To evaluate the impact of primary and secondary interventions on the development of complications from diabetes, we modeled the effects of primary and secondary interventions for diabetes on a single well-studied complication, diabetic retinopathy.
A model was developed to predict cumulative incidence of retinopathy in IDDM and NIDDM. Risk functions are based on duration of diabetes. The effects of intervention strategies were simulated by altering the retinopathy risk. The effects of the simulations were assessed using cumulative incidence.
Simulations of delaying the onset of IDDM from 2 to 8 yr and decreasing the retinopathy rates by 20–80% were performed for each type of retinopathy. Simulating primary prevention shifted the cumulative incidence curves to the right, and simulating secondary intervention shifted the curves downward. Primary prevention was less effective than secondary prevention. This difference was more apparent for IDDM than for NIDDM, where disease duration and exposure to retinopathy risk were shorter. All interventions shifted the development of retinopathy to later in life.
The greatest effect on cumulative incidence of all forms of retinopathy occurs when primary and secondary interventions are combined.