Predictors of survival and functional outcomes after spinal surgery for multiple myeloma: a nationwide study of 200 patients

OBJECTIVE: To identify predictors of survival after spinal surgery for multiple myeloma (MM) and evaluate postoperative ambulation and pain at six weeks. METHODS: This retrospective nationwide cohort study included 200 patients from the Swedish Spine Registry and the Swedish Myeloma Registry (2011-2023). Survival was estimated using Kaplan-Meier methods. Multivariable Cox regression models assessed predictors including International Staging System (ISS) stage, hemoglobin, age, preoperative ambulation, and synchronous (≤ 90 days from MM diagnosis) versus metachronous (> 90 days) spinal involvement. RESULTS: Median overall survival from MM diagnosis was 72 months (95% CI, 49.4-94.6), and median postoperative survival was 58 months (95% CI, 38.3-77.7). Multivariable analysis identified ISS stage III (HR, 3.2; 95% CI, 1.2-8.0), older age (HR, 1.03; 95% CI, 1.01-1.06), preoperative non-ambulation (HR, 2.4; 95% CI, 1.3-4.2), and metachronous disease (HR, 3.3; 95% CI, 1.7-6.3) as independent predictors of poorer survival. Paired preoperative and 6-week postoperative data were available for 94 of 200 patients (47%) for ambulation and 113 of 200 patients (56.5%) for pain. Among patients with paired data, 64% of initially non-ambulatory patients regained ambulation, 96% of initially ambulatory patients maintained ambulation, and 72% (81/113) reported improved pain. CONCLUSION: Advanced ISS stage, older age, preoperative non-ambulation, and metachronous disease were independent predictors of reduced survival after spinal surgery for MM. In selected patients with available follow-up data, surgery restored or preserved mobility and provided pain relief, supporting its role in the multidisciplinary management of spinal manifestations of MM.