Variation and Disparities in Awareness of Myocardial Infarction Symptoms Among Adults in the United States

Key Points Question What are the prevalence and characteristics of adults in the United States who remain unaware of the symptoms of and the appropriate response to a myocardial infarction? Findings In this cross-sectional study of 25 271 US adults, 5.8% were not aware of any myocardial infarction symptoms, and 4.5% chose a different response than calling emergency medical services in response to these symptoms. These numbers were substantially higher in certain sociodemographic groups. Meaning Many individuals in the United States remain unaware of the symptoms of and appropriate response to a myocardial infarction.


Introduction
Although mortality rates among patients hospitalized for myocardial infarction (MI) have seen a decreasing trend, patients with MI continue to have a delayed presentation to the hospital, and a large number of them die before reaching the hospital. 1,2 A critical aspect of lowering mortality associated with MI is ensuring timely access to lifesaving emergency cardiac care, for which prompt recognition of symptoms of a myocardial infarction (MI) and appropriate rapid emergency response are crucial. 3 Previous studies from the United States have shown that, although awareness of MI symptoms has increased over the years, less than 50% of adults are aware of the 5 common symptoms (ie, chest pain or discomfort; shortness of breath; pain or discomfort in arms or shoulders; feeling weak, lightheaded, or faint; and jaw, neck, or back pain). [4][5][6][7][8] Although Healthy People 2020 set targets to improve awareness of these common symptoms, 9 there is little information on the prevalence and characteristics of individuals who are not aware of any symptoms. Additionally, previous studies on MI symptom awareness have focused on disparities across limited demographic subgroups (eg, age, sex, and race/ethnicity); however, the association of sociocultural factors (eg, education level, socioeconomic status [SES], insurance status, and immigration status) and the cumulative association of these potential risk factors with awareness remains largely unknown. 4,10 Given that previous community interventions to improve awareness of symptoms and emergency medical service (EMS) use in MI have largely been unsuccessful, [11][12][13][14] this information can help identify subgroups that are most in need of and may benefit from targeted public health awareness initiatives, which can subsequently reduce mortality and morbidity attributable to MI. Accordingly, we used nationally representative data to estimate awareness of MI symptoms among adults in the United States, characterizing sociodemographic groups, both individually and in combination, that were particularly at risk of not being aware of any symptoms.

Study Design and Population
We included 26 742 individuals aged 18 years and older, using data from the 2017 National Health Interview Survey (NHIS), which is an annual, cross-sectional, national, weighted survey that provides estimates on the noninstitutionalized US population using multistage sampling. 15 Additional details of the NHIS survey are provided in the eMethods in the Supplement. We excluded 1471 participants because of missing information on awareness of MI symptoms (eFigure 1 in the Supplement). This study was exempt from review by the Yale University institutional review board committee because NHIS data are publicly available and deidentified. The study was reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.

Awareness of MI Symptoms
Awareness was assessed by an individual's responses to the question, "Which of the following would you say are the symptoms that someone may be having a heart attack?": (1) chest pain or discomfort; (2) shortness of breath; (3) pain or discomfort in arms or shoulders; (4) feeling weak, lightheaded, We also assessed the awareness of the 3 most common symptoms (ie, chest pain or discomfort;

JAMA Network Open | Cardiology
shortness of breath; and pain or discomfort in arms or shoulders) separately.

Response to a Perceived MI
We assessed the prevalence of adults who were aware of the need to access immediate emergency care by calling EMS in response to a perceived MI by their response to the question, "What is best thing to do when someone is having a heart attack?" Responses included call 9-1-1 or another emergency number, advise them to drive to the hospital, advise them to call their physician, call spouse or family member, and other. We studied all responses individually, then dichotomized the responses to calling 9-1-1 or another emergency number vs all other options.

Independent Variables
Other variables included in this study were age (ie, 18-

Statistical Analysis
The NHIS uses complex sampling techniques to select the sample. After adjusting for nonresponse, age, sex, and race/ethnicity (based on the population estimates produced by the US Census Bureau), final person-level weights are created, which can then be used to provide national estimates. We described the survey-weighted proportions (with Rao-Scott χ 2 ) of awareness for each of the 5 symptoms individually, the distribution of overall awareness (from 0 to 5), and the awareness of the 3 most common symptoms across different sociodemographic characteristics. Next, we assessed the association of these characteristics with not being aware of any MI symptoms using unadjusted and adjusted survey-specific logistic regression and multinomial regression models. Logistic regression was used to evaluate dichotomous outcome variables (eg, being aware of none vs any MI symptoms), while multinomial regression was used to study categorical outcome variables (eg, being aware of 0 vs 1 vs 2 vs 3 vs 4 vs all 5 MI symptoms). Explanatory variables included age, sex, race/ ethnicity, immigration status, education level, SES, insurance status, and region. We also created a composite score using race/ethnicity (non-Hispanic white vs non-Hispanic black and Hispanic), immigration status (US-born vs non-US-born), education level (Նsome college vs Յhigh school), SES (high or middle income vs low or lowest income), and insurance status (insured vs uninsured) to study the cumulative association of these factors with awareness of MI symptoms. We also assessed the proportion of individuals who chose a different response than calling EMS as a reaction to a perceived MI, both overall and by awareness of MI symptoms. We identified individual characteristics associated with not calling EMS in response to a MI, using unadjusted and adjusted survey-specific logistic regression models.
We considered P < .05 statistically significant a priori for all analyses in our study, and all tests were 2-tailed. All analyses were performed using Stata version 13.0 (StataCorp) and accounted for the survey design of the NHIS, including sampling weights, to ensure that our results were nationally representative.

Population Characteristics
Our study population included 25 271 individuals corresponding to more than 233. 4

Sociodemographic Characteristics Associated With Lack of Awareness
Overall, several individual characteristics were associated with not being aware of any MI symptoms ( Figure 1). In an unadjusted model, we found that higher odds of not being aware of any symptoms were associated with black race (odds ratio [OR], 1.71; 95% CI, 1.30-2.24; P < .001) and Hispanic ethnicity (OR, 2.83; 95% CI, 2.28-3.50; P < .001) compared with non-Hispanic white race/ethnicity,

Cumulative Association of Sociodemographic Factors With Awareness
We evaluated 5 variables (ie, race/ethnicity, immigration status, education, income, and insurance status) associated with the greatest risk of not being aware of any MI symptoms and examined their combined association with awareness. Compared with the reference group with no high-risk characteristics (8793 white and US-born individuals who belonged to the middle-income or highincome subgroup, had insurance, and had a higher education level), those with 1, 2, 3, 4, and 5 highrisk characteristics had a stepwise decrease in awareness (Figure 2 Figure 2). Using logistic regression analysis, we found that, compared with the reference group, those with all 5 highrisk characteristics had more than 6-fold higher odds of not being aware of any symptoms (OR, 6.34; 95% CI, 3.92-10.26; P < .001) ( Table 2).    the symptoms, 55 (12.5%; 95% CI, 9.2%-16.8%) chose a different response than calling EMS compared with 155 (4.2%; 95% CI, 3.4%-5.1%) who belonged to the low-income or lowest-income subgroups and were aware of all 5 symptoms (P < .001) (Figure 3).

Discussion
In this nationally representative cross-sectional study, we found that nearly 6% of individuals, or an estimated 13.5 million adults nationally, were not aware of a single symptom of a MI and nearly 1 in 12 individuals, or an estimated 19.1 million adults nationally, did not consider chest pain or discomfort a MI symptom. These numbers were substantially higher for individuals who were non-Hispanic black or Hispanic, were not born in the United States, had lower education levels, were uninsured, and  States being aware of all 5 symptoms in 2014. 4 Our results not only showed a small increase in awareness of all 5 symptoms since 2014 but also suggest that, even today, millions of individuals in the United States remain unaware of the most critical symptoms of a MI (eg, chest pain) and, therefore, are at a high risk of adverse outcomes after an MI.
Second, to our knowledge, this study is the first to describe awareness rates across such diverse sociodemographic subgroups based on SES, insurance status, and immigration status. We found significant disparities across subgroups based on age, race/ethnicity, and education level, which were consistent with previous reports on awareness 4,10,16,18,19 and, additionally, identified non-US-born individuals, uninsured individuals, and individuals from the low-income and lowest-income subgroups as high-risk subgroups for not being aware of any symptoms.
Third, to our knowledge, this is the first report studying the awareness of MI symptoms among immigrants and describing the association of acculturation factors (eg, English proficiency and duration of US residence) with awareness. We found that nearly 1 in 8 (12%) of the estimated 5 million non-US-born individuals were not aware of any symptoms and that acculturation factors had a significant association with awareness among immigrants. Given the increasing number of individuals in the United States who were born in other countries and the low symptom awareness rates among these individuals, 20 public health professionals may need to tailor awareness campaigns according to these individuals' linguistic and cultural needs.
Fourth, to our knowledge, our study is the first to describe the cumulative association of the potential high-risk characteristics (ie, non-Hispanic black or Hispanic race/ethnicity, non-US-born, low income, uninsured, lower education level) with awareness. We reported a stepwise increase in the proportion of individuals who were not aware of any MI symptoms as the number of these highrisk characteristics increased. Among individuals with all 5 high-risk characteristics, nearly 1 in 5 individuals were not aware of any of the symptoms. As such, our findings underscore the importance of targeting public health initiatives toward these socioeconomically disadvantaged groups to improve awareness and subsequently reduce the mortality associated with MI.
Finally, our assessment of the use of EMS in response to a perceived MI suggests that, although the use of EMS has increased from that previously reported in the literature (91.8% in 2008 and 93.4% in 2014), 8 millions of individuals continued to choose a different response than immediately calling EMS. As expected, individuals who were unaware of the symptoms were also more likely to not call EMS; however, a significant number of adults with optimal symptom awareness also chose to not call EMS. Some possible explanations for this could be denial of symptoms, misattribution to symptoms to a noncardiac cause, perceived loss of control and ability to act, self-treatment strategies, fear or embarrassment of being wrong, and concerns about cost. 4,10,21-23 Given that early intervention in patients with MI is crucial to limit ischemic damage, prompt recognition of MI symptoms and rapid decision to seek care can reduce delays from symptom-onset to hospital presentation and improve survival. As such, it is critical to not only improve awareness of warning signs of a MI and the importance of early access to medical care but also to better understand and address the barriers that prevent individuals from accessing emergency medical care.

Limitations
This study has limitations. First, our assessment of awareness of MI symptoms was based on an arbitrary list, and while the most prevalent symptoms were listed, presentation of a MI may not be limited to these symptoms. Nevertheless, we showed that millions of individuals were unaware of even these most common symptoms of a MI. Second, not all MI symptoms included in this study should be weighted equally because some symptoms (eg, chest pain or discomfort) may be more easily identifiable than others. Therefore, although we provided the distribution of awareness of all MI symptoms and a composite score, we chose to focus our analyses on those who were not aware of any symptoms. Third, our assessment of MI symptom awareness was based on a set of closedended questions (ie, yes or no) that may bias responses, and offering of a set of symptoms could have led to an overestimation of the awareness rates. As such, the actual awareness rates may be even lower than those reported in our study. Fourth, although we studied and adjusted for the most important sociodemographic variables, MI awareness can inherently be driven by personal or familial exposure, which we were not able to assess because NHIS does not include this information. Fifth, because of the low sample size of Asian and other racial/ethnic groups, we could evaluate disparities only among the non-Hispanic white, non-Hispanic black, and Hispanic subgroups. Sixth, we could have overestimated the proportion of individuals choosing to call the EMS in response to a perceived MI because of a social desirability bias in responding; survey respondents may tend to answer questions in a manner that will be viewed favorably by the interviewer. Despite that, millions of individuals chose a different response than immediately calling EMS and could benefit from increasing awareness regarding the importance of early access to medical care.

Conclusions
Our study found that 53% of US adults in this study, representing 123.7 million adults in the United States, were aware of all 5 MI symptoms, and nearly 6% of individuals in our study, or an estimated 13.5 million adults nationally, were not aware of a single symptom of a MI. Additionally, significant sociodemographic disparities were seen in both the awareness of and appropriate response to MI symptoms. These findings highlight the need for targeted educational campaigns to not only improve awareness of MI symptoms but also emphasize the importance of early access to emergency medical care across all sociodemographic subgroups.