Multi-state models and diabetic retinopathy.

This paper discusses the application of a multi-state model to diabetic retinopathy under the assumption that a continuous time Markov process determines the transition times between disease stages. The multi-state model consists of three transient states that represent the early stages of retinopathy, and one final absorbing state that represent the irreversible stage of retinopathy. By using a model with covariables, we explore the effects of factors that influence the onset, progression, and regression of diabetic retinopathy among subjects with insulin-dependent diabetes mellitus. We can also introduce time-dependent covariables in the model by assuming that the covariables remain constant between two observations. We can also obtain survival-type curves from each stage of the disease and for any combination of patient risk factors.