title: A simple risk stratification for time to development of sight-threatening diabetic retinopathy.
abstract: OBJECTIVE
  The American Diabetes Association and the English NHS Diabetic Eye Screening Program recommend annual screening for diabetic retinopathy (DR) with referral to ophthalmology clinics of patients with sight-threatening DR (STDR). Using only longitudinal data from retinal photographs in the population-based NHS Diabetic Eye Screening Program in Gloucestershire, we developed a simple means to estimate risk of STDR.
  
  
  METHODS
  From 2005, 14,554 patients with no DR or mild nonproliferative DR only at two consecutive annual digital photographic screenings were categorized by the presence of DR in neither, one, or both eyes at each screening and were followed for a further median 2.8 years.
  
  
  RESULTS
  Of 7,246 with no DR at either screening, 120 progressed to STDR, equivalent to an annual rate of 0.7%. Of 1,778 with no DR in either eye at first screening and in one eye at second screening, 80 progressed to STDR, equivalent to an annual rate of 1.9% and to a hazard ratio (HR) of 2.9 (95% CI 2.2-3.8) compared with those with no DR. Of 1,159 with background DR in both eyes at both screenings, 299 progressed to STDR equivalent to an annual rate of 11% and an HR of 18.2 (14.7-22.5) compared with individuals with no DR.
  
  
  CONCLUSIONS
  Combining the results from 2 consecutive years of photographic screening enables estimation of the risk of future development of STDR. In countries with systematic screening programs, these results could inform decisions about screening frequency.
authors.affiliation: Gloucestershire Diabetic Retinopathy Research Group, Cheltenham General Hospital, Cheltenham, Gloucestershire, United Kingdom. irene.stratton@nhs.net
authors.forename: Irene M
authors.initials: IM
authors.lastname: Stratton
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Aldington
authors.forename: David J
authors.initials: DJ
authors.lastname: Taylor
authors.forename: Amanda I
authors.initials: AI
authors.lastname: Adler
authors.forename: Peter H
authors.initials: PH
authors.lastname: Scanlon
mesh_terms: D000368:Aged; D003930:Diabetic Retinopathy / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D010781:Photography; D012307:Risk Factors