RA increases vascular disease and angiogenesis, yet a 1964 Lancet report paradoxically linked RA to lower diabetic retinopathy. Our objective was to examine RA as a risk factor for diabetic retinopathy compared with other vascular risk factors.
This cohort study compared the prevalence of diabetic retinopathy in diabetes patients with and without RA in a 5% Medicare sample. We analysed the impact of RA on the prevalence of diabetic retinopathy using multivariate logistic regression calculating adjusted rate ratios (ARRs) controlling for sociodemographics, co-morbidity and health utilization. Sensitivity analysis examined eye exam rates.
Among 256 331 Medicare diabetes patients, 5572 (2%) had RA. Diabetic retinopathy was less prevalent in patients with RA compared with those without RA (13.7% vs 16.1%, P ≤ 0.01). Compared with patients without RA, the adjusted model demonstrated that patients with diabetes and RA were 28% less likely to have diabetic retinopathy and 4% more likely to receive an eye exam [ARR 0.72 (95% CI 0.67, 0.77), ARR 1.04 (95% CI 1.02, 1.06)].
Findings support the 1964 paradox observing decreased diabetic retinopathy in patients with RA. These findings pose new questions regarding whether RA physiology or treatments protect against diabetic retinopathy and how intraocular factors vary in contrast to adverse vascular changes elsewhere.