Abstract 11390: A Readmission Risk Model for Older Adults Hospitalized With Acute Myocardial Infarction: The SILVER-AMI Study.

Background: Readmissions among older adults hospitalized for acute myocardial infarction (AMI) are costly, disruptive, and difficult to predict. Aging-related functional impairments may improve risk prediction, but have not been measured in most studies. Our objective was therefore to develop a readmission risk model for older adults hospitalized for AMI that considered functional impairments. Methods: SILVER-AMI is a prospective cohort study of 3006 patients age ≥75 hospitalized with AMI at 96 U.S. hospitals. Participants underwent in-hospital assessment of functional impairments including cognition, vision, hearing, and mobility. Clinical variables traditionally associated with readmission risk, as well as patient reported health status, were also collected. The outcome was all-cause readmission at 30 days. We used backward selection and Bayesian model averaging to derive (N=2004) a risk model that was subsequently validated in a separate sample (N=1002). Model discrimination and calibration were respectively evaluated with the C-statistic and the Hosmer-Lemeshow test. Results: Mean age was 81.5 years, 44.4% were women, and 10.5% were nonwhite. Within 30 days, 547 participants (18.2%) experienced readmission (61.0% cardiac cause). Participants who were readmitted were older, had more comorbidities, and had a higher prevalence of functional impairments including activity of daily living disability (17.0% vs. 13.0%, P=0.01), weak grip strength (64.4% vs. 59.2%, P<0.01), and impaired mobility measured by Timed Up and Go (TUG) (72.5% vs. 53.6%, P<0.001). The final readmission risk model contained 8 variables; mobility was the only functional impairment retained, but was the strongest predictor (Figure). The model was well calibrated (P value >0.05 for Hosmer-Lemeshow statistic) and had moderate discrimination (C-statistic: 0.65 derivation cohort, 0.63 validation cohort) across all multiply imputed datasets. Conclusion: In our final risk model, functional mobility was the strongest predictor of 30-day readmission among older adults after AMI. The modest C-statistic indicates that much of the variability in readmission among this older adult population remains unexplained by patient-level factors. [ABSTRACT FROM AUTHOR]