Authors: Vinay Kansal, James J. Armstrong, Cindy Hutnik
Author Disclosure Block: V. Kansal: None. J.J. Armstrong: None. C. Hutnik: None.

Abstract Body:

Purpose: To evaluate trends in Canadian glaucoma surgery billing code usage in the era of minimally invasive glaucoma surgery (MIGS).
Study Design: Population-based, retrospective cohort study
Methods: All patients who underwent a publicly funded glaucoma filtration procedure from January 2003 to December 2016 in 6 provinces representing most of the Canadian population. Frequency of glaucoma-related procedures performed in each province were adjusted against Statistics Canada and primary open angle glaucoma (POAG) prevalence data, then expressed as number of procedures per 1000 POAG patients. Frequency of all glaucoma filtration procedures, with and without implantation of a drainage device in each province per year are reported.
Results: For the total Canadian sample, glaucoma filtration procedures per 1000 POAG patients per year remained constant, with increased drainage device implantation over time (P<0.0001). Ontario and Nova Scotia mirrored the overall population. British Columbia and Saskatchewan showed increased rates of glaucoma filtration surgery, with increased drainage device implantations. In Quebec, overall filtration surgery decreased, while the rate of device implantation increased (p<0.0001). Alberta showed a decline in filtration surgery and device implantations from 2003-2008, and increase thereafter.
Conclusions: Over the study period, there was a distinct trend towards a greater proportion of surgeries involving indwelling glaucoma devices in most provinces. Challenges encountered during this investigation highlight the need for identifiers in provincial health databases to better delineate between ab interno and ab externo. Implementation of procedures in the absence of specific billing codes prevents accurate analyses of contemporary patient management and its cost implications.