title: Grader agreement, and sensitivity and specificity of digital photography in a community optometry-based diabetic eye screening program.
abstract: BACKGROUND
  Digital retinal photography with mydriasis is the preferred modality for diabetes eye screening. The purpose of this study was to evaluate agreement in grading levels between primary and secondary graders and to calculate their sensitivity and specificity for identifying sight-threatening disease in an optometry-based retinopathy screening program.
  
  
  METHODS
  This was a retrospective study using data from 8,977 patients registered in the North Nottinghamshire retinal screening program. In all cases, the ophthalmology diagnosis was used as the arbitrator and considered to be the gold standard. Kappa statistics were used to evaluate the level of agreement between graders.
  
  
  RESULTS
  Agreement between primary and secondary graders was 51.4% and 79.7% for detecting no retinopathy (R0) and background retinopathy (R1), respectively. For preproliferative (R2) and proliferative retinopathy (R3) at primary grading, agreement between the primary and secondary grader was 100%. Where there was disagreement between the primary and secondary grader for R1, only 2.6% (n=41) were upgraded by an ophthalmologist. The sensitivity and specificity for detecting R3 was 78.2% and 98.1%, respectively. None of the patients upgraded from any level of retinopathy to R3 required photocoagulation therapy. The observed kappa between the primary and secondary grader was 0.3223 (95% confidence interval 0.2937-0.3509), ie, fair agreement, and between the primary grader and ophthalmology for R3 was 0.5667 (95% confidence interval 0.4557-0.6123), ie, moderate agreement.
  
  
  CONCLUSIONS
  These data provide information on the safety of a community optometry-based retinal screening program for screening as a primary and as a secondary grader. The level of agreement between the primary and secondary grader at a higher level of retinopathy (R2 and R3) was 100%. Sensitivity and specificity for R3 were 78.2% and 98.1%, respectively. None of the false-negative results required photocoagulation therapy.
authors.affiliation: Diabetic Medicine Department, Nottingham University Hospitals, Nottingham, UK ; North Nottinghamshire Eye Screening Service, Sherwood Forest Hospitals Foundation Trust, University of Nottingham, Nottingham, UK.
authors.forename: Luckni
authors.initials: L
authors.lastname: Sellahewa
authors.affiliation: North Nottinghamshire Eye Screening Service, Sherwood Forest Hospitals Foundation Trust, University of Nottingham, Nottingham, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: Simpson
authors.affiliation: North Nottinghamshire Eye Screening Service, Sherwood Forest Hospitals Foundation Trust, University of Nottingham, Nottingham, UK.
authors.forename: Prema
authors.initials: P
authors.lastname: Maharajan
authors.affiliation: North Nottinghamshire Eye Screening Service, Sherwood Forest Hospitals Foundation Trust, University of Nottingham, Nottingham, UK.
authors.forename: John
authors.initials: J
authors.lastname: Duffy
authors.affiliation: Division of Medical Sciences and Graduate Entry Medicine, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: Iskandar
authors.initials: I
authors.lastname: Idris
keywords: community; diabetes; optometry; public health; retinopathy; screening
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