Prognosis in SLE: comparison of Markov model to life table analysis.
A Markov model of prognosis was evaluated by comparing the duration of disease activity states and life expectancy with Kaplan-Meier survival curves for 98 patients with systemic lupus erythematosus with 1080 patient-years of observation. A four state (remission, active, flare and death) homogeneous Markov chain was constructed to determine the transition probabilities between disease states, the probability of disease states over the subsequent 25 years, time in each disease state, and life expectancy. Approximately 85% of the clinical course of patients was in the active disease state; no patient made a transition directly between remission and flare; virtually all deaths occurred from the flare disease state. The proportion of the patient population in each disease state over time provided a convenient graphic summary of the natural history of SLE that supplemented the Kaplan-Meier survival curves. A Markov model analysis yields a clinically useful description of outcome for multistate diseases that supplements survival curves.