14th September 2022, Dr Chee L Khoo
Diabetic retinopathy (DR) will affect up to 1 in 3 of our patients with diabetes. It is a sad statistic but it’s even more scary in women. In fact, DR is the leading cause of irreversible blindness in women of reproductive age. Much of the risk can be minimised or prevented in primary care. Although the changes that occurred during pregnancy is mostly temporary, any progression to sight threatening disease is not reversible, and the risk of this progression persisted for up to 12 months post-partum. How common is DR in pregnant women?
In 1989, the St Vincent Declaration (SVD) established an optimised standard of care for pregnant women with diabetes (ie, gestational and pre-existing type 1 diabetes [T1D] or type 2 diabetes [T2D]) to achieve similar pregnancy outcomes as women without diabetes.5 These outcomes included reducing the rate of maternal complications, such as diabetes related blindness in pregnant women with pre-existing diabetes and preeclampsia, and reducing the rate of adverse foetal and neonatal complications, such as congenital malformations, perinatal mortality, and preterm delivery.
Reported DR prevalence ranged from 8-63% and reported progression rates ranged from 5- 41.5%. With such wide range, it is difficult to estimate the disease burden of DR in pregnant women. These lead to difficulty in worldwide consensus on guidelines on management. A recent systematic review and meta-analysis of the literature may help to shine some light of the extent of our problem.
Widyaputri F. et al recently conducted a systematic search of available observational studies using keywords “pregnant”, “pregnancy” and “diabetic retinopathy”. They extracted the following: year of publication, country, study design, participant characteristics, sample size, year of participants’ first retinal examination, the retinal assessment method used, how DR severity/status was graded, and the outcome data of interest.
18 studies had sufficiently well-reported data and rigorous ophthalmic reports for prevalence analysis. 16 studies had sufficient data for progression analysis.
The Results
The overall any DR prevalence per 100 pregnancies in early pregnancy was 52 and around delivery was 57.8. Now this is 1 in 2 women with diabetes who are pregnant! For proliferative diabetic retinopathy (PDR), the prevalence per 100 pregnancies in early pregnancy was 6.1 and around delivery was 8.2.
The pooled prevalence of any DR during pregnancy was higher than the pooled prevalence estimated in the nonpregnant diabetic population (52.3%-57.8% vs 34.6%). The pooled prevalence of PDR in early pregnancy was similar between pregnant and non-pregnant women (6.1%vs 6.81%), the pooled prevalence of PDR around delivery was also higher (8.2% in both pregnant and non-pregnant women).
The pooled progression rate was higher in pregnant women with pre-existing DR (ranging from 6.3% for progression from NPDR to PDR up to 37.0% for worsened PDR) than in those without DR in early pregnancy. Unlike in the prevalence estimations, no significant difference was found between the progression rate in T1D and T2D studies, with one notable exception: the rate for the development of new DR was substantially higher in women with T1D than in women with T2D. Taken together, these findings suggest that women with T1D have a higher risk of developing new DR during pregnancy, but that once a woman has DR, her risk of DR progression is similar in pregnancy irrespective of her diabetes type.
Limitation of the study
The meta-analysis had considerable heterogeneity, suggesting that there was clinical or methodological diversity among the included studies.
Reference:
- Widyaputri F, Rogers SL, Kandasamy R, Shub A, Symons RCA, Lim LL. Global Estimates of Diabetic Retinopathy Prevalence and Progression in Pregnant Women With Preexisting Diabetes: A Systematic Review and Meta-analysis. JAMA Ophthalmol. 2022 May 1;140(5):486-494. doi: 10.1001/jamaophthalmol.2022.0050. PMID: 35357410; PMCID: PMC8972153.
- Zhou S, Shen C. Statistical Considerations for Meta-analysis of Diabetic Retinopathy Prevalence. JAMA Ophthalmol. Published online September 08, 2022. doi:10.1001/jamaophthalmol.2022.3470