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Experts do not agree when to treat retinopathy of prematurity based on plus disease
  1. Carina Slidsborg1,
  2. Julie Lyng Forman2,
  3. Alistair R Fielder3,
  4. Sven Crafoord4,
  5. Kirsten Baggesen5,
  6. Regitze Bangsgaard1,
  7. Hans Callø Fledelius1,
  8. Gorm Greisen6,
  9. Morten la Cour1
  1. 1Department of Ophthalmology, Copenhagen University Hospital, Glostrup Hospital, Glostrup, Denmark
  2. 2Departmant of Biostatistics, University of Copenhagen, Copenhagen, Denmark
  3. 3Department of Optometry and Visual Science, City University, London, UK
  4. 4Department of Ophthalmology, Orebro University Hospital, and Orebro University, Orebro, Sweden
  5. 5Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
  6. 6Department of Neonatology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
  1. Correspondence to Carina Slidsborg, Department of Ophthalmology, Glostrup Hospital, Nordre Ringvej 57, Glostrup 2600, Denmark; carinaslidsborg{at}


Objectives To investigate inter-reader agreement on five severity levels of central vascular changes (none, mild, moderate, severe pre-plus disease, plus disease) and aggressive posterior retinopathy of prematurity (ROP), and to see whether an unintended shift in indication for treatment occurred.

Methods Four international ROP readers participated. Before the grading of the photographs, the readers were informed that a high proportion of advanced ROP cases were included. In total, 243 photographs/948 quadrants were available from 136 infants. As a standard series of photographs was available, grading was performed under optimised conditions.

Results The four readers agreed on the quadrant scores of only 70 (7.38%) of the 948 quadrants—that is, on 1, 5, 15, 4 and 45 quadrants for scores 0, 1, 2, 3 and 4, respectively. The mean scores differed systematically between the readers (permutation test, p<0.0001). Agreement on presence of aggressive posterior ROP from all four readers was not obtained for any of the photographs. Readers scored plus disease in at least two quadrants in 95.5% of the eyes for which treatment was indicated. All four readers agreed on the scoring of indication for treatment for 195 eyes (80.2%); however, treatment was only recommended in 18 (7.4%) eyes. One reader was found to differ systematically from the others in indicating treatment (Rasch analysis; p=0.0001). Finally, a significant shift in indication for treatment occurred between birth period 2000–2002 and 2003–2006 (Mann–Whitney rank sum test, p<0.001).

Conclusions Inter-reader agreement on central vascular changes is poor, especially when based on more than two rating categories. The subjective nature of diagnosing such vascular changes possibly resulted in earlier treatment of preterm infants in Denmark over the entire study period (1997–2006). The recent increased incidence of treated infants in Denmark is, at least in part, explained by a significant shift in indication for treatment.

  • Preterm delivery
  • retinopathy of prematurity
  • plus disease
  • pre-plus disease
  • aggressive posterior retinopathy of prematurity
  • RetCam photographs
  • inter-reader agreement
  • indication for treatment
  • diagnostic tests/investigation
  • epidemiology
  • public health
  • imaging
  • telemedicine
  • child health (paediatrics)
  • embryology and development
  • macula

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  • Funding This work was supported by grants from the Danish Eye Health Society, Bagenkop Nielsens Myopi- and Eye Foundation, VELUX Foundation, Aase and Ejnar Danielsens Foundation, Dagmar Marshalls Foundation, Direktør Jacob Madsen and Hustru Olga Madsens Foundation, P. A. Messerschmidt and Hustrus Foundation.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.