Low Household Income Predicts Risk of Death During STEMI Hospitalization

ATLANTA, GA—Household income is a predictor of death during hospitalization for STEMI, with those in the lowest income bracket being most at risk, a new study shows. Compared with high-income patients, those with the lowest income were more often female, Black, Hispanic, and Native American.

Abdul Mannan Khan Minhas, MD (Hattiesburg Clinic Hospital Care Service, MS), the study’s lead author, told TCTMD that the data come as no surprise and add to increasing evidence of the connection between social determinants of health and cardiovascular disease outcomes. The influence of income across a spectrum of MI care has been shown in multiple prior studies; increases in heart failure readmissions have been linked to living in deprived neighborhoods; and implicit biases in the way that patients are treated based on race and socioeconomic status were shown to be strongly associated with differences in a number of CV-related hospital outcomes.

“One thing that we consistently see is that patients who are from poor socioeconomic backgrounds have the worst cardiovascular outcomes,” Minhas said. “These patients usually don't have insurance and so automatically they have less access to care.”

Minhas and colleagues’ analysis of hospital discharge data in the United States between 2016 and 2018 also showed that compared with the highest-income patients, those in the lowest-income group were about 2 years younger and had longer lengths of stay. They also were more likely to require mechanical ventilation, likely a marker of being sicker compared with patients in other income levels, Minhas noted.

However, their overall costs for care while hospitalized were lower than those of the highest-income patients ($26,503 vs $30,540; P < 0.001).

“One of the major driving factors of cost is length of stay, but in our patient population we found that the lowest-income residents had the [longest] length of stay and the cost was low,” he added. While procedures certainly drive cost, Minhas said there didn’t seem to be a huge difference between low-income patients and high-income patients in terms of the percentage who received PCI, although it was slightly more likely to be performed in the high-income group. He said further analysis might help tease out differences in types of procedures or other aspects of hospitalized care that the low-income patients don’t seem to be getting.

The study was released early ahead of its scheduled presentation at the Society for Cardiovascular Angiography and Interventions (SCAI) 2022 Scientific Sessions.

Implications for STEMI Care

Minhas and colleagues looked at discharge data from the National Inpatient Sample (NIS) on 639,300 weighted STEMI hospitalizations. Patients were divided into quartiles based on the median household income of the mailing zip code in which they lived. Weighted multivariable logistic regression models adjusted for patient-level and hospital-level characteristics were used to compare the outcomes among the four groups.

Nearly all comorbidities were higher in the lowest- versus highest-income group. Overall, in-hospital mortality was 11.8% in the low-income STEMI group and 10.4% in the high-income group (adjusted OR 1.22; 95% CI 1.14-1.30). The lowest-income patients had a rate of invasive mechanical ventilation of 15.9%, compared with 14.1% for those in the highest-income group (P = 0.001).

The study also supports growing evidence of the need to address gaps in STEMI systems of care for those living in rural or remote areas. While the highest-income patients were more likely to be hospitalized in urban settings, the lowest-income residents had more hospitalizations in rural hospitals or urban nonteaching sites.

“This does have a lot of implications for STEMI care and on general cardiovascular care,” Minhas said. “Socioeconomic status and where people live is right up there with [comorbidities] as something that affects the lowest-income patients and leads to worse outcomes.” He added that the study is more evidence of the need to focus on addressing these disparities through public health efforts and policies directed at minimizing differences in the clinical management of hospitalized STEMI patients.