A new risk model that includes information on functional impairments may help predict six-month mortality rates after acute myocardial infarction (MI), according to a recent study.
Researchers used data from the SILVER-AMI study, a prospective observational study of patients ages 75 years or older who were hospitalized for acute MI at 94 U.S. hospitals, to develop the risk model. Patients in the SILVER-AMI study received a baseline assessment at hospitalization that include demographic characteristics, symptoms, health status, functional impairments (e.g., cognition, mobility, muscle strength, vision, and hearing), and other conditions, such as unintended weight loss, that are common with age. The primary outcome of SILVER-AMI was death within six months of hospital discharge. The derivation cohort included 2,004 participants, and the validation cohort included 1,002 participants. Results of the study were published Dec. 10 by Annals of Internal Medicine.
All participants were ages 75 years or older and were discharged alive after hospitalization for acute MI. Mean age was 81.5 years, 44.4% were women, and 10.5% were of nonwhite ethnicity. Two hundred sixty-six participants (8.8%) died within six months of hospital discharge, 184 in the derivation cohort and 82 in the validation cohort. Patents who died were more likely to have cognitive impairment (33.2% vs. 15.6%), unintentional weight loss (38.8% vs. 20.9%), and impaired mobility (83.7% vs. 64.0%). Fifteen factors were associated with six-month mortality in the multivariable model, including hearing impairment, mobility impairment, unintended weight loss, and lower patient-reported health status, and were included in the final model. Model calibration and discrimination were good (area under the curve, 0.84 for the validation cohort), and the additional of functional impairments appeared to significantly improve model performance.
The researchers noted that their model was not validated externally, that vision and hearing impairment rates in their study were lower than those seen in other published studies, and that functional impairments are not routinely assessed during hospitalization, among other limitations. However, they concluded that their novel risk model, which included information on traditional risk factors, functional impairment, and other aging-related variables, helped predict risk for death in older patients within six months of acute MI hospitalization and could be used for prognostication at hospital discharge. A Web-based calculator for six-month mortality after MI was developed based on the results from the multivariable model.
The authors of an accompanying editorial said that the model could potentially be used to improve clinical decision making once the current results are replicated, if the added measures on function could be routinely collected and if clinicians are informed about what do with the information. “Routine use of risk prediction models is valuable only if they actually enhance clinical decision making in a way that improves outcomes for older adults at the highest risk,” the editorialists wrote, noting that it is not clear whether the functional predictors should be targeted for intervention or whether they are markers for other features that require attention.
The editorialists noted that frail elderly patients who have recently had MIs are at particularly high risk for death and that the current study makes an important contribution to the literature by developing a model that helps quantify that risk. “If the ultimate goal of a health system is to improve health, we will increasingly need to be willing to use prediction models to identify our highest-risk patients and develop, test, and deploy interventions to help address this increased risk,” the editorialists wrote.