Minimum Clinically Important Difference and Substantial Clinical Benefit in Pain, Functional, and Quality of Life Scales in Failed Back Surgery Syndrome Patients

Study Design.. Prospective observational 1-year study. Objective.. To determine minimum clinically important difference (MCID) and substantial clinical benefit (SCB) of outcome measures in failed back surgery syndrome (FBSS) patients, as these metrics enable assessment of whether and when an intervention produces clinically meaningful effects in a patient. Summary of Background Data.. Several methods have been devised to quantify clinically important difference, but MCID and SCB for FBSS patients has yet to be determined. Methods.. Patients with persisting/recurrent low back pain (LBP) and/or leg pain after lumbar surgery who completed 16 weeks of treatment (n = 105) at two hospitals in Korea from November 2011 to September 2014 were analyzed. Global perceived effect was used to determine receiver operating characteristic curves in visual analogue scale (VAS), Oswestry disability index (ODI), and short form-36 (SF-36) in an anchor-based approach. Results.. MCIDs for ODI, LBP and leg pain VAS, physical component summary, mental health component summary (MCS), and overall health scores of SF-36 were 9.0, 22.5, 27.5, 10.2, 4.0, and 8.9, and SCBs were 15.0, 32.5, 37.0, 19.7, 19.3, and 21.1, respectively. MCID and SCB area under the curve was ≥0.8, and ≥0.7, respectively. Conclusion.. LBP and leg pain VAS, ODI, and physical component summary of SF-36 may be used to measure responsiveness in FBSS patients. Level of Evidence: 3