Utilization of the Fragility Index to Assess Randomized Controlled Trials Comparing Cervical Total Disc Arthroplasty to Anterior Cervical Discectomy and Fusion.

Study designSystematic Review.ObjectivesCervical total disc arthroplasty (CTDA) remains an alternative to anterior cervical discectomy and fusion (ACDF) in select patients with cervical radiculopathy or myelopathy secondary to degenerative disc disease. Studies comparing CTDA to ACDF often have conflicting conclusions and varying quality. The purpose of this study was to utilize the fragility index (FI) to assess the robustness of randomized controlled trials (RCT) comparing CTDA to ACDF.MethodsA systematic review was performed by searching PubMed, Ovid MEDLINE, Web of Science, and Embase for RCTs with 2 parallel study arms and 1:1 allocation of subjects investigating CTDA vs ACDF with at least 1 statistically significant, dichotomous outcome. The FI was calculated by individually shifting 1 patient from the event group to the non-event group with re-calculation of Fisher's Exact test until the reported P value was no longer statistically significant (P > 0.05).ResultsThe search identified 934 abstracts with 19 RCTs meeting inclusion criteria. The mean patient sample size was 276.4 (median 209, range 30-541). The number of patients lost to follow-up ranged from 0-229 (mean 69.7, median 45). The mean FI was 4.6 (range 0-30, median 2) with 3 (13.6%) of the studies having an associated FI of 0. Loss to follow up exceeded the fragility index in all but 2 studies.ConclusionRCTs comparing ACDF to CTDA are often fragile with only 1-2 patients experiencing an alternative outcome or lost to follow-up to change the studied outcome.