title: Inadequacy of 3-month Oswestry Disability Index outcome for assessing individual longer-term patient experience after lumbar spine surgery.
abstract: OBJECTIVE Prospective longitudinal outcomes registries are at the center of evidence-driven health care reform. Obtaining real-world outcomes data at 12 months can be costly and challenging. In the present study, the authors analyzed whether 3-month outcome measurements sufficiently represent 12-month outcomes for patients with degenerative lumbar disease undergoing surgery. METHODS Data from 3073 patients undergoing elective spine surgery for degenerative lumbar disease were entered into a prospective multicenter registry (N(2)QOD). Baseline, 3-month, and 12-month follow-up Oswestry Disability Index (ODI) scores were recorded. The absolute differences between actual 12- and 3-month ODI scores was evaluated. Additionally, the authors analyzed the absolute difference between actual 12-month ODI scores and a model-predicted 12-month ODI score (the model used patients' baseline characteristics and actual 3-month scores). The minimal clinically important difference (MCID) for ODI of 12.8 points and the substantial clinical benefit (SCB) for ODI of 18.8 points were used based on the previously published values. The concordance rate of achieving MCID and SCB for ODI at 3-and 12-months was computed. RESULTS The 3-month ODI scores differed from 12-month scores by an absolute difference of 11.9 ± 10.8, and predictive modeling estimations of 12-month ODI scores differed from actual 12-month scores by a mean (± SD) of 10.7 ± 9.0 points (p = 0.001). Sixty-four percent of patients (n = 1982) achieved an MCID for ODI at 3 months in comparison with 67% of patients (n = 2088) by 12 months; 51% (n = 1731) and 61% (n = 1860) of patients achieved SCB for ODI at 3 months and 12 months, respectively. Almost 20% of patients had ODI scores that varied at least 20 points (the point span of an ODI functional category) between actual 3- and 12-month values. In the aggregate analysis of achieving MCID, 77% of patients were concordant and 23% were discordant in achieving or not achieving MCID at 3 and 12 months. The discordance rates of achieving or not achieving MCID for ODI were in the range of 19% to 27% for all diagnoses and treatments (decompression with and without fusion). The positive and negative predictive value of 3-months ODI to predict 12-month ODI was 86% and 60% for MCID and 82% and 67% for SCB. CONCLUSIONS Based on their findings, the authors conclude the following: 1) Predictive methods for functional outcome based on early patient experience (i.e., baseline and/or 3-month data) should be used to help evaluate the effectiveness of procedures in patient populations, rather than serving as a proxy for long-term individual patient experience. 2) Prospective longitudinal registries need to span at least 12 months to determine the effectiveness of spine care at the individual patient and practitioner level.
authors.affiliation: Department of Neurological Surgery, Carolina Neurosurgery and Spine Associates and Neurological Institute, Carolinas Healthcare System, Charlotte, North Carolina;
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Asher
authors.affiliation: Department of Orthopaedic Surgery, Vanderbilt Spine Center, Vanderbilt University Medical Center;
authors.forename: Silky
authors.initials: S
authors.lastname: Chotai
authors.affiliation: Department of Orthopaedic Surgery, Vanderbilt Spine Center, Vanderbilt University Medical Center;
authors.forename: Clinton J
authors.initials: CJ
authors.lastname: Devin
authors.affiliation: Geriatric Research Education Clinical Center, Tennessee Valley Health System, Veterans Health Administration;
authors.forename: Theodore
authors.initials: T
authors.lastname: Speroff
authors.affiliation: Department of Biostatistics, Vanderbilt University School of Medicine;
authors.forename: Frank E
authors.initials: FE
authors.lastname: Harrell
authors.affiliation: Department of Biostatistics, Vanderbilt University School of Medicine;
authors.forename: Hui
authors.initials: H
authors.lastname: Nian
authors.affiliation: Geriatric Research Education Clinical Center, Tennessee Valley Health System, Veterans Health Administration;|Departments of Medicine and Biostatistics, Division of General Internal Medicine and Public Health, Center for Health Services Research, Vanderbilt University School of Medicine, Nashville, Tennessee;
authors.forename: Robert S
authors.initials: RS
authors.lastname: Dittus
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California;
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Mummaneni
authors.affiliation: Department of Neurosurgery, Atlantic Neurosurgical Specialists, Morristown, New Jersey;
authors.forename: John J
authors.initials: JJ
authors.lastname: Knightly
authors.affiliation: Department of Orthopedic Surgery, University of Louisville and the Norton Leatherman Spine Center, Louisville, Kentucky;
authors.forename: Steven D
authors.initials: SD
authors.lastname: Glassman
authors.affiliation: Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota;
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bydon
authors.affiliation: Department of Orthopaedic Surgery, Vanderbilt Spine Center, Vanderbilt University Medical Center;|Department of Physical Medicine and Rehabilitation, Vanderbilt University Medical Center, Nashville; and.
authors.forename: Kristin R
authors.initials: KR
authors.lastname: Archer
authors.affiliation: Department of Neurosurgery, University of Tennessee Health Sciences Center, Semmes-Murphey Neurologic & Spine Institute, Memphis, Tennessee.
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Foley
authors.affiliation: Department of Neurological Surgery, Carolina Neurosurgery and Spine Associates and Neurological Institute, Carolinas Healthcare System, Charlotte, North Carolina;
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: McGirt
mesh_terms: D000368:Aged; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis / Q000601:surgery*; D007405:Intervertebral Disc Displacement / Q000175:diagnosis / Q000601:surgery*; D016015:Logistic Models; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012042:Registries; D013130:Spinal Stenosis / Q000175:diagnosis / Q000601:surgery*; D013168:Spondylolisthesis / Q000175:diagnosis / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome
keywords: MCID = minimal clinically important difference; N2QOD; N2QOD = National Neurosurgery Quality and Outcome Database; ODI; ODI = Oswestry Disability Index; Oswestry Disability Index; PRO patient-reported outcome; SCB = substantial clinical benefit; long-term; lumbar; patient-reported outcomes; registry; surgery