Discussion
In the current study, we demonstrated that inpatient mortality post-LVAD implantation was lower in individuals with a lower income (50th percentile or below) when combining data from 2011 to 2017. Other salient findings of our analysis can be summarized as: i) the low-income group represented a younger population of individuals receiving LVADs despite increased rates of comorbidities, ii) the high-income group present at later stages of chronic diseases, iii) there is an increased cost of hospital admission among higher income individuals, and iv) the high-income group had higher rates of severe post-LVAD outcomes.
Previous published studies agreed with our results indicating that the primary population of LVAD recipients are middle-aged men of lower socioeconomic class (10). Our study further demonstrates that low-income recipients had a younger average age at 55 years. Increased burden of medical comorbidities in lower income communities has been long recognized and provides added risk factors for individuals to experience more severe illness at a young age (3, 11, 12). Several studies have shown that the higher prevalence of cardiovascular risk factors underlies the earlier age of heart failure onset in African Americans, who coincidentally also make up a larger population of the lower socioeconomic class (9, 13-15). It is estimated that African Americans are 30% more likely to die from heart disease and are significantly more prone to comorbidities including diabetes, hypertension, and obesity, among many others, which leads to the use of advanced therapies at an earlier age in this population (14-16). The REVIVAL Registry further delves into how socioeconomic factors impact patient preference for LVAD devices. Consistent with our study demonstrating higher LVAD use and acceptance among socioeconomically disadvantaged patients, the REVIVAL study has shown that there is a greater preference for LVAD devices among patients with high school education or less and those with an annual income less than $40,000 (9). The reasoning behind this decision making is complex and may reflect limited health literacy, lack of knowledge of alternative therapies, and ineligibility for heart transplantation (9, 17).
The National Survey of Families and Households, the Survey of Income and Program Participation, and the National Health Interview Survey represent the keystone of information necessary to study the link between income and health. Researchers have long noted a positive correlation between wealth and longevity, with higher income individuals having greater life expectancy compared to low-income counterparts (18). It has been previously shown that the incidence of obesity and smoking has declined as wealth increases in the general United States population, whereas those in the poorest wealth category have a 2.5- and 5-times higher incidence of obesity and tobacco smoking, respectively (19). However, it would be incorrect to say that higher wealth individuals do not experience health adversity as well. Diseases of affluence primarily reflect chronic non-communicable ailments including, but not limited to: cancer, degenerative autoimmune diseases, chronic lung diseases, type 2 diabetes mellitus, and hypertension (20). These comorbidities and their chronic progression are risk factors for cardiovascular disease, providing a rudimentary explanation for heart failure and the need for advanced cardiac intervention at a later point in the lives of wealthy individuals (3, 21).
When differentiating between patients eligible for transplantation versus alternative therapies, many patients with significant comorbidities are deemed ineligible for transplantation, leaving LVADs as one of the few advanced therapy options available (17). Previous studies indicate that individuals are more willing to receive an LVAD as the severity of their disease worsens and as their health-related quality of life diminishes. Furthermore, many wealthy individuals have at least one contraindication to heart transplantation often stemming from chronic diseases and ailments such as pulmonary hypertension and advanced age (22). Despite limited options, higher socioeconomic status patients are significantly more reluctant to undergo LVAD implantation as opposed to a heart transplant for a multitude of reasons (9). Potential reasons for this decision-making include perception of quality-of-life restrictions with the device, death as simply another alternative to refusing therapy rather than a definitive event, and lack of knowledge about both the LVAD device and associated procedure. Patients may instead elect to seek out other options and underestimate the severity of their illness (9). Delayed decision-making may lead to progression of disease, which might reduce LVAD utility (23).
For those who elect to undergo LVAD implantation, the mean cost for the procedure alone is $175,420 (24). Patients then remain in the hospital for at least two to three weeks as care is adjusted to meet individual patient needs with the median length of stay at 20 days (24, 25). Our study found a significantly longer hospital stay for both groups at 35 days and 37 days for low- and high-income groups, respectively. A number of pre- and peri-implant factors contribute to hospital length of stay. Increased age, as with the high-income population, is one of the largest risk factors for increased hospital length of stay (25). Prolonged admission time inevitably increases the all-encompassing cost of this procedure. Thus, longer hospital stays in the high-income population are also reflected in correlational higher hospital charge. Other factors that have been shown to increase length of hospital stay include prior cardiac procedures, such as coronary artery bypass and valve surgery, as well as significant comorbid factors that are taken into consideration when determining LVAD recipient eligibility (20).
In 2013, the Centers for Medicare and Medicaid Services published strict criteria for destination therapy LVAD eligibility. Several risk assessment tools have been developed to predict postoperative complications and mortality and to determine which patients are qualified to receive these therapeutic devices (15). Most studies have focused on patient populations of men >60 years with ischemic cardiomyopathy (22). The tremendous impact of patient selection on the outcomes of LVAD implantation has long been recognized. Patients are classified as “high risk” for this intervention if they have any form of liver or renal dysfunction, hematological and coagulation abnormalities, or lower serum albumin levels (22). As demonstrated in the aforementioned study, many of these high-risk patients crossover with those in the high-income group. Our study shows that compared with lower socioeconomic status individuals, high-income patients are more likely to experience ischemic strokes, acute kidney injury, bleeding abnormalities, and to undergo extracorporeal membrane oxygenation. We also found that higher-income patients have a higher post-LVAD all-cause inpatient mortality (unadjusted and adjusted for comorbidities). Prior studies show that important determinants of in-hospital mortality include poor nutrition, hematological abnormalities, markers of end-organ or right ventricular dysfunction, and lack of inotropic support (22). Although difficult to assess the primary cause of mortality in our study due to the nature of the NIS database, we did find a higher proportion of post-operative complications as detailed in Table 2. Taking into consideration all of the above-mentioned factors and in line with the REMATCH trial, there are significant benefits associated with the long-term use of LVAD devices for end-stage heart failure (26). As we continue to elucidate the benefits of these devices and incorporate them into routine practice, it is imperative to find the balance between survival benefit and risk of surgery when discussing the appropriate timing for LVAD implantation.