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Neurosurg Focus. 2018 Jan;44(1):E2. doi: 10.3171/2017.10.FOCUS17554.

Defining the minimum clinically important difference for grade I degenerative lumbar spondylolisthesis: insights from the Quality Outcomes Database.

Author information

1Department of Neurosurgery, Carolina Neurosurgery and Spine Associates and Neuroscience Institute, Carolinas HealthCare System, Charlotte, North Carolina.
2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.
3Department of Neurologic Surgery, University of California, San Francisco, California.
4Department of Neurologic Surgery, University of Utah, Salt Lake City, Utah.
5Norton Leatherman Spine Center, Louisville, Kentucky.
6Department of Neurologic Surgery, University of Tennessee, Memphis, Tennessee.
7Geisinger Health, Danville, Pennsylvania.
8Department of Neurologic Surgery, Indiana University; Goodman Campbell Brain and Spine, Indianapolis, Indiana.
9Department of Neurologic Surgery, University of Virginia Health System, Charlottesville, Virginia.
10Atlantic Neurosurgical Specialists, Morristown, New Jersey.
11Department of Neurologic Surgery, University of Michigan, Ann Arbor, Michigan; and.
12Department of Neurologic Surgery, Weill Cornell Medical College, New York, New York.
13Department of Orthopedic Surgery, Vanderbilt University.
14Department of Physical Medicine and Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee.


OBJECTIVE Patient-reported outcomes (PROs) play a pivotal role in defining the value of surgical interventions for spinal disease. The concept of minimum clinically important difference (MCID) is considered the new standard for determining the effectiveness of a given treatment and describing patient satisfaction in response to that treatment. The purpose of this study was to determine the MCID associated with surgical treatment for degenerative lumbar spondylolisthesis. METHODS The authors queried the Quality Outcomes Database registry from July 2014 through December 2015 for patients who underwent posterior lumbar surgery for grade I degenerative spondylolisthesis. Recorded PROs included scores on the Oswestry Disability Index (ODI), EQ-5D, and numeric rating scale (NRS) for leg pain (NRS-LP) and back pain (NRS-BP). Anchor-based (using the North American Spine Society satisfaction scale) and distribution-based (half a standard deviation, small Cohen's effect size, standard error of measurement, and minimum detectable change [MDC]) methods were used to calculate the MCID for each PRO. RESULTS A total of 441 patients (80 who underwent laminectomies alone and 361 who underwent fusion procedures) from 11 participating sites were included in the analysis. The changes in functional outcome scores between baseline and the 1-year postoperative evaluation were as follows: 23.5 ± 17.4 points for ODI, 0.24 ± 0.23 for EQ-5D, 4.1 ± 3.5 for NRS-LP, and 3.7 ± 3.2 for NRS-BP. The different calculation methods generated a range of MCID values for each PRO: 3.3-26.5 points for ODI, 0.04-0.3 points for EQ-5D, 0.6-4.5 points for NRS-LP, and 0.5-4.2 points for NRS-BP. The MDC approach appeared to be the most appropriate for calculating MCID because it provided a threshold greater than the measurement error and was closest to the average change difference between the satisfied and not-satisfied patients. On subgroup analysis, the MCID thresholds for laminectomy-alone patients were comparable to those for the patients who underwent arthrodesis as well as for the entire cohort. CONCLUSIONS The MCID for PROs was highly variable depending on the calculation technique. The MDC seems to be a statistically and clinically sound method for defining the appropriate MCID value for patients with grade I degenerative lumbar spondylolisthesis. Based on this method, the MCID values are 14.3 points for ODI, 0.2 points for EQ-5D, 1.7 points for NRS-LP, and 1.6 points for NRS-BP.


AUC = area under the curve; HTI = health transition item; MCID; MCID = minimum clinically important difference; MDC = minimum detectable change; NASS = North American Spine Society; NRS-BP = numeric rating scale for back pain; NRS-LP = NRS for leg pain; ODI = Oswestry Disability Index; PRO = patient-reported outcome; QOD = Quality Outcomes Database; Quality Outcomes Database; ROC = receiver operating characteristic; SD = standard deviation; SEM = standard error of measurement; TLIF = transforaminal interbody fusion; VAS = visual analog scale; lumbar; minimum clinically important difference; patient-reported outcomes; quality of life; spondylolisthesis


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