title: The Negative Relationship between Bilirubin Level and Diabetic Retinopathy: A Meta-Analysis.
abstract: OBJECTIVE
  Findings on the relationship between total bilirubin level (TBL) and diabetic retinopathy (DR) are inconsistent. Thus, we carried out a meta-analysis to investigate the relationship between TBL and the risk of DR.
  
  
  METHODS
  Relevant studies were selected from six databases up to 31 May 2016 using a search strategy. The relevant data were extracted from the included studies according to the inclusion and exclusion criteria, and the mean value with standard errors or odds ratio (OR) with 95% confidence intervals (CIs) were calculated. We compared TBL in patients with DR with that in patients with diabetes but without retinopathy (NDR), and analyzed the dose-response relationship between TBL and the risk of DR.
  
  
  RESULTS
  Twenty-four studies were selected in this meta-analysis. Twenty studies were included to calculate the pooled SMD, and the results showed that TBL in the DR group was lower than that in the NDR group (SMD: -0.52, 95% CI: -0.67, -0.38). Nine studies were included to calculate the pooled ORs, and the results showed that there was a significant negative relationship between TBL and the risk of DR (OR: 0.19, 95% CI: 0.14, 0.25). Six studies were included to investigate the dose-response relationship between TBL and the risk of DR, and we found a nonlinear relationship between TBL and the risk of DR. The results of our meta-analysis were found to be reliable using subgroup and sensitivity analyses.
  
  
  CONCLUSIONS
  The results of our meta-analysis indicate that higher TBL may be protective against DR in subjects with diabetes, and TBL could be used as a biomarker to predict the risk of DR.
authors: Department of Cancer Prevention and Treatment, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, People's Republic of China.
authors: Bo
authors: http://orcid.org/0000-0002-1062-1295
authors: B
authors: Zhu
authors: Department of Clinical Epidemiology and Evidence Medicine, The First Hospital of China Medical University, Shenyang, People's Republic of China.
authors: Xiaomei
authors: X
authors: Wu
authors: Department of Occupational Health, Liaoning Disease Prevention and Control Center, Shenyang, People's Republic of China.
authors: Kang
authors: K
authors: Ning
authors: Center of Health Management, Shenyang 242 Hospital, Shenyang, People's Republic of China.
authors: Feng
authors: F
authors: Jiang
authors: Department of Cancer Prevention and Treatment, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, People's Republic of China.
authors: Lu
authors: L
authors: Zhang
mesh_terms: D001663:Bilirubin / Q000378:metabolism*; D016001:Confidence Intervals; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D016017:Odds Ratio; D012307:Risk Factors
chemical_list: D001663:Bilirubin