Multilevel socioeconomic status and incidence of frailty post myocardial infarction

Frailty predicts mortality and hospitalizations in post-myocardial infarction (MI) patients. Socioeconomic status (SES) demonstrates a clear relationship with post-MI outcomes and is also associated with community frailty; however this relationship has yet to be evaluated in post-MI patients. We investigated the predictive value of socioeconomic factors in the development of post-MI frailty.

A cohort of 1151 post-MI patients was followed up from initial hospitalization in 1992-1993 for 10-13 years. Individual and neighborhood SES measures were assessed at baseline and frailty was assessed during follow-up via an index of deficit accumulation. Logistic regression models and discrimination indices enabled determination of the predictive value of socioeconomic factors over basic clinical variables in classifying frailty risk.

During follow-up, 399 patients (35%) developed frailty. Individual and neighborhood SES were significantly and independently associated with the risk of developing frailty. Low income patients had more than twice the risk of becoming frail compared with those with high income [odds ratio (OR), 2.29, 95% CI 1.41-3.73]; while being in the lower vs. upper neighborhood SES tertile was associated with a 60% increased odds (OR, 1.60, 95% CI 1.03-2.49). Inclusion of multilevel SES yielded substantial gains in c-statistic (0.70 to 0.76), net reclassification improvement (21.4%) and integrated discrimination improvement (6.4%) over basic clinical factors (all p<0.001), indicating increased predictive value and gains in sensitivity and specificity.

Individual and neighborhood socioeconomic factors influence the development of frailty post-MI, and contribute to risk discrimination in this population.