Noninferiority of Microhook to Trabectome: Trabectome versus Ab Interno Microhook Trabeculotomy Comparative Study (Tram Trac Study)

Abstract

Purpose: To elucidate the noninferiority of ab interno microhook trabeculotomy (μTLO) using a recently developed reusable stainless spatula-type microhook device to incise the trabecular meshwork to Trabectome (Neomeix, Inc) surgery in terms of the 1-year postoperative outcomes of Japanese patients with glaucoma by means of propensity score analyses.

Design: Multicenter, retrospective cohort study.

Participants: We enrolled 553 and 392 patients who underwent Trabectome surgery and μTLO, respectively, between January 2014 and March 2020 at 10 facilities.

Methods: Logistic regression analysis was conducted to calculate the propensity score, which indicates the likelihood of treatment assignment (Trabectome or μTLO). We set the following factors as outcome-related covariates: age, sex, facility, glaucoma disease types, preoperative intraocular pressure (IOP), glaucoma drug score, mean deviation of Humphrey visual field test results, antithrombotic drug use, the presence or absence of combined cataract surgery, and incision range of the trabecular meshwork (1 or 2 quadrants). We analyzed 4 different methods (matching, inverse probability of treatment weighting [IPTW], stratification, and regression adjustment) using the propensity score. We set 15% as the noninferiority margin based on previous Trabectome meta-analysis results.

Main outcome measures: The primary outcome was surgical success at 1 year after surgery. We defined surgical success as satisfying all 3 criteria: (1) IOP within 5 to 21 mmHg, (2) IOP reduction of 20% or more from preoperative IOP, and (3) no additional glaucoma surgery.

Results: The 95% confidence interval of risk difference of surgical failure in μTLO in reference to Trabectome surgery was -12.1% to +9.5% in matching, -12.7% to +11.1% in IPTW, -12.2 to +7.0 in stratification, and -9.7% to +8.1% in regression adjustment, all of which fell within the predetermined noninferiority margin of 15%.

Conclusions: Surgical success of μTLO at 1 year after was not inferior to that of Trabectome surgery.

Keywords: Ab interno trabeculotomy; Microhook; Minimally invasive glaucoma surgery; Propensity score; Trabectome.