Determination of Minimum Clinically Important Difference (MCID) in Pain, Disability and Quality of Life After Revision Fusion for Symptomatic Pseudoarthrosis
Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USAThe spine journal: official journal of the North American Spine Society (Impact Factor: 2.43). 11/2012; 12(12). DOI: 10.1016/j.spinee.2012.10.006
BACKGROUND CONTEXT: Spinal surgical outcome studies rely on patient reported outcome (PRO) measurements to assess the effect of treatment. A shortcoming of these questionnaires is that the extent of improvement in their numerical scores lacks a direct clinical meaning. As a result, the concept of minimum clinically important difference (MCID) has been used to measure the critical threshold needed to achieve clinically relevant treatment effectiveness. Post hoc anchor-based MCID methods have not been applied to the surgical treatment for pseudoarthrosis. PURPOSE: To determine the most appropriate MCID values for visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form (SF)-12 physical component score (PCS), and European Quality of Life 5-Dimensions (EQ-5D) in patients undergoing revision lumbar arthrodesis for symptomatic pseudoarthrosis. STUDY DESIGN/ SETTING: Retrospective cohort study. METHODS: In 47 patients undergoing revision fusion for pseudoarthrosis-associated back pain, PRO measures of back pain (BP-VAS), ODI, physical quality of life (SF-12 PCS), and general health utility (EQ-5D) were assessed preoperatively and 2 years postoperatively. Four subjective post hoc anchor-based MCID calculation methods were used to calculate MCID (average change; minimum detectable change; change difference; and receiver operating characteristic curve analysis) for two separate anchors (health transition index (HTI) of SF-36 and satisfaction index). RESULTS: All patients were available for a 2-year PRO assessment. Two years after surgery, a significant improvement was observed for all PROs; Mean change score: BP-VAS (2.3±2.6; p<.001), ODI (8.6%±13.2%; p<.001), SF-12 PCS (4.0±6.1; p=.01), and EQ-5D (0.18±0.19; p<.001). The four MCID calculation methods generated a wide range of MCID values for each of the PROs (BP-VAS: 2.0-3.2; ODI: 4.0%-16.6%; SF-12 PCS: 3.2-6.1; and EQ-5D: 0.14-0.24). There was no difference in response between anchors for any patient, suggesting that HTI and satisfaction anchors are equivalent in this patient population. The wide variations in calculated MCID values between methods precluded any ability to reliably determine what the true value is for meaningful change in this disease state. CONCLUSIONS: Using subjective post hoc anchor-based methods of MCID calculation, MCID after revision fusion for pseudoarthrosis varies by as much as 400% per PRO based on the calculation technique. MCID was suggested to be as low as 2 points for ODI and 3 points for SF-12. These wide variations and low values of MCID question the face validity of such calculation techniques, especially when applied to heterogeneous disease and patient groups with a multitude of psychosocial confounders such as failed back syndromes. The variability of MCID thresholds observed in our study of patients undergoing revision lumbar fusion for pseudoarthrosis raises further questions to whether ante hoc or Delphi methods may be a more valid and consistent technique to define clinically meaningful, patient-centered changes in PRO measurements.
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ABSTRACT: A recent evaluation of the state of U.S. health from 1990 to 2010 placed neck pain as the fourth condition leading to disability, with low back pain being the number one. Multiple treatment modalities have been described in managing neck and upper extremity pain secondary to cervical disc herniation after the failure of conservative management. The treatment modalities for chronic persistent pain of cervical disc herniation include surgery and epidural injections. The growth of interventional techniques in managing chronic spinal pain in recent years has been enormous. Evidence for the efficacy of cervical interlaminar epidural injections, however, continues to be debated, despite positive evidence derived from controlled randomized trials and systematic reviews. A randomized, double-blind, active control trial. A private, specialty referral, interventional pain management practice in the United States. To evaluate the effectiveness of epidural injections in managing chronic pain related to cervical disc herniation. Patients were randomly assigned to one of 2 groups of 60, with a total of 120 patients. Group I patients received cervical epidural injections with lidocaine 0.5% preservative-free, 5 mL, whereas Group II patients received 0.5% preservative-free lidocaine mixed with 1 mL or 6 mg of non-particulate betamethasone. Multiple outcome measures included the numeric rating pain scale (NRS), the Neck Disability Index (NDI), employment status, opioid intake with assessment at 3, 6, 12, 18, and 24 months post treatment. Significant improvement was described as pain relief with a 50% improvement in functional status. This evaluation showed significant improvement as 50% pain relief and improvement in functional status in 72% of the patients at 2 year follow-up in the local anesthetic group and 68% in those patients receiving local anesthetic and steroid. In the successful group of participants however, significant improvement was seen in 77% in Group I and 80% in Group II. Overall, the average number of procedures was 5 to 6 in both groups. The average total relief for 2 years was 75.9 ± 29.9 weeks in Group I and 72.7 ± 31.1 in Group II, the successful group of participants. Taking into consideration all of the participants, the average total relief for 2 years was 69.6 ± 35 weeks in Group I and 62.1 ± 38.4 weeks in Group II. The results of the study are limited by the lack of a placebo group. Cervical epidural injections with or without local anesthetic may offer significant benefit to patients suffering with chronic, persistent pain and disability related to cervical disc herniation.
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ABSTRACT: Commentary on: Parker SL, Adogwa O, Mendenhall SK, et al. Determination of minimum clinically important difference (MCID) in pain, disability, and quality of life after revision fusion for symptomatic pseudoarthrosis. Spine J 2012;12:1122-8 (in this issue).
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ABSTRACT: To date, there has been no study to comprehensively assess the effectiveness of suboccipital craniectomy (SOC) for Chiari Malformation I (CMI) using validated patient-reported outcome (PRO) measures. We set out to determine the effectiveness and minimum clinically important difference (MCID) thresholds of SOC for treatment of adult patients with CMI utilizing PRO metrics. Fifty patients undergoing first-time SOC and C1 laminectomy for CMI at a single institution were followed for 1 year. Baseline and 1-year post-operative pain, disability, quality of life, patient satisfaction, and return to work were assessed. MCID thresholds were calculated using 2 anchors: health transition index (HTI) and NASS satisfaction. The severity of headaches improved in 37 (74%) patients. Improvement in syrinx size was seen in 12 (63%) and myelopathy was seen in 12 (60%) patients. All PROs showed significant improvement 1-year post-operatively (p value <0.05). Of the 38 (76%) patients employed preoperatively, 29 (76%) returned to work post-operatively at a median time of 6 weeks [IQR: 4-12 weeks]. MCID thresholds following SOC for CMI were 4.4 points for NRS-Head, 0.7 points for NRS-Neck, 13.8 percentage points for HDI, 14.2 percentage points for NDI, 7.0 points for SF-12 PCS, 6.1 points for SF-12 MCS, 4.5 points for Zung depression, 1.7 points for mJOA, and 0.34 QALYs for EQ-5D. Surgical management of CMI in adults via SOC provides significant and sustained improvement in pain, disability, general health, and quality of life, as assessed by patient-reported outcomes. This patient-centered assessment suggests that suboccipital decompression for CMI in adults is an effective treatment strategy.
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