Risk Factors Associated With Failure to Reach Minimal Clinically Important Difference in Patient-reported Outcomes Following Minimally Invasive Transforaminal Lumbar Interbody Fusion for Spondylolisthesis.

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To determine risk factors associated with failure to reach the minimal clinically important difference (MCID) in patient-reported outcomes (PROs) for patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) for spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The MCID of PROs are often utilized to determine the benefit of spinal procedures. However, negative predictive factors for reaching MCID in patients surgically treated for lumbar spondylolisthesis have been difficult to elucidate.

MATERIALS AND METHODS

A prospectively maintained surgical database of patients who were diagnosed with lumbar spondylolisthesis and surgically treated with a single level MIS TLIF from 2010 to 2016 was reviewed. Patients with incomplete PRO survey data or <6-month follow-up were excluded from the analysis. MCID for visual analogue scale (VAS) back, VAS leg, and Oswestry Disability Index (ODI) was obtained from established values in the literature. All risk factors were then assessed for association with failure to reach MCID using bivariate and multivariate regression adjusting for preoperative characteristics.

RESULTS

A total of 165, 76, and 73 patients treated with MIS TLIF for spondylolisthesis had complete PRO data for VAS back, VAS leg, and ODI, respectively, and were thus included in the analysis for the respective PRO. Overall, 75.76%, 71.05%, and 61.64% of patients treated with a single level MIS TLIF for spondylolisthesis reached MCID for VAS back, VAS leg, and ODI, respectively. On multivariate analysis, patients were less likely to achieve MCID for VAS back following surgical treatment if they received workers' compensation (P<0.001). No other measured factors were noted to independently correlate with MCID achievement.

CONCLUSIONS

The results of this study suggest that a majority of patients with spondylolisthesis achieve MCID for commonly measured PROs following MIS TLIF for spondylolisthesis. However, worker's compensation insurance status may serve as a negative predictive factor for reaching MCID.