Postoperative Outcomes Based on American Society of Anesthesiologists Score After Minimally Invasive Transforaminal Lumbar Interbody Fusion

Study Design: A retrospective cohort study. Objective: To examine the association between the American Society of Anesthesiologists (ASA) score and patient-reported outcomes (PROs) after minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). Summary of Background Data: Few studies have investigated the correlation between ASA score and PROs after MIS TLIF. Methods: Patients undergoing primary, single-level MIS TLIF were retrospectively reviewed and placed into 3 cohorts: ASA score <= 2 and outpatient status, ASA score <= 2 and inpatient status, and ASA score >2. Oswestry Disability Index (ODI), visual analog scale (VAS) back and leg pain, and Short Form-12 Physical Component Score (SF-12 PCS) were administered preoperatively and at 6-week, 12-week, and 6-month time points. ASA scores were tested for association with improvements in PROs using linear regression. Results: A total of 187 patients had an ASA score <= 2 and 41 patients had an ASA score >2. Higher ASA scores were associated with older age, obesity, higher comorbidity burden, and an increased length of stay. ASA subgroups demonstrated a significant difference in preoperative ODI and VAS back pain scores and improvement in VAS back pain scores at the 12-week and 6-month time points; however, there was no discernible pattern of improvement amongst cohorts. No statistically significant differences were observed with improvements in PROs. Conclusions: The study suggests ASA scores are not associated with postoperative recovery in pain and disability after MIS TLIF. Our results indicate that regardless of the preoperative ASA score, patients are likely to achieve similar improvements in PROs through 6 months follow-up. Although using ASA as a risk stratification tool to predict perioperative complications, its utility in predicting improvement in PROs is still uncertain at this time.