-1.99), pain catastrophizing (d = 0.84-0.97), kinesiophobia (d = 0.76-0.92) and low back pain-related disability (d = 1.39-1.91); and process variables, including psychological flexibility (d = 1.71-2.44) and pain acceptance (d = 2.33-3.04). Across time, no significant between-group differences in pain severity were observed. No indirect effects of ACT (vs. TAU) on outcomes through process variables were found. Clinically relevant number needed to treat values for pain interference response were obtained at 3-month (NNT = 4), 6-month (NNT = 2) and 12-month (NNT = 4) post-surgery follow-ups. CONCLUSIONS: Overall, these findings support the importance of delivering ACT before surgery to improve pain-related outcomes. SIGNIFICANCE STATEMENT: This randomized controlled trial provides evidence that preoperative group-based Acceptance and Commitment Therapy (ACT) improves pain-related outcomes following lumbar surgery. ACT produced reductions in pain interference, depressive/anxiety symptoms, pain catastrophizing, kinesiophobia, low back pain-related disability, psychological flexibility and pain acceptance, with clinically meaningful numbers needed to treat. These findings extend existing evidence by demonstrating the effectiveness of ACT delivered before surgery and support the integration of perioperative psychological interventions into routine surgical care for patients with degenerative lumbar conditions.