Initial Assessment of the Viability and Utility of an MIS Prospective Registry Joseph A. Sclafani MD1,2, Kevin Liang PhD 2, Choll W Kim MD,PhD1 1Spine Institute of San Diego, Minimally Invasive Spine Surgery Center of Excellence 2Milestone Research Organization INTRODUCTION Although there are several studies of minimally invasive outcomes, most are limited by a small sample size and the exclusion of patients with complex diagnoses. The MIS Prospective Registry was established to overcome these limitations by collecting outcome data on a large population of MIS patients with a wide spectrum of degenerative deformities on a level-by-level basis. MATERIALS AND METHODS A multi-site, prospective registry to collect data on patients who underwent MIS TLIF, LLIF, ALIF, ACDF, endoscopic foraminotomy or hemilaminectomy procedures. Patients were asked 552 total questions and physicians were asked 289 questions per patient over a 2 year-period to assess patient diagnosis, symptoms and HRQOL measures through VAS, ODI and SF-12 case report forms A progressive outreach strategy was devised to obtain missing data through correspondence on patients that were greater than 13 months post-op and did not have complete 12 month follow-up information Figure 1. Treatment procedure of the overall registry population Figure 2. Algorithm detailing correspondence method used to obtain missing 1 year post-operative follow-up information. Email based surveys were sent to the remaining patients with missing information without any additional form acquisition RESULTS Overall Population 478 patients (235 female:243 male) aged 58.9 ± 15.2 years were enrolled from April 2011-November 2012. A response rate less than 50% was observed for 78 patient directed and 24 surgeon directed questions. One year patient follow-up data was obtained at a rate of 65% (64/98) during regular clinic visits. This rate increased to 86% (84/98) after implementing a progressive correspondence algorithm. MIS TLIF Subgroup 98 MIS TLIF patients with a median age of 64.5 years (range 25-91 years) had a one year follow-up rate of 89% (40/45 patients). ODI scores in the MIS TLIF patients that had reached the one year postoperative time point were 46.5 ± 15.2 pre-op (n = 45), and 26.2 ± 20.4 at 1 year post-op (n = 40, p = 0.0001) There was also improvement in VAS scores in this group of patients: pre-operative (back = 6.7 ± 1.3, leg = 5.4 ± 2.8, n = 45), and 1 year post-operative (back = 3.2 ± 2.5, leg = 1.7 ± 2.8, n = 40, p = 0.0001) All patients that were discharged on the first post-operative day (n = 14) underwent a single-level procedure and had lower pre-op ODI score than those discharged on POD 3-5 (43.7 ± 15.5 vs. 56.0 ± 18.3, p = 0.04) Figure 3. Multiple questions were infrequently answered and did not produce meaningful results. Elimination of these questions from surveys will decrease physician/patient burden CONCLUSIONS Initial findings of the MIS Prospective Registry show patients can be enrolled in a relatively short time period and with an acceptable follow-up rate (86% at 1 year follow-up). 1-year follow-up can be optimized through a combination of scheduled clinic visits and correspondence techniques The results of the MIS Prospective Registry MIS TLIF cohort were consistent with previously published MIS TLIF studies. As the registry grows, analysis of additional subgroups will be pursued Figure 4. There is significant improvement in ODI score, walking disability and employment disability starting at the 6 week post-operative time point for all age groups. Patients with pre-operative ODI scores greater than 50 demonstrated significant improvement starting at the 6 week post-operative time point, a pre-operative ODI between 35-50 showed significant improvement starting at 3 months and a pre-operative ODI score less than 35 had an initial period of increased disability with a trend towards significant improvement by 3 months post-op.