Study design:

Retrospective longitudinal cohort study.

Objective:

This study aimed to elucidate factors affecting the likelihood of achieving minimum clinically important difference (MCID) to patient-reported outcomes defined by the Scoliosis Research Society-22r (SRS-22r) among patients with adult spinal deformity (ASD) who underwent extensive corrective fusion surgery from the thoracic spine to the pelvis.

Summary of background data:

Achieving MCID for SRS-22r parameters was a measure of surgical efficacy. Patient characteristics and surgical and radiographic factors that affect the likelihood of achieving MCID for SRS-22r parameters are unknown.

Methods:

Data from patients with ASD who underwent extensive corrective fusion surgery from the thoracic spine to the pelvis during 2010 to 2016 were retrospectively reviewed. Data from a total of 167 patients with ≥2 years of follow-up were included. Multivariate analysis was used to investigate factors associated with the likelihood of achieving MCID for each of the SRS-22r domains (Function, Pain, Subtotal) 2 years after surgery. The following MCID values were used: 0.90 for Function, 0.85 for Pain, and 1.05 for the Subtotal.

Results:

MCID achievement rate was 36.5% for Function, 46.1% for Pain, and 44.3% for the Subtotal domain. In multivariate analysis, preoperative SRS-22r Function (odds ratio [OR] = 0.204, 95% confidence interval [CI] 0.105-0.396) increased the likelihood of achieving MCID for SRS-22r Function. Preoperative SRS-22r Subtotal (OR = 0.211, 95% CI, 0.107-0.413), preoperative pelvic tilt (OR = 1.072, 95% CI, 1.012-1.136), preoperative pelvic incidence minus lumbar lordosis (OR = 0.965, 95% CI, 0.934-0.997), and postoperative sagittal vertical axis (OR = 0.985, 95% CI, 0.974-0.995) affected the likelihood of achieving MCID for the SRS-22r Subtotal.

Conclusion:

Patients with poor preoperative health-related quality of life were more likely to achieve improvement in SRS-22r parameters after extensive corrective fusion surgery for ASD. Achieving postoperative sagittal alignment increased the likelihood of achieving MCID for the SRS-22r Subtotal domain.Level of Evidence: 3.