Factors Associated with Failure to Achieve Minimal Clinical Important Differences in VAS Following Lumbar Disc Arthroplasty: A Multi-Institutional Experience

Introduction: Lumbar disc arthroplasty (LDA) is increasingly performed due to advantages including motion preservation and a low risk of surgical complications compared to traditional spinal fusion. There is still limited evidence examining factors associated with its efficacy in the management of back pain, which is a common indication for LDA. We aimed to identify risk factors of failure to achieve minimal clinically important difference (MCID) in visual analog scale (VAS) back pain scores following LDA.

Methods: A retrospective analysis of patients who underwent LDA with available 3-month follow-up at the three participating sites was conducted. Patient demographics, surgical details, and VAS back pain scores were analyzed. Patients were categorized into two groups based on their achievement or non-achievement of MCID in VAS scores.

Results: Our study comprised of 111 patients, with mean age 39.58 ± 9.43 years and 48 (43.2%) females, that met the inclusion criteria. Among these eligible patients, 26 (23.4%) failed to reach MCID in VAS scores following LDA at the 3-month. Younger age (35.50 ± 8.64 vs. 40.82 ± 9.35 years, p=0.01), depression (13 (50.0%) vs. 19 (22.4%), p=0.01), and preoperative unemployed status (18 (69.2%) vs. 74 (88.1%), p =0.02) were associated with failure to achieve MCID in VAS at the 3-month followup. The multivariate regression model reported young age (OR: 0.93 (0.88 – 0.99), p =0.03) and depression (OR: 4.54 (1.28 – 16.08), p =0.02) to be independently associated with failure to achieve MCID in VAS at three months following LDA. Additionally, depression (9 (52.9%) vs. 15 (24.6%), p =0.03) and preoperative unemployed status (11 (64.7%) vs. 55 (91.7%), p =0.01) also remained associated with failure to achieve MCID in VAS at the 12-month followup, which was observed in 17 (21.8%) patients.

Conclusion : Our study reported younger age, depression, and preoperative unemployment to be significant risk factors for failure to achieve MCID for VAS back pain scores following LDA. Future studies can provide a more comprehensive understanding of the correlations between these factors and patient-reported outcomes.