The electronic frailty index and outcomes in patients with myocardial infarction

Abstract

Background: Frailty is increasingly present in patients with acute myocardial infarction. The electronic Frailty Index (eFI) is a validated method of identifying vulnerable older patients in the community from routine primary care data. Our aim was to assess the relationship between the eFI and outcomes in older patients hospitalised with acute myocardial infarction.

Study design and setting: Retrospective cohort study using the DataLoch Heart Disease Registry comprising consecutive patients aged 65 years or over hospitalised with a myocardial infarction between October 2013 and March 2021.

Methods: Patients were classified as fit, mild, moderate, or severely frail based on their eFI score. Cox-regression analysis was used to determine the association between frailty category and all-cause mortality.

Results: In 4670 patients (median age 77 years [71-84], 43% female), 1865 (40%) were classified as fit, with 1699 (36%), 798 (17%) and 308 (7%) classified as mild, moderate and severely frail, respectively. In total, 1142 patients died within 12 months of which 248 (13%) and 147 (48%) were classified as fit and severely frail, respectively. After adjustment, any degree of frailty was associated with an increased risk of all-cause death with the risk greatest in the severely frail (reference = fit, adjusted hazard ratio 2.87 [95% confidence intervals 2.24 to 3.66]).

Conclusion: The eFI identified patients at high risk of death following myocardial infarction. Automatic calculation within administrative data is feasible and could provide a low-cost method of identifying vulnerable older patients on hospital presentation.

Keywords: electronic frailty index; frailty; myocardial infarction; older people; routine data.

Figure 1

Cumulative incidence of all-cause mortality at 12 months. Cumulative incidence plot of 12-month all-cause mortality by electronic frailty index classification.

Figure 2

Electronic frailty index and risk of all-cause mortality. Forest plot of cox-regression analysis assessing the associated hazard for all-cause mortality within 12 months of admission by electronic frailty index category (reference = fit). Model adjusted for age, sex, peak troponin value, and myocardial infarction classification (NSTEMI vs STEMI). eFI = electronic frailty index, hs-cTnI = high-sensitivity cardiac troponin I.

Figure 3

Electronic frailty index and additional adverse outcomes following myocardial infarction. Forest plot showing output of cox-regression and logistic regression analysis assessing the association of electronic frailty index categories with cardiovascular mortality within 12 months, all-cause mortality at 3 years, in-patient all-cause mortality, and unplanned hospital re-admission within 12-months of discharge. Adjusted for age, sex, peak troponin value and myocardial infarction classification (NSTEMI vs STEMI).