The Statistical Fragility of Trials Comparing Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion

Abstract

Study Design. Meta-analysis. Objective. To assess the robustness of randomized controlled trials (RCTs) that compared cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic degenerative cervical pathology by using fragility indices. Summary of Background Data. RCTs comparing these surgical approaches have shown that CDA may be equivalent or even superior to ACDF due to better preservation of normal spinal kinematics. Materials and Methods. RCTs reporting clinical outcomes after CDA versus ACDF for degenerative cervical disc disease were evaluated. Data for outcome measures were classified as continuous or dichotomous. Continuous outcomes included: Neck Disability Index, overall pain, neck pain, radicular arm pain, and modified Japanese Orthopedic Association scores. Dichotomous outcomes included: any adjacent segment disease (ASD), superior-level ASD, and inferior-level ASD. The fragility index (FI) and continuous FI (CFI) were determined for dichotomous and continuous outcomes, respectively. The corresponding fragility quotient (FQ) and continuous FQ were calculated by dividing FI/CFI by sample size. Results. Twenty-five studies (78 outcome events) were included. Thirteen dichotomous events had a median FI of 7 [interquartile range (IQR): 3–10], and the median FQ was 0.043 (IQR: 0.035–0.066). Sixty-five continuous events had a median CFI of 14 (IQR: 9–22) and a median continuous FQ of 0.145 (IQR: 0.074–0.188). This indicates that, on average, altering the outcome of 4.3 patients out of 100 for the dichotomous outcomes and 14.5 out of 100 for continuous outcomes would reverse trial significance. Of the 13 dichotomous events that included a loss to follow-up data, 8 (61.5%) represented ≥7 patients lost. Of the 65 continuous events reporting the loss to follow-up data, 22 (33.8%) represented ≥14 patients lost. Conclusion. RCTs comparing ACDF and CDA have fair to moderate statistical robustness and do not suffer from statistical fragility.

The impact of surgical randomised controlled trials on the management of FAI syndrome: a citation analysis

“…Few studies have utilised this methodology in the orthopaedic literature due to its recent introduction [44,57]. Nonetheless, the median CFI of trials comparing surgical vs. non-surgical management of FAIS (CFI = 19) is higher than values reported in prior orthopaedic studies including Ortiz-Babilonia et al's study on trials assessing the management of degenerative cervical pathology (median CFI = 14, IQR: 9-22) [44], and Xu et al's study on trials assessing the use of platelet-rich plasma in the management of chronic non-insertional Achilles tendinopathy (median CFI = 5, IQR: 3.5-9) [57]. The trend of FAIS trials being less fragile than other orthopaedic trials is no longer present when studies assessing either minor or major variations in surgical techniques are included (median CFI = 4.8; range 1-32.2).…”

“…Another notable correlation demonstrated by our study was between the continuous fragility index and citation density (R = 0.95, p = 0.015) with a median CFI of 4.8 across all studies. Few studies have utilised this methodology in the orthopaedic literature due to its recent introduction [44,57]. Nonetheless, the median CFI of trials comparing surgical vs. non-surgical management of FAIS (CFI = 19) is higher than values reported in prior orthopaedic studies including Ortiz-Babilonia et al's study on trials assessing the management of degenerative cervical pathology (median CFI = 14, IQR: 9-22) [44], and Xu et al's study on trials assessing the use of platelet-rich plasma in the management of chronic non-insertional Achilles tendinopathy (median CFI = 5, IQR: 3.5-9) [57].…”