Abstract
Introduction: Spinal cord stimulation (SCS) is a well-established treatment for chronic back and leg pain. However, careful patient selection remains crucial to optimize outcomes and minimize treatment failure. The PROSTIM study aims to identify distinct subgroups within a diverse patient population using a biopsychosocial approach to guide personalized SCS therapy, helping to determine which patients benefit most from this therapy.
Materials / Methods: The PROSTIM study is a prospective, multicenter, observational study involving 101 patients with Persistent Spinal Pain Syndrome (PSPS) type 2. Baseline variables—including demographics, pain scores (back and leg Visual Analog Scale, VAS), quality of life (EuroQol-5D, EQ-5D), disability (Oswestry Disability Index, ODI) and psychological measures (Pain Catastrophizing Scale, PCS)—were collected. Missing data were handled with multiple imputation. A cluster analysis was conducted using the k-means algorithm on standardized baseline variables (EQ-5D, ODI, PCS, back and leg VAS) to identify subgroups of patients with similar characteristics. Changes in primary outcomes (back and leg VAS, ODI, EQ-5D) from baseline to 6–12 months post-SCS will be compared between clusters and stimulation subtypes. Secondary outcomes included return to work, decreased opioid use, sleep quality and patient satisfaction.
Results: Two distinct patient clusters were identified. Cluster 1 represented patients with higher baseline pain intensity, greater disability, and lower quality of life, while Cluster 2 consisted of patients with less severe symptoms. SCS significantly improved VAS, ODI and QOL after 6-12 months in both clusters. The improvement in QOL was greater (0,26; 95%CI 0,03-0,49) in cluster 1, compared to cluster 2 (p=0,0265). The improvement in disability was not significantly different between the two clusters.
Expected probabilities for secondary outcomes—such as return to work, reduction in medication use, sleep quality and treatment satisfaction—were comparable between clusters (all p > 0.05). The expected probability of reduction in medication use was 0.65 (95% CI: 0.35–0.86) in cluster 1 and 0.71 (95% CI: 0.27–0.94) in cluster 2 (p = 0.8563). Improved sleep quality was reported with a probability of 0.51 (95% CI: 0.29–0.73) in cluster 1 and 0.63 (95% CI: 0.17–0.93) in cluster 2 (p = 0.5028). Lastly the probability for treatment satisfaction was 0.73 (95% CI: 0.51–0.88) in cluster 1 and 0.79 (95% CI: 0.33–0.97) in cluster 2 (p = 0.7382).
Discussion: This study identified two distinct patient clusters with differing baseline biopsychosocial profiles. Despite these differences, both clusters showed comparable improvements in pain and disability following SCS, except from QOL improvement. These findings suggest that SCS is effective regardless of initial symptom severity and support the use of biopsychosocial profiling to guide personalized treatment strategies and optimize patient selection in clinical practice. Patients in clusters 1 might benefit from additional rehabilitation to improve disability after SCS treatment.
Conclusions: The PROSTIM study has successfully identified two distinct patient clusters based on biopsychosocial factors. Outcomes of SCS for PSPS type II are comparable for both clusters, indicating a successful treatment independent from the severity of the baseline characteristics. The improvement in QOL is greater in patients with preoperative worse health status (cluster 1). These findings could guide more effective patient selection and multidisciplinary optimization of SCS therapy in real-world clinical practice.
Poster presentation.