Hospital readmission rates: the impacts of age, payer, and mental health diagnoses.

We examine impacts of age, payer, and mental health conditions upon hospital readmissions and the comparability of same-hospital and multiple-hospital readmission rates. Medicaid primary payment and extreme age are associated with significantly higher readmission rates. We find low correlation between same-hospital and multiple-hospital readmission rates and identify urban hospitals with high proportions of Medicaid patients and mental health admissions as factors driving the use of multiple hospitals within readmission chains. Hospital payment incentives and performance measures using readmission rates will be distorted if factors leading to higher readmission rates are ignored, or if readmissions to different hospitals cannot be identified.