THE TREATMENT OF LOW back pain (LBP) is controversial,

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1 1011 ORIGINAL ARTICLE The Relationship Between Repeated Epidural Steroid Injections and Subsequent Opioid Use and Lumbar Surgery Janna Friedly, MD, Isuta Nishio, MD, PhD, Michael J. Bishop, MD, Charles Maynard, PhD ABSTRACT. Friedly J, Nishio I, Bishop MJ, Maynard C. The relationship between repeated epidural steroid injections and subsequent opioid use and lumbar surgery. Arch Phys Med Rehabil 2008;89: Objectives: To evaluate whether the use of epidural steroid injections (ESIs) is associated with decreased subsequent opioid use in patients in the Department of Veteran s Affairs (VA) and to determine whether treatment with multiple injections are associated with decreased opioid use and lumbar surgery after ESIs. Design: VA patients undergoing ESIs during the study period for specific low back pain (LBP) diagnoses were identified, and lumbar surgery and opioid use were examined for 6 months before and after ESI. Setting: National VA administrative data. Participants: U.S. veterans (retrospective data analysis). Interventions: Not applicable. Main Outcome Measures: Opioid use and lumbar surgery after ESIs. Results: During the 2-year study period, 13,741 different VA patients underwent an ESI for LBP. The majority of patients were using opioids before their ESIs (64%), as were the majority after their ESIs (67%). Of patients not on opioids before the ESIs, 38% were prescribed opioids afterward, whereas only 16% of people on opioids before the ESIs stopped using opioids afterward. Patients who received more than 3 injections were more likely than patients receiving fewer injections to start taking opioids after ESIs (19% vs 13%, P.001) and to undergo lumbar surgery after ESIs (8.7% vs 6.3%, P.003). Conclusions: Opioid use did not decrease in the 6 months after ESIs. In this population, patients who received multiple injections were more likely to start taking opioids and to undergo lumbar surgery within the 6 months after treatment with ESIs. These findings are concerning because our data suggest that ESIs are not reducing opioid use in this VA population. Key Words: Injections, epidural; Low back pain; Rehabilitation; Spinal stenosis. From the Departments of Rehabilitation Medicine and Comparative Effectiveness, Costs and Outcomes Research Center, Harborview Medical Center (Friedly), VA Puget Sound Health Care System Epidemiologic Research Information Center and Department of Health Services (Maynard), and Department of Anesthesiology, University of Washington, Seattle, WA; and Department of Anesthesiology (Nishio, Bishop). Puget Sound VA Health Care System, Seattle, WA (Nishio, Bishop). Supported by the National Institutes of Health, Rehabilitation Medicine Scientist K12 Program (grant no. 2K12HD ) and the Office of Research and Development, Puget Sound VA Health Care System, Seattle, WA. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Janna Friedly, MD, Dept of Rehabilitation Medicine and Center for Cost and Outcomes Research, University of Washington, Harborview Medical Center, Box , 325 Ninth Ave, Seattle, WA 98127, friedlyj@ u.washington.edu /08/ $34.00/0 doi: /j.apmr by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation THE TREATMENT OF LOW back pain (LBP) is controversial, as evidenced by wide variability in the treatment modalities used. 1 Opioid use for non cancer-related chronic pain is a controversial treatment. Opioid use has been criticized for the potential for a variety of side effects, dependence, and addiction as well as for a lack of efficacy in various chronic pain syndromes. 2 However, opioid use for spine pain is particularly common, with 1 prior study 3 of veterans in an orthopedic spine clinic showing that a majority of patients (66%) are using opioids for the treatment of spine pain. Lumbar surgery is another controversial invasive treatment for LBP syndromes with questionable effectiveness and substantial cost. 4-7 Epidural steroid injections (ESIs) have become increasingly popular as an alternative to lumbar surgery or opioid use when more conservative measures fail to adequately relieve the symptoms of LBP and/or radicular pain. Given the magnitude of the epidemic of LBP within the United States and the extraordinary health care costs associated with its treatment, 8,9 many have examined the use of ESIs as potentially a more effective, less invasive, safer, and less costly alternative to either lumbar surgery or opioids for spine pain syndromes The current literature 20 reports success rates of 18% to 90% for ESIs. Few studies have been randomized controlled trials; all studies have suffered from methodologic limitations, and treatment effects have often been small and short term. 19,21-26 There is also considerable uncertainty as to the optimal number of injections to perform and the frequency with which to perform injections, particularly for chronic LBP disorders. However, even with the uncertainty in terms of the optimal use of these injections, this procedure has developed widespread acceptance and is often used as a treatment for LBP disorders. 1,27 Much of the variability in results stems from the methodology of the studies, including the outcome measures that are used. One outcome measure is the use of opioid medications for the treatment of pain. If ESIs are effective in terms of pain reduction, one would expect that opioid use would decrease in the months after ESI use. Few studies have specifically measured opioid use as an outcome measure, and those that have typically have found no change in opioid use after the ESIs. 19 Another commonly measured outcome with mixed results in clinical studies of ESIs is subsequent lumbar surgery. 13,21,28,29 Although ESIs are sometimes used as a presurgical diagnostic tool to determine the location of the pain generator, more often they are used in an attempt to avoid surgery. However, as the rates of ESI use have been increasing over time so have the surgical rates for the treatment of degenerative spine problems. 7 Medicare claims data also suggest an increase in the percentage of people receiving both ESIs as well as surgery. 30 In this study, we examined both opioid use and lumbar surgery rates after ESIs in the Department of Veterans Affairs (VA) population. We specifically hypothesized that

2 1012 EPIDURAL STEROID INJECTIONS ON OPIOID USE AND LUMBAR SURGERY, Friedly opioid use would decrease after ESIs in patients with LBP. We also hypothesized that patients receiving repeat injections would be more likely to decrease opioid use and would be less likely to undergo subsequent surgery than those patients receiving fewer injections. METHODS We used national VA administrative data during a 2-year period from October 2001 through September 2003 to examine the use of ESIs and their relationship to lumbar surgery and opioid use. Clinical encounters in the VA s health care system are captured in this administrative dataset in a similar manner to commercial claims data. These national data are stored in a central location and made available for research purposes. We abstracted clinical data relating to all ESIs performed within the VA health care system during the study period. The dataset included the Current Procedural Technology (CPT) procedure codes, the International Classification of Diseases 9th Revision Clinical Modifications (ICD-9-CM) diagnosis codes, dates of service, patient age, sex, ethnicity, use of fluoroscopy, lumbar surgeries, and use of opioids in the 6-month period before and after ESI administration. Patients undergoing ESIs during the study period with CPT codes (interlaminar or caudal) and (transforaminal) for specific LBP diagnoses were included in this analysis. In addition, the injection codes must have been associated with 1 of 5 diagnostic categories of LBP ICD-9 codes (herniated disk, radiculopathy, spinal stenosis, degenerative disease, other LBP). These categories were chosen to be consistent with studies on LBP and lumbar surgery rates and have been previously described and validated. 30,31 The other LBP category included ICD-9 codes for LBP, lumbago, and lumbosacral sprain. The scope of this analysis was limited to lumbosacral injections. We excluded cervical and thoracic steroid injections for 2 reasons. First, cervical spine disorders differ clinically from lumbar spine disorders and may be the result of different disease processes. Second, cervical and thoracic ESIs are much less common, representing less than 10% of all ESIs performed. 1,32 Lumbar surgeries were identified by using Healthcare Common Procedure Coding System codes for 6 months before and after ESIs, and opioid use was determined by examining VA pharmacy data for 6 months before and after an ESI. Opioid use was classified into use or nonuse such that if a patient had any prescription for opioids filled during the 6-month period, he/she was considered to use opioids. For those patients who underwent multiple ESIs during the study period, prior lumbar surgery and opioid use were calculated from the date of the first injection performed, whereas subsequent surgery and opioid use were calculated based on the date of the last injection performed. Statistical analyses were performed by using SPSS software. a Demographics were analyzed descriptively. The Pearson chi-square test was used for dichotomous, nominal outcomes measures (ie, surgery and opioid use) that met the assumptions for using this test (ie, large enough sample size, categorical data). ESI use (exposure) was divided into 2 groups ( 3, 3). A P value of.05 (2-tailed for all analyses) was considered statistically significant. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported for the outcome measure, lumbar surgery after ESI. RESULTS Demographics During the 2-year study period, 13,741 VA patients underwent an ESI for LBP, and a total of 25,733 injections were performed. The average age of patients in this study was years. Most patients were male (93%). Over half (52.4%) of the patients had 1 injection, and the vast majority (91%) had 3 or fewer injections during the 2-year study period. The mean standard deviation number of injections a patient received over the 2-year study period was Two hundred fifty-three people (1.8%) had 6 or more injections over the 2-year study period. Patients aged 60 and over were more likely to have greater than 3 injections (25% vs 18%, P.001). Of the injections performed, 85% were caudal or interlaminar, and 15% were transforaminal. Diagnoses Most patients who received injections were diagnosed with lumbar spinal stenosis (n 10,119 [74%]). Approximately 30% of patients had diagnoses of herniated disk or radiculitis or radiculopathy, and the vast majority of patients (90%) were assigned more than 1 LBP diagnosis. Every patient with spinal stenosis was also assigned another LBP diagnosis. Approximately one third (37%) of patients with lumbar spinal stenosis were also diagnosed with radiculitis or radiculopathy or herniated disk, and two thirds (68%) were described as also having nonspecific LBP. Therefore, 46% (n 6375) of patients overall had injections for spinal stenosis without a documented diagnosis of radiculopathy or herniated disk. Patients with spinal stenosis were also twice as likely as patients with other diagnoses to have greater than 3 injections (10% vs 5%, P.001). Those aged 60 and over were also more likely to be diagnosed with spinal stenosis (75% vs 70%, P.003). Diagnoses were not correlated with prior surgery; however, patients with diagnoses of radiculopathy were slightly more likely than patients without radiculopathy to undergo lumbar surgery within 6 months after their injection (8.3% vs 6.9%, P.008). There were no other differences between diagnoses in terms of subsequent lumbar surgery rates. Diagnosis was not statistically related to prior or subsequent opioid use in this study. Opioid Use The majority of all patients were using opioids in the 6 months before their ESI (64%) as were the majority after their ESI (67%). Therefore, overall opioid use did not decrease in this patient population in the 6 months after an ESI. Of the patients not on opioids before the ESI, 38% were prescribed opioids afterward, whereas only 16% of people on opioids before the ESI stopped using opioids afterward. The majority of patients on opioids before their ESI continued to use opioids after ESI (84%). Patients on opioids before ESI were more likely than patients not on opioids before ESI to take them within 6 months after ESI (84% vs 38%, P.001). Conversely, patients not on opioids before were more likely not to be taking them after ESI (62% vs 16%, P.001). Diagnosis, age, and sex were not correlated with prior or subsequent opioid use. Patients who received multiple injections during the study period (ie, 3) were less likely to stop taking opioids than patients receiving fewer injections (8% vs 11%, P.001) and were more likely to start taking opioids after treatment with ESIs (19% vs 13%, P.001) (tables 1, 2). These findings persisted when patients with a history of surgery either before or after ESI were removed from the sample. A smaller percentage of patients who received greater than 3 injections were

3 EPIDURAL STEROID INJECTIONS ON OPIOID USE AND LUMBAR SURGERY, Friedly 1013 Table 1: The Relationship Between Repeated ESIs and Opioid Use Number of ESIs 3 ESIs 3 ESIs Started Opioids (n 1840) No Change in Opioid Use (n 10,465) Stopped Opioids (n 1436) Total No. of Patients Receiving ESI 1607 (13)* 9571 (76)* 1344 (11)* 12,522 (100) NOTE. Values are n (%). *P (19) 894 (73) 92 (8) 1219 (100) Table 3: The Effect of Frequency of ESIs on Surgery Rates No. of ESIs Yes Surgery Total (7.0)* 11,644 (93.0) 12,522 (100.0) (9.1)* 1108 (90.9) 1219 (100.0) Total 989 (7.2) 12,752 (92.8) 13,741 (100.0) NOTE. Values are n (%). *P.001. No taking opioids before ESI treatment than those patients who received fewer injections (55% vs 64%, P.001) (see table 2). Lumbar Surgery Thirteen percent (n 1791) of patients had at least 1 surgery within 6 months before ESIs, and 7% (n 989) of patients had at least 1 surgery within 6 months after ESIs. Of the patients who had a history of surgery before the ESIs, 960 (54%) underwent a fusion, 92 (5%) underwent a laminectomy with diskectomy, 280 (16%) had a diskectomy, and 459 (26%) had a laminectomy alone. Patients with a history of surgery in the 6 months before ESIs were twice as likely to undergo a subsequent surgery after their ESIs (12% vs 6%; OR 1.75; 95% CI, ; P.001). Controlling for the history of prior surgery, patients who received 4 or more injections during the study period were also more likely to undergo lumbar surgery after receiving the ESIs (8.7% vs 6.3%, P.003) (see tables 2, 3). Patients with diagnoses of radiculopathy were slightly more likely than patients without radiculopathy to undergo lumbar surgery within 6 months after their injection (8.3% vs 6.9%; OR 1.16; 95% CI, ; P.008). Patients with radiculopathy were less likely to undergo a fusion procedure as compared with patients without radiculopathy (50% vs 54%, P.012). Age and sex did not correlate with prior or subsequent lumbar surgery. DISCUSSION In this national study of VA patients, we found that the majority receiving ESIs were also using opioid medications. This finding is consistent with a prior study 3 of opioid use among patients in a VA orthopedic spine clinic (66% use). Table 2: VA Patients Receiving ESIs and Opioid Use and Surgery ESIs and Opioid Use Total No. Receiving ESIs No. Receiving 3 ESIs No. Receiving 3 ESIs Total 13,741 12, Opioid use before 8728 (64) 8051 (64) 677 (55) No use after No change No opioid use 5013 (36) 4471 (36) 542 (45) before No change Use after Surgery before 1791 (13) 1626 (13) 165 (14) No surgery after Surgery after No surgery before 11,950 (87) 10,896 (87) 1054 (86) No surgery after 11,175 10, Surgery after NOTE. Values are n (%) for the main subgroups and n otherwise. There has been growing concern regarding chronic opioid use because of risks associated with dependence, side effects, and addiction. Opioid use is frequently considered 1 outcome measure of interventions for a variety of pain syndromes. Although in this study we did not examine the indications for opioid prescription and concomitant pain syndromes in addition to LBP, it is reasonable to hypothesize that opioid use would decrease after ESI for LBP. However, contrary to our hypothesis, opioid use did not decrease in the 6 months after an ESI in this population, and over a third of patients who were not taking opioids before the ESI received opioids afterward. In addition, we found that patients who underwent more frequent injections were more likely than patients receiving fewer injections to start opioids if they were not taking them before their first ESI and were less likely to stop taking opioids if they were taking them before their first ESI. This finding may reflect that patients with more severe pathology or pain are more likely to undergo multiple ESIs and therefore may be more likely to use opioid medications. However, patients undergoing repeated ESIs in this study were no more likely to have been taking opioids before receiving the injections than those only undergoing 1 to 2 injections. In fact, patients receiving fewer injections were more likely to be taking opioids before ESI treatment (64%) than those receiving a repeat ESI (56%). In addition, diagnoses did not vary between those receiving 4 or more injections and those receiving fewer injections (ie, each group had similar numbers of patients with documented radiculopathy and spinal stenosis). In this population, ESIs were primarily used for spinal stenosis (73%) despite the lack of evidence to support their use for this diagnosis. The best evidence regarding the effectiveness of ESIs is for symptoms of sciatica or radiculopathy. However, during this study period, nearly half of the veterans receiving injections had spinal stenosis without documented radiculopathy. We also found that patients over the age of 60 were more likely to receive repeat injections ( 3 in the 2-year study period) and were more likely to be diagnosed with spinal stenosis. Patients who received more than 3 injections during the study period were also no more likely to stop using opioids and were more likely to undergo subsequent lumbar surgery. These findings suggest that ESIs in this VA population are not being substituted for lumbar surgery and are not decreasing opioid use. There are several potential reasons for these findings. First, it must be acknowledged that this study reflects outcomes in actual clinical practice rather than in the controlled environment of a randomized clinical trial. Therefore, these findings suggest that the use of ESIs in an uncontrolled environment (ie, outside of the realm of a controlled trial with very specific inclusion and exclusion criteria and standardized techniques) is not associated with decreasing opioid use and is not substituting for lumbar surgery. These outcomes certainly may be different than those in a controlled setting with standardized

4 1014 EPIDURAL STEROID INJECTIONS ON OPIOID USE AND LUMBAR SURGERY, Friedly patient selection criteria and injection techniques. These findings suggest that it may be important to have more standardized criteria for patient selection and/or injection technique to improve outcomes in actual clinical practice. Second, chronic pain syndromes may be more prevalent within the VA population and therefore patients may be using opioids for reasons other than LBP or sciatica. One would not expect to see changes in opioid use after ESI for those patients who take opioids for other pain conditions. We did not have access to specific information regarding comorbidities and other pain complaints or diagnoses for which opioids may have been used. We also did not have access to data regarding the indication for the opioid prescription. Pain relief from the ESI in this study may also not have been substantial enough for patients to discontinue use of opioids or to prevent surgery. We did not include self-reported pain as an outcome measure in this study and chose to use opioid use as 1 measure of pain. Additionally, the reasons for choosing to undergo an ESI may be different in the VA health care system than in others. For example, patients may undergo ESI as routine care preceding an anticipated surgery to better delineate the pain generator or to provide temporary pain relief in anticipation of surgery. The VA health care system may be different from the private sector in that there is less direct financial influence on procedures performed and less constraint in the use of procedures because of insurance coverage. Currently, there are no evidence-based guidelines regarding the appropriate number of injections, the optimal frequency and timing of injections, or the appropriate use for the injections in patients considering lumbar surgery. Our data suggest that patients who receive repeat injections are more likely to use opioids and are more likely to undergo surgery, calling into question the rationale for using repeat injections, particularly in this population of patients with primarily spinal stenosis. Further research is needed to better understand this relationship between the use of repeated ESIs and the effect on subsequent surgical rates and opioid use. In addition, more research is needed to determine if repeated ESIs are of benefit in the long-term management of spinal stenosis for those patients who are not candidates for surgery, particularly in terms of function and quality of life measures. Study Limitations There are several limitations to our study. This retrospective study examines a specific patient population, VA patients who are primarily men. The use of steroid injections in this population may be different than in a more general population. The distribution of diagnoses for which these injections are performed may be different than in other populations. Another limitation is that some of the variations in diagnoses may be related to coding errors, diagnostic ambiguity, or local conventions. Because the VA system is not reliant on third-party reimbursement, coding may not be as accurate as in the private sector. However, prior studies 33 on other conditions have found that the VA database is very accurate in coding diagnoses. In this study, we classified opioid use as simply yes or no rather than determining dosing. Therefore, we were only able to tell if patients stopped opioid use or started using opioids after their injections. It is possible that patients were able to decrease their dose of opioids after ESI. We also were not able to capture any data outside of the VA system. If patients received medications or services from alternative providers, we may have underestimated the number of people using opioids or undergoing lumbar surgery both before and after ESI. Another limitation is that patients were tracked for only 6 months before and after receiving ESIs. It is possible that some patients received lumbar surgery either before or after the study period. However, this would suggest that our findings underestimate the number of people receiving surgery after ESI and would not contradict our findings. It is also possible that patients undergoing ESI discontinued the use of opioids after 6 months of treatment; however, the benefits, if any, of ESIs are typically less than 6 months in duration. Therefore, we would not expect that discontinuation of opioids after 6 months was directly because of treatment with ESIs and was likely because of another intervention or natural recovery. Study Strengths The strengths of this study are that it represents the first published study on ESIs using national VA data with a large sample size. We also were able to capture both clinical and pharmacy data to determine the actual use of various interventions commonly used in clinical practice. This study provides important information regarding how ESIs are used outside of the confines of clinical trials and their effect of subsequent opioid use and lumbar surgery rates. CONCLUSIONS Three quarters of all lumbar ESIs were performed for spinal stenosis, and nearly half were for spinal stenosis without radiculopathy despite the equivocal data to support their use in this clinical situation. Patients with spinal stenosis were more likely to receive repeated ESIs ( 4). Patients receiving repeated ESIs were more likely to start opioid use after ESI than patients receiving fewer ESIs and were more likely to undergo subsequent lumbar surgery than patients receiving fewer ESIs. 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