Statins and/or fbrates for diabetic retinopathy: a systematic review and meta-analysis

Abstract

Evidence from observational studies have found a relationship between serum cholesterol and diabetic retinopathy (DR). Apart of the assumption that cholesterolemic control has benefts for patients with diabetes with or without retinopathy, the efects of lipid-lowering drugs have not been properly mapped and critically assessed so far. The objective of this study was to evaluate the efects of statins and/or fbrates on prevention and progression of DR. We conducted a Systematic review of randomized controlled trials (RCTs) following the Cochrane Handbook for Sys tematic Reviews of Interventions and reported in accordance to PRISMA Statement. GRADE approach was used to summarize the certainty of the evidence. Eight RCTs that fulflled our eligibility criteria were included, assessing the efects of fbrates (n=4), statins (n=3) and fbrate plus statins (n=1) for therapy (n=8) or prevention (n=4) of DR. Overall, the main concern regarding risk of bias assessment was due to incomplete outcome data because high rate of losses in fve RCTs. Furthermore, the risk of reporting bias was rated unclear due the lack of previously published protocol in seven RCTs. Fibrates seemed to be associated with a 45% risk reduction of macular edema incidence (Rela tive Risk 0.55, 95% confdence interval of 0.38 to 0.81, 1309 participants, 2 RCTs, I 2=0%, low certainty of the evidence). The certainty of evidence for other outcomes was also very low or low, and we are uncertain regarding the efects of fbrates for DR. Overall, adverse events seemed to be similar between fbrate and placebo, but again based on the width of the confdence intervals, an important increase of adverse events cannot be rule out. The combination sta tin/fbrate did not seem to have beneft for visual acuity but is likely that further studies can modify this estimate since the current evidence is limited. Adverse events and quality of life were not measured or reported. Concluding, this study found eight RCTs, with limited methodological quality, that assessed the efects of fbrates and/or statins for DR. Based on these fndings, we are uncertain about the efects of statins for DR. Fibrates seemed to reduce the incidence of macular edema (low certainty evidence) without increase adverse events (low to very low certainty evidence).