Statistical Fragility of Endoscopic Lumbar Decompression Outcomes: A Systematic Review of Randomized Controlled Trials

Study Design Systematic Review. Introduction Randomized controlled trials (RCTs) on lumbar endoscopic decompression inform treatment decisions for disk disease, radiculopathy, and lumbar spinal stenosis. This study assessed the fragility of statistical outcomes in these RCTs. Methods PubMed, Embase, and MEDLINE were queried for RCTs reporting dichotomous outcomes with at least 1 endoscopic decompression arm. The fragility index (FI) and reverse FI (rFI) represented the number of event reversals needed to change significance for significant and nonsignificant outcomes, respectively. The fragility quotient (FQ) was calculated by dividing FI by sample size. Subgroup analysis was performed by outcome type. Results 37 RCTs met the inclusion criteria for analysis. A total of 160 outcomes were analyzed. The median FI was 4 (IQR: 3-5) and FQ 0.038 (IQR: 0.017-0.067). Significant outcomes (n = 23) had a median FI of 7 (IQR: 2-13), FQ 0.024 (IQR: 0.012-0.056); nonsignificant outcomes (n = 137) had FI 4 (IQR: 3-5), FQ 0.041 (IQR: 0.020-0.068). Revisions/reoperations were most robust (FI: 5, FQ: 0.037); microscopic outcomes most fragile (FI: 4, FQ: 0.022). Pain outcomes had FI 4 (FQ: 0.051); complications FI 4 (FQ: 0.038). In 47.5% of outcomes, patients lost to follow-up exceeded FI. Conclusions Findings from RCTs on lumbar endoscopic decompression are vulnerable to small changes in outcome events. In nearly half of outcomes, patients lost to follow-up outnumbered the FI. Reporting FI and FQ with P -values may improve interpretation and reliability of trial results.