Determining diabetic retinopathy screening interval based on time from no retinopathy to laser therapy

Is diabetic retinopathy screening worthwhile among people first diagnosed with diabetes at older ages? A cohort study of Norfolk diabetic retinopathy screening programme

AIMS

England's Diabetic Eye Disease Screening Programme offers screening to every resident over age 12 with diabetes, starting as soon as possible after diagnosis and repeated annually. People first diagnosed with diabetes at older ages have shorter life expectancy and therefore may be less likely to benefit from screening and treatment. To inform decisions about whether diabetic eye screening policy should be stratified by age, we investigated the probability of receiving treatment according to age at first screening episode.

METHODS

This was a cohort study of participants in the Norfolk Diabetic Retinopathy Screening Programme from 2006 to 2017, with individuals' programme data linked to hospital treatment and death data recorded up to 2021. We estimated and compared the probability, annual incidence and screening costs of receiving retinal laser photocoagulation or intravitreal injection and of death, in age groups defined by age at first screening episode.

RESULTS

The probability of death increased with increasing age at diagnosis, while the probability of receiving either treatment decreased with increasing age. The estimated cost of screening per person who received either or both treatments was £18,608 among all participants, increasing with age up to £21,721 in those aged 70-79 and £26,214 in those aged 80-89.

CONCLUSIONS

Diabetic retinopathy screening is less effective and less cost-effective with increasing age at diagnosis of diabetes, because of the increasing probability of death before participants develop sight-threatening diabetic retinopathy and can benefit from treatment. Upper age limits on entry into screening programmes or risk stratification in older age groups may, therefore, be justifiable.

A systematic review of diabetic retinopathy screening intervals

The current evidence on whether annual diabetic retinopathy (DR) screening intervals can be extended was reviewed. A systematic review protocol was followed (PROSPERO ID: CRD42022359590). Original longitudinal articles that specifically assessed DR screening intervals were in English and collected data after 2000 were included. Two reviewers independently conducted the search and reviewed the articles for quality and relevant information. The heterogeneity of the data meant that a meta-analysis was not appropriate. Twelve publications were included. Studies were of good quality and many used data from DR screening programs. Studies fit into three categories; those that assessed specific DR screening intervals, those that determined optimal DR screening intervals and those that developed/assessed DR screening risk equations. For those with type 2 diabetes, extending screening intervals to 3- to 4-yearly in those with no baseline DR appeared safe. DR risk equations considered clinical factors and allocated those at lower risk of DR progression screening intervals of up to five years. Those with baseline DR or type 1 diabetes appeared to have a higher risk of progression to STDR and needed more frequent screening. DR screening intervals can be extended to 3-5 yearly in certain circumstances. These include patients with type 2 diabetes and no current DR, and those who have optimal management of other risk factors such as glucose and blood pressure.

Prevalence and severity of diabetic retinopathy in pregnant women with diabetes-time to individualize photo screening frequency

AIMS

To evaluate the prevalence and severity of diabetic retinopathy including macular oedema in pregnant women with diabetes and to identify women in whom the frequency of retinal screening can be reduced to minimize the burden of health care visits.

METHODS

A cohort study of 348 women with pre-existing diabetes were routinely screened with retinal photo in early (12 weeks) and late pregnancy (27 weeks). Diabetic retinopathy was classified in five stages in accordance with National Danish Guidelines based on the eye with the highest retinopathy level. Sight-threatening retinopathy was defined as the presence of proliferative retinopathy and/or clinically significant macular oedema (CSMO).

RESULTS

Retinopathy was present in 52% (116/223) vs. 14% (17/125), with sight-threatening retinopathy in 16% (35/223) vs. 6% (7/125) of women with type 1 and type 2, respectively. Women without retinopathy in early and late pregnancy were characterized by shorter diabetes duration (p < 0.0001 and p = 0.008) and predominance of type 2 diabetes. Amongst the 50% (175/348) of the cohort having no retinopathy in early pregnancy and HbA1c<53 mmol/mol (7.0%), none developed sight-threatening retinopathy and 94% (165/175) remained without any retinopathy during pregnancy. Development of sight-threatening retinopathy was mainly observed in women with retinopathy in early pregnancy. Treatment for sight-threatening retinopathy was given to a minority (2.7 and 2.4%, respectively).

CONCLUSION

Good glycaemic control and no retinopathy was seen in a large proportion of women in early pregnancy and none of these women developed sight-threatening retinopathy. The frequency of retinal screening can probably be safely reduced during pregnancy in these women.

Screening Intervals for Diabetic Retinopathy and Implications for Care

PURPOSE OF REVIEW

The purpose of this study is to review the evidence that lower risk groups who could safely be screened less frequently for sight-threatening diabetic retinopathy (DR) than annually.

RECENT FINDINGS

Data have demonstrated that people with no DR in either eye are at a low risk of progression to sight-threatening DR over a 2-year period (event rate 4.8 per 1000 person years), irrespective of whether the screening method is one-field non-mydriatic or two-field mydriatic digital photography. Low risk has been defined as no retinopathy on two consecutive screening episodes or no retinopathy on one screening episode combined with risk factor data. The risk of an extension to 2 years is less than 5 per 1000 person years in a population with a national screening programme, and the general standard of diabetes care is relatively good, whether low risk is defined as no retinopathy on two consecutive screening episodes or no retinopathy on one screening episode combined with other risk factor data. The definition used in different populations is likely to depend on the availability of data.