Two types of financial incentives are not effective at increasing attendance at eye screening for people with diabetes who do not regularly attend screening. Surprisingly, financial incentives may even reduce the numbers of people attending screening.
Retinopathy is a type of eye disease common to people with diabetes. Sight deteriorates only in the later stages and early diagnosis and treatment can prevent blindness. Annual eye screening is offered for people with diabetes but take-up could be improved. This trial examined the effectiveness of a small fixed fee incentive and a lottery incentive compared to an invitation letter.
Contrary to expectation the financial incentives were worse than the letter, though uptake remained very low in all three groups. It remains difficult to know what other approaches might work for this hard-to-reach target group. However, this study suggests caution in implementing what seem like good ideas without testing them first.
Why was this study needed?
Diabetes affects approximately 6% of the UK population. An estimated 10% of the NHS budget is spent on treating diabetes and its complications including retinopathy. Each year in England there are 1,280 new cases of blindness from diabetic retinopathy.
Only 81% of people attend screening, meaning many people are at risk of developing avoidable sight loss. Screening rates are also lower in more socially deprived areas.
Financial incentives are sometimes used to encourage healthy behaviours. Evidence suggests they could be more effective at promoting infrequent behaviours (e.g. dental check-ups) than more complex behaviours (e.g. diet and physical activity). However, incentive schemes are controversial. Some people believe that they are unfair to people who already make the right choices.
Given the estimated cost of blindness per person per year is £12,466 these researchers set out to assess the effect of financial incentives in improving the uptake of diabetic eye screening.
What did this study do?
Incentives in Diabetic Eye Assessment by Screening (IDEAS) was an NIHR-funded randomised controlled trial. It included 1,051 people aged 16 years and older with diabetes who had not attended an eye screening appointment for two years or more.
Participants were assigned to one of three groups:
- a ‘fixed incentive’ of £10 for screening attendance
- a ‘lottery incentive’ of a 1% chance of winning £1,000 for screening attendance (a similar overall cost to the service as the cash payment)
- an invitation letter only (usual care)
The trial was well-designed and carried out in a single London clinic covering a small geographical area. This area had higher than average rates of deprivation but lower than average rates of diabetes, so findings may not be applicable to other areas in England. The travel distance to screening was also higher for trial participants than the national average so this may have underestimated the effectiveness of incentives.
What did it find?
- The rates of screening attendance were 7.8% for control participants, 5.5% for those from the fixed group and 3.3% from the lottery group.
- Participants who were offered incentives (fixed or lottery) were 44% less likely to attend screening than those that received usual care (risk ratio [RR] 0.56, 95% confidence interval [CI] 0.34 to 0.92).
- Analysis of each incentive group separately showed participants who received a lottery incentive were 58% less likely to attend screening than those that received usual care (RR 0.42, 95% CI 0.18 to 0.98). There was no significant difference between participants who received a fixed incentive or usual care (RR 0.70, 95% CI 0.35 to 1.39). There was also no significant difference between the fixed and lottery incentive groups (RR 1.66, 95% CI 0.65 to 4.21).
- Further analysis showed no significant associations between attendance and sociodemographic factors including gender, age, deprivation and distance from screening location.
- The main reasons participants gave for not attending eye screening in the past were organisational problems, practical logistical problems and not thinking that they needed to be screened.
What does current guidance say on this issue?
NICE guidance for type 1 and type 2 diabetes recommends immediate referral for eye screening following diabetes diagnosis and annual eye screening thereafter. The guidance states that reasons for and success of, eye screening should be explained so that attendance is not reduced by lack of knowledge or fear of outcome. No recommendations are included on incentives to increase eye screening attendance.
The NHS diabetic eye screening (DES) programme offers eye screening for all people with type 1 and type 2 diabetes aged 12 years and over. People already under the care of an ophthalmologist are not invited for screening. No incentives are provided.
What are the implications?
The findings from this trial were surprising. Compared to usual care, two types of financial incentives were not found to be effective at increasing attendance at eye screening for people with diabetes who were regular non-attenders. An unexpected finding was that financial incentives may even reduce the numbers of people attending.
It’s possible that the fixed amount of £10 was too little to incentivise attendance. Other possible reasons for non-attendance include people feeling well and not appreciating the risk. Diabetic retinopathy does not usually cause symptoms until the disease has progressed. Though the analysis did not find factors such as age affecting the likelihood of attendance, this was based on very small numbers of people, so may not be reliable.
Given these results, future research could focus on investigating barriers to attendance and better ways to overcome these disappointing levels.
Citation and Funding
Judah G, Darzi A, Vlaev I et al. Incentives in Diabetic Eye Assessment by Screening (IDEAS) trial: a three-armed randomised controlled trial of financial incentives. Health Serv Deliv Res. 2017;5(15).
This project was funded by the National Institute for Health Research Health Service and Delivery Research programme (12/64/112).
NICE. Type 1 diabetes in adults: diagnosis and management. NG17. London: National Institute of Health and Care Excellence; 2015.
NICE. Type 2 diabetes in adults: management. NG28. London: National Institute of Health and Care Excellence; 2015.
Public Health England. Diabetic eye screening: programme overview. 2014.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre