Severity of diabetic retinopathy linked to incidence of nephropathy

A large population-based study has identified a significant association between the severity of retinopathy and the incidence of nephropathy in patients with diabetes. In addition, disease severity appears to be linked to a family history of diabetes.

Nedal H. Arar, PhD, and colleagues working in conjunction with the FIND (Family investigation of nephropathy and diabetes) Eye Study evaluated the genetic basis of diabetic nephropathy and its correlation with retinopathy among 2,368 diabetic patients from 767 families in the United States who were of American Indian, European, African or Mexican descent. Half of these patients were of Mexican descent.

Specifically, the study enrolled 767 diabetic nephropathy probands, 1,442 diabetic siblings and 159 other diabetic relatives.

The prevalence of retinopathy for the entire cohort was 73.4%, of which 9.5% of patients had mild nonproliferative retinopathy, 22.8% of patients had moderate nonproliferative retinopathy, 7.5% of patients had severe nonproliferative retinopathy and 33.4% of patients had proliferative retinopathy.

"[Proliferative diabetic retinopathy] was more frequent in the [diabetic nephropathy] probands than in the nonprobands; whereas lack of [diabetic retinopathy] was more common among nonprobands than among [diabetic nephropathy] probands," the study authors said.

According to phenotype and heightened serum creatinine concentration, the investigators identified a significant link between the severity of retinopathy and nephropathy (P < .0001).

For the entire cohort the sibling-to-sibling correlation for retinopathy severity was 0.1358; this correlation was 0.1224 among the Mexican-American population alone.

The investigators estimated the broad-sense heritability at approximately 27% for the entire cohort and 24% in the Mexican-American families alone, according to the study, published in the September issue of Investigative Ophthalmology & Visual Science.