title: Dyslipidemia and Diabetic Macular Edema: A Systematic Review and Meta-Analysis.
abstract: OBJECTIVE
  A systematic review and meta-analysis of dyslipidemia and diabetic macular edema (DME).
  
  
  CONCLUSIONS
  Diabetic macular edema causes impairment of vision in patients with diabetes, and dyslipidemia has been reported as a risk factor for its development. A systematic review with a meta-analysis was undertaken to examine the evidence of an association between dyslipidemia and DME.
  
  
  METHODS
  We defined eligibility criteria as randomized controlled trials (RCTs) and cohort, case-control, and cross-sectional studies reporting on the relationship between blood lipid levels and DME. We performed a literature search in MEDLINE, PubMed, and Embase from inception to September 2014. We used the Newcastle-Ottawa scale to assess the quality of case-control, cross-sectional, and cohort studies, and the Cochrane risk of bias tool for RCTs.
  
  
  RESULTS
  The search strategy identified 4959 publications. After screening, we selected 21 articles for review (5 cross-sectional, 5 cohort, 7 case-control, and 4 RCTs). Meta-analysis of case-control studies revealed that mean levels of total serum cholesterol (TC), low-density lipoproteins (LDLs), and serum triglycerides (TGs) were significantly higher in patients with DME compared with those without DME (TC: 30.08; 95% confidence interval [CI], 21.14-39.02; P < 0.001; LDL: 18.62; 95% CI, 5.80-31.43; P < 0.05; TG: 24.82; 95% CI, 9.21-40.42; P < 0.05). Meta-analysis of RCTs did not show significant risk in worsening of hard exudates and severity of DME in the lipid-lowering group compared with placebo (hard exudates: relative risk, 1.00; 95% CI, 0.47-2.11; P = 1.00; DME: relative risk, 1.18; 95% CI, 0.75-1.86; P = 0.48).
  
  
  CONCLUSIONS
  Despite evidence from the cohort studies and meta-analysis of the case-control studies suggesting a strong relationship between lipid levels and DME, this was not confirmed by the meta-analysis that included only prospective RCTs. Therefore, given the significant public health relevance of the topic, the relationship between lipid levels and DME deserves further investigation.
authors.affiliation: Center for Experimental Medicine, Institute of Clinical Science, Queen's University Belfast, Belfast, Ireland.
authors.forename: Radha
authors.initials: R
authors.lastname: Das
authors.affiliation: Center for Experimental Medicine, Institute of Clinical Science, Queen's University Belfast, Belfast, Ireland.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Kerr
authors.affiliation: Center for Experimental Medicine, Institute of Clinical Science, Queen's University Belfast, Belfast, Ireland.
authors.forename: Usha
authors.initials: U
authors.lastname: Chakravarthy
authors.affiliation: Center for Experimental Medicine, Institute of Clinical Science, Queen's University Belfast, Belfast, Ireland. Electronic address: r.e.hogg@qub.ac.uk.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Hogg
mesh_terms: D016022:Case-Control Studies; D002784:Cholesterol / Q000097:blood; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D050171:Dyslipidemias / Q000503:physiopathology*; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood; D008269:Macular Edema / Q000503:physiopathology*; D014280:Triglycerides / Q000097:blood
chemical_list: D008077:Lipoproteins, LDL; D014280:Triglycerides; D002784:Cholesterol