The Tube Versus Trabeculectomy IRIS® Registry Study: Cohort Selection and Follow-up and Comparisons to the Randomized Controlled Trial

Abstract

Purpose: To assess the feasibility of replicating a randomized controlled trial (RCT) with a cohort of eyes, from IRIS® Registry data, analogous to the Tube Versus Trabeculectomy (TVT) RCT cohort and compare characteristics and follow-up.

Design: Comparison of RCT and IRIS Registry cohorts and follow-up.

Methods: We identified a cohort of IRIS Registry eyes (2013-2017) that received either a glaucoma drainage implant (tube) or trabeculectomy after a previous trabeculectomy and/or cataract extraction; extracted clinical and demographic characteristics for baseline surgery and follow-up visits through 1 year; and compared treatment groups in the IRIS Registry cohort and this cohort to the TVT RCT cohort.

Results: The IRIS Registry cohort included 419 eyes: 183 (43.7%) trabeculectomy; 236 (56.3%) tube. There were significant differences between treatment groups, including race (White: trabeculectomy 61.8%, tube 44.9%; Black: trabeculectomy 20.8%, tube 35.6%; P = .003) and the percentage of follow-up visits completed (trabeculectomy 88.4%, tube 83.8%, P = .004). There were also significant differences between the TVT IRIS Registry cohort and the TVT RCT cohort in the percentage of follow-up visits completed (IRIS Registry 85.6%, RCT 96.1%, P < .001) and in the probability of having a 1-year follow-up visit (IRIS Registry 81.4%, RCT 89.2%, P = .011).

Conclusion: The TVT IRIS Registry cohort had several significant treatment group differences at baseline, whereas there had been none in the TVT RCT cohort. Follow-up in the TVT IRIS Registry cohort was inferior to that of the TVT RCT. Some data needed to refine the selection of eyes for the cohort were not available in the IRIS Registry.