Neuromodulation: Technology at the Neural Interface Received: October 21, 2014
Revised: January 19, 2015
Accepted: February 10, 2015
(onlinelibrary.wiley.com) DOI: 10.1111/ner.12287
Increased Pain Catastrophizing Associated With Lower Pain Relief During Spinal Cord Stimulation: Results From a Large Post-Market Study Jason C. Rosenberg, MD*; David M. Schultz, MD†; Luis E. Duarte, MD‡; Steven M. Rosen, MD§; Adil Raza, MPH¶ Background: Pain catastrophizing is a negative cognitive distortion to actual or anticipated pain. Our aim was to determine if greater catastrophizing has a deleterious relationship with pain intensity and efficacy outcomes in patients receiving SCS. Methods: As part of an ongoing Institutional Review Board-approved, multi-site, single arm post-market study, 386 patients were implanted with an Eon Mini™ SCS system and had follow-up visits at 3, 6, and 12 months post-implant. Outcomes collected during the study included, but were not limited to pain intensity using the numeric rating scale (NRS), patient reported pain relief (PRP), satisfaction with their SCS system, quality of life (QOL), pain catastrophizing scale (PCS) and state-trait anxiety index (STAI). Results: NRS scores were associated with higher PCS scores at six months (r = 0.50, p < 0.001). The PCS was a strong predictor of the NRS when controlled for known confounders. Patients with PCS ≥30 at 6-months post-implant had a lower six-month PRP (p < 0.001) and were five times more likely to report dissatisfaction with their SCS device (p < 0.001, OR = 5.46, 95% CI: 2.51–6.35). Additionally, at six months, those who were clinically catastrophizing were three times more likely to report deterioration in QOL (p < 0.002, OR = 3.12, 95% CI: 1.62–5.51). These findings were similar at the 12 months follow visit. Conclusions: Our results indicate that patients with greater catastrophizing, post-implant, were more likely to report higher pain intensity and lower pain relief, quality of life and satisfaction with SCS. These results indicate that associations between pain intensity and pain-related mental health may contribute to influence the overall efficacy of SCS. Keywords: Catastrophizing, chronic pain, fear avoidance, neuromodulation, spinal cord stimulations Conflict of Interest: Dr. Rosenberg is a consultant for St. Jude Medical, engaged as a speaker and instructor. He receives funding from St. Jude Medical, Vertos, and Pfizer. He is the founder and owner of South Carolina Pain and Spine Specialists institute. Dr. Schultz is a paid consultant of Medtronic and is a principle investigator for Medtronic and Boston Scientific. Dr. Duarte receives royalties from Depuy, Amendia, Spine Smith, and Pioneer. He also is a consultant for Flowonics, St. Jude Medical, Amendia, Aurora, 4CWeb, and Spine Smith. Dr. Rosen is a speaker for St. Jude Medical. He also is a physician advisor for Flowonix. Mr. Raza is an employee of St. Jude Medical.
INTRODUCTION
www.neuromodulationjournal.com
Address correspondence to: Adil Raza, MPH, St. Jude Medical, Research, 6901 Preston Road, Plano, TX 75024, USA. Email: [email protected] * South Carolina Pain and Spine Specialists, Murrells Inlet, SC, USA; † Medical Advanced Pain Specialists, Edina, MN, USA; ‡ Shannon Health, San Angelo, TX, USA; § Fox Chase Pain Management, Feasterville Trevose, PA, USA; and ¶ St. Jude Medical, Plano, TX, USA For more information on author guidelines, an explanation of our peer review process, and conflict of interest informed consent policies, please go to http:// www.wiley.com/bw/submit.asp?ref=1094-7159&site=1
© 2015 International Neuromodulation Society
Neuromodulation 2015; 18: 277–284
277
Chronic pain is a debilitating condition that has been shown to cause severe psychosocial complications and disability (1). The American Chronic Pain Association (ACPA) estimates that nearly one third of Americans will experience chronic pain at some point in their lives (2). The ACPA also estimates that health care costs in the United States due to chronic pain have exceeded $500 billion annually. Most Americans with chronic pain have multiple locations of pain including low back pain (28%), severe headache or migraine (16%), neck pain (15%), knee pain (20%), shoulder pain (9%), finger pain (8%), and hip pain (7%) (3). Spinal cord stimulation has been widely used in patients with chronic neuropathic pain who respond poorly to conventional therapies. Today, SCS is commonly used to treat conditions such as chronic back and leg pain, failed back surgery syndrome (4), complex regional pain syndrome type I and II (5) and cancer related
pain (6). Although therapies, including SCS, have been effective in treating chronic pain conditions, psychosocial complications have been shown to play a vital role in influencing the effectiveness of these therapies (7,8).
ROSENBERG ET AL.
278
The Fear Avoidance Model (FAM), introduced by Lethem et al. in 1983, explains how a number of psychosocial factors can lead to pain-related fear which further leads to a greater focus of attention to hypervigilance and avoidance (9). These factors can aggregate to increase overall disability leading to greater pain perception, which in turn cycles back to increase pain-related fear and avoidance. This cycle conceptualizes the Fear Avoidance Model and has been supported in scientific literature (10–14). Within these psychosocial factors of the Fear Avoidance Model is pain catastrophizing, which, according to Sullivan et al., is a collection of exaggerated negative thoughts that occur during actual or anticipated pain (15). Catastrophizing is a construct consisting of elements of rumination (“I worry all the time about whether the pain will end”), magnification (“I become afraid that the pain will get worse”) and helplessness (“I can’t seem to keep it out of my mind”). Studies show that higher levels of catastrophizing are associated with greater persistence of chronic postsurgical pain (16,17). Furthermore, there are reports of greater catastrophizing prospectively predicting an increase in pain and disability (18,19). One study even reported associations of catastrophizing with pain intensity in patients with multiple sclerosis (20). In fact, there have been numerous studies demonstrating the role of catastrophizing in chronic pain patients (21–28). A systematic review of the influence of catastrophizing concluded that catastrophizing might influence treatment response by delaying recovery time; moreover, the review emphasizes the importance of establishing cut-off levels to identify patients who are at a risk of catastrophizing (29). Together, these studies suggest that minimizing catastrophic thinking also may reduce the persistence of pain and disability, and while these studies have provided a strong link between catastrophizing with pain perception, to our knowledge, there have been only two large SCS studies evaluating this relationship. Lamé et al. examined whether pain catastrophizing influences the efficacy of SCS outcomes (30). In 36 patients with complex regional pain syndrome (CRPS) type I, the study found no evidence for the prospective predictability of catastrophizing on the efficacy of SCS. The study concluded that catastrophizing is not a contraindication for SCS treatment of CRPS Type I. Sumner and Lofland investigated the role of catastrophizing with pain intensity scores in patients receiving SCS (31). In 58 patients suffering primarily from complex regional pain syndrome and low back pain, the study found associations, albeit very weak, between catastrophizing and pain intensity scores before SCS therapy but no associations with pain intensity scores post-SCS therapy. The study concluded that although causality was not proven, it was possible that reductions in pain intensity, as a result of SCS therapy, resulted in less catastrophizing. Neither of these SCS studies found associations of pain catastrophizing with changes in pain intensity. Thus, it is still unclear whether the psychosocial factor of catastrophizing is indicative of higher pain intensity in patients receiving SCS therapy in a large trial. The purpose of this study was to evaluate the role of catastrophizing in a large SCS trial. Specifically, we sought to determine whether post-SCS catastrophizing associates with long-term ratings of pain intensity. Furthermore, relevant cutoff values for clinically catastrophizing patients were used to determine if clinically catastrophizing patients reported greater pain intensity compared with non-clinically catastrophizing patients. Based on previous studies, we hypothesized that higher levels of catastrophizing would be associated with higher patient-reported pain intensity scores. www.neuromodulationjournal.com
METHODS Study Design and Participants The EMPOWER (Eon Mini Product Options, Wellness, Effectiveness and Relief ) study, a multi-center, prospective study evaluating the safety and efficacy of the Eon-Mini™ Implantable Pulse Generator (St. Jude Medical) began enrolling patients in February 2012 dispersed across 45 active US investigational sites. Briefly, the average number of patients enrolled per site was 28, ranging from 1 to 53 enrollments. Patients who were enrolled prior to June 2013 were included in the interim analysis resulting in the data presented here. Patients were included into the study if they: 1. Had chronic intractable pain of the trunk and/or limbs. 2. Were at least 18 years of age. 3. Had a baseline pain intensity of at least 6 on the numeric rating scale (NRS). Patients were excluded from the study if they: 1. Had a systemic infection. 2. Were diagnosed with chronic pain as a result of a malignant disease. 3. Had a life expectancy of less than one year. 4. Were pregnant. 5. Had demand-type cardiac pacemakers. 6. Had a peripheral nerve stimulation system (PNS) or peripheral nerve field stimulation system (PNfS) implanted. Prior to the initiation of any study procedures, all patients provided written informed consent and were screened according to the inclusion/exclusion criteria. Following screening and baseline evaluations, participating patients received and SCS trial system for approximately five days. Patients who provided a Patient Reported Pain Relief (PRP) of greater than 50% at the end of the trial phase, were implanted with an Eon Mini™ permanent IPG and leads (St. Jude Medical, Plano, TX), and were followed for one year with follow-up visits at 3, 6, and 12 months post-implant. Since the study’s primary endpoint was six months post-implant and one of our aims was to determine if catastrophizing was persistently associated with SCS efficacy through the end of the study, only 6 and 12 months post-implant data were included in this analysis. Moreover, since the EMPOWER study is still an on-going study, only patients who have completed visits are included in this analysis. Data Collection and Measures Patient demographics and characteristics were collected at baseline. Questionnaires were administered at baseline and during scheduled follow-up visits at 3, 6, and 12 months post-implant. Measures included: 1. Patient Reported Pain Relief (PRP) Self-reported pain relief that asks the patient to estimate the magnitude of relief provided by the implant (0% represents no relief; 100% represents complete relief ). A PRP of 50% or greater is considered clinically significant pain relief (32). 2. Pain Catastrophizing Pain catastrophizing was measured at all pre- and post-implant visits using the Pain Catastrophizing Scale (PCS). The PCS is a 13-item questionnaire that has shown to have validity and reliability (15). Elements of the PCS include scores of magnification,
© 2015 International Neuromodulation Society
Neuromodulation 2015; 18: 277–284
CATASTROPHIZING AND PAIN IN SPINAL CORD STIMULATION
3.
4.
5.
6.
rumination and helplessness. Together, these elements provide an overall score of catastrophizing (each item on a scale from 0–4 totaling 52) with higher scores indicating greater catastrophizing. Anxiety Patient anxiety was measured at all pre-and post-implant visits using the State-Trait Anxiety Index (STAI). Elements of the STAI include state anxiety (“I am tense”) and trait anxiety (“I worry too much over something that really doesn’t matter”). State anxiety is a temporary product of perceived threats (i.e. chronic pain), while trait anxiety is a more permanent product of personality and beliefs. Each sub-scale has 20-items with higher scores indicating greater anxiety. Spielberger et al. have shown the STAI to have validity and reliability (33). Quality of Life (QoL) Patients rated their health, compared to before their SCS implant, recorded on a 5-point Likert scale ranging from “greatly deteriorated (−2)” to “greatly improved (+2)” relative to pre-SCS. Satisfaction Patients rated their overall level of satisfaction with the SCS device recorded on a 5-point Likert scale ranging from “very dissatisfied (−2)” to “very satisfied (+2)”. Pain Intensity Pain intensity was scored using the Numeric Rating Scale at all pre- and post-implant visits, with 0 signifying “no pain” and 10 signifying “worst possible pain”.
www.neuromodulationjournal.com
Demographics and Sample Characteristics Patient demographics and baseline characteristics for the 386 enrolled patients are reported in Table 1. Briefly, 620 patients were enrolled from February 2012 through the cut-off date of June, 2013. A total of 386 patients, were implanted with a permanent system and followed throughout the study. The average age of patients was 55.8 and ranged from 21 years of age to 88 years of age. The ratio of female to male was approximately 3:2. Most patients were diagnosed with FBSS (42.8%) followed by radiculopathies (32.4%). Average time since onset of pain was approximately 10 years and ranged from 4 months to 65 years. The majority of patients (88.3%) were Caucasian. Around 60% of patients at the beginning of the study were considered clinically catastrophizing (PCS score ≥30). Nearly 36% of patients were disabled and 25% of patients were retired. At the time of this analysis, 242 patients had completed their six-month visit and 157 patients had completed their 12-month visit. Pre- and Post-SCS Outcomes Efficacy outcomes were assessed across visits to determine if preand post-SCS implant differences existed. Descriptive statistics for Table 1. Baseline Characteristics of the Permanent Implant Patients. N = 386
Characteristic Gender % Female Male Age in years mean (SD) Ethnicity % African-American Asian Caucasian Hispanic Other Work status Disabled Full time Homemaker Not working Retired Volunteer Part time BMI mean(SD) Pain duration in years mean (SD) Pain intensity Pain catastrophizing scale mean (SD) Total Magnification Rumination Helplessness Clinically catastrophizing % (≥30) Not clinically catastrophizing % (
Revised: January 19, 2015
Accepted: February 10, 2015
(onlinelibrary.wiley.com) DOI: 10.1111/ner.12287
Increased Pain Catastrophizing Associated With Lower Pain Relief During Spinal Cord Stimulation: Results From a Large Post-Market Study Jason C. Rosenberg, MD*; David M. Schultz, MD†; Luis E. Duarte, MD‡; Steven M. Rosen, MD§; Adil Raza, MPH¶ Background: Pain catastrophizing is a negative cognitive distortion to actual or anticipated pain. Our aim was to determine if greater catastrophizing has a deleterious relationship with pain intensity and efficacy outcomes in patients receiving SCS. Methods: As part of an ongoing Institutional Review Board-approved, multi-site, single arm post-market study, 386 patients were implanted with an Eon Mini™ SCS system and had follow-up visits at 3, 6, and 12 months post-implant. Outcomes collected during the study included, but were not limited to pain intensity using the numeric rating scale (NRS), patient reported pain relief (PRP), satisfaction with their SCS system, quality of life (QOL), pain catastrophizing scale (PCS) and state-trait anxiety index (STAI). Results: NRS scores were associated with higher PCS scores at six months (r = 0.50, p < 0.001). The PCS was a strong predictor of the NRS when controlled for known confounders. Patients with PCS ≥30 at 6-months post-implant had a lower six-month PRP (p < 0.001) and were five times more likely to report dissatisfaction with their SCS device (p < 0.001, OR = 5.46, 95% CI: 2.51–6.35). Additionally, at six months, those who were clinically catastrophizing were three times more likely to report deterioration in QOL (p < 0.002, OR = 3.12, 95% CI: 1.62–5.51). These findings were similar at the 12 months follow visit. Conclusions: Our results indicate that patients with greater catastrophizing, post-implant, were more likely to report higher pain intensity and lower pain relief, quality of life and satisfaction with SCS. These results indicate that associations between pain intensity and pain-related mental health may contribute to influence the overall efficacy of SCS. Keywords: Catastrophizing, chronic pain, fear avoidance, neuromodulation, spinal cord stimulations Conflict of Interest: Dr. Rosenberg is a consultant for St. Jude Medical, engaged as a speaker and instructor. He receives funding from St. Jude Medical, Vertos, and Pfizer. He is the founder and owner of South Carolina Pain and Spine Specialists institute. Dr. Schultz is a paid consultant of Medtronic and is a principle investigator for Medtronic and Boston Scientific. Dr. Duarte receives royalties from Depuy, Amendia, Spine Smith, and Pioneer. He also is a consultant for Flowonics, St. Jude Medical, Amendia, Aurora, 4CWeb, and Spine Smith. Dr. Rosen is a speaker for St. Jude Medical. He also is a physician advisor for Flowonix. Mr. Raza is an employee of St. Jude Medical.
INTRODUCTION
www.neuromodulationjournal.com
Address correspondence to: Adil Raza, MPH, St. Jude Medical, Research, 6901 Preston Road, Plano, TX 75024, USA. Email: [email protected] * South Carolina Pain and Spine Specialists, Murrells Inlet, SC, USA; † Medical Advanced Pain Specialists, Edina, MN, USA; ‡ Shannon Health, San Angelo, TX, USA; § Fox Chase Pain Management, Feasterville Trevose, PA, USA; and ¶ St. Jude Medical, Plano, TX, USA For more information on author guidelines, an explanation of our peer review process, and conflict of interest informed consent policies, please go to http:// www.wiley.com/bw/submit.asp?ref=1094-7159&site=1
© 2015 International Neuromodulation Society
Neuromodulation 2015; 18: 277–284
277
Chronic pain is a debilitating condition that has been shown to cause severe psychosocial complications and disability (1). The American Chronic Pain Association (ACPA) estimates that nearly one third of Americans will experience chronic pain at some point in their lives (2). The ACPA also estimates that health care costs in the United States due to chronic pain have exceeded $500 billion annually. Most Americans with chronic pain have multiple locations of pain including low back pain (28%), severe headache or migraine (16%), neck pain (15%), knee pain (20%), shoulder pain (9%), finger pain (8%), and hip pain (7%) (3). Spinal cord stimulation has been widely used in patients with chronic neuropathic pain who respond poorly to conventional therapies. Today, SCS is commonly used to treat conditions such as chronic back and leg pain, failed back surgery syndrome (4), complex regional pain syndrome type I and II (5) and cancer related
pain (6). Although therapies, including SCS, have been effective in treating chronic pain conditions, psychosocial complications have been shown to play a vital role in influencing the effectiveness of these therapies (7,8).
ROSENBERG ET AL.
278
The Fear Avoidance Model (FAM), introduced by Lethem et al. in 1983, explains how a number of psychosocial factors can lead to pain-related fear which further leads to a greater focus of attention to hypervigilance and avoidance (9). These factors can aggregate to increase overall disability leading to greater pain perception, which in turn cycles back to increase pain-related fear and avoidance. This cycle conceptualizes the Fear Avoidance Model and has been supported in scientific literature (10–14). Within these psychosocial factors of the Fear Avoidance Model is pain catastrophizing, which, according to Sullivan et al., is a collection of exaggerated negative thoughts that occur during actual or anticipated pain (15). Catastrophizing is a construct consisting of elements of rumination (“I worry all the time about whether the pain will end”), magnification (“I become afraid that the pain will get worse”) and helplessness (“I can’t seem to keep it out of my mind”). Studies show that higher levels of catastrophizing are associated with greater persistence of chronic postsurgical pain (16,17). Furthermore, there are reports of greater catastrophizing prospectively predicting an increase in pain and disability (18,19). One study even reported associations of catastrophizing with pain intensity in patients with multiple sclerosis (20). In fact, there have been numerous studies demonstrating the role of catastrophizing in chronic pain patients (21–28). A systematic review of the influence of catastrophizing concluded that catastrophizing might influence treatment response by delaying recovery time; moreover, the review emphasizes the importance of establishing cut-off levels to identify patients who are at a risk of catastrophizing (29). Together, these studies suggest that minimizing catastrophic thinking also may reduce the persistence of pain and disability, and while these studies have provided a strong link between catastrophizing with pain perception, to our knowledge, there have been only two large SCS studies evaluating this relationship. Lamé et al. examined whether pain catastrophizing influences the efficacy of SCS outcomes (30). In 36 patients with complex regional pain syndrome (CRPS) type I, the study found no evidence for the prospective predictability of catastrophizing on the efficacy of SCS. The study concluded that catastrophizing is not a contraindication for SCS treatment of CRPS Type I. Sumner and Lofland investigated the role of catastrophizing with pain intensity scores in patients receiving SCS (31). In 58 patients suffering primarily from complex regional pain syndrome and low back pain, the study found associations, albeit very weak, between catastrophizing and pain intensity scores before SCS therapy but no associations with pain intensity scores post-SCS therapy. The study concluded that although causality was not proven, it was possible that reductions in pain intensity, as a result of SCS therapy, resulted in less catastrophizing. Neither of these SCS studies found associations of pain catastrophizing with changes in pain intensity. Thus, it is still unclear whether the psychosocial factor of catastrophizing is indicative of higher pain intensity in patients receiving SCS therapy in a large trial. The purpose of this study was to evaluate the role of catastrophizing in a large SCS trial. Specifically, we sought to determine whether post-SCS catastrophizing associates with long-term ratings of pain intensity. Furthermore, relevant cutoff values for clinically catastrophizing patients were used to determine if clinically catastrophizing patients reported greater pain intensity compared with non-clinically catastrophizing patients. Based on previous studies, we hypothesized that higher levels of catastrophizing would be associated with higher patient-reported pain intensity scores. www.neuromodulationjournal.com
METHODS Study Design and Participants The EMPOWER (Eon Mini Product Options, Wellness, Effectiveness and Relief ) study, a multi-center, prospective study evaluating the safety and efficacy of the Eon-Mini™ Implantable Pulse Generator (St. Jude Medical) began enrolling patients in February 2012 dispersed across 45 active US investigational sites. Briefly, the average number of patients enrolled per site was 28, ranging from 1 to 53 enrollments. Patients who were enrolled prior to June 2013 were included in the interim analysis resulting in the data presented here. Patients were included into the study if they: 1. Had chronic intractable pain of the trunk and/or limbs. 2. Were at least 18 years of age. 3. Had a baseline pain intensity of at least 6 on the numeric rating scale (NRS). Patients were excluded from the study if they: 1. Had a systemic infection. 2. Were diagnosed with chronic pain as a result of a malignant disease. 3. Had a life expectancy of less than one year. 4. Were pregnant. 5. Had demand-type cardiac pacemakers. 6. Had a peripheral nerve stimulation system (PNS) or peripheral nerve field stimulation system (PNfS) implanted. Prior to the initiation of any study procedures, all patients provided written informed consent and were screened according to the inclusion/exclusion criteria. Following screening and baseline evaluations, participating patients received and SCS trial system for approximately five days. Patients who provided a Patient Reported Pain Relief (PRP) of greater than 50% at the end of the trial phase, were implanted with an Eon Mini™ permanent IPG and leads (St. Jude Medical, Plano, TX), and were followed for one year with follow-up visits at 3, 6, and 12 months post-implant. Since the study’s primary endpoint was six months post-implant and one of our aims was to determine if catastrophizing was persistently associated with SCS efficacy through the end of the study, only 6 and 12 months post-implant data were included in this analysis. Moreover, since the EMPOWER study is still an on-going study, only patients who have completed visits are included in this analysis. Data Collection and Measures Patient demographics and characteristics were collected at baseline. Questionnaires were administered at baseline and during scheduled follow-up visits at 3, 6, and 12 months post-implant. Measures included: 1. Patient Reported Pain Relief (PRP) Self-reported pain relief that asks the patient to estimate the magnitude of relief provided by the implant (0% represents no relief; 100% represents complete relief ). A PRP of 50% or greater is considered clinically significant pain relief (32). 2. Pain Catastrophizing Pain catastrophizing was measured at all pre- and post-implant visits using the Pain Catastrophizing Scale (PCS). The PCS is a 13-item questionnaire that has shown to have validity and reliability (15). Elements of the PCS include scores of magnification,
© 2015 International Neuromodulation Society
Neuromodulation 2015; 18: 277–284
CATASTROPHIZING AND PAIN IN SPINAL CORD STIMULATION
3.
4.
5.
6.
rumination and helplessness. Together, these elements provide an overall score of catastrophizing (each item on a scale from 0–4 totaling 52) with higher scores indicating greater catastrophizing. Anxiety Patient anxiety was measured at all pre-and post-implant visits using the State-Trait Anxiety Index (STAI). Elements of the STAI include state anxiety (“I am tense”) and trait anxiety (“I worry too much over something that really doesn’t matter”). State anxiety is a temporary product of perceived threats (i.e. chronic pain), while trait anxiety is a more permanent product of personality and beliefs. Each sub-scale has 20-items with higher scores indicating greater anxiety. Spielberger et al. have shown the STAI to have validity and reliability (33). Quality of Life (QoL) Patients rated their health, compared to before their SCS implant, recorded on a 5-point Likert scale ranging from “greatly deteriorated (−2)” to “greatly improved (+2)” relative to pre-SCS. Satisfaction Patients rated their overall level of satisfaction with the SCS device recorded on a 5-point Likert scale ranging from “very dissatisfied (−2)” to “very satisfied (+2)”. Pain Intensity Pain intensity was scored using the Numeric Rating Scale at all pre- and post-implant visits, with 0 signifying “no pain” and 10 signifying “worst possible pain”.
www.neuromodulationjournal.com
Demographics and Sample Characteristics Patient demographics and baseline characteristics for the 386 enrolled patients are reported in Table 1. Briefly, 620 patients were enrolled from February 2012 through the cut-off date of June, 2013. A total of 386 patients, were implanted with a permanent system and followed throughout the study. The average age of patients was 55.8 and ranged from 21 years of age to 88 years of age. The ratio of female to male was approximately 3:2. Most patients were diagnosed with FBSS (42.8%) followed by radiculopathies (32.4%). Average time since onset of pain was approximately 10 years and ranged from 4 months to 65 years. The majority of patients (88.3%) were Caucasian. Around 60% of patients at the beginning of the study were considered clinically catastrophizing (PCS score ≥30). Nearly 36% of patients were disabled and 25% of patients were retired. At the time of this analysis, 242 patients had completed their six-month visit and 157 patients had completed their 12-month visit. Pre- and Post-SCS Outcomes Efficacy outcomes were assessed across visits to determine if preand post-SCS implant differences existed. Descriptive statistics for Table 1. Baseline Characteristics of the Permanent Implant Patients. N = 386
Characteristic Gender % Female Male Age in years mean (SD) Ethnicity % African-American Asian Caucasian Hispanic Other Work status Disabled Full time Homemaker Not working Retired Volunteer Part time BMI mean(SD) Pain duration in years mean (SD) Pain intensity Pain catastrophizing scale mean (SD) Total Magnification Rumination Helplessness Clinically catastrophizing % (≥30) Not clinically catastrophizing % (
