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.
[Show abstract][Hide abstract] 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).
The spine journal: official journal of the North American Spine Society 12/2012; 12(12):1129-31. DOI:10.1016/j.spinee.2012.11.022 · 2.43 Impact Factor
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] ABSTRACT: Obesity is a growing public health problem. A considerable number of patients undergoing cervical spine surgery are obese, but the correlation between obesity and surgical outcome is still unclear. In this study, we investigate the impact of body mass index (BMI) on patients' and surgeons' perception of spine surgery outcomes.
We analyzed a prospectively collected spine surgery registry with patient-reported outcome (PRO) measures and surgeon ratings. Mixed-effects linear models and linear regression models were applied to investigate the relationship between different WHO obesity classifications and surgical outcome.
88 patients had surgery for degenerative cervical spine disease with 97.72% follow-up at 3 months and 94.31% at 6 months postoperatively. Mean BMI was 27.92 kg/m(2)±7.9. 28.57% were overweight (BMI 25-29.9) and 31.57% were obese (Class I obesity, BMI 30-34.9). We found a positive correlation between BMI and VAS at 6 months (R(2): 0.298, p<0.05) and between BMI and change in NDI (R(2): 0.385, p<0.01) suggesting that obese patients had less improvement and more pain 6 months postoperatively than non-obese patients. Overweight patients had worse MCS values (R(2): -0.275, p<0.05) and obese patients had worse VAS values 6 months after surgery (R(2): 0.284, p<0.03). Interestingly, surgeon ratings matched the above results. Patients with higher BMI had worse surgeon ratings 3 and 6 months postoperatively (R(2): 0.555, p<0.05), while normal weight patients had better outcomes when rated from the surgeon's perspective (R(2): -0.536, p<0.05).
Obese patients had worse postoperative PRO scores and less overall patient-rated improvement when compared to non-obese patients. Patients with BMI > 25 reported less improvement after surgery both in the patients' and in the surgeons' perspectives.
World Neurosurgery 10/2013; 82(1-2). DOI:10.1016/j.wneu.2013.09.053 · 2.88 Impact Factor
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