Validation of a model to estimate personalised screening frequency to monitor diabetic retinopathy
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Our study aimed to validate a model to determine a personalised screening frequency for diabetic retinopathy.
A model calculating a personalised screening interval for monitoring retinopathy based on patients’ risk profile was validated using the data of 3,319 type 2 diabetic patients in the Diabetes Care System West-Friesland, the Netherlands. Two-field fundus photographs were graded according to the EURODIAB coding system. Sight-threatening retinopathy (STR) was considered to be grades 3–5. Validity of the model was assessed using calibration and discrimination measures. We compared model-based time of screening with time of STR diagnosis and calculated the differences in the number of fundus photographs using the model compared with those in annual or biennial screening.
During a mean of 53 months of follow-up, 76 patients (2.3%) developed STR. Using the model, the mean screening interval was 31 months, leading to a reduced screening frequency of 61% compared with annual screening and 23% compared with biennial screening. STR incidence occurred after a mean of 26 months after the model-based time of screening in 67 patients (88.2%). In nine patients (11.8%), STR had developed before the model-based time of screening. The discriminatory ability of the model was good (C-statistic 0.83; 95% CI 0.74, 0.92). Calibration showed that the model overestimated STR risk.
A large reduction in retinopathy screening was achieved using the model in this population of patients with a very low incidence of retinopathy. Considering the number of potentially missed cases of STR, there is room for improvement in the model. Use of the model for personalised screening may eventually help to reduce healthcare use and costs of diabetes care.
KeywordsDiabetic retinopathy Retinal screening Screening intervals
Diabetes Care System West-Friesland
We gratefully acknowledge M. S. A. Suttorp-Shulten (Department of Ophthalmology, OLVG, Amsterdam, the Netherlands) for grading of the fundus photographs.
This study was funded by ZonMw, the Netherlands organisation for health research.
Duality of interest
The authors declare that there is no duality of interest associated with this manuscript.
AAWAvdH was involved in the conception and design of the study, analysis and interpretation of the data and drafting of the manuscript. IW was involved in the analysis and interpretation of the data and drafting of the manuscript. EvtR, TA, SHL, PE, BCPP, ACM, JEEK, JMD and GN were involved in the interpretation of the data and revision of the manuscript. GN was involved in the conception of the study, interpretation of the data and revision of the manuscript. All authors approved the final version of the manuscript. AAWAvdH and IW are the guarantors of this work, had full access to the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
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