Effectiveness of an Annular Closure Device in a "real-world" Population: Stratification of Registry Data Using Screening Criteria from a Randomized Controlled Trial

Purpose: Increased focus has been put on the use of "'real-world" data to support randomized clinical trial (RCT) evidence for clinical decision-making. The objective of this study was to assess the performance of an annular closure device (ACD) after stratifying a consecutive series of "real-world" patients by the screening criteria of an ongoing RCT.

Materials And Methods: This was a single-center registry analysis of 164 subjects who underwent limited discectomy combined with ACD for symptomatic lumbar disc herniation. Patients were stratified into two groups using the selection criteria of a pivotal RCT on the same device: Trial (met inclusion; n=44) or non-Trial (did not meet inclusion; n=120). Patient-reported outcomes, including Oswestry Disability Index (ODI) and visual analog scale (VAS) for leg and back pain, and adverse events were collected from baseline to last follow-up (mean: Trial - 15.6 months; non-Trial - 14.6 months). Statistical analyses were performed with significance set at <0.05.

Results: Patient-reported outcomes were not significantly different between groups at last (≥0.15) and clinical success (≥15-point improvement in ODI score; ≥20-point improvement in VAS scores) was achieved in both the groups. Three non-Trial (2.5%) and three Trial (6.8%) patients experienced symptomatic reherniation (=0.34). Rates of reoperation, ACD mesh dislocation/separation, and other radiographic findings were similar between groups (=1.00).

Conclusion: Outcomes with the ACD appeared advantageous in both the groups, particularly in comparison with historical reherniation rates reported in the same high-risk, large annular defect population. Stratification of this "real-world" series on the basis of RCT screening criteria did not result in significant between-group differences. These findings suggest that the efficacy of the ACD extends beyond the strictly defined patient population being studied in the RCT of this device. Furthermore, reducing the reherniation rate following lumbar discectomy has positive clinical and economic implications.