RESUMEN
PURPOSE: To elucidate the minimum clinically important change (MCIC) of the physical component summary (PCS) of the Short Form-12, Oswestry Disability Index (ODI), EuroQOL-5 dimensions (EQ-5D), and the Core Outcome Measures Index (COMI) in patients aged ≥ 75 years undergoing lumbar spine surgery. METHODS: We retrospectively reviewed patients aged ≥ 75 years with degenerative lumbar spine disease who underwent lumbar spine decompression or fusion surgery within three levels between April 2017 and June 2018. We also evaluated patients aged < 75 years in the same period as reference. We evaluated the baseline and postoperative PCS, ODI, EQ-5D, and COMI scores. Patients were asked to answer an anchor question regarding health transition for MCICs using the anchor-based method. RESULTS: A total of 247 patients aged ≥ 75 years and 398 patients aged < 75 years were included for analysis. Of patients aged ≥ 75 years, 83.4% showed at least "somewhat improved" outcomes, while 91.0% of patients aged < 75 years reported this outcome. PCS change score was not adequately correlated to health transition in patients aged ≥ 75 years. Receiver operating characteristic curve analyses revealed MCICs of 17.8 for ODI, 0.18 for EQ-5D, and 1.6 for COMI in patients aged ≥ 75 years, and 12.7 for ODI, 0.19 for EQ-5D, and 2.3 for COMI in patients aged < 75 years. CONCLUSION: In patients aged ≥ 75 years, PCS may not be feasible for evaluation of health transition. The MCIC value for ODI score was higher and that for EQ-5D/COMI score was lower in patients aged ≥ 75 years, compared with those in patients aged < 75 years.