1. Table 1.Total Interventional Procedures Background Degenerative lumbar spondylolisthesis is a spinal instability that results from progressive degeneration of the facet joints, intervertebral discs, and ligamentous structures without disruption of the posterior vertebral ring. There remains no consensus on the appropriate treatment algorithm for this condition, which has resulted in highly varied practices among providers. Interventional treatments include selective options to diagnostically isolate and treat the pain generator (transforaminal epidural injections, facet interventions) and non-specific treatment options such as interlaminar and caudal epidural injections. The aims of this study were (1) to evaluate the incidence of degenerative spondylolisthesis within Medicare beneficiaries from 2000 through 2011; and (2) to describe the utilization of spinal interventional techniques within this newly diagnosed population. Descriptive Analysis of Interventional for Degenerative Lumbar Spondylolisthesis from 2000-2011 Figure 1 Mean number of Interventional procedures performed per beneficiary by post-diagnosis year Joseph A. Sclafani MD 1,3, Alexandra Constantin PhD 3, Pei-Shu Ho PhD 3, Venu Akuthota MD 2, Leighton Chan MD 3. 1.Medstar Georgetown University/ National Rehabilitation Hospital 2.University of Colorado, Denver 3.The National Institutes of Health Methods This study used an initial cohort comprised of 5% of all patients with ICD-9 codes for back pain recorded in the Medicare Carrier, Outpatient, or Inpatient files, from 2000 to 2011. A previously validated coding definition model was utilized to determine all inclusion and exclusion ICD-9 codes. Beneficiaries with a new diagnosis of degenerative lumbar spondylolisthesis were isolated through a two-step process. First, all subjects assigned a primary or secondary ICD-9 diagnosis code for degenerative lumbar spondylolisthesis (738.4, 756.12) were extracted from the initial cohort. Second, this subpopulation was refined to determine the initial use of these diagnosis codes by eliminating all subjects with an association of a spondylolisthesis ICD-9 code to a billable office visit, therapy session, imaging study, or procedure during the previous 365 day period. Current procedural terminology (CPT) codes for lumbar interventional techniques from 2000 to 2011 were used to identify the number of procedures performed each post-diagnosis year, including a sub-analysis of utilization by billing provider specialty. Conclusion An initial diagnosis of degenerative spondylolisthesis was commonly assigned to Medicare beneficiaries. This study demonstrates that interventional techniques are frequently used as a treatment modality for symptomatic degenerative spondylolisthesis. Anatomically selective intervention is utilized with varying frequency depending on provider specialty. Future studies will investigate the clinical impact of injection selectivity. Understanding utilization of these techniques is important to determine relative clinical efficacies and to optimize future health care expenditures. Results 95,647 individuals identified with an initial degenerative spondylolisthesis diagnosis (approximately 1.9 million individuals after multiplying the frequency of diagnosis in the 5% sample by a factor of 20). Greater than 40% of beneficiaries included in this analysis underwent at least one injection over the study period (216,088 total procedures). Injection therapy was most frequently utilized during the initial year of a degenerative spondylolisthesis diagnosis (Fig 1.) The utilization of each injection technique by post-diagnosis year is illustrated in Table 1. The ratio of selective (transforaminal and facet) to non-selective (interlaminar/caudal) procedures was 2.4 times greater for the specialty of Physical Medicine and Rehabilitation compared to INOS (Interventional Radiologists, Neurosurgeons, and Orthopedic Surgeons) and 2.9 times greater for Physical Medicine specialists compared to Anesthesiologists (Figure 2). R Figure 2 Femoral Head Femoral Neck Needle Figure 2 Selective (transforaminal epidural injections and facet interventions) versus non-selective (interlaminar) interventions by physician specialty. Post-Diagnosis Year Procedure012345678910+ Bilateral ProcedureTotal Discogram 29277573423121300000508 Adhesiolysis 4732331701401176860482921001,359 Facet, lumbar or sacral, 3+ levels 1,183505383305243236162143102116911,8865,355 RFA Lumbar or sacral facet additional level 1,8991,0147405354803402461959074291,4917,133 RFA Lumbar or sacral facet, single level 1,9631,0837775615163492582049777301,6177,532 Facet, lumbar or sacral, second level 1,9778395914873993682832261621791473,2208,878 Facet, lumbar or sacral; single level 2,4081,0097065754684373282732062091953,93810,752 SI joint; arthrography and/or anesthetic seroid 3,9842,2431,6351,3601,0657775804642861731374,72617,430 Trigger point procedure 5,0053,2622,6282,0441,5541,206867610454313311018,254 Lumbar transforaminal, additional level 12,7214,9143,4382,6462,0391,5351,0977554912311628,72738,756 Interlaminar epidural lumbar, sacral 32,57810,1917,4225,6833,9052,8872,2041,463992602445068,372 Lumbar Transforaminal, first level 25,1389,2896,4034,9083,7132,8421,9931,42186047232518,49575,859 Patients included in analysis95,64781,87068,96357,27847,17338,06429,76122,32515,89610,7619,735