Age variation in the minimum clinically important difference in SRS-22r after surgical treatment for adult spinal deformity - A single institution analysis in Japan

Abstract

Background: The Scoliosis Research Society-22r (SRS-22r) has been shown to be reliable, valid and responsive to change in patients with adult spinal deformity (ASD) undergoing surgery. The minimum clinically important difference (MCID) quantifies a threshold value of improvement that is clinically relevant to the patient. Health-related quality of life scores depend on age. The purpose of this study was to assess MCID threshold values stratified by age for SRS-22r domains in patients with ASD undergoing surgical correction.

Methods: We identified a consecutive series of 184 Japanese ASD patients who completed the SRS-22r and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) preoperatively and 1 year postoperatively. Effectiveness as measured on the JOABPEQ was used as the anchor to determine MCID for the Function, Pain, and Mental health domains using receiver-operating-characteristic (ROC) curve analysis. We performed MCID analysis stratified by age (<70 or ≥70).

Results: Mean preoperative SRS-22r Function score was 2.69 improving to 3.23 at postoperatively (p < 0.001). Mean preoperative SRS-22r Pain score was 3.04 improving to 3.78 at postoperatively (p < 0.001). Mean preoperative SRS-22r Mental health score was 2.72 improving to 3.25 at postoperatively (p < 0.001). There was a statistically difference in change in domain score between "not effective" and "effective" (p < 0.001). The ROC curve analysis methods yielded MCID values of 0.58 for Function, 0.55 for Pain, and 0.70 for Mental health domains. There was difference of MCID value for Function and Mental health domain between aged <70 and ≥70; 0.78 and 0.55 for Function; 0.70 and 0.48 for Mental health.

Conclusion: Results of this study showed that MCID threshold values for SRS-22 Function and Mental health domains in older than 70 was lower than in younger than 70, potentially implying that older patients have lower expectation.