Exploratory analysis of diabetic retinopathy progression through 3 years in a randomized clinical trial that compares intravitreal triamcinolone acetonide with focal/grid photocoagulation

Abstract

Objective: To compare the effect of intravitreal triamcinolone acetonide with focal/grid photocoagulation on the progression of diabetic retinopathy.

Methods: We performed an exploratory analysis of participants with diabetic macular edema randomly assigned to receive laser therapy or intravitreal triamcinolone acetonide (1 or 4 mg). Fundus photographs were obtained at baseline and 1, 2, and 3 years. The main outcome measure was progression to proliferative diabetic retinopathy or worsening of 2 or more severity levels on reading-center masked assessment of 7-field fundus photographs, plus additional eyes that received panretinal photocoagulation or had a vitreous hemorrhage.

Results: From July 15, 2004, through May 5, 2006, 840 eyes from 693 participants were enrolled in the study and randomly assigned to receive laser therapy (n = 330), 1 mg of triamcinolone acetonide (n = 256), or 4 mg of triamcinolone acetonide (n = 254). The cumulative probability of progression of retinopathy at 2 years was 31% (laser group), 29% (1-mg group), and 21% (4-mg group) (P = .64 in the 1-mg group and .005 in the 4-mg group compared with the laser group). These differences appeared to be sustained at 3 years.

Conclusions: Intravitreal triamcinolone acetonide (4 mg) appeared to reduce the risk of progression of diabetic retinopathy. Given the exploratory nature of this analysis and because intravitreal triamcinolone adverse effects include cataract formation and glaucoma, use of this treatment merely to reduce the rates of progression of proliferative diabetic retinopathy or worsening of the level of diabetic retinopathy does not seem warranted at this time.

Figure 1

Cumulative probability of progression of retinopathy by treatment group over time defined as progression from non-proliferative diabetic retinopathy at baseline to proliferative diabetic retinopathy up to the given follow-up visit based on reading center assessment of fundus photographs, worsened by 2 or more levels up to the given follow-up visit on the ETDRS diabetic retinopathy scale based on reading center assessment of fundus photographs, panretinal photocoagulation received up to the given follow-up visit, or vitreous hemorrhage reported up to the given follow-up visit. Cumulative probabilities calculated using the life-table method. Subjects who dropped prior to an event were censored in the interval after their last completed visit.