Predictive factors for successful non-operative treatment and achieving MCID improvement in health-related quality of life in adult spinal deformity

BACKGROUND: Adult spinal deformity is a spectrum of degenerative spinal diseases with increasing prevalence and healthcare burden worldwide. Identification of patients who are more likely to improve through conservative management may reduce cost and potentially prevent surgery and its associated costs and complications. This study aims to identify predictive factors for MCID in improvement of ODI and SRS-22r questionnaires in patients with adult spinal deformity treated with conservative treatment. METHODS: A prospective, observational cohort study of 46 patients was conducted at a spine specialist clinic. Inclusion criteria were 30–80 years of age, diagnosis of neglected adolescent idiopathic scoliosis, de-novo scoliosis, degenerative spondylolisthesis, and sagittal plane deformities (thoracic hypokyphosis, lumbar hypolordosis), presenting with mechanical back pain with or without radicular leg pain. All patients received conservative management including medication and physiotherapy. Radiological and clinical parameters were measured at baseline and at 1-year follow-up. Primary outcomes were ODI and SRS-22r scores. Secondary outcomes were EQ-5D-5L scores and requiring spine surgery during conservative treatment. Predictors for MCID improvement in ODI and SRS-22r were identified using multivariate regressions and receiver operating characteristic (ROC) analyses. RESULTS: At baseline, patients who reached MCID in ODI and/or SRS-22r showed less comorbidities (diabetes mellitus, hypertension, ischemic heart disease, osteoarthritis, cancer), smaller range of lateral spinal flexion, larger trunk shift, larger pelvic incidence, a higher EQ-5D-5L anxiety/depression dimension score, a lower SRS-22r total score, and presence of spondylolisthesis. Lateral flexion range < 25 degrees, trunk shift > 14 mm, pelvic incidence > 50 degrees, EQ-5D-5L anxiety/depression dimension score > 1, and SRS-22r total score < 3.5 were the cut-off values generated by ROC analysis. CONCLUSIONS: Both radiological and clinical predictive factors for MCID improvement in health-related quality of life were identified. Future research should identify subgroups of patients who are responsive to specific conservative treatment modalities, so as to provide information for personalized medicine. LEVEL OF EVIDENCE: II