Letters to the Editor / The Spine Journal 14 (2014) 724–726
evaluation. We believe that NPWT should be a better solution for symptomatic postoperative SEH. References [1] Amiri AR, Fouyas IP, Cro S, et al. Postoperative spinal epidural hematoma (SEH): incidence, risk factors, onset, and management. Spine J 2013;13:134–40. [2] Kou J, Fischgrund J, Biddinger A, et al. Risk factors for spinal epidural hematoma after spinal surgery. Spine 2002;27:1670–3. [3] Glotzbecker MP, Bono CM, Wood KB, et al. Postoperative spinal epidural hematoma: a systematic review. Spine 2010;35:E413–20. [4] Aono H, Ohwada T, Hosono N, et al. Incidence of postoperative symptomatic epidural hematoma in spinal decompression surgery. J Neurosurg Spine 2011;15:202–5. [5] Uribe J, Moza K, Jimenez O, et al. Delayed postoperative spinal epidural hematomas. Spine J 2003;3:125–9. [6] Yi S, Yoon do H, Kim KN, et al. Postoperative spinal epidural hematoma: risk factor and clinical outcome. Yonsei Med J 2006;47:326–32. [7] Tuncel U, Erkorkmaz U, Turan A. Clinical evaluation of gauze-based negative pressure wound therapy in challenging wounds. Int Wound J 2013;10:152–8. [8] Braakenburg A, Obdeijn MC, Feitz R, et al. The clinical efficacy and cost effectiveness of the vacuum-assisted closure technique in the management of acute and chronic wounds: a randomized controlled trial. Plast Reconstr Surg 2006;118:390–7. discussion 398–400. [9] Vicario C, de Juan J, Esclarin A, et al. Treatment of deep wound infections after spinal fusion with a vacuum-assisted device in patients with spinal cord injury. Acta Orthop Belg 2007;73:102–6. [10] Stannard JP, Robinson JT, Anderson ER, et al. Negative pressure wound therapy to treat hematomas and surgical incisions following high-energy trauma. J Trauma 2005;60:1301–6.
Xiaobo Luo, MD Yuanzheng Ma, MD Orthopedic Center The 309th Hospital of Chinese People’s Liberation Army No.17A, Heishanhu Rd, Haidian District Beijing 100091, China FDA device/drug status: Not applicable. Author disclosures: XL: Nothing to disclose. YM: Nothing to disclose. 1529-9430/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved http://dx.doi.org/10.1016/j.spinee.2013.05.044
Evaluating patient, procedure, and provider characteristics as risk factors for postoperative complications
725
variables relating to patients, operative characteristics, hospitals, and surgeons that could contribute to the risk of postoperative complications. Regarding patient characteristics, Schoenfeld et al. [1] do not mention socioeconomic status or employmentdboth of which are known to be important factors in spine surgery. In addition, the authors do not provide any information about insurance status or race, which might be valuable prognostic indicators. For example, using NSQIP data, Scarborough et al. [2] have reported a higher rate of complications after appendectomy among blacks than whites, even after controlling for comorbidities. Regarding procedure characteristics, Schoenfeld et al. [1] do not report the number of spine levels being fused, time of day of the operation, or the need for blood transfusion. Because of a longer operative time and greater anatomic complexity, the risk of complications might be higher after long fusions than one-level procedures. Based on NSQIP data, Kelz et al. [3,4] have demonstrated that the risk of complications after general and vascular surgery may vary depending on the time of day when an operation is performed. Preexisting anemia has recently been identified as a risk factor for early complications of spine surgery [5]; intraoperative blood lossdparticularly if severe enough to necessitate transfusiondmight plausibly be associated with adverse outcomes in the postoperative period. Regarding provider characteristics, it would be useful to know whether the size of the hospital and the number of spinal arthrodesis procedures per year are associated with the risk of complications. Facilities with a large volume of fusions and other spine operations might have a dedicated risk mitigation program in place and thus a lower rate of complications. Similarly, the surgeon’s experience (eg, number of years in practice and number of spinal fusions performed each year) should also be analyzed for a possible association with postoperative complications. The burden of surgical complications is high, in terms of both the human cost and health-care dollars. Schoenfeld et al. [1] have provided important information, but further investigation is warranted. Identifying additional prognostic factors may improve the risk management process and ultimately lead to the prevention or reduction of postoperative complications.
References To the Editor: Using data from the National Surgical Quality Improvement Program (NSQIP), Schoenfeld et al. [1] have identified several risk factors for major and minor complications after spinal arthrodesis. Their large and well-designed retrospective study addresses many patient factors and procedure characteristics, including some that are potentially modifiable. However, the authors have omitted several important
[1] Schoenfeld AJ, Carey PA, Cleveland AW III, et al. Patient factors, comorbidities, and surgical characteristics that increase mortality and complication risk after spinal arthrodesis: a prognostic study based on 5,887 patients. Spine J 2013 Apr 9. [2] Scarborough JE, Bennett KM, Pappas TN. Racial disparities in outcomes after appendectomy for acute appendicitis. Am J Surg 2012;204:11–7. [3] Kelz RR, Tran TT, Hosokawa P, et al. Time-of-day effects on surgical outcomes in the private sector: a retrospective cohort study. J Am Coll Surg 2009;209:434–445.e2.
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Letters to the Editor / The Spine Journal 14 (2014) 724–726
[4] Kelz RR, Freeman KM, Hosokawa PW, et al. Time of day is associated with postoperative morbidity: an analysis of the national surgical quality improvement program data. Ann Surg 2008;247:544–52. [5] Seicean A, Seicean S, Alan N, et al. Pre-operative anemia and perioperative outcomes in patients who undergo elective spine surgery. Spine 2013;38:1331–41.
Emily Jane Woo, MD, MPH Center for Biologics Evaluation and Research US Food and Drug Administration HFM-222, 1401 Rockville Pike Rockville, MD 20852, USA FDA device/drug status: Not applicable. Author disclosures: EJW: Nothing to disclose. Disclaimer: This letter reflects the views of the author and should not be construed to represent Food and Drug Administration’s views or policies. 1529-9430/$ - see front matter Published by Elsevier Inc. http://dx.doi.org/10.1016/j.spinee.2013.05.043
Re: ‘‘The rise and fall of the ‘minimum clinically important difference’’’
To the Editors: I read your editorial in the April 2010 issue of The Spine Journal on minimum clinically important difference [1] and wish to comment. You state, ‘‘FDA used motion of up to five degrees on dynamic radiographs to establish the oxymoronic ‘solid’ but ‘mobile’ fusion rate when assessing the BAK device.’’ I managed the Bagby and Kuslich study for Spine-Tech, from study design through Food and Drug Administration (FDA) approval and have heard many criticisms that this does not pass the ‘‘chuckle test.’’ I hope to add some clarity and science behind the five degree decision. First, neither the company nor FDA referred to the radiographic results of this study as solid but mobile. I do not know where that label came from. In defense of the late Dr Steven Kuslich, we did a significant amount of preclinical assessments of dynamic radiographs, independently and with radiologists, to make the five degree determination. Please remember that the state of the art in 1991, when this study was submitted to FDA, was to use the overlay method of flexion and extension X-rays, and if two adjacent vertebrae appeared to be superimposed on one another, that spine segment was considered ‘‘fused.’’ The company used a digitizing pad to improve accuracy in measuring motion. Dr Panjabi wrote that even this method had an intraoperator variability of 1.9 . We replicated his results. The company consulted with two very credible radiologists from the Minneapolis area who were, and may still be,
members of North American Spine Society. After having these radiologists evaluate many films, we determined that using the overlay method and comparing it with results using a digitizing pad, the naked eye cannot detect less than five degrees of motion. I believe the following results substantiate that claim. For purposes of the study, films were first digitized and the results recorded, then the films were read by one of the two radiologists. Hundreds of films were measured using the digitizing pad and results recorded. If the measured motion was five degrees or less, it was considered fused, and if more than five degrees, it was considered not fused. The films were then read by one of these two radiologists who did not know the results of the digitizing process. The radiologist’s determination of fused or not fused is what was used in the FDA data submitted for Premarket approval. Of the hundreds of films read, there were 22 sets of Flexion and Extension (F/E) films, where the digitizing method said they were fused, and the radiologist said they were not fused. And, there were 24 sets of F/E films, where the digitizing method said they were not fused, and the radiologist said they were fused. That means that, of hundreds of films evaluated in the 947-patient BAK study, there was a net difference of two assessments between these two methods. The only conclusion we could come to is that using the overlay method, the naked eye cannot detect less than five degrees of motion. So when the overlay method is used, the reader of those films may say a patient is fused, but the reality is that they can only claim there is no ‘‘visible motion’’ and that the motion is very likely less than five degrees. Other companies in that era doing clinical research made claims of ‘‘fused’’ or ‘‘not fused’’ using the same method and criticized the BAK study. In reality, less than five degrees is all anyone could claim, but Dr Kuslich was the only one willing to tell it like it was. Reference [1] Carragee EJ. The rise and fall of the ‘‘minimum clinically important difference.’’ Spine J 2010;10:283–4.
Richard C. Jansen, PharmD Apple Valley, MN, USA FDA device/drug status: Not applicable. Author disclosures: RJC: Stock Ownership: Kspine, Inc (100,000 shares, 1% ownership). 4-Web (!1% ownership); Consulting: Alexandria Research Technologies (A), Amendia LLC (B), ApaTech (B), Bagby Family, LLC (B), Devicix (A), Direct Spine Resources (B), Jessee Hunt (A), Magellan Medical Services Inc (B), R Tree Innovations (B), SpineX Tec LLC (B), Theken Spine (B), Titan Spine (C); Board of Directors: Excellen Biomechanics Laboratory (Nonfinancial). 1529-9430/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved http://dx.doi.org/10.1016/j.spinee.2010.06.022
evaluation. We believe that NPWT should be a better solution for symptomatic postoperative SEH. References [1] Amiri AR, Fouyas IP, Cro S, et al. Postoperative spinal epidural hematoma (SEH): incidence, risk factors, onset, and management. Spine J 2013;13:134–40. [2] Kou J, Fischgrund J, Biddinger A, et al. Risk factors for spinal epidural hematoma after spinal surgery. Spine 2002;27:1670–3. [3] Glotzbecker MP, Bono CM, Wood KB, et al. Postoperative spinal epidural hematoma: a systematic review. Spine 2010;35:E413–20. [4] Aono H, Ohwada T, Hosono N, et al. Incidence of postoperative symptomatic epidural hematoma in spinal decompression surgery. J Neurosurg Spine 2011;15:202–5. [5] Uribe J, Moza K, Jimenez O, et al. Delayed postoperative spinal epidural hematomas. Spine J 2003;3:125–9. [6] Yi S, Yoon do H, Kim KN, et al. Postoperative spinal epidural hematoma: risk factor and clinical outcome. Yonsei Med J 2006;47:326–32. [7] Tuncel U, Erkorkmaz U, Turan A. Clinical evaluation of gauze-based negative pressure wound therapy in challenging wounds. Int Wound J 2013;10:152–8. [8] Braakenburg A, Obdeijn MC, Feitz R, et al. The clinical efficacy and cost effectiveness of the vacuum-assisted closure technique in the management of acute and chronic wounds: a randomized controlled trial. Plast Reconstr Surg 2006;118:390–7. discussion 398–400. [9] Vicario C, de Juan J, Esclarin A, et al. Treatment of deep wound infections after spinal fusion with a vacuum-assisted device in patients with spinal cord injury. Acta Orthop Belg 2007;73:102–6. [10] Stannard JP, Robinson JT, Anderson ER, et al. Negative pressure wound therapy to treat hematomas and surgical incisions following high-energy trauma. J Trauma 2005;60:1301–6.
Xiaobo Luo, MD Yuanzheng Ma, MD Orthopedic Center The 309th Hospital of Chinese People’s Liberation Army No.17A, Heishanhu Rd, Haidian District Beijing 100091, China FDA device/drug status: Not applicable. Author disclosures: XL: Nothing to disclose. YM: Nothing to disclose. 1529-9430/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved http://dx.doi.org/10.1016/j.spinee.2013.05.044
Evaluating patient, procedure, and provider characteristics as risk factors for postoperative complications
725
variables relating to patients, operative characteristics, hospitals, and surgeons that could contribute to the risk of postoperative complications. Regarding patient characteristics, Schoenfeld et al. [1] do not mention socioeconomic status or employmentdboth of which are known to be important factors in spine surgery. In addition, the authors do not provide any information about insurance status or race, which might be valuable prognostic indicators. For example, using NSQIP data, Scarborough et al. [2] have reported a higher rate of complications after appendectomy among blacks than whites, even after controlling for comorbidities. Regarding procedure characteristics, Schoenfeld et al. [1] do not report the number of spine levels being fused, time of day of the operation, or the need for blood transfusion. Because of a longer operative time and greater anatomic complexity, the risk of complications might be higher after long fusions than one-level procedures. Based on NSQIP data, Kelz et al. [3,4] have demonstrated that the risk of complications after general and vascular surgery may vary depending on the time of day when an operation is performed. Preexisting anemia has recently been identified as a risk factor for early complications of spine surgery [5]; intraoperative blood lossdparticularly if severe enough to necessitate transfusiondmight plausibly be associated with adverse outcomes in the postoperative period. Regarding provider characteristics, it would be useful to know whether the size of the hospital and the number of spinal arthrodesis procedures per year are associated with the risk of complications. Facilities with a large volume of fusions and other spine operations might have a dedicated risk mitigation program in place and thus a lower rate of complications. Similarly, the surgeon’s experience (eg, number of years in practice and number of spinal fusions performed each year) should also be analyzed for a possible association with postoperative complications. The burden of surgical complications is high, in terms of both the human cost and health-care dollars. Schoenfeld et al. [1] have provided important information, but further investigation is warranted. Identifying additional prognostic factors may improve the risk management process and ultimately lead to the prevention or reduction of postoperative complications.
References To the Editor: Using data from the National Surgical Quality Improvement Program (NSQIP), Schoenfeld et al. [1] have identified several risk factors for major and minor complications after spinal arthrodesis. Their large and well-designed retrospective study addresses many patient factors and procedure characteristics, including some that are potentially modifiable. However, the authors have omitted several important
[1] Schoenfeld AJ, Carey PA, Cleveland AW III, et al. Patient factors, comorbidities, and surgical characteristics that increase mortality and complication risk after spinal arthrodesis: a prognostic study based on 5,887 patients. Spine J 2013 Apr 9. [2] Scarborough JE, Bennett KM, Pappas TN. Racial disparities in outcomes after appendectomy for acute appendicitis. Am J Surg 2012;204:11–7. [3] Kelz RR, Tran TT, Hosokawa P, et al. Time-of-day effects on surgical outcomes in the private sector: a retrospective cohort study. J Am Coll Surg 2009;209:434–445.e2.
726
Letters to the Editor / The Spine Journal 14 (2014) 724–726
[4] Kelz RR, Freeman KM, Hosokawa PW, et al. Time of day is associated with postoperative morbidity: an analysis of the national surgical quality improvement program data. Ann Surg 2008;247:544–52. [5] Seicean A, Seicean S, Alan N, et al. Pre-operative anemia and perioperative outcomes in patients who undergo elective spine surgery. Spine 2013;38:1331–41.
Emily Jane Woo, MD, MPH Center for Biologics Evaluation and Research US Food and Drug Administration HFM-222, 1401 Rockville Pike Rockville, MD 20852, USA FDA device/drug status: Not applicable. Author disclosures: EJW: Nothing to disclose. Disclaimer: This letter reflects the views of the author and should not be construed to represent Food and Drug Administration’s views or policies. 1529-9430/$ - see front matter Published by Elsevier Inc. http://dx.doi.org/10.1016/j.spinee.2013.05.043
Re: ‘‘The rise and fall of the ‘minimum clinically important difference’’’
To the Editors: I read your editorial in the April 2010 issue of The Spine Journal on minimum clinically important difference [1] and wish to comment. You state, ‘‘FDA used motion of up to five degrees on dynamic radiographs to establish the oxymoronic ‘solid’ but ‘mobile’ fusion rate when assessing the BAK device.’’ I managed the Bagby and Kuslich study for Spine-Tech, from study design through Food and Drug Administration (FDA) approval and have heard many criticisms that this does not pass the ‘‘chuckle test.’’ I hope to add some clarity and science behind the five degree decision. First, neither the company nor FDA referred to the radiographic results of this study as solid but mobile. I do not know where that label came from. In defense of the late Dr Steven Kuslich, we did a significant amount of preclinical assessments of dynamic radiographs, independently and with radiologists, to make the five degree determination. Please remember that the state of the art in 1991, when this study was submitted to FDA, was to use the overlay method of flexion and extension X-rays, and if two adjacent vertebrae appeared to be superimposed on one another, that spine segment was considered ‘‘fused.’’ The company used a digitizing pad to improve accuracy in measuring motion. Dr Panjabi wrote that even this method had an intraoperator variability of 1.9 . We replicated his results. The company consulted with two very credible radiologists from the Minneapolis area who were, and may still be,
members of North American Spine Society. After having these radiologists evaluate many films, we determined that using the overlay method and comparing it with results using a digitizing pad, the naked eye cannot detect less than five degrees of motion. I believe the following results substantiate that claim. For purposes of the study, films were first digitized and the results recorded, then the films were read by one of the two radiologists. Hundreds of films were measured using the digitizing pad and results recorded. If the measured motion was five degrees or less, it was considered fused, and if more than five degrees, it was considered not fused. The films were then read by one of these two radiologists who did not know the results of the digitizing process. The radiologist’s determination of fused or not fused is what was used in the FDA data submitted for Premarket approval. Of the hundreds of films read, there were 22 sets of Flexion and Extension (F/E) films, where the digitizing method said they were fused, and the radiologist said they were not fused. And, there were 24 sets of F/E films, where the digitizing method said they were not fused, and the radiologist said they were fused. That means that, of hundreds of films evaluated in the 947-patient BAK study, there was a net difference of two assessments between these two methods. The only conclusion we could come to is that using the overlay method, the naked eye cannot detect less than five degrees of motion. So when the overlay method is used, the reader of those films may say a patient is fused, but the reality is that they can only claim there is no ‘‘visible motion’’ and that the motion is very likely less than five degrees. Other companies in that era doing clinical research made claims of ‘‘fused’’ or ‘‘not fused’’ using the same method and criticized the BAK study. In reality, less than five degrees is all anyone could claim, but Dr Kuslich was the only one willing to tell it like it was. Reference [1] Carragee EJ. The rise and fall of the ‘‘minimum clinically important difference.’’ Spine J 2010;10:283–4.
Richard C. Jansen, PharmD Apple Valley, MN, USA FDA device/drug status: Not applicable. Author disclosures: RJC: Stock Ownership: Kspine, Inc (100,000 shares, 1% ownership). 4-Web (!1% ownership); Consulting: Alexandria Research Technologies (A), Amendia LLC (B), ApaTech (B), Bagby Family, LLC (B), Devicix (A), Direct Spine Resources (B), Jessee Hunt (A), Magellan Medical Services Inc (B), R Tree Innovations (B), SpineX Tec LLC (B), Theken Spine (B), Titan Spine (C); Board of Directors: Excellen Biomechanics Laboratory (Nonfinancial). 1529-9430/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved http://dx.doi.org/10.1016/j.spinee.2010.06.022
