Racial Disparities in Patient Characteristics and Survival After Acute Myocardial Infarction

Abstract

Importance: Black patients experience worse outcomes than white patients following acute myocardial infarction (AMI).

Objective: To examine the degree to which nonrace characteristics explain observed survival differences between white patients and black patients following AMI.

Design, setting, and participants: This cohort study used the extensive socioeconomic and clinical characteristics from patients recovering from an AMI that were prospectively collected at 31 hospitals across the contiguous United States between 2003 and 2008 for the Prospective Registry Evaluating Myocardial Infarction: Events and Recovery registry and the Translational Research Investigating Underlying Disparities in Acute Myocardial Infarction Patients' Health Status registry. Survival was assessed using data from the National Death Index. Data were analyzed from December 2016 to July 2018.

Main outcomes and measures: Patient characteristics were categorized into 8 domains, and the degree to which each domain discriminated self-identified black patients from white patients was determined by calculating propensity scores associated with black race for each domain as well as cumulatively across all domains. The final propensity score was associated with 1- and 5-year mortality rates.

Results: Among 6402 patients (mean [SD] age, 60 [13] years; 2127 [33.2%] female; 1648 [25.7%] black individuals), the 5-year mortality rate following AMI was 28.9% (476 of 1648) for black patients and 18.0% (856 of 4754) for white patients (hazard ratio, 1.72; 95% CI, 1.54-1.92; P < .001). Most categories of patient characteristics differed substantially between black patients and white patients. The cumulative propensity score discriminated race, with a C statistic of 0.89, and the propensity scores were associated with 1- and 5-year mortality rates (hazard ratio for the 75th percentile of the propensity score vs 25th percentile, 1.72; 95% CI, 1.43-2.08; P < .001). Patients in the lowest propensity score quintile associated with being a black individual (regardless of whether they were of white or black race) had a 5-year mortality rate of 15.5%, while those in the highest quintile had a 5-year mortality rate of 31.0% (P < .001). After adjusting for the propensity associated with being a black patient, there was no significant mortality rate difference by race (adjusted hazard ratio, 1.09; 95% CI, 0.93-1.26; P = .37) and no statistical interaction between race and propensity score (P = .42).

Conclusions and relevance: Characteristics of black patients and white patients differed significantly at the time of admission for AMI. Those characteristics were associated with an approximately 3-fold difference in 5-year mortality rate following AMI and mediated most of the observed mortality rate difference between the races.

Figure 1.. Color-Gradient Density Plots Indicating the Propensity for Being a Black Individual Based on Each Individual Domain, Analyzed Separately for White Patients and for Black Patients

Color intensity reflects concentration of data; black lines indicate median propensity scores; and overlap of scores in a domain for white patients and black patients indicates that for that domain, the patients are more similar.

Figure 2.. Color-Gradient Density Plots Indicating the Propensity for Being a Black Individual Based on the Listed Domain and All Prior Domains (Each Step Added a Domain), Analyzed Separately for White Patients and Black Patients

Color intensity reflects concentration of data; black lines indicate median propensity scores; and overlap of scores for white patients and black patients indicates similarity of patients.

Figure 3.. Association Between the Propensity to Be a Black Individual and 1- and 5-Year Mortality Rates

P values for (race × propensity) interaction scores.