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

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.