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.