Minimum Clinically Important Difference in Patients Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion

Abstract

BACKGROUND: Few studies have established the minimum clinically important difference (MCID) in patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for physical function and pain. OBJECTIVE: To establish MCID for physical function and pain patient-reported outcome measures (PROMs) for MIS-TLIF through anchor- and distribution-based methods using the Oswestry Disability Index (ODI) as the anchor. METHODS: Ninety-eight patients undergoing primary MIS-TLIF with preoperative and 1-year postoperative ODI scores were identified. MCID was calculated using anchor- and distribution-based methods. ODI responders were classified as patients who decreased by 1 disability classification. PROMs of Patient-Reported Outcome Measurement Information System-Physical Function (PROMIS-PF), 12-Item Short Form Physical Component Score (SF-12 PCS), Visual Analog Scale (VAS) back/leg, and ODI were collected preoperatively and 1-year postoperatively. Anchor-based methods were average change, minimum detectable change, change difference, receiver operating characteristic curve, and cross-sectional analysis. Distribution-based methods were standard error of measurement, receiver change index, effect size, and 0.5 ∗ ΔSD. RESULTS: Anchor-based methods ranged from 4.2 to 11.9 for PROMIS-PF, 6.0 to 15.8 for SF-12 PCS, 1.8 to 4.6 for VAS back, and 2.1 to 4.0 for VAS leg. The area under the curve for receiver operating characteristic analysis ranged from 0.66 to 0.81. Distribution-based methods ranged from 1.1 to 3.9 for PROMIS-PF, 1.6 to 10.4 for SF-12 PCS, 0.5 to 1.6 for VAS back, and 0.6 to 1.8 for VAS leg. CONCLUSION: Patients undergoing MIS-TLIF had a wide range of MCID values. The receiver operating characteristic curve was selected as the most clinically appropriate method. The corresponding MCID values were 4.2 for PROMIS-PF, 6.8 for SF-12 PCS, 1.8 for VAS back, and 2.4 for VAS leg.