Clinical relevance of frailty trajectory post myocardial infarction

Background: Frailty describes the heterogeneity of vulnerability in older people and has been shown to predict mortality, disability, and institutionalization. Little is known about the clinical relevance of frailty post myocardial infarction (MI). Design: The Rockwood frailty index, based on accumulation of deficits, was adapted in a cohort of MI survivors followed up for 20 years, in order to assess trajectory and predictive value for clinical outcomes. Methods: Participants were 1521 patients aged <= 65 years admitted to one of eight Israeli hospitals with first acute MI between 1992 and 1993. A frailty index (on a 0-1 continuous scale) was developed comprising 32 variables, including self-rated health, functional limitations, comorbidity, weight loss, and physical activity. Frailty was assessed at baseline and 10-13 years after MI. Results: Median frailty score increased from 0.08 to 0.19 during follow up. Participants in the frailest group (>= 0.25) at baseline had twice the multivariable-adjusted mortality risk of those in the least frail group (<0.10) (hazard ratio, HR, 2.02, 95% CI 1.46-2.79). Frailty index modelled as a time-dependent variable showed a substantially stronger association (HR 3.61, 95% CI 2.82-4.63) and provided incremental value in risk discrimination beyond clinical and socio-demographic variables (p < 0.001 for improvement in c-statistic). The frailest patients were more than twice as likely to be hospitalized during follow up compared to the least frail (adjusted rate ratio 2.14, 95% CI 1.63-2.81). Conclusions: Frailty, calculated via an index of deficits, was associated with mortality and hospitalizations following MI. Beyond predictive value, accurate identification of frailty may indicate which individuals will benefit most from preventive interventions.