Poor muscle health and low preoperative ODI are independent predictors for slower achievement of MCID after minimally invasive decompression

BACKGROUND CONTEXT: Although some previous studies have analyzed predictors of non-improvement, most of these have focused on demographic and clinical variables and have not accounted for radiological predictors. In addition, while several studies have examined the degree of improvement after decompression, there is less data on the rate of improvement. PURPOSE: To identify the risk factors and predictors (both radiological and nonradiological) for slower as well as nonachievement of minimal clinically important difference (MCID) after mini-mally invasive decompression. DESIGN: Retrospective cohort. PATIENT SAMPLE: Patients who underwent minimally invasive decompression for degenera-tive lumbar spine conditions and had a minimum of 1-year follow up were included. Patients with preoperative Oswestry Disability Index (ODI) <20 were excluded. OUTCOME MEASURE: MCID achievement in ODI (cut off 12.8). METHODS: Patients were stratified into two groups (achieved MCID, did not achieve MCID) at two timepoints (early & LE;3 months, late & GE;6 months). Nonradiological (age, gender, BMI, comorbid-ities, anxiety, depression, number of levels operated, preoperative ODI, preoperative back pain) and radiological (MRI - Schizas grading for stenosis, dural sac cross-sectional area, Pfirrmann grading for disc degeneration, psoas cross-sectional area and Goutallier grading, facet cyst/effu-sion; X-ray - spondylolisthesis, lumbar lordosis, spinopelvic parameters) variables were assessed with comparative analysis to identify risk factors and with multiple regression models to identify predictors for slower achievement of MCID (MCID not achieved by & LE;3 months) and nonachieve-ment of MCID (MCID not achieved at & GE;6 months). RESULTS: A total of 338 patients were included. At & LE;3 months, patients who did not achieve MCID had significantly lower preoperative ODI (40.1 vs 48.1, p<0.001) and worse psoas Goutal-lier grading (p=.048). At & GE;6 months, patients who did not achieve MCID had significantly lower preoperative ODI (38 vs 47.5, p<.001), higher age (68 vs 63 years, p=.007), worse average L1-S1 Pfirrmann grading (3.5 vs 3.2, p=.035), and higher rate of pre-existing spondylolisthesis at the oper-ated level (p=.047). When these and other probable risk factors were put into a regression model, low preoperative ODI (p=.002) and poor Goutallier grading (p=.042) at the early timepoint and low preoperative ODI (p<.001) at the late timepoint came out as independent predictors for MCID nonachievement. CONCLUSION: After minimally invasive decompression, low preoperative ODI and poor muscle health are risk factors and predictors for slower achievement of MCID. For nonachievement of MCID, low preoperative ODI, higher age, greater disc degeneration, and spondylolisthesis are risk factors and low preoperative ODI is the only independent predictor. & COPY; 2023 Elsevier Inc. All rights reserved.

Automated summary

The aim of this study was to identify the risk factors and predictors (both radiological and nonradiological) for slower achievement and nonachievement of minimal clinically important difference (MCID) after minimally invasive decompression. The results showed that low preoperative Oswestry Disability Index (ODI) and poor muscle health were risk factors and predictors for slower achievement of MCID. For nonachievement of MCID, low preoperative ODI, higher age, greater disc degeneration, and spondylolisthesis were risk factors, and low preoperative ODI was the only independent predictor.