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Background Context: Minimum clinically important difference (MCID) for patient-reported outcome measures is commonly used to assess clinical improvement. However, recent literature suggests that an absolute point-change may not be an effective or reliable marker of response to treatment for patients with low or high baseline patient-reported outcome scores. The multitude of established MCIDs also makes it difficult to compare outcomes across studies and different spine surgery procedures.Purpose: To determine whether a 30% reduction from baseline in disability and pain is a valid method for determining clinical improvement after lumbar spine surgery.Study Design: Retrospective analysis of prospective data from a national spine registry, the Quality Outcomes Database.Patient Sample: There were 23,280 participants undergoing elective lumbar spine surgery for degenerative disease who completed a baseline and follow-up assessment at 12 months.Outcome Measures: Patient-reported disability (Oswestry Disability Index [ODI]), back and leg pain (11-point Numeric Rating Scale [NRS]), and satisfaction (NASS scale).Methods: Patients completed baseline and a 12-month postoperative assessment to evaluate the outcomes of disability, pain, and satisfaction. The change in ODI and NRS pain scores was categorized as met (≥30%) or not met (<30%) percent reduction MCID. The 30% reduction from baseline was compared with a wide range of well-established absolute point-change MCID values. The relationship between 30% reduction and absolute change values and satisfaction were primarily compared using receiver operating characteristic (ROC) curves, area under the curve (AUROC), and logistic regression analyses. Analyses were conducted for overall scores and for disability and pain severity categories and by surgical procedure.Results: Thirty percent reduction in ODI and back and leg pain predicted satisfaction with more accuracy than absolute point-change values for the total population and across all procedure categories (p<.001), except for when compared with the highest absolute point-change threshold for leg pain (3.5-point reduction). The largest AUROC differences, in favor of 30% reduction, were found for the lowest disability (ODI 0-20%: 21.8%) and bed-bound disability (ODI 81%-100%: 13.9%) categories. For pain, there was a 3.4%-12.4% and 1.3%-9.8% AUROC difference for no/mild back and leg pain (NRS 0-4), respectively, in favor of a 30% reduction threshold.Conclusions: A 30% reduction MCID either outperformed or was similar to absolute point-change MCID values. Results indicate that a 30% reduction (baseline to 12 months after surgery) in disability and pain is a valid method for determining clinically relevant improvement in a broad spine surgery population. Furthermore, a 30% reduction was most accurate for patients in the lowest and highest disability and lowest pain severity categories. A 30% reduction MCID allows for a standard cut-off for disability and pain that can be used to compare outcomes across various spine surgery procedures. [ABSTRACT FROM AUTHOR]

Minimal clinically important difference (MCID) represents the smallest, clinically relevant change in a patient-reported outcome (PRO) score. However, the literature suggests that an absolute change from baseline may not be a reliable marker of response to treatment for patients with a low or high baseline PRO score. An alternative to MCID is a threshold of clinical relevance defined by percent reduction from baseline PRO score. The purpose of this study was to determine whether a clinically relevant percent reduction (CRPR) of 30% in disability and pain scores is a valid method for determining clinical improvement at 12 months after lumbar spine surgery. Retrospective evaluation of prospectively collected data from a national surgical spine registry, the Quality Outcomes Database (QOD). A total of 23,280 participants undergoing elective surgery for a lumbar degenerative condition (primary stenosis, disc herniation, spondylolisthesis (Grade I) and symptomatic mechanical disc collapse or revision surgery for recurrent same-level disc herniation, pseudarthrosis and adjacent segment disease). Outcomes were disability (ODI), back and leg pain (NRS-BP/LP), and satisfaction (NASS scale). Participants completed a preoperative assessment and follow-up assessment at 1-year. The change in ODI and NRS-BP/LP scores were categorized as met CRPR (percent change ≥30%) or not met CRPR (percent change < 30%) and by achieving MCID or not achieving MCID. MCID was based on established values of 12.8 for ODI, 1.2 for NRS-BP, and 1.6 for NRS-LP. The relationship between each categorization (30% CRPR and MCID) and satisfaction were compared with logistic regression models and receiver operating characteristic (ROC) curves. Analyses were conducted in the entire sample and by surgical procedure (microdiscectomy, decompression, decompression with fusion). In addition, the ability of CRPR and MCID to predict satisfaction was examined by severity of disability and pain. Significance was set at p <.05. Results from the satisfaction prediction models found that the OR for 30% ODI CRPR was 11.1 (10.2 to 12.1) and for ODI MCID was 7.8 (7.2 to 8.4), while 30% NRS-BP and NRS-LP CRPR was 7.9 (7.3 to 8.5) and 6.7 (6.2 to 7.2) compared to MCID ORs of 5.5 (5.1 to 5.9) and 5.6 (5.2 to 6.0) (p <.001). A CRPR threshold of 30% reduction in ODI and NRS-BP/LP predicted satisfaction with 76.9%, 73.7% and 70.9% accuracy, respectively, whereas MCID thresholds predicted satisfaction with 73.5%, 69.5% and 68.2% accuracy. Accuracy was similar across surgical procedure categories. The largest difference in predictive power for 30% CRPR compared to MCID was found for patients with minimal disability (ODI 0-20%: 75.6% vs 65.1%) and bed-bound disability (ODI 81-100%: 74.8% vs 60.9%). For pain, there was no difference in predictive power for patients with moderate pain (NRS 5-6), however there was a 3.9% and 1.7% difference for no/low back and leg pain (NRS 0-4) and a 3.8% and 2.6% difference for severe back and leg pain (NRS 7-10) in favor of a 30% CRPR threshold. CRPR may be a more clinically relevant method for identifying response to treatment since it can be applied to broad spinal surgery populations and takes into account the baseline PRO score. Furthermore, a 30% CRPR appears to outperform established MCID thresholds for patients with either low or high preoperative disability and pain scores. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]