Prevalence, Demographics, and Treatment Characteristics of Visual Impairment due to Diabetic Macular Edema in a Representative Canadian Cohort

Diabetic macular edema (DME) is the leading cause of blindness in the diabetic population. However, there is limited understanding of the epidemiology of DME with visual impairment (VI) and treatment in patients with diabetes in Canada. This observational, retrospective study used records from the Southwestern Ontario database to observe the demographics, prevalence, and treatment characteristics of VI due to DME compared to a healthy population in a real-world Canadian setting. Data was compared between a cohort of 8,368 diabetic (type 1 or 2) patients, who were ≥18 years old and had a diagnosis of DME with VI (visual acuity <20/40 in Snellen equivalent), and 76,077 age- and gender-matched subjects representing a healthy population. Among diabetic patients, prevalence of DME was 15.7%, and prevalence of VI due to DME was 2.56%. Laser monotherapy was the most frequently used treatment. Public funding covered costs for 85% of persons with DME while 18% were paid for with private funds. This study provides insight into the demographics, prevalence, and treatment of VI due to DME in a representative Canadian cohort. This data can help to inform evaluation of current DME treatment patterns and of proposed new treatment on drug plan budgets in Canada. 1. Introduction Diabetic macular edema (DME), a complex disease of multifactorial origin, is the leading cause of blindness in the diabetic population [1]. Clinically significant macular edema, as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS), includes any one of the following lesions: retinal thickening at or within 500 microns from the center of the macular; hard exudates at or within 500 microns from the center of the macular associated with thickening of the adjacent retina; an area or areas of retinal thickening at least 1 disk area in size, at least part of which is within 1 disk diameter of the center of the macular [2]. The common pathway that results in DME is disruption of the blood-retinal barrier [1]. As macular edema (ME) develops, blurring occurs in the middle or to the side of the central visual field. If untreated, ME can lead to vision loss. DME is closely associated with the duration and type of diabetes a patient has and the degree of diabetic retinopathy that is present [3]. The Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) reported the 25-year cumulative incidence of ME to be 29%, with annualized incidences of ME at 2.3%, 2.1%, 2.3%, and 0.9% in the first, second, third, and fourth follow-up periods of the study, respectively [4]. Findings from the