An interrater reliability study of a new 'zonal' classification for reporting the location of retinal haemorrhages in childhood for clinical, legal and research purposes

Background/Aims To develop and assess a zonal classification of the retina to facilitate description of the location of retinal haemorrhages in children. Methods A novel zonal classification of the retina was devised based on the anatomical landmarks of the optic disc and vascular arcades, by reviewing a large number of wide field digital retinal images drawn from our database of children with accidental and non-accidental head injury and other encepthalopathies. Four expert examiners then independently 'located' 142 retinal haemorrhages by zone, from 31 high quality photographs. Results Cohen's unweighted kappa scores for all possible pairs of the four raters (ie, six pairs) ranged from 0.86 to 0.92, that is 'almost perfect' agreement. Fleiss' kappa for agreement between multiple raters (four) and for multiple categories (three) was 0.8841, that is 'almost perfect' agreement. Cohen's unweighted kappa statistic for intrarater reliability gave an overall concordance that ranged from 'substantial' to 'perfect' agreement. Conclusion This new retinal zone classification and the use of photographs and templates is a very reliable tool for reporting the location of retinal haemorrhages from multiple aetiologies in children, and may be useful for research and medico-legal reports.