Development of a cost-effectiveness model for optimisation of the screening interval in diabetic retinopathy screening

Abstract

BackgroundThe English NHS Diabetic Eye Screening Programme was established in 2003. Eligible people are invited annually for digital retinal photography screening. Those found to have potentially sight-threatening diabetic retinopathy (STDR) are referred to surveillance clinics or to Hospital Eye Services.ObjectivesTo determine whether personalised screening intervals are cost-effective.DesignRisk factors were identified in Gloucestershire, UK using survival modelling. A probabilistic decision hidden (unobserved) Markov model with a misgrading matrix was developed. This informed estimation of lifetime costs and quality-adjusted life-years (QALYs) in patients without STDR. Two personalised risk stratification models were employed: two screening episodes (SEs) (low, medium or high risk) or one SE with clinical information (low, medium–low, medium–high or high risk). The risk factor models were validated in other populations.SettingGloucestershire, Nottinghamshire, South London and East Anglia (all UK).ParticipantsPeople with diabetes in Gloucestershire with risk stratification model validation using data from Nottinghamshire, South London and East Anglia.Main outcome measuresPersonalised risk-based algorithm for screening interval; cost-effectiveness of different screening intervals.ResultsData were obtained in Gloucestershire from 12,790 people with diabetes with known risk factors to derive the risk estimation models, from 15,877 people to inform the uptake of screening and from 17,043 people to inform the health-care resource-usage costs. Two stratification models were developed: one using only results from previous screening events and one using previous screening and some commonly available GP data. Both models were capable of differentiating groups at low and high risk of development of STDR. The rate of progression to STDR was 5 per 1000 person-years (PYs) in the lowest decile of risk and 75 per 1000 PYs in the highest decile. In the absence of personalised risk stratification, the most cost-effective screening interval was to screen all patients every 3 years, with a 46% probability of this being cost-effective at a £30,000 per QALY threshold. Using either risk stratification models, screening patients at low risk every 5 years was the most cost-effective option, with a probability of 99-100% at a £30,000 per QALY threshold. For the medium-risk groups screening every 3 years had a probability of 43 –48% while screening high-risk groups every 2 years was cost-effective with a probability of 55–59%.ConclusionsThe study found that annual screening of all patients for STDR was not cost-effective. Screening this entire cohort every 3 years was most likely to be cost-effective. When personalised intervals are applied, screening those in our low-risk groups every 5 years was found to be cost-effective. Screening high-risk groups every 2 years further improved the cost-effectiveness of the programme. There was considerable uncertainty in the estimated incremental costs and in the incremental QALYs, particularly with regard to implications of an increasing proportion of maculopathy cases receiving intravitreal injection rather than laser treatment. Future work should focus on improving the understanding of risk, validating in further populations and investigating quality issues in imaging and assessment including the potential for automated image grading.Study registrationIntegrated Research Application System project number 118959.Funding detailsThe National Institute for Health Research Health Technology Assessment programme.

Review of economic evaluations of teleophthalmology as a screening strategy for chronic eye disease in adults

“…There is limited evidence on the cost-effectiveness of optimal screening intervals for DR. A recent health technology assessment in the UK found DR screening every 3 years, irrespective of risk, was most likely to be cost-effective, while screening every 5 years for low-risk groups and every 2 years for high-risk groups was cost-effective 42. Our review showed similar findings using teleophthalmology as a screening strategy showing frequency up to twice-in-a-lifetime, once every 5, 3 or 2 years increased cost and QALYs gained and remained cost-effective; however, annual screening was not as cost-effective 23…”

Individualised variable-interval risk-based screening for sight-threatening diabetic retinopathy: the Liverpool Risk Calculation Engine

“…An RCE development dataset was extracted from the data warehouse containing covariates with ≥ 80% completeness in people with diabetes who were screen negative (non-referable retinopathy) at the first of at least two episodes that occurred in a 5 year sample period. Disease duration was defined as duration of known diabetes mellitus (first recorded date of diabetes or measure of HbA 1c in primary care [11]) and assigned at the first screening episode. Values of clinical risk factors prior and nearest to the screen episode date were used.…”

Diabetic Retinopathy in Italy: Epidemiology Data and Telemedicine Screening Programs

“…Moreover, adopting biennial screening approach, a reduction in approximately 25% of screening costs can be obtained without increased risk to the patient [44]. Two recent studies reported cost-effectiveness of adopting risk-stratified approaches to extended screening intervals in the national DR screening programs in England and Scotland [45, 46]. Scanlon et al conducted a modelling study and reported that for patients without DR on two consecutive screening examinations the adoption of 2-year screening intervals would save on average 225000 pounds per QUALY (quality-adjusted life years) lost compared with annual screening in England [45].…”