300 Section - Evaluating Clinically Meaningful Outcomes in Adult Spinal Deformity Surgery: MCID Analysis of Functional and Social Improvements

Objectives : Calculate and evaluate the clinical significance of minimum clinically important difference (MCID) in PROMIS Physical Function, Pain Interference, and Social Role outcomes among adult deformity patients undergoing spinal correction surgery. Measurements were taken preoperatively and at the 1-year postoperative mark.

Design: We conducted an analysis of 84 adult deformity patients who underwent spinal correction surgery via the traditional posterior open approach. MCID was calculated using the 0.5 Standard Deviation (SD) method, which is a widely accepted distribution-based method.

Results: The mean age of the cohort was 56.2 years. The MCID values were 3.21 for PF, 3.32 for PI, and 3.92 for SR. Overall, 68.2% of patients achieved MCID for PF, 68.2% for SR, but only 6.8% for PI. These findings suggest that improvements in physical function and social interaction were more common than improvements in pain. Older patients (≥60 years) were more likely to achieve meaningful gains in PF, with 75% reaching MCID compared to 60% of younger patients. This may reflect the greater relative benefit experienced by older patients with advanced deformity or baseline functional limitations, while younger patients with higher baseline function perceive less improvement. Postoperative gains in SR correlated strongly with PF improvement (r = 0.65, p < 0.05), underscoring the link between mobility and social participation. In contrast, changes in PI did not correlate with PF, highlighting persistent challenges in pain management.

Conclusion: The majority of patients undergoing adult spinal deformity surgery experienced clinically meaningful improvements in PF and SR, with over two-thirds of patients achieving MCID for these outcomes. PI, however, showed limited improvement, as only 6.8% of patients achieved MCID. This suggests that while the surgery successfully restores mobility and improves social participation, postoperative pain management requires further attention.