Preoperative emotional stress and postoperative pain after lumbar fusion surgery: secondary analysis of a randomized trial of adjunctive S-ketamine in oxycodone patient-controlled analgesia

Abstract Background Acute postoperative pain after lumbar fusion surgery varies considerably despite standardized multimodal analgesia. Psychological vulnerability may contribute to unfavorable pain trajectories, but brief preoperative risk assessment tools remain insufficiently evaluated. Methods We conducted a secondary analysis of the randomized DoseRespKeta trial of adjunctive S-ketamine in oxycodone patient-controlled analgesia after lumbar fusion surgery. Preoperative emotional stress was assessed using the Brief Measure of Emotional Preoperative Stress (B-MEPS) and analyzed as a standardized latent trait. The primary outcome was the association between preoperative emotional stress and severe postoperative pain (NRS ≥ 7) during the first 72 postoperative hours, using mixed-effects logistic regression. The secondary outcome was cumulative oxycodone consumption during the first 24 postoperative hours. Results Of the 100 patients completing the parent trial, 98 had complete B-MEPS and postoperative outcome data. A one-unit increase in preoperative emotional stress was associated with severe pain at rest (NRSR ≥ 7; OR 2.73 [95% CI 1.20–6.24], p = 0.017) and during movement (NRSM ≥ 7; OR 2.52, [95% CI 1.29–4.92], p = 0.007) during the first 72 hours. In contrast, preoperative emotional stress was not independently associated with cumulative 24-hour oxycodone consumption (β 4.58 mg per one-unit increase in standardized emotional stress, 95% CI − 4.37–13.53, p = 0.319). Conclusions Preoperative emotional stress assessed using the B-MEPS was associated with less favorable postoperative pain trajectories despite standardized multimodal analgesia. These findings suggest that preoperative emotional stress is a marker of vulnerability within a biopsychosocial recovery process but do not validate the B-MEPS as a clinical prediction tool. Trial registration The study was registered before patient enrollment at clinicaltrials.gov (NCT02994173; Principal investigator: Teijo I. Saari; Date of registration: November 11, 2016) and in the EudraCT database (2016–002887–14; Principal investigator: Teijo I. Saari; Date of registration: October 12, 2016).