title: Use of Global Visual Acuity Data in a time trade-off approach to calculate the cost utility of cataract surgery.
abstract: OBJECTIVE
  To determine the cost utility of cataract surgery worldwide using visual acuity (VA) outcomes and utility values determined by the time trade-off (TTO) method.
  
  
  METHODS
  Some cost data were taken from a previous search conducted for 1995 to 2006 and we searched MEDLINE and Scopus and Google for more recent data (2006 and 2007).
  
  
  METHODS
  Articles were identified from the literature using "cataract surgery" in combination with the terms outcome or visual acuity. Additional searches were conducted using individual countries as a term in combination with VA, outcome, or cost. Regression curves were constructed from utility values derived from a TTO study and VA data. Gains in quality-adjusted life-years (QALYs) were calculated based on life expectancy tables from the World Health Organization and discounts of 3% for both cost and benefit. Sensitivity analyses explored the effect of changes in discounting, life expectancy, preoperative VA, and cost.
  
  
  METHODS
  If the data were usable, they were kept; otherwise they were discarded.
  
  
  RESULTS
  Preoperative VA (logMAR) correlated with increasing gross national income per capita (Pearson correlation coefficient, -0.784; P < .001) and showed that in developing countries preoperative vision is much poorer compared with developed countries. Cost utility data ranged from $3.5 to $834/QALY in developing countries to $159 to $1356/QALY in developed countries. Sensitivity analysis showed that changing life expectancy, VA, and discount rate resulted in moderate changes.
  
  
  CONCLUSIONS
  The TTO approach demonstrates that cataract surgery is extremely cost-effective.
authors.affiliation: Fundacion Vision, Asuncion, Paraguay.
authors.forename: Van C
authors.initials: VC
authors.lastname: Lansingh
authors.forename: Marissa J
authors.initials: MJ
authors.lastname: Carter
mesh_terms: D002386:Cataract / Q000191:economics*; D002387:Cataract Extraction / Q000191:economics*; D003362:Cost-Benefit Analysis; D019049:Developed Countries; D003906:Developing Countries; D004467:Economics; D014943:Global Health; D017048:Health Care Costs; D006302:Health Services Research; D006801:Humans; D008017:Life Expectancy; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D013997:Time Factors; D014792:Visual Acuity