Baseline American Society of Anesthesiologists classification predicts worse anxiety and pain interference following Lumbar Interbody Fusion

Abstract

Background: The American Society of Anesthesiologists (ASA) classifications allow physicians to briefly assess a patient's risk for general anesthesia and surgical intervention. Although simple to calculate, a patient's ASA score may correlate with differences in outcomes following spinal operations. The purpose of this study is to establish the effect of ASA score on Patient-Reported Outcomes Measurement Information System (PROMIS) outcomes following Lateral Lumbar Interbody Fusion (LLIF).

Methods: All patient data was collected from a single spinal surgeon database. Patients were separated into cohorts of "Lower ASA" (ASA < 3) and "Higher ASA" (ASA ≥ 3). Demographics, perioperative characteristics, preoperative Patient-Reported Outcomes (PROs), and postoperative PROs at 6 weeks and final postoperative time points were compared statistically. These included Visual Analog Scales for back and leg pain (VAS-B, VAS-L), the Oswestry Disability Index (ODI), the 9-item Patient Health Questionnaire (PHQ-9), and PROMIS measures for Physical Function (PROMIS-PF), Sleep Disturbance (PROMIS-SD), Anxiety (PROMIS-A), and Pain Interference (PROMIS-PI). PRO improvements between preoperative and postoperative time points and Minimum Clinically Important Difference (MCID) were also compared.

Results: In total, 154 patients were included (111 and 43 in the Lower and Higher ASA cohorts, respectively). Patient age, body mass index (BMI), presence of diabetes, and Charlson Comorbidity Index (CCI) score were significantly different between the two cohorts (Table 1, p < 0.004 for all). Primary vs. non-primary surgery, number of spinal levels fused, postoperative length of stay, and rates of isthmic spondylolisthesis and foraminal stenosis also significantly differed (Table 2, p < 0.05 for all). Patients with a higher ASA score were found to have higher PROMIS-A preoperatively (Table 3, p = 0.029). These patients also had higher PROMIS-A and PROMIS-PI at final postoperative evaluation (p values of 0.007 and 0.047, respectively). Score changes over time and MCID achievement did not seem to be impacted by baseline ASA score.

Conclusions: Patients with a higher preoperative ASA score were found to have worse anxiety pre-operatively and worse anxiety and pain interference at the final postoperative evaluation. Clinical improvement over time was not significantly affected by the ASA score.

Keywords: ASA Classification; Lateral Lumbar Interbody Fusion; Patient-Reported Outcomes.