Interventions to prevent readmission. The constraints of cost and efficacy.

Decision analysis was used to examine the interrelationship of cost and success for an intervention program designed to prevent unexpected readmissions to an acute care hospital. Three separate strategies were considered: 1) intervention for patients who are at high risk for unexpected readmission; 2) intervention for all patients who are admitted to the medical service; and 3) no intervention. Risk and cost data were derived from an analysis of 4,769 patients discharged from Boston's Beth Israel Hospital medical service during a 1-year period. It was found that interventions that cost $250.00 per patient could be cost saving given reasonable expectations of success. If an intervention for high risk patients costs $250.00 per patient, overall costs would be reduced if the success rate of the intervention was 9% or greater. If the success rate exceeded 17%, offering the intervention to all patients would reduce costs. If the cost of an intervention increases by a factor of two, it must be twice as likely to succeed to achieve the same economic benefit. Decision analysis provides a useful framework for evaluation of the economic implications of intervention strategies, and it is recommended that these methods be used in the planning and implementing of medical interventions.