Preoperative Zung depression scale predicts patient satisfaction independent of the extent of improvement after revision lumbar surgery

Background context: Patient satisfaction ratings are increasingly being used in health care as a proxy for quality and are becoming the focal point for several quality improvement initiatives. Affective disorders, such as depression, have been shown to influence patient-reported outcomes and self-interpretation of health status. We hypothesize that patient psychiatric profiles influence reported satisfaction with care, independent of surgical effectiveness. Purpose: To assess the predictive value of preoperative depression on patient satisfaction after revision surgery for same-level recurrent stenosis. Study design: Retrospective cohort study. Patient sample: Fifty-three patients undergoing a revision surgery for symptomatic same-level recurrent stenosis. Outcome measures: Patient-reported outcome measures were assessed using an outcomes questionnaire that included questions on health state values (EuroQol-5D [EQ-5D]), disability (Oswestry Disability Index [ODI]), pain (visual analog scale [VAS]), depression (Zung self-rating depression scale), and Short Form 12 (SF-12) physical and mental component scores (PCS and MCS). Patient satisfaction was dichotomized as either "YES" or "NO" on whether they were satisfied with their surgical outcome 2 years after the surgery. Methods: A total of fifty-three patients undergoing revision neural decompression and instrumented fusion for same-level recurrent stenosis-associated back and leg pain were included in this study. Preoperative Zung self-rating depression score (ZDS), education status, comorbidities, and postoperative satisfaction with surgical care and outcome was assessed for all patients. Baseline and 2-year VAS for leg pain (VAS-LP), VAS for low back pain (VAS-BP), ODI, SF-12 PCS and MCS, and health-state utility (EQ-5D) were assessed. Factors associated with patient satisfaction after surgery were assessed via multivariate logistic regression analysis. Results: Two years after surgery, a significant improvement was reported in all outcome measures: VAS-BP (5±2.94 vs. 9.28±1, p<.001), VAS-LP (3.43±2.95 vs. 9.5±0.93, p<.001), ODI (21.75±12.07 vs. 36.01±6, p<.001), SF-12 PCS (32.30±11.01 vs. 25.13±5.84, p<.001), SF-12 MCS (47.48±10.96 vs. 34.91±12.77, p<.001), EQ-5D (0.60±0.31 vs. 0.18±0.22, p<.001), and ZDS (37.52±11.98 vs. 49.90±10.88, p<.001). Independent of postoperative improvement in pain and disability (surgical effectiveness), increasing preoperative Zung depression score was significantly associated with patient dissatisfaction 2 years after revision lumbar surgery (Odds ratio=0.67 [confidence interval: 0.38, 0.87], p<.001). Conclusions: Our study suggests that independent of the surgical effectiveness, the extent of preoperative depression influences the reported patient satisfaction after revision lumbar surgery. Quality improvement initiatives using patient satisfaction as a proxy for quality should account for the patients' baseline depression as potential confounders.