Introduction: Methodological limitations exist for previously reported MCID and SCB calculations including: 1) an inability to accurately report >1 year outcomes using traditional anchor questions such as the SF-36 Q2; and 2) lack of disease specific values for ASD. This study proposes an alternative MCID and SCB calculation using an anchor-based approach based on strictly dominant health states from the SF-6D and applies this methodology to the calculation of MCID and SCB values for surgical treatment of ASD.
Methods: Analysis of prospective, multi-center, consecutively enrolled patients surgically treated for ASD. HRQOL (SF36, ODI and SRS-22) was obtained at baseline, 1 and 2 year post-op, with SF-6D health states calculated from the SF-36. Minimum improvement was defined as: 1) no health domain in which follow-up SF-6D were below baseline; and 2) improvement in the lower 50th percentile among those who improved. Substantial improvement defined as total improvement in the upper 50th percentile among those who improved. ODI and SRS-22 MCID and SCB were calculated using the area under the receiver operator curve (AUC).
Results: One-year and two-year follow-up data were available for 217 of 256 (85%) and 149 of 230 (65%) patients, respectively. MCID and SCB values are summarized in Table 1. Compared to traditional SF-36 Q2 anchor results, the proposed methodology generates higher MCID and SCB values and greater sensitivity and specificity (based on AUC). Statistical differences were also observed in MCID and SCB values between patients with low (below average) versus high (above average) baseline HRQOL scores.
Conclusions: At one-year follow-up, MCID values for ASD surgery where higher than those reported in comparable studies of AIS. The analysis also revealed large differences in MCID and SCB values across follow-up periods and patient groups, highlighting the need to consider such factors in determining if post-op MCID or SCB is achieved.
Patient Care: Improve our understanding of how to assess health-related quality of life outcomes for adults with spinal deformity undergoing treatment.
Learning Objectives: By the conclusion of this session, participants should be able to: (1) Understand the concepts of minimal clinically important difference (MCID) and substantial clinical benefit (SCB); (2) Appreciate the importance of disease-specific measures of MCID and SCB; (3) Appreciate that there are large differences in MCID and SCB values across follow-up periods and patient groups, highlighting the need to consider such factors in determining if post-op MCID or SCB is achieved.