1. 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. 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 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 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 = )
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 = )
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 ± 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 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.