Abstract
Aims/hypothesisIndividualised variable-interval risk-based screening offers better targeting and improved cost-effectiveness in screening for diabetic retinopathy. We developed a generalisable risk calculation engine (RCE) to assign personalised intervals linked to local population characteristics, and explored differences in assignment compared with current practice.MethodsData from 5 years of photographic screening and primary care for people with diabetes, screen negative at the first of > 1 episode, were combined in a purpose-built near-real-time warehouse. Covariates were selected from a dataset created using mixed qualitative/quantitative methods. Markov modelling predicted progression to screen-positive (referable diabetic retinopathy) against the local cohort history. Retinopathy grade informed baseline risk and multiple imputation dealt with missing data. Acceptable intervals (6, 12, 24 months) and risk threshold (2.5%) were established with patients and professional end users.ResultsData were from 11,806 people with diabetes (46,525 episodes, 388 screen-positive). Covariates with sufficient predictive value were: duration of known disease, HbA1c, age, systolic BP and total cholesterol. Corrected AUC (95% CIs) were: 6 months 0.88 (0.83, 0.93), 12 months 0.90 (0.87, 0.93) and 24 months 0.91 (0.87, 0.94). Sensitivities/specificities for a 2.5% risk were: 6 months 0.61, 0.93, 12 months 0.67, 0.90 and 24 months 0.82, 0.81. Implementing individualised RCE-based intervals would reduce the proportion of people becoming screen-positive before the allocated screening date by > 50% and the number of episodes by 30%.Conclusions/interpretationThe Liverpool RCE shows sufficient performance for a local introduction into practice before wider implementation, subject to external validation. This approach offers potential enhancements of screening in improved local applicability, targeting and cost-effectiveness.
Highlights
Systematic screening for sight-threatening diabetic retinopathy (STDR) has been introduced in several European countries and regionally throughout the world, and has been a major driver of improved detection and early treatment
While current recommendations are for annual screening intervals in most locations [3], there has been a recent move to recommend biennial screening for people with no retinopathy [4,5,6,7], including in one systematic review [8], and this was recently endorsed by the UK National Screening Committee [9]
Data were collected for all people recorded in primary care as having diabetes mellitus attending the Liverpool Diabetes Eye Screening Programme (LDESP) from the systems used for routine service, anonymised and compiled before transmission to the warehouse
Summary
Systematic screening for sight-threatening diabetic retinopathy (STDR) has been introduced in several European countries and regionally throughout the world, and has been a major driver of improved detection and early treatment. As a doubling of the global prevalence of diabetes mellitus is expected by 2030 [1], with over 10% having STDR [2], there is an urgent need to improve the cost-effectiveness of screening. Screening at 3-yearly intervals has been introduced in Sweden, based on data from one programme [10], and is supported as being cost-effective in a recent UK modelling study [11]. Risk engines have been developed in recent years, including in diabetes mellitus for risk of CHD [14], and one has been proposed for diabetic retinopathy [15]. Reliable flows of data need to be established and designs need to be applicable across a range of populations and health settings
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