Need for Two-Year Patient-Reported Outcomes Score for Lumbar Spine Surgery Is Procedure-Specific

Study Design. Retrospective analysis of prospectively collected data. Objective. The aim of this study was to determine whether 1-year patient-reported outcomes (PROs) can accurately assess effective care for patients undergoing surgery for degenerative lumbar spine disease. Summary of Background Data. Prospective longitudinal PROs registries provide a means to accurately assess outcomes and determine the relative effectiveness of various spine treatments. Obtaining long-term PROs can be costly and challenging. Methods. Patients enrolled into a prospective registry who underwent lumbar spine surgery for degenerative disease were included. Baseline, 1-year, and 2-year Oswestry Disability Index (ODI) scores were captured. Previously published minimum clinically important difference (MCID) for ODI (14.9) was used. Multivariable linear regression model was created to derive model-estimated 2-year ODI scores. Absolute differences between 1-year and 2-year ODI were compared to absolute differences between 2-year and model-estimated 2-year ODI. Concordance rates in achieving MCID at 1-year and 2-year and predictive values were calculated. Results. A total of 868 patients were analyzed. One-year ODI scores differed from 2-year scores by an absolute difference of 9.7±8.9 points and predictive model-estimated 2-year scores differed from actual 2-year scores by 8.8±7.3 points. The model-estimated 2-year ODI was significantly different than actual 1-year ODI in assessing actual 2-year ODI for all procedures (P=0.001) except for primary (P=0.932) and revision microdiscectomy (P=0.978) and primary laminectomy (P=0.267). The discordance rates of achieving or not achieving MCID for ODI ranged from 8% to 27%. Concordance rate was about 90% for primary and revision microdiscectomy. The positive and negative predictive value of 1-year ODI to predict 2-year ODI was 83% and 67% for all procedures and 92% and 67% for primary and 100% and 86% for revision microdiscectomy respectively. Conclusion. One-year disability outcomes can potentially estimate 2-year outcomes for patient populations, but cannot reliably predict 2-year outcomes for individual patients, except for patients undergoing primary and revision microdiscectomy.