Longitudinal study examining the risk factors for proliferative retinopathy and maculopathy in type-I diabetes: The Royal College of Physicians of Edinburgh Diabetes Register Group

Abstract

Purpose: The aim of this study was to determine whether there were any differences in the risk factors for developing proliferative diabetic retinopathy or maculopathy in patients with type-I diabetes.

Method: In all, 1632 patients aged 35 years or younger at diagnosis and treated with insulin, attending six hospital diabetes clinics in Scotland and included on the Royal College of Physicians of Edingburgh Diabetes Register were followed up for a median of 4.0 (2.5-5.5 years: interquartile range). All patients were screened at least annually for diabetic retinopathy using direct ophthalmoscopy, and positive findings were confirmed using slit lamp by an ophthalmologist.

Results: Duration of diabetes and HbA1c were the important risk factors for developing proliferative retinopathy, while the duration of diabetes, systolic blood pressure, and HbA1c were the important factors of maculopathy. The adjusted relative incidence for proliferative retinopathy with a HbA1c in the highest quartile was 26.7, while for maculopathy it was only 2.29. Carstairs deprivation score was not associated with either retinal pathology. There was a plateau effect for systolic blood pressure of 140 mmHg and for duration of diabetes of 16 years for developing either maculopathy or proliferative retinopathy.

Conclusion: Duration of diabetes is a strong predictor for maculopathy and proliferative disease, but is relatively more important for proliferative disease. Raised systolic blood pressure is relatively more important for predicting maculopathy, while raised HbA1c is relatively more important for developing proliferative retinopathy.