Purpose: We aimed to perform a systematic literature search on the latest evidence of the role of statin in reducing diabetic retinopathy and its need for intervention.
Methods: A comprehensive search on cohort studies/clinical trials that assess statins and diabetic retinopathy up until August 2019 was performed. The outcome measured was the incidence of diabetic retinopathy and its need for intervention.
Results: There were 558.177 patients from six studies. Statin was associated with a lower incidence of diabetic retinopathy (hazard ratio: 0.68 (0.55, 0.84), p < 0.001; I2: 95%). For the subtypes of diabetic retinopathy, statin lowers the incidence of proliferative diabetic retinopathy (hazard ratio: 0.69 (0.51, 0.93), p = 0.01; I2: 90%), non-proliferative diabetic retinopathy (hazard ratio: 0.80 (0.66, 0.96), p = 0.02; I2: 93%), and diabetic macular edema (hazard ratio: 0.56 (0.39, 0.80), p = 0.002; I2: 82%). Statin was associated with a reduced need for retinal laser treatment with a hazard ratio of 0.70 (0.64, 0.76) (p < 0.001; I2: 0%), intravitreal injection with a hazard ratio of 0.82 (0.79, 0.85) (p < 0.001; I2: 0%), and vitrectomy with a hazard ratio of 0.64 (0.48, 0.85) (p < 0.001; I2: 75%). Overall, statin was associated with a reduced need for intervention for diabetic retinopathy with a hazard ratio of 0.72 (0.64, 0.80) (p < 0.001; I2: 73%). The regression-based Egger's test showed statistically significant small-study effects for non-proliferative diabetic retinopathy (p = 0.011) outcomes.
Conclusion: Statin was associated with a decreased risk of diabetic retinopathy and its subtypes. Statin also reduced the need for intervention with retinal laser treatment, intravitreal injection, and vitrectomy.
Keywords: Diabetic maculopathy; diabetic retinopathy; intravitreal injection; retinal laser treatment; statin; vitrectomy.