title: Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis.
abstract: BACKGROUND
  Age-related macular degeneration (AMD) is the leading cause of blindness in Western countries. Numerous risk factors have been reported but the evidence and strength of association is variable. We aimed to identify those risk factors with strong levels of evidence which could be easily assessed by physicians or ophthalmologists to implement preventive interventions or address current behaviours.
  
  
  METHODS
  A systematic review identified 18 prospective and cross-sectional studies and 6 case control studies involving 113,780 persons with 17,236 cases of late AMD that included an estimate of the association between late AMD and at least one of 16 pre-selected risk factors. Fixed-effects meta-analyses were conducted for each factor to combine odds ratio (OR) and/or relative risk (RR) outcomes across studies by study design. Overall raw point estimates of each risk factor and associated 95% confidence intervals (CI) were calculated.
  
  
  RESULTS
  Increasing age, current cigarette smoking, previous cataract surgery, and a family history of AMD showed strong and consistent associations with late AMD. Risk factors with moderate and consistent associations were higher body mass index, history of cardiovascular disease, hypertension, and higher plasma fibrinogen. Risk factors with weaker and inconsistent associations were gender, ethnicity, diabetes, iris colour, history of cerebrovascular disease, and serum total and HDL cholesterol and triglyceride levels.
  
  
  CONCLUSIONS
  Smoking, previous cataract surgery and a family history of AMD are consistent risk factors for AMD. Cardiovascular risk factors are also associated with AMD. Knowledge of these risk factors that may be easily assessed by physicians and general ophthalmologists may assist in identification and appropriate referral of persons at risk of AMD.
authors.affiliation: Centre for Vision Science, Queen's University Belfast, Northern Ireland, UK. U.Chakravarthy@qub.ac.uk
authors.forename: Usha
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: Tien Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Astrid
authors.initials: A
authors.lastname: Fletcher
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Piault
authors.forename: Christopher
authors.initials: C
authors.lastname: Evans
authors.forename: Gergana
authors.initials: G
authors.lastname: Zlateva
authors.forename: Ronald
authors.initials: R
authors.lastname: Buggage
authors.forename: Andreas
authors.initials: A
authors.lastname: Pleil
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000375:Aging; D002318:Cardiovascular Diseases / Q000150:complications; D002387:Cataract Extraction / Q000009:adverse effects; D048909:Diabetes Complications; D019317:Evidence-Based Medicine / Q000379:methods; D005127:Eye Color; D005340:Fibrinogen / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D006801:Humans; D008268:Macular Degeneration / Q000209:etiology*; D009765:Obesity / Q000150:complications; D016017:Odds Ratio; D044469:Racial Groups; D012306:Risk; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects
chemical_list: D005340:Fibrinogen