Retinopathy may predict nephropathy, be predicted by nonhealing ulcers

The presence of diabetic retinopathy was associated with the risk of other complications, two recent studies concluded.

The first study, a meta-analysis of 26 papers involving 2,012 patients, concluded that proliferative diabetic retinopathy may be a highly specific indicator for diabetic nephropathy.

The paper, which was published online in Diabetologia on Dec. 12, found that pooled sensitivity of diabetic retinopathy to predict diabetic nephropathy was 0.65 (95% CI, 0.62 to 0.68) and the specificity was 0.75 (95% CI, 0.73 to 0.78). The pooled positive predictive value of diabetic retinopathy to predict diabetic nephropathy was 0.72 (95% CI, 0.68 to 0.75) and the negative predictive value was 0.69 (95% CI, 0.67 to 0.72).

The area under the summary receiver-operating characteristic curve was 0.75, and the diagnostic odds ratio was 5.67 (95% CI, 3.45 to 9.34). For proliferative diabetic retinopathy, the pooled sensitivity was 0.25 (95% CI, 0.16 to 0.35), while the specificity was 0.98 (95% CI, 0.92 to 1.00).

Researchers wrote that while kidney biopsy is the gold standard method for identifying diabetic nephropathy, it cannot be done in all cases and requires 24 hours of observation to watch for complications. “In contrast, assessment of DR [diabetic retinopathy] is very convenient and is routinely performed as part of a physical examination in outpatient departments,” the authors wrote. “Although the overall test performance was not as high as expected, measuring DR may be considered useful for predicting DN [diabetic nephropathy] in the light of its simplicity and non-invasiveness.”

A second study considered whether non-ophthalmic consequences of diabetes (including nephropathy but also elevated hemoglobin A1c [HbA1c] levels and nonhealing ulcers) could predict the progression of diabetic retinopathy from nonproliferative to proliferative. Researchers conducted a retrospective cohort analysis using a claims database of all eye care recipients 30 years or older enrolled in a large managed care network from 2001 to 2009. Results appeared Jan. 3 in Diabetes Care.

Among the 4,617 enrollees with newly diagnosed nonproliferative diabetic retinopathy, 307 (6.6%) progressed to proliferative cases. Every 1-point increase in HbA1c was associated with a 14% increase in risk of developing progressive retinopathy (adjusted hazard ratio, 1.14; 95% CI, 1.07 to 1.21). Those with nonhealing ulcers had a 54% increased risk of progressing to proliferative retinopathy (hazard ratio, 1.54; 95% CI, 1.15 to 2.07) compared to those without. Those with nephropathy had a 29% increased risk of progression compared to those without, but the statistical significance of this finding was marginal (hazard ratio, 1.29; 95% CI, 0.99 to 1.67).

The 5-year probability of progression for those with nonproliferative diabetic retinopathy was 5% (range, 2% to 8%) for those who had few risk factors, but 38% (range, 14% to 55%) for those with multiple risk factors.

“If confirmed, the association between nonhealing ulcers and retinopathy progression could have important implications for clinical practice,” the authors wrote. “Control of nonhealing ulcers may help to reduce progression of NPDR [nonproliferative diabetic retinopathy] to PDR [proliferative diabetic retinopathy], the risk of vision loss, and the need for laser surgery.”