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The paper by Tye et al1 looking at the incidence of diabetic retinopathy that needs treatment in the over-90s appears to imply that the detection rate of diabetic retinopathy,which might need treatment and actually goes on to treatment, in this group is unacceptably low; however, the figures are similarly low in the whole annual photographic diabetic screening program. The sample size of only 179 might give a misleading picture. In the reported study, the incidence was 2/179 (1.12%); one of these had laser, thus bringing the incidence rate down to 0.56%. In the Newcastle and North of Tyne screening program, 43571 diabetics were screened between April 2014 and March 2015 leading to 120 R3A (active proliferative diabetic retinopathy) and 814 R2/M1 (severe non-proliferative and maculopathy) referrals, which is at a rate of 2.14%. Incidentally, the number sent for a slit lamp clinic, as they were un-gradable on photography, was 1134 (2.60%) and an additional 13% of diabetics on the single-collated register did not attend for screening. Of those who were un-gradable, if the incidence of referable diabetic retinopathy was the same as in the other screened patients at 2.14%, then only 24 patients would be expected to have referable retinopathy. Of the 934 who were referred to hospital, <200 were treated although on follow-up some more may eventually be treated; 200/43571 gives an incidence rate of 0.46%, which was actually less than in the over-90 cohort reported.
The screening service is effective at detecting retinopathy that might need treatment and preventing blindness,2 however at increasing cost. A systematic review in 2014 looked at the evidence for extending the screening interval beyond 1 year in the UK and did not find robust evidence to support this due to the lack of randomized trials of such an approach.3 What it did not seem to address is what annual incidence rate justifies screening annually and based on that if any group could have less frequent screening or no screening at all. This is a cost–benefit argument where decisions need to be made on what level of risk of missing sight-threatening retinopathy is acceptable.
The authors declare no conflict of interest.