Understanding variation in chronic disease outcomes.

We propose an explanation for variation in disease outcomes based on patient adaptation to the conditions of chronic disease. We develop a model of patient adaptation using the example of Type 2 diabetes mellitus and assumptions about the process entailed in transforming self-care behaviors of compliance with treatment, compliance with glucose monitoring, and patient's knowledge seeking behavior into health outcomes of glycemic control and patient satisfaction. Using data from 609 adults with diagnosed Type 2 diabetes we develop an efficiency (fitness) frontier in order to identify best practice (maximally adapted) patients and forms (archetypes) of patient inefficiency. Outcomes of frontier patients are partitioned by categories of returns to scale. Outcomes for off-frontier patients are associated with disease severity and patient archetype. The model implicates strategies for improved health outcomes based on fitness and self-care behaviors.