Risk Factors for Postoperative Non-Satisfaction despite ODI Improvement in Patients undergoing Elective Lumbar Surgery

Study design. Secondary analysis of prospective study. Objective. To assess the risk factors for postoperative non-satisfaction despite improvement in the Oswestry Disability Index (ODI) two years after elective lumbar surgery. Background. The ODI and postoperative satisfaction are important markers of postoperative success. While ODI improvement is expected to correlate with satisfaction, their exact relationship remains unclear. Additionally, some patients may achieve functional improvement yet report non-satisfaction postoperatively. Methods. A secondary analysis was performed on a prospective study of patients undergoing lumbar surgery for degenerative conditions. Patients with a 2-year ODI and satisfaction follow-up were included. Risk factors for non-satisfaction despite ODI improvement were investigated using t-tests, Wilcoxon-tests, and Fisher’s-exact-tests. Significant variables were analyzed with multivariable logistic regression, adjusting for covariates. Results. 355 patients (65±10 y, 58% female) were included. Non-satisfied patients showed significantly higher scores in pre- (64[52-76], P <0.001) and postoperative (36[20-44], P <0.001) ODI and lower absolute (18[8-30], P <0.001) and percentage (30[17-52], P <0.001) improvement rates from pre- to postoperatively. Higher baseline (OR1.03, 95%CI 1.01-1.05, P <0.001) and postoperative (OR1.08, 95%CI 1.06-1.10, P <0.001) ODI scores, and lower absolute (OR0.94, 95%CI 0.92-0.96, P <0.001) and percentage (OR0.95, 95%CI 0.94-0.97, P <0.001) improvement rates, were significant risk factors for experiencing non-satisfaction, despite ODI improvement. Higher fat infiltration (FI) of the multifidus (MF) (OR1.03, 95%CI 1.00–1.06, P =0.042) or the erector spinae (ES) (OR1.06, 95%CI 1.03–1.09, P <0.001) were significantly correlated with postoperative non-satisfaction, after adjusting for covariates. Conclusion. Higher pre- and postoperative ODI scores and lower ODI improvement were linked to postoperative non-satisfaction. Higher FI in the MF or ES was also a significant risk factor for postoperative non-satisfaction, despite ODI improvement. The findings highlight that postoperative satisfaction is influenced by various factors affected by ODI-measured disability. Additionally, paraspinal muscle health greatly affects postoperative outcomes and should guide preoperative planning and postoperative care.