Prediction of proliferative diabetic retinopathy with hemoglobin level.

OBJECTIVE To investigate the role of hemoglobin (HGB) level in predicting proliferative diabetic retinopathy (PDR). METHODS We assessed 426 individuals without PDR at baseline (213 men; 213 women) from the Pittsburgh Epidemiology of Diabetes Complications Study, an 18-year prospective cohort study of childhood-onset type 1 diabetes. Presence of PDR was determined by stereo fundus photography. Cox proportional hazards modeling with stepwise regression was used to determine the independent association of HGB level with PDR. Analyses were sex specific. RESULTS There were 206 events. Although the incidence of PDR did not vary by sex (48% in both men and women), in men, HGB exhibited a positive linear relationship with 18-year incidence of PDR (hazard ratio, 1.33; 95% confidence interval, 1.10-1.60; P = .003), while in women, HGB level exhibited a quadratic relationship with PDR (P < .001). After multivariable adjustment for univariately significant covariates, HGB level remained significantly predictive of PDR in both men (P = .004) and women (P = .04). CONCLUSION Higher HGB level predicts the incidence of PDR in type 1 diabetes mellitus, though the association varies by sex, being linear and positive in men and quadratic in women.